WELL MANAGEMENT SYSTEMS AND METHODS

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 63/633,021, filed on Apr. 11, 2024, which is hereby incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO APPENDIX

Not applicable.

BACKGROUND OF THE INVENTION

The present disclosure generally relates to systems and methods for use in a downhole artificial lift system of the type that may be used to remove hydrocarbons from the ground.

One challenge associated with conventional artificial lift systems is that they are often plagued by fluid pound or gas pound, a condition where a quickly moving pump traveling valve (TV) makes contact with fluid and/or gas within the pump subject to the system to damaging stresses. Such conventional systems often either operate at speeds that produce substantial fluid or gas pound (and thus stresses that can degrade the system) or—in an effort to avoid fluid pound—operate at such low operating speeds that the displacement (or pumping capacity) provided by the system is significantly reduced.

Another challenge with the traditional VSD pump fillage control is the number of parameters and frequent adjustments operators must maintain to accommodate wells conditions. In many conventional control systems, a large number of settings (including, as possible examples, Speed increase, Speed Decrease, and Stroke delay and/or pump fillage % setpoint) may be required to be modified by the user to dynamically control pump fillage.

Another challenge associated with conventional well controllers is the manner in which the downhole dynagraph card is typically displayed to users of the system. Specifically, in conventional controllers, the downhole card is typically displayed in such a manner that it depicts loads, such as significant negative load values in the downhole card and/or in the form of an adjusted downhole card, that do not reflect the actual pump loads. Such loads can include, for example, loads resulting from conditions in deviated wells have sections of the rod string laying on the tubing, and part of the rod weight rests on the tubing. Because the conventional (vertical) downhole card calculations do not consider deviation, they often simply subtract the dry rod weigh and, therefore, subtract more weight than needed. Additionally, because deviation surveys tend to distort the actual deviation in the well, even using a deviated downhole card calculation based on a deviation survey, still presents some challenges for the position of a calculated downhole card to mimic that of a measured downhole card Such representations often give rise to confusion and alarm by those attempting to evaluate the operation of the well system based. These negatives loads have been the result of, up until now, missing real time well parameters, which have posed significant challenges to obtaining such as real time tubing gradient, consistent dry rod weight data, and accurate measured buoyant rod weight at the polished rod. Despite attempts to address the issue, conventional approaches have been unsuccessful in their attempts to remove the buoyant rod weigh by removing dry rod weigh and by assuming or inferring a tubing gradient, resulting in excessive negative loads displayed in the calculated downhole dynagraph.

It is an object of the disclosure contained herein to overcome some or all of the limitations and issues described above with respect to conventional systems. It is a further object of the present disclosure to Automatic pump fillage adjustment will create a speed setpoint for each well condition and automatically adjust the speed for the next condition using two initial parameters, TV_Max and Max_Speed_at_Low_PF % Speed.

It is to be understood that the discussion above is provided for illustrative purposes only and is not intended to and does not limit the scope or subject matter of the appended or ultimately issued claims or those of any related patent application or patent. Thus, none of the appended claims, ultimately issued claims or claims of any related application or patent are to be limited by the above discussion or construed to address, include, or exclude each or any of the above-cited features or disadvantages merely because such were mentioned herein.

BRIEF SUMMARY OF THE INVENTION

A brief non-limiting summary of one of the many possible embodiments of the inventions disclosed herein is a method of controlling a sucker rod pumping system, the sucker rod pumping system including a sucker rod and a sucker rod pump, the sucker rod pump including a traveling valve that travels over a pump stroke in response to movement of the sucker rod, the traveling valve contacting fluid within the pump at a point in the pump stroke, the method comprising the steps of: operating the sucker rod pump over at least one pump stroke at a pump operating speed associated with a first pump operating speed setpoint; generating a downhole dynagraph card corresponding to the operation of the pump at the pump operating speed corresponding to the first pump operating speed setpoint; determining, for at least one sucker rod position, a traveling valve speed using the generated downhole dynagraph card; generating a second pump operating speed setpoint if the determined traveling valve speed is equal to or above a predetermined maximum traveling valve speed setpoint, wherein the second pump operating speed setpoint is less than the first pump operating speed setpoint; and operating the sucker rod pump at a pump operating speed associated with the second pump operating speed setpoint.

None of these brief summaries of the inventions is intended to limit or otherwise affect the scope of what has been disclosed and enabled or the appended claims, and nothing stated in this Brief Summary of the Invention is intended as a definition of a claim term or phrase or as a disavowal or disclaimer of claim scope.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The following figures form part of the disclosure of inventions and are included to demonstrate further certain aspects of the inventions. The inventions may be better understood by reference to one or more of these figures in combination with the detailed description of certain embodiments presented herein in which:

FIG. 1 illustrates one exemplary embodiment of an improved artificial lift system constructed in accordance with the teachings of the present disclosure.

FIG. 2A illustrates an exemplary HMI that may be presented by controller constructed in accordance with certain teachings of the present disclosure to a user.

FIG. 2B illustrates a Surface and Pump Card.

FIG. 2C illustrates a Pump Velocity versus Position graph

FIG. 2D illustrates a Pump Velocity versus Position graph

FIGS. 3A, and 3B-1 to 3B-2 illustrate aspects of processes by which a controller constructed in accordance with certain teachings of the present disclosure can determine the traveling speed of the traveling valve.

FIGS. 4A-1, 4A-2, and 4B illustrate an embodiment of a controller constructed in accordance with teachings of the present disclosure to automatically control the operating speed of TV throughout and within each stroke of the pump in such a manner that it tends to both: (a) ensure that the speed of the TV at the point of fluid or gas contact is below a preset maximum traveling speed (referred to herein as TV_Max) to provide uniform fluid pound or gas pound protection and (b) provide greater pump displacement (and thus greater pumping potential) that is available from conventional artificial lift control systems.

FIGS. 5A-5C illustrate an embodiment of a controller constructed in accordance with teachings of the present disclosure to control the pump 108 to operate in an efficient manner that tends to avoid unwanted stresses on the system but that will not result in significant intra-pump stroke speed change.

FIGS. 6A, 6B and 6C illustrate a still further alternate embodiment of a control system constructed in accordance with certain teachings of the present disclosure that may be used in situations where an operator wants to attempt to match the pump inflow to continuously match reservoir inflow.

FIGS. 7A-7D illustrate an embodiment constructed in accordance with certain teachings of the present disclosure in which the controller can display a downhole dynamometer card where the card is positioned to reflect the low fluid load line as the zero load of the system.

FIG. 8 illustrates an alternative exemplary artificial lift system that may be used to implement the various functionalities described in this disclosure.

FIG. 9 illustrates one exemplary process 904 that may be implemented by the controller for a speed adjustment limitation process.

FIG. 10 depicts an exemplary speed adjustment process that may be implemented by the controller.

FIG. 11 illustrates an exemplary process that may be implemented by the controller to develop speed ratios that may be used for control purposes.

FIG. 12 illustrates an exemplary process for determining TV speed.

FIG. 13 illustrates an exemplary process for capturing downstroke TV Profiles.

FIG. 14 illustrates various data items received or determined by an exemplary controller constructed in accordance with certain teachings of the present disclosure including: load v position data plot 1400 of data received by the controller; TV speed v position data plot 1402 determined by the controller; a slope of load data plot 1403 determined by the controller; an acceleration of the load data plot 1404 as determined by the controller; and an acceleration of the TV plot 1406 as determined by the controller.

FIG. 15 illustrates an enlarged version of the acceleration plot 1406 if FIG. 14 and highlights the region between points 1402-1 and 1402-2 (designated as 1502) and the region between points 1402-2 and 1406-2 (designated 1501).

FIG. 16 illustrates an exemplary HMI that may be provided by a controller constructed and configured in accordance with certain teachings of the present disclosure.

FIG. 17 depicts one exemplary manner in which a controller constructed in accordance with teachings of the present disclosure may make speed adjustments.

FIG. 18 illustrates one exemplary approach by which the controller can calculate such deacceleration.

While the inventions disclosed herein are susceptible to various modifications and alternative forms, only a few specific embodiments have been shown by way of example in the drawings and are described in more detail below. The figures and detailed descriptions of these embodiments are not intended to limit the breadth or scope of the inventive concepts or the appended claims in any manner. Rather, the figures and detailed written descriptions are provided to illustrate the inventive concepts to a person of ordinary skill in the art and to enable such person to make and use the inventive concepts illustrated and taught by the specific embodiments.

DETAILED DESCRIPTION

The Figures described above, and the written description of specific structures and functions below, are not presented to limit the scope of the inventions disclosed or the scope of the appended claims. Rather, the Figures and written description are provided to teach a person skilled in this art to make and use the inventions for which patent protection is sought.

A person of skill in this art having benefit of this disclosure will understand that the inventions are disclosed and taught herein by reference to specific embodiments, and that these specific embodiments are susceptible to numerous and various modifications and alternative forms without departing from the inventions we possess. For example, and not limitation, a person of skill in this art having benefit of this disclosure will understand that Figures and/or embodiments that use one or more common structures or elements, such as a structure or an element identified by a common reference number, are linked together for all purposes of supporting and enabling our inventions, and that such individual Figures or embodiments are not disparate disclosures. A person of skill in this art having benefit of this disclosure immediately will recognize and understand the various other embodiments of our inventions having one or more of the structures or elements illustrated and/or described in the various linked embodiments. In other words, not all possible embodiments of our inventions are described or illustrated in this application, and one or more of the claims to our inventions may not be directed to a specific, disclosed example. Nonetheless, a person of skill in this art having benefit of this disclosure will understand that the claims are fully supported by the entirety of this disclosure.

Persons skilled in this art will appreciate that not all features of a commercial embodiment of the inventions are described or shown for the sake of clarity and understanding. Persons of skill in this art will also appreciate that the development of an actual commercial embodiment incorporating aspects of the present inventions will require numerous implementation-specific decisions to achieve the developer's ultimate goal for the commercial embodiment. Such implementation-specific decisions may include, and likely are not limited to, compliance with system-related, business-related, government-related, and other constraints, which may vary by specific implementation, location and from time to time. While a developer's efforts might be complex and time-consuming in an absolute sense, such efforts would be, nevertheless, a routine undertaking for those of skill in this art having benefit of this disclosure.

Further, the use of a singular term, such as, but not limited to, “a,” is not intended as limiting of the number of items. Also, the use of relational terms, such as, but not limited to, “top,” “bottom,” “left,” “right,” “upper,” “lower,” “down,” “up,” “side,” and the like are used in the written description for clarity in specific reference to the Figures and are not intended to limit the scope of the invention or the scope of what is claimed.

Aspects of the inventions disclosed herein may be embodied as an apparatus, system, method, or computer program product. Accordingly, specific embodiments may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects, such as a “circuit,” “module” or “system.” Furthermore, embodiments of the present inventions may take the form of a computer program product embodied in one or more computer readable storage media having computer readable program code.

When implementing one or more of the inventions disclosed herein, any combination of one or more computer readable storage media may be used. A computer readable storage medium may be, for example, but not limitation, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific, but non-limiting, examples of the computer readable storage medium may include the following: a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a portable compact disc read-only memory (CD-ROM), a digital versatile disc (DVD), a Blu-ray disc, an optical storage device, a magnetic tape, a Bernoulli drive, a magnetic disk, a magnetic storage device, a punch card, integrated circuits, other digital processing apparatus memory devices, or any suitable combination of the foregoing, but would not include propagating signals. In the context of this disclosure, a computer readable storage medium may be any tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device.

Computer program code for carrying out operations of one or more of the present inventions may be written in any combination of one or more programming languages, including an object-oriented programming language such as Java, Python, C++ or the like and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. The remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an exterior computer for example, through the Internet using an Internet Service Provider.

Furthermore, the described features, structures, or characteristics of one embodiment may be combined in any suitable manner in one or more other embodiments. In the following description, numerous specific details are provided, such as examples of programming, software modules, user selections, network transactions, database queries, database structures, hardware modules, hardware circuits, hardware chips, etc., to provide a thorough understanding of embodiments of the disclosure. Those of skill in the art having the benefit of this disclosure will understand that the inventions may be practiced without one or more of the specific details, or with other methods, components, materials, and so forth. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the disclosure.

Aspects of the present disclosure are described below with reference to schematic flowchart diagrams and/or schematic block diagrams of methods, apparatuses, systems, and computer program products according to embodiments of the disclosure. It will be understood by those of skill in the art that each block of the schematic flowchart diagrams and/or schematic block diagrams, and combinations of blocks in the schematic flowchart diagrams and/or schematic block diagrams, may be implemented by computer program instructions. Such computer program instructions may be provided to a processor of a general-purpose computer, special purpose computer, or other programmable data processing apparatus to create a machine or device, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, structurally configured to implement the functions/acts specified in the schematic flowchart diagrams and/or schematic block diagrams block or blocks. These computer program instructions also may be stored in a computer readable storage medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable storage medium produce an article of manufacture including instructions which implement the function/act specified in the schematic flowchart diagrams and/or schematic block diagrams block or blocks. The computer program instructions also may be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions that execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

The schematic flowchart diagrams and/or schematic block diagrams in the Figures illustrate the architecture, functionality, and/or operation of possible apparatuses, systems, methods, and computer program products according to various embodiments of the present inventions. In this regard, each block in the schematic flowchart diagrams and/or schematic block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s).

It also should be noted that, in some possible embodiments, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more blocks, or portions thereof, of the illustrated figures.

Although various arrow types and line types may be employed in the flowchart and/or block diagrams, they do not limit the scope of the corresponding embodiments. Indeed, some arrows or other connectors may be used to indicate only the logical flow of the depicted embodiment. For example, but not limitation, an arrow may indicate a waiting or monitoring period of unspecified duration between enumerated steps of the depicted embodiment. It will also be noted that each block of the block diagrams and/or flowchart diagrams, and combinations of blocks in the block diagrams and/or flowchart diagrams, may be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

The description of elements in each Figure may refer to elements of proceeding Figures. Like numbers refer to like elements in all figures, including alternate embodiments of like elements. In some possible embodiments, the functions/actions/structures noted in the figures may occur out of the order noted in the block diagrams and/or operational illustrations. For example, two operations shown as occurring in succession, in fact, may be executed substantially concurrently or the operations may be executed in the reverse order, depending upon the functionality/acts/structure involved.

Reference throughout this disclosure to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one of the many possible embodiments of the present inventions. The terms “including,” “comprising,” “having,” and variations thereof mean “including but not limited to” unless expressly specified otherwise. An enumerated listing of items does not imply that any or all of the items are mutually exclusive and/or mutually inclusive, unless expressly specified otherwise. The terms “a,” “an,” and “the” also refer to “one or more” unless expressly specified otherwise.

The description of elements in each Figure may refer to elements of proceeding Figures. Like numbers refer to like elements in all figures, including alternate embodiments of like elements.

Turning now to several descriptions, with reference to Figures, of particular embodiments incorporating one or more aspects of the disclosed inventions, FIG. 1 illustrates one exemplary embodiment of an improved artificial lift system 100 constructed in accordance with the teachings of the present disclosure.

The illustrated system includes a sucker rod pump 102, that is connected to a sucker rod 104. The sucker rod 102 may be positioned within a tubing string (not illustrated) that is configured to be in fluid communication with a reservoir. The pump 102 and sucker rod 104 are positioned within a space that, in the illustrated example, is defined by the open are within a casing string 106 positioned within a subsurface wellbore.

In the illustrated example, pump 102 is positioned such that it may be stroked downwards and upwards within an annulus which, in the example of FIG. 1, corresponds to an interior space defined by the casing string. In the illustrated example, during such strokes, the pump 102 moves within a body of fluid having a fluid upper level 108. The fluid may take many forms and can be a fluid formed of a mixture of various hydrocarbons, water and/or any other fluid. The pump 102 may, during a single downwards and upwards stroke, be fully or partially located within the fluid during the entirety of the stroke.

In the illustrated example, as the pump 102 strokes downwards within the fluid, a cavity within the pump will be filled with fluid. As the pump 102 strokes upward fluid within the pump is released into cavity and pumped upward and out of the wellbore.

In one exemplary embodiment, the exemplary system 100 includes an electronic control system 110 that includes a variable speed drive system for driving a variable speed motor 112 driving the crank of a beam pumping assembly 114. In such an embodiment, the variable speed drive system within the control system 110 may be configured to excite the variable speed motor 112 in such a manner that the rotational speed of the motor 112, and thus, the pumping speed of the beam pumping assembly 114 is varied.

The electronic controller 110 may take the form of a programmable processer operating off of stored instructions which cause the processor to perform the steps, operations and functions described herein. The processor in controller may take the form of a microprocessor-based computer. The electronic controller 110 may include a Human Machine Interface (“HMI”) in the form of a local or remote screen using LCD or other technology to present the images and displays to a user, some of which are describe herein.

Alternate embodiments, however, are envisioned wherein the motor 112 and controller 110 are such that the motor does not operate over a range of continuously variable speeds, but rather operates at one of several fixed speed settings. Still alternate forms of motors (and suitably matched variable speed drives) are envisioned wherein the motor 112 takes the form of a standard induction motor, a squirrel cage induction motor, a permanent magnet motor, a permanent magnet DC motor, a switched reluctance motor, or any other suitable motor. Further various forms of variable speed drives can be used with the appropriate drive selected based on the motor to be used with the drive. The variable speed drive can, with respect to the rotating speed of the motor, be operated either as an open loop drive or a closed loop drive.

In several of the embodiments discussed below, the controller 110 will control the system based on downhole data associated with a downhole dynamometer card (sometimes referred to as a “downhole card” or “downhole pump card”). In such embodiments, the downhole data used to generate the downhole dynamometer card may obtained via calculations performed by the well controller 110 on rod load and position information provided by the surface sensors as well as other information provided to the controller such as information relating to physical characteristics of the pump, the rod, the pumping assembly, and other variables that could impact the operation of the pumping system. As those of ordinary skill in the rod pumping art will appreciate, a variety of approaches are known for converting surface pump card data to downhole pump card data and any suitable conversion methodology can be used to implement concepts of the present disclosure.

The variable speed motor 112 and the variable speed drive may take different forms. In one exemplary embodiment, the variable speed motor 112 is a variable speed induction motor and the variable speed drive 110 within the control system varies the frequency of the electrical signals applied to the motor 112 so as to vary the rotational speed of the motor 112, and thus the pumping rate of the pump 102.

As will be appreciated, given the relationship between the frequency of the electrical signals applied by the controller 110, typically referenced in terms of Hertz (Hz.) to the rotational speed of variable speed motor 112, typically referenced in terms of rotations per minute (RPMs), and the relationship between the rotational speed of the variable speed motor 112 and the pumping rate of the pump, typically referenced in terms of strokes per minute (SPM), the overall “speed” of the system can be referenced in either Hz., RPMs, or SPMs. It will be understood by those of skill in the applicable art that the selection of one or more of Hz., RPMs and/or SPM to define the operating rate of the system can be made based on preference and that the use of any of Hz., RPM, or SPM to define the operating rate of the system will be equivalent to the use of any of the other terms.

For purposes of the following discussion, the operating rate of the system will be referenced in terms of the output frequency of the controller 110 in Hz. It will be appreciated, however, that such reference could have alternatively been made in terms of RPM or SPMs.

As discussed above, under certain operating conditions including pump off and gas interference conditions, an artificial lift system can experience the undesirable phenomenon known as “fluid pound.” To avoid the extreme stresses that can result from fluid pound, the exemplary controller 110 implements an automatic pump fillage adjustment process that balances the desire to maintain a high and desired level of production for the controlled pump with the desire to avoid the damage that can be inflicted upon a pumping system as the result of pump off.

The present inventor has recognized that the level of undesired stresses on the system associated with fluid pound is correlated with the speed of the pump traveling valve at the time the traveling valve contacts the fluid or the gas inside the pump and that in rod pump system the travelling valve speed can be naturally low for some pump fillage %, offering opportunities to pump at full speed. Specifically, the present inventor has recognized that by controlling or limiting the speed at which the traveling valve contacts the fluid or gas inside the pump, one can control or limit the stresses imposed upon the system by such contact.

Additionally, the present inventor has recognized that pressurized gas inside the pump tends to soften the impact of the travelling valve with the fluid and has identified that an assessment of the deceleration experienced by the traveling valve within the pump can help make the distinction between gas pound and fluid pound to further control and mitigate the effects of fluid or gas pound.

In one exemplary embodiment, the controller of the present disclosure will control the speed of the traveling valve in the pump (the “TV”) such that the speed of the TV at the time of contact with the fluid or gas inside the pump is at or below a value in inches per second as preset by the system operator or to a desired pump fillage percentage (PF %). In such an exemplary embodiment, the controller can present the use of a system with a human machine interface (HMI) generally as shown in FIG. 2A.

Because the speed setpoint is reduced only as much as necessary to meet the travelling valve speed limit or TV_Max, using travelling valve speed to adjust the speed setpoint prevents the speed from completely dropping to minimum speed as soon as the PF % drops below the traditional PF % setpoint, relieving the operator from adjusting the pump fillage setpoint % as well conditions change. A common problem with traditional VSD control is that the speed drops to min as soon as gas drops the current PF % below PF Setpoint, and because gas can now enter the pump without significantly affecting pump displacement, the algorithm will equip operators with a tool to deal with gas Interface. As pump fillage drops significantly, specifically below the intersection of TV_Max near the bottom of the stroke, and because the amount of fluid displacement at the pump will be relatively low, an operator will be prompted to enter the maximum speed for that section, which is graphically represented in section 468 of FIG. 4A-2.

Because travelling speed patterns can intersect at different PF % near the bottom of the stroke, the operator has the option to set a Low Pump fillage % Setpoint to set the starting point for the traveling valve speed control to begin. If the Low Pump fillage % Setpoint is set to 25% then the algorithm will execute travelling valve speed control as soon as PF % surpasses 25%, providing a consistent PF % from which to start TV speed control.

Any sections with travelling valve below the TV_Max will make the algorithm adjust the speed setpoint to maximum working speed, which normally uses the full nominal frequency of the motor (60 Hz or 50 Hz).

FIG. 2A illustrates an exemplary HMI 20 that may be presented by controller 110 to a user. Such HMI may be presented on a screen physically coupled to the controller 110, a screen physically close to the controller 110 and in communication (wired, or wireless) with the controller, or a screen located remote form the controller 110 and communicating with the controller over a suitable communication link (e.g., the Internet or a cellular/radio communications link).

As shown in FIG. 2A, the illustrated HMI allows a user of the system to input three setpoints: a first set point 202 (referred to herein as TV_Max and referenced in Inches per second) corresponding to the maximum desired speed of the traveling valve (TV) at the time it contacts gas or fluid within the pump; and a second setpoint 204 (referred to herein as the Min PF %_Setpoint and referenced in terms of where TV speed control begins); and a third Max_Speed_at_Low_PF %, which defines the maximum speed in the section 468 of FIG. 4A2. While the example of FIG. 2A allows the system user to specify TV_Max, Low PF %_Setpoint, and Max_Speed_at_Low_PF %, it will be appreciated that one or these variables can be provided automatically by the controller, set as default values, and/or varied automatically by the controller 110, or by a supervisory control and data acquisition (SCADA) in response to an overriding control methodology.

Referring to FIGS. 2B and 2C, in one embodiment, an operator that wants to further increase displacement during gas interference can enter either a deadland (%) around the current pump fillage % or a specific deceleration value in inches/sec2 to temporality increase TV_Max during gas interference.

In certain embodiments, default parameters can be provided. One exemplary set of default parameters, including an approach for determining a default Min Working Speed, is provided below:

• • Default TV_Max: 40 inches/second.
  • Default Max_Speed_Low_PF % (SPM): (this parameter will be matched to Min. Working Speed)
  • Default Low PF %_Setpoint: 50%.
  • Default Min Working Speed: Calculated by setting Min Speed to 30 Hz, and the equivalent SPM is:

Min ⁢ Working ⁢ Speed = 30 ⁢ ( Hz ) * Synch ⁢ Speed Nominal ⁢ Speed ⁢ Motor ⁢ ( 60 ⁢ or ⁢ 50 ⁢ HZ ) * NREV

• • • (where NREV: Number of RPM pulses per crank rotation).
  • Default Synch Speed: 1200 RPM or 1800 RPM.

The above provided default parameters are exemplary only and other default parameters can be used. For example, in certain embodiments of the present disclosure, the default value of the Low PF %_Setpoint can be based on whether the pump location is above or below the well perforation. This is because it has been determined that, in wells where the pump is above the perforation, a Low PF %_Setpoint can increase overall in production by maintaining the back pressure as low as possible. Further, because embodiments of the present disclosure can produce automatic fillage adjustments that can potentially pump at full speed at low pump fillage, the Low PF % Setpoint can, in certain embodiments, be set to 0%, approximately 0% (e.g., 0%+/−7%) or as close to 0% as permitted by the operation of the system. Such a Low PF % Setpoint can be beneficial in wells where the pump is located at or below the perforation. In wells above the perforation, it can be beneficial to be set Low PF %_Setpoint as low as possible. In wells above the perforation, this parameter can be set relatively higher.

It will be appreciated that, in some embodiments, defining TV_Max will have substantially the same effect for control purposes as defining a PF % setpoint. In such an embodiment, each TV Max setting will generally correspond to a specific Percentage Fill Setpoint (PF % setpoint). For example, referring to the exemplary surface and downhole dynagraphs and corresponding pump velocity vs position graph reflected in FIG. 2B, a TV_Max setting of =50 inches/sec, would correspond to a PF % setpoint=80/100 or 80%. Note alternate embodiments are envisioned wherein the user would select a Percentage Fill setpoint (PF % Setpoint).

In the present example, the controller 110 will control the traveling speed of the traveling valve TV in the pump in real time by extracting the traveling speed of the TV using a real time downhole dynagraph card and traveling speed measurements obtained from previous downhole dynagraph cards.

In one embodiment, the controller will operate the system at Maximum speed (when possible) while keeping TV Speed below TV_Max and ensuring the system does not get surprised with drastic changes in PF % that lead to drastic changes in TV from one stroke to the next. Alternatively, or additionally, the controller could simply set the speed setpoint to maximum speed once it has a complete travelling speed pattern at full speed and TV below TV_Max in the section between TV-Max and the top of the stroke. In such embodiments, the controller can use previous TV measurements to estimate the optimum control speed, as in when the controller needs to transition from minimum pump strokes, which occurs at Min Working Speed, to TV Speed control, and measure the current TV speed to adjust and keep the TV speed within the target TV Max set by the operator. This process is further explained in FIG. 10 that depicts an exemplary speed adjustment process that may be implemented by the controller.

FIGS. 3A, 3B-1 and 3B-2 illustrate aspects of processes by which the controller 110 can determine the traveling speed of the traveling valve.

Turning first to FIG. 3A, a process 300 for assessing the traveling speed of the TV at various positions of the sucker rod 104 for a given operation speed of the system (in Hz) is shown. The exemplary process 300 is illustrated in the context of an artificial lift system that is to be initially operated in a startup mode and transition to a controlled operating mode.

Referring to FIG. 3A, upon start up, the controller will initially operate the system at a first “start-up” operating speed over a startup Step 302. The Start Up speed may be a pre-set speed used only during the initial use of system starting up from a condition where it is not in use. Such Start up speed may be selected to be a very slow speed (e.g., the default=20 Hz. or 1 SPM) such that no significant stresses are imposed upon the system during start up. The duration of the startup step can vary, but embodiments are envisioned wherein the startup step 300 lasts for one full stroke or the rod pump or for a specified period of time (e.g., 60 seconds).

In the example of FIG. 3A, during the Start Up period within Step 302, the controller 110 can determine, using a real time downhole dynagraph card, the traveling speed of the traveling valve at various positions of the sucker rod 104. In the illustrated example, the controller can do this on a second-by-second basis using EQUATION 1 below, where the traveling speed is determined, by subtracting the position of the TV (in inches) at a first time (in seconds) of the calculation from the position of the TV at a prior time (also measured in seconds).

TV_Speed = ( TV ⁢ Position ⁢ at ⁢ Time ⁢ T X - TV ⁢ Position ⁢ at ⁢ Time ⁢ T X - 1 ) ⁠ / ( Time ⁢ T X ⁢ _ - Time ⁢ T X - 1 )

Alternatively, the TV speed can be determined using the position of the valve divided by the delta in milliseconds between position points from the real time Downhole Dynagraph and averaging the up to three pairs of position and time data before the traveling valve contacts the fluid or gas.

TV ⁢ Speed ⁢ 1 = Pos ⁢ 2 - Pos ⁢ 1 Delta ⁢ ( ms ) Median = Pos ⁢ 2 - Pos ⁢ 1 Delta ⁢ ( ms ) , Pos ⁢ 2 - Pos ⁢ 3 Delta ⁢ ( ms ) , Pos ⁢ 3 - Pos ⁢ 4 Delta ⁢ ( ms )

Such Equation will provide an indication, for each position, of the TV speed of the TV in Inches/second during periods where the system is operating at the start up speed.

In the example of FIG. 3A, after the controller 110 operates the system in the Start Up Step 302, it will transition to operate the system at its minimum operating speed during a Minimum Operating Speed Step 304. Such minimum operating speed will typically be higher than the start up speed and could, for example, be a speed corresponding to a controller frequency output of 30 Hz. In the present example, the controller 110 will determine the TV speed over a full pump stroke for each position of the sucker rod 104 in the manner described above with respect to Step 304. In this example, the TV speed profile determined in Step 304 will correspond to a system operating speed of 30 Hz.

As with the Start Up Step 302, the Minimum Operating Speed Step 304 can extend over a duration associated with a time period or a given number of pump strokes (e.g., a Minimum of 3 pump strokes).

Referring back to FIG. 3A, in the illustrated example, after operating the system in the Minimum Operating Speed Step 304, the controller 110 will begin operating the system in a controlled manner during the Active Control Step 306. In the exemplary embodiment, during the Active Control Step 306, the controller will actively control the system in accordance with one or more control goals. For example, in one embodiment, the controller 110 can control the system such that it both maximizes the overall pump displacement (typically by running the system at maximum safe operating speed) while also controlling the speed during portions of the pump cycle (as necessary) to ensure that the speed of the TV at the point it contacts the fluid or gas within the pump is below a specified maximum value. An alternative embodiments, the controller may, during the Active control Step, maintain the operating speed of the system to attempt to place the system into an operating condition where the pump fillage percentage during each pump stroke equals, or is within a defined deadband, the pump fillage percentage setpoint, or PF %_Setpoint, and at the same time maximize the displacement of the pump as PF % drops the pump fillage setpoint while limiting the overall speed of the system to ensure that the speed of the TV at the point it contacts the fluid or gas within the pump is below a specified maximum value. Still further, mixed or hybrid control strategies can be implemented.

Using the process described above in connection with Step 302, the controller 110 may, for each operating speed implemented in the Active Control Step 306, determine the speed of the TV at various positions of the sucker rod 104. In this manner, the controller 110 may develop TV speed profiles for one or more operating speeds of the system where each TV speed profile corresponds to the traveling speed of the TV at multiple positions of the sucker rod 104 for a given operating speed. FIG. 11 illustrates an exemplary process that may be implemented by the controller to develop such speed profiles.

By implementing the process described above, the controller 110 may, over time, develop a number of different TV speed profiles for different operating speeds of the system (e.g., 20 Hz, 30 Hz., 40 Hz., 50 Hz. 60 Hz.). In one embodiment, the controller can improve the accuracy of each such speed profile by regularly calculating the TV speed for various sucker rod 104 positions and then averaging the calculated values for a given position, at a given operating speed, such that the TV Speed Profile provides the average calculated TV Speed for a given rod position.

In certain exemplary embodiments the controller will maintain two records: Speed Ratios and the Downstroke sections of the TV Speed profiles. Aspects of such embodiments are reflected in FIG. 11 and FIG. 13, with FIG. 13 illustrating an exemplary process for capturing downstroke TV Profiles.

The processes described in connection with FIG. 3A may result in the operation of the system at an operating speed that is not identically associated with a previously developed TV Speed Profile. For example, a condition could arise where the controller is operating the system at a new speed corresponding to 35 Hz. while the system had previously developed TV Speed Profiles only for 30 Hz. and 40 Hz. In such situations, the controller 110 could be configured to either select one of the previously developed TV Speed Profiles for use for control purposes (until a TV Speed Profile for the new speed is created), e.g., the closest higher speed, or implement an interpolation algorithm to estimate the TV speeds for the new frequency. In a similar manner, the controller 110 may need to determine the TV Speed at a given sucker rod 104 position, but not have a TV Speed Profile point exactly corresponding to that position. In such situations, the controller could estimate the TV Speed for the given position by selecting the speed at the closest position for which a TV Speed Profile exists, or by implementing an interpolation or calculative approach.

While the process described above may be adequate for determining the TV Speed at differing sucker rod positions for a given system operating speed, the present inventor has discovered that the TV Speed for a given system can for a given operating speed and given sucker rod position, vary depending on the operating condition of the pump. In particular, the present inventor has discovered that the speed of the TV for a given rod position and a given system operating speed will vary in response to the fillage percentage of the pump and that the speed of the TV valve without the fluid load in a full pump will differ from the speed of the TV with the fluid load in an incompletely filled pump, with the TV speed during periods of incomplete pump fillage being slightly greater than the TV speed during periods of complete pump fillage. For this reason, TV Speed data calculated for a given position where there is incomplete pump fillage may be preferred over TV Speed data for the same position calculated during a period of complete pump fillage because the TV Speed data determined for the incomplete fillage condition will more accurately reflect the maximum speed of the TV at that position at-the time contact with the fluid. Thus, in one embodiment, data used to generate the TV Speed profiles over portions of the pump cycle during a condition of complete fillage will be replaced with data over such portions corresponding to data generated during conditions of incomplete pump fillage, which data associated with incomplete fillage is available. A further issue associated with determining the TV Speed based on downhole card data is that, under situations of incomplete pump fillage, the determined speed of the TV valve at the point at which it contacts the fluid or gas within the pump may occur at an inflection point on the TV Speed profile in a section that precedes the current pump fillage %. Such a situation is generally illustrated in FIG. 3B-1, which reflects an exemplary case where the anticipated contact between the TV and the fluid or gas within the valve is anticipated to happen at the point 312 right before the fluid load is transferred at a point after 310 (which is an inflection point in the speed of the TV valve). In example of FIG. 3B-1, point 310 is the speed at with the travelling valve decelerates to, and 312 is the point at where the travelling valve begins to decelerate. In the example, at 310 the slope of TV transitions from negative to positive and, at 312, there is an inflection in the slope of TV, causing the slope to increase as it approaches PF %. Further details of exemplary embodiments of this example are discussed below in connection with FIGS. 19, 20 and 21. To more accurately assess the speed of the TV at the time of contact in situations like that illustrated in FIG. 3B-1, embodiments of the preset disclosure are envisioned in which the speed at the point of contact is set by the controller as the TV speed at a position point 5% of Gross Stroke from the PF % (or some other selected percentage, e.g., 10% Gross Stroke) before the anticipated point of contact. The determination of the speed at a position that is within a percentage of the Gross Stroke from the PF % is because it has been determined that, in some embodiments, it is preferred to control the system based on the travelling valve speed at the time of contact with the fluid (as opposed to the final speed at which the travelling valve decelerates to once in contact with the fluid). As will be appreciated, as the TV valve moves towards contact with the fluid in the pump, the travelling valve speed decreases progressively because of gas compression or the impact with the fluid, so the final or Minimum traveling speed once the fluid load transfer occur does not reflect the speed at the initial contact. This is because there is an initial impact on the travelling valve under such conditions, then the travelling valve will decelerate to a final point, in which the fluid load is transferred from the travelling valve to the standing valve. In the unlikely event that neither the inflection point on the slope curve nor the intersection of patterns can successfully detect the point of contact, some embodiments will estimate that the travelling valve contacts the fluid or gas at 5-7% of gross stroke from pump fillage %. Such an event could be possible in highly deviated wells, in which high friction can potentially prevent the mathematical models explained in the next sections from capturing these inflection points.

This manner of determining the TV speed at the time of contact is generally reflected in FIG. 2C. In the case shown in FIG. 2C, we see that the TV speed close to the point of pump fillage was approximately 40 inches/second before deaccelerating to 10 inches/second at pump fillage. So, using the process described above, the controller would set TV Speed at the time of contact at 40 inches/second, or approximately 40 inches/second (e.g., 40+/−5%).

Alternative embodiments are envisioned wherein the controller will estimate the TV speed at by mathematically predicting what the TV Speed would be over the range of interest under an incomplete pump fillage condition (as reflected by the dashed line 314 in FIG. 3B-2) and determining what the TV Speed would be based on that projection (e.g., the TV Speed corresponding to point 316 in FIG. 3B-2). As reflected in FIG. 3B-2, the speed at point 310 would correspond to the speed once the TV has deaccelerated (after contacting the fluid) and the speed at point 316 would be the estimated speed used by the controller as the speed immediately preceding contact between the TV and the fluid. Further alternative approaches for determining TV speed are depicted in FIG. 12 and FIG. 19.

In one exemplary embodiment of the present disclosure, the controller 110 automatically control the operating speed of TV throughout and within each stroke of the pump in such a manner that it tends to both: (a) ensure that the speed of the TV at the point of fluid or gas contact is below a preset maximum traveling speed (referred to herein as TV_Max) to provide uniform fluid pound or gas pound protection; (b) provide greater pump displacement (and thus greater pumping potential) that is available from conventional artificial lift control systems; and (c) take advantage of naturally occurring low travelling speed to pump at full speed (such as the Max Working Speed. One such system is illustrated in FIGS. 4A-1, 4A-2 and 4B.

FIG. 4A-1 is intended to reflect the TV Speed Profile, calculated by the controller 110 using the downhole dynagraph card for the TV during conditions where the controller 110 is operating the system at a given operating speed. For example, FIG. 4A-1 could correspond to the TV Speed Profile of the system when operating at its maximum operating speed (e.g., 60 Hz. excitation signals to the motor).

As reflected in FIG. 4A-1, during a complete stroke of the system the speed of the TV (beginning at the leftmost zero crossing in FIG. 4A-1) will increase in the positive direction (corresponding to upward movement of the TV), drop then rise and drop again as it reaches the point where TV will begin to move downward towards the fluid/gas within the pump (at the rightmost zero crossing). As shown in the portion of FIG. 4A-1 below the zero horizontal axis, as the TV moves towards and into the fluid/gas within the pump, the speed of the TV will vary significantly during its travel. For example, moving from right to left in FIG. 4A-1 the TV Speed will alternately increase and decrease across a first region of travel (unlabeled), reach a first peak negative value at point 452, increase in speed to an intermediate negative value at point 452, and speed up again (in the negative direction) to a second negative speed peak at point 454.

As noted above, in the control embodiment under discussion, the controller 110 will operate the system such that the speed of the TV Valve is maintained below a maximum speed at the time of contact with the fluid or gas within the pump TV_Max. For purposes of discussion, it is presumed that the TV_Max setting was made at 35 Inches/Sec, although it will be understood that this is a representative example setting and that other settings can be used.

FIG. 4A-2 represents the TV Speed profile of FIG. 4A-1 with some added designations. For reference, the zero (0) TV Speed is reflected by the upper dash line and the TV_Max designation of −35 Inches/Second is reflected by the lower dash line. As reflected in the figure, the TV_Max designation interests the determined TV Speed Profile in four locations, corresponding to Points A, B. C and D. The regions between these points are reflected by vertical solid lines in FIG. 4A-2 to define five exemplary operating regions 460, 462, 464, 466, 468.

Referring first to exemplary regions 460, 464, and 468. In these regions it will be seen that the operation of the system at the set operating speed (in this example the maximum operating speed) will result in the speed of the TV over such regions being above (i.e., less negative) the TV_Max valve such that the measured speed will be below the absolute value of the TV_Max setting. Thus, over these regions there is no concern that the absolute speed of the TV will exceed the TV_Max setting and there is no need for the controller 110 to reduce the operation speed over those regions of operations. For regions 462 and 466, however, it will be seen that if the system is run at the current speed setting (which in the example is the maximum operating speed setting) the absolute speed of the TV would exceed the TV_Max setting. Thus, in the present example, over these regions, the controller 110 will reduce the speed of the system for that portion of the pump stroke to tend to drive the TV speed to or have an absolute value below the TV_Max value. In this manner, the “excess speed” regions (reflected in the solid black regions of FIG. 4A-2) will be trimmed. Note that in this example, in Step 464, the controller will increase the speed as long as the Measured_TV_Speed remains below TV_Max. and Maximum Working Speed, and in Section 468, the algorithm will clamp the speed at Max_Speed_Below_PF %_Setpoint or Max_Speed_at_Low_PF %.

Thus, using the control approach reflected in FIGS. 4A-1 and 4A-2, the controller 110 can operate the system at a preset operating speed (which may be the maximum operating speed) over regions where such operations will result in the absolute speed of the TV being below the TV_Max setting and reduce the speed of the system only over those portions of the pump stroke where the lack of a speed adjustment would result in the absolute TV Speed exceeding the TV_Max value. Thus, under this control approach, the system will operate as fast as possible when it is safe to do so (thus tending to maximize pump displacement) while protecting the system from excess stresses during those portions of the pump stroke where it is appropriate to do so. Because this control approach is based on the determined TV Speed, operator intervention is minimized as the pump fillage adjustment is automated.

FIG. 4B illustrates a process that may be practiced by the controller 110 to implement the control process described above.

For purposes of FIG. 4B, it is presumed that the initial Speed_Setpoint is the maximum designated operating speed of the system. This presumption is made because, in many instances, an operator will want to run the pumping system as fast as safely possible to get the maximum pump displacement. However, alternate embodiments are envisioned wherein the speed setpoint used in the process is set by an outer control loop (not illustrated) in which the Speed_Setpoint is determined based on a target PF % or some other control variable. In such embodiments, the controller will increase the speed Setpoint if Measured TV Speed<TV_Max and the system has not reached Max_Working_Speed.

In some embodiments of the present disclosure, the controller can be configured such that the system operates in a hybrid mode were the speed does not change inside the deadband, and the controller controls the TV Control Speed between either Low PF % Setpoint or the leftmost intersection of the TV pattern and the deadband. In such embodiments, above the deadband, 110 the controller controls the system at Max working speed.

Of note, in the example of FIG. 4B, the controller 110 will initially operate the system at a given speed corresponding to the then existing Speed_Setpoint during a first step, Step 402 which may, at an initial or at some given time, corresponds to a maximum operation speed of the system, e.g., 60 Hz.

The controller 110 will then calculate the downhole dynagraph at Step 404 for the system and, using one or more of the processes described herein, measure and predict the speed of the TV (Measured_TV_Speed). This step may be on a periodic time basis, such as every second, every 0.5 second, or some other period. In certain embodiments, stroke TV will be measured at the current PF %. In such embodiments, the controller can then assess or predict how fast it can set Speed setpoint using the profiles and the current state of TV measured vs Limit TV.

Once the controller 110 has Measured the TV_Speed it can then assess, in Step 406, whether the Measured_TV_Speed is within a deadband range (e.g., +/−5%) of the TV_Max setpoint. If the Measured_TV_Speed is within this deadband, the controller can then return to Step 402 and continue to operate the system at the current Speed_Setpoint. If the difference between the Measured_TV_Speed and the TV_Max value is outside the specified deadband, the controller can then adjust the Speed_Setpoint in Step 408 to either increase the operating speed setpoint for the system (if the absolute value Measured_TV_Speed is less than TV_Max and if the system was not otherwise operating at the maximum possible operating speed) or decrease the operating speed setpoint for the system (if the absolute value of the Measured_TV_Speed is greater than TV_Max). By making such adjustments, the system controller 110 will tend to operate the pump 108 to provide the greatest overall pump displacement that avoids exceeding the TV_Max value by more than a deadband (and thus avoid undue stresses on the system).

In some embodiments, the controller can use the predicted TV speed to estimate the next control speed for a given pump fillage, when the controller transitions from minimum pump strokes to TV speed control for example, and use measured speed to assess whether the TV is within the +/−5% target.

In one exemplary embodiment the adjustment of the Speed_Setpoint in Step 408 may implemented by the controller in accordance with EQUATION 2, below:

Speed_Setpoint_Adjustment=(TV_Max-Measured_TV_Speed)/(TV Speed/Hz. Ratio). In addition to the equation set forth above, in some embodiments the controller 110 may initially set a small increment in the desired of the desired action in the event the speed ratio is not available.

Alternatively, the controller can determine the speed adjustment using the following Equation: Speed Adjustment (Hz)=C*(TV_Max-TV measured)/TV_Max (where C is a constant).

FIG. 17 depicts the manner in which such an adjustment may be made. Referring to FIG. 17 TV Speeds for a unit running at 1.3 SPM (in blue), 2.3 SPM (in purple), and 2.8 SPM (in green), are depicted, which represent in hertz 25.3 Hz, 44.5 Hz and 54.18 Hz respectively. Assuming one wants to calculate the Speed Setpoint adjustment at the arrow in the blue graph and to increase the speed to 54.18 Hz, we obtain=

Speed ⁢ adjustment = 23.31 - 18.24 5 ⁢ 8 . 1 ⁢ 8 - 44.5 Hz = 0.35 inches / sec Hz

Assuming one wants to increase the speed to 20 inches/second from 18.57 inches/sec, the adjustment in hertz would be:

= 2 ⁢ 0 - 1 ⁢ 8 . 5 ⁢ 7 0 . 3 ⁢ 5 = 4.02 Hz

In accordance with EQUATION 2, the Speed_Setpoint_Adjustment is determined by subtracting the Measured_TV_Speed from the TV_Max setpoint and dividing that difference by a TV_Speed/Hz Ratio. In Step 408, the controller 110 can then set a new Speed_Setpoint by adding the Speed_Setpoint_Adjustment to the Speed_Setpoint. As will be appreciated, using EQUATION2, the Speed_Setpoint_Adjustment will be negative (thus resulting in decrease in the Speed_Setpoint) when the Measured_TV_Speed is greater than the TV_Max Setpoint and positive (thus resulting in increase in the Speed_Setpoint) when the Measured_TV_Speed is less than the TV_Max Setpoint.

In some embodiments a limit can be placed on the magnitude of any step adjustment such that there is maximum permitted step adjustment defined wither in terms of a maximum Hz. change (e.g., a 15 Hz. speed change) or a maximum percentage speed change (e.g., 15%).

The TV_Speed/Hz Ratio may be value provided to the controller 110 or may be one that is determined by the controller 110 during operation of the pumping system. In embodiments wherein the controller determines the TV_Speed/Hz Ratio it may do so by considering the TV_Speed at different operating speeds and different operating positions and determining for each change in operating speed in terms of Hz., the average change in TV_Speed (or the change in speed for a given sucker rod position) in terms of Inches or PF %. The controller 110 can determine TV_Speed/Hz Ratio at discrete times during the operation of the system (e.g., when the system transitions from the Startup Speed to the Minimum Operating Speed) or can determine and update the TV_Speed/Hz Ratio each time the operation speed of the system is changed.

In certain examples, the controller can capture the required speed ratios during the transition from Start up to Minimum pump strokes and then enter into a TV speed control mode and keep updating and storing the necessary speed ratios. In such embodiments, if any speed ratio is needed, the controller can execute the routines depicted in FIG. 10 and FIG. 11.

Alternate embodiments are envisioned wherein an approach other than one associated with EQUATION 2 is used to adjust the operating speed of the system. For example, in some embodiments, the operating speed could be increased or decreased (when such an adjustment is warranted) by a fixed value (e.g., 3 Hz. or 5 Hz.) or the use of predictive software such as SROD. Alternatively, or additionally, such predictive software (e.g., SROD) can be used to estimate speed profiles (including TV Speed profiles).

In some exemplary embodiments, the process of FIG. 4B will be periodically performed on a regular time basis, such as once every 0.5 Sec, 1.0 Sec, 1.5 Sec. or other period. In such embodiments the time period for the pump to complete a single pumping stroke will exceed the period over which the control process of FIG. 4B is run (typically by multiples of time) such that the operating speed of the pump can be varied intra-pump stroke (i.e., within a single stroke or as an inner stroke adjustment) to tend to always run the system at the maximum operating speed when safe to do so and reduce the operating speed only over regions of the pump operating stroke when operation of the system at the maximum speed would introduce undesired stresses on the system.

In other embodiments, speed adjustments can be made at the end of a stroke, so the VSD can execute the speed adjustment during the upstroke and keep the TV speed within target during the downstroke. In such embodiments, because the profiling and logging to obtain the speed ratios, the controller can aim to get the speed within target in a limited number of cycles (e.g., two cycles at the most). Such embodiments can provide an ability to provide higher pump displacement without inner stroke speed changes.

In addition to the operating process reflected in FIG. 4B, alternative processes can be implemented by controller 110 to control the pump 108 to operate in an efficient manner that tends to avoid unwanted stresses on the system but that will not result in significant intra-pump store speed change. Once such alternative process is reflected in FIGS. 5A, 5B, and 5C.

Referring first to FIG. 5A, an exemplary HMI is illustrated reflecting parameters that may be set by the user. In the illustrated example, the user (or alternatively the controller 110 or a supervisory SCADA system) can set the following operating parameter: TV_Max 550, PF %_Setpoint 552, a Startup_Speed parameter 554 (discussed below) and system Speed_Max 556 and Speed_Min parameters 556, 558 (also discussed below).

Referring next to FIG. 5B, in the exemplary embodiment the system may start in a Step 502 where the system can be provided with a TV_Max value and a Low PF %_Setpoint. These values can be provided in the manner described above with respect to FIG. 2A.

The controller can then operate the system at a predicted speed, based on pump fillage from previous stroke and expected TV Speed at contact, initial or existing Speed_Setpoint at Step 504 and, in Step 506, calculate the downhole dynagraph, determine the present PF % and the Measured_TV_Contact_Speed at step 506, where the Measured_TV_Contact_Speed is the measured value of the TV at the time the TV makes contact with the fluid or gas within the pump.

Once determining the Measured_TV_Contact_Speed in Step 506, the controller 110 can then determine, in Step 508, whether the operating PF % of the system is above the first or rightmost intersection, or its equivalent PF % Setpoint, of TV_Max with the travelling valve speed pattern (Section 460 of FIG. 4A-2).

If the controller 110 determines that the present pump fill percentage is above the rightmost intersection of TV_Max with the travelling valve speed pattern, then the controller either continue setting the Speed_Setpoint to a Speed_Max value corresponding to the maximum operating speed of the system or proceed to 520 to adjust the Speed_Setpoint until is equal to Speed_Max, in both cases controller return to operation at Step 504.

If controller determines in Step 508 that the PF % is NOT above the rightmost intersection of TV_Max, then the controller verifies that current PF % is above Low PF % Setpoint and proceed to Step 520 in FIG. 5C. If current PF % is below Low PF % Setpoint, then the Speed_Setpoint is set to Max_Speed_at_Low_PF %, and the controller proceeds back to step 504.

Referring to FIG. 5C. at Step 520, the controller 110 will determine whether the Measured_TV_Contact_Speed is within a set deadband of the TV_Max. If so, setting aside optional Step 521 for the moment, the controller 110 may then make no change to the Speed_Setting and return to Step 504 in FIG. 5B.

If the controller determines that the Measured_TV_Contact_Speed is not within a set deadband of the TV_Max, setting aside optional Step 523 for the moment, the controller 110 can proceed to Step 522 where it can calculate a Speed Adjustment using EQUATION 2 in the manner described above in connection with Step 408 and determine a Potential_Speed_Setpoint by adding the Speed Adjustment to the existing Speed_Setpoint.

In embodiments where the system has a minimum and a maximum speed setting, the controller can then proceed to Step 524 where it will set a new Speed_Setpoint to either the Potential_Speed_Setpoint (if the Potential_Speed_Setpoint was equal to one of, or in between, the minimum and the maximum speed settings) or clamp the Speed_Setpoint to the minimum speed setting (if the Potential_Speed_Setpoint was below the minimum speed setting) or to the maximum speed setting (if the Potential_Speed_Setpoint was above the maximum speed setting). The controller can then return to Step 504 where it can operate the system at the new Speed_Setpoint.

It should be noted that, in most embodiments, settings for Min. Working Seed and Max Working speed limits will always present with the Max Working speed limit being set by predicting programs such as SROD to prevent overload on rods, gearbox etc.

In addition to reflecting the steps described above, FIG. 5C illustrates optional Steps 521, 523 and 525 that may be implemented in certain embodiments. Steps 521, 523 and 525 illustrate steps associated with a Stroke Delay functionality which may be implemented to adjust the manner in which speed changes are made to the system in response to the variability of the system in terms its pump fillage percentage and/or its TV speed. In systems where the pump fillage percentage (PF %) and/or TV speed are not highly variably, the controller 110 may delay the implementation of a speed change until the conditions warranting a speed change are detected to occur within multiple strokes of the pump. This optional functionality is reflected in FIG. 5C.

The Stroke Delay value can be set by a user of the system 100, by a supervisor SCADA system, or can, in some embodiments, be determined by the controller 110 based on analysis of the variability of the TV speed (and/or in other embodiments the PF %) over the operation of the pump. In systems where the variability is high, i.e., where the standard deviation of the variable at issue is above a certain number, the Stroke Delay can be set to zero or a low a specific stroke number to implanting a speed change in response to a single detected speed intended. For example, in one exemplary embodiment, the variability of the parameter to be controlled (e.g., the TV Speed can be determined by the controller over a given time period (e.g., three minutes). The Stroke Delay parameter can then be proportionally adjusted based on the standard deviation of the parameter at issue. For example, in one exemplary embodiment, if the standard deviation of the parameter at issue (TV Speed) over the specified time interface is below 5, then the Stroke Delay could be set at 1 stroke. Alternatively, if the standard deviation of TV Speed is greater than 5, the Stroke Delay could be set at 0 strokes.

It should be noted that the approach for setting the Stroke Delay described above is exemplary only. For example, embodiments are envisioned where the determined standard deviation of the parameter at issue, which is the standard deviation of the TV Speed, (often referred to as “σ” over a specified period defines the Stroke Delay as follows:

0 ⁢ % < σ < 3 ⁢ Stroke ⁢ Delay = 3 3 <= σ ⁢ Stroke ⁢ Delay = 0 ⁢ ( 3 ⁢ to ⁢ make ⁢ range ⁢ continuous )

Still further embodiments are envisioned wherein the standard deviation used to determine the Stroke Delay is based on assessing the standard deviation over a particular number of strokes (e.g., a 10 stroke interval, or a running 10 stroke interval) rather than a time-based interval.

FIGS. 6A, 6B and 6C illustrate a still further alternate embodiment of a control system constructed in accordance with certain teachings of the present disclosure that may be used in situations where an operator wants to attempt to match the pump displacement to the inflow of the reservoir.

FIG. 6A illustrates an example HMI 670 that may be used by the controller to obtain the control variables used in this alternative embodiment. As reflected in the figure, certain of the variables correspond to those discussed above in connection with previously disclosed embodiments (e.g., TV_Max 650, PF %_Setpoint 652, Startup_Speed 654; Speed_Max 656, and Speed_Min 658). The exemplary interface 670 includes a further control parameter, Max_Speed_at_Low_PF % defined in SPM, which will limit the speed once the TV_Max parameter is no longer surpassed below the leftmost intersection of the TV_Max with the travelling speed pattern.

The exemplary interface 670 includes a further control parameter, Max_Speed_at_Low_PF % 660 that can reflect a maximum operating speed of the system to be implemented under conditions where the percentage fillage of the pump is below PF %_Setpoint and below the last or leftmost Intersection of the TV_Max with the travelling speed pattern or below Low PF % Setpoint. Such a variable can be used under conditions where the operator of the system wants to control the maximum operating speed of the system when the pump fillage is below the PF %_Setpoint or below the last Intersection of the TV_Max with the travelling speed pattern. In this embodiment, Max_Speed_at_Low_PF % will be the speed the system will clamp the speed to in Section 468 of FIG. 4A-2 (i.e., the speed from the last intersection of TV_Max with the travelling speed pattern to the bottom of the stroke). This setting can provide a way for a user to prevent excessive high speed when the displacement is too low, given PF % is low. Because this leftmost or last intersection referred above can happen at different PF % this embodiment provides a Low PF % Setpoint, which provides an exact or consistent PF %, at the low end, to start TV Speed control.

FIGS. 6B and 6C illustrate a control process that the controller 110 may implement in accordance with this further embodiment.

Referring to FIG. 6B, the system will initially begin operation under conditions in Step 602 where the TV_Max and PF %_Setpoint variables have been set or determined. The controller will then proceed to Step 604 where it will operate the system at a present Speed_Setpoint, which could be a predetermined setpoint or a speed setpoint set through a prior implementation of the control process disclosed in FIGS. 6B and 6C. Certain embodiments can use the previous stroke pump fillage % and the profiles to estimate the speed Setpoint and make adjustments after the TV Speed is measured.

In some embodiments, the controller can transition from Startup (20 Hz), to Minimum pumps stroke (e.g., 30 Hz), and based on the last TV Contact measurement and use the current PF % to determine how much to increase the speed until the TV_Measure is within target or the Max working speed is reached. In such embodiments, the current PF % measured in the last stroke will determine the appropriate speed ratio and with that the new speed will be calculated.

The controller 110 will then proceed to Step 606 where it will calculate, among potentially other things, the downhole dynagraph for the system and the PF % and Measured_TV_Contact_Speed for the system.

The system will then proceed to Step 608 where it will determine whether the determined PF % for the system is within a deadband (e.g., +/−5% of the PF %_Setpoint). If so the controller 110 will maintain the current operating speed of the system and return to Step 604.

If the controller 110 determines at Step 608 that the PF % for the system is outside of the deadband from the PF % Setpoint it will then determine, at Step 610, if the PF % is less than the PF %_Setpoint. If the controller determines in Step 610 that the determined PF % is not less than the PF %_Setpoint (i.e., that it is above the lower end of the deadband), it will proceed to Step 612 where it will maintain the previous, which in some cases can be the Max Speed, value and return to Step 604 where it will then proceed to operate the system at the new Speed_Setpoint value (which under the described circumstances would be the Speed_Max value).

In certain embodiments, the controller can initially set the maximum working speed to align with the speed as of the first time PF % drops below the lower end of the deadband at the current speed. In such embodiments, as the PF % moves from low PF % and enters the deadland it needs to surpass the higher end of the deadband to return to Max speed.

If the controller 110 determines at Step 608 that the PF % is less than that of the lower end of the deadband, or <PF Setpoint %-Deadband %, the controller will then proceed to Step 620 in FIG. 6C.

If the controller 110 determines that the PF % is below the Low PF % Setpoint, then the controller will set the speed to the value configured in Max_Speed_at_Low_PF %.

Referring to FIG. 6C, in Step 620, the controller 110 will determine either the Measured_TV_Contact_Speed is above the upper end of the deadband surrounding the TV_Max value (e.g., more than 5% above, or in some embodiments 10%, more than 10% above, the TV_Max value). If the controller 110 determines in Step 620 that the Measured_TV_Contact_Speed is NOT above the higher end of the deadband surrounding the TV_Max setting, it will then proceed to Step 629 to verify that PF % is below the last intersection of TV_Max with the travelling valve speed at Maximum working speed or Speed_Max (this refers to section 468 of FIG. 4A-2), and adjust the Speed_Setpoint to be equal to the Max_Speed_at_Low_PF % and then return to Step 604 in FIG. 5B.

If the controller 110 determines in step 629 that the PF % is below leftmost intersection of TV_Max and the current Speed_Setpoint is below Speed_Max, then the controller will adjust, while verifying that TV_Max is not exceeded, the Speed Setpoint until it reaches Max_Speed_at_Low_PF %.

If the controller 110 determines in Step 629 that PF % is still above section 468 of figure FIG. 4A-2, then the algorithm will continue in 623, 622, 624 to increase the speed setpoint using the Speed_Setpoint_Adjustment until either Maximum Working speed is reached or the Measured_TV_Speed is within the deadband

If the controller determines in Step 620 that the Measured_TV_Contact_Speed is above the upper end of the deadband surrounding the TV_Max value is above the high end of the deadband, the controller will then (setting aside optional step 623 for the moment) proceed to Step 622 where it will calculate a Speed_Setpoint Adjustment, in this case reduce the speed, and Potential_Speed_Setpoint, to Step 624 where it can clamp the Speed_Setpoint at or within the Speed_Min and Speed_Max values, and to Step 626 where it will adjust the Speed_Setpoint based on the prior steps. These Steps can be implemented in accordance with any of the procedures described above in connection with Steps 522, 524, and 526 in FIG. 5C. After adjusting the new speed setting in Step 626, the controller 110 will return to Step 604 in FIG. 6B.

As reflected in FIG. 6C, as with the alternative embodiment reflected in FIGS. 5A-5C, the alternative embodiment of FIGS. 6A-6C can implement a Stroke Delay functionality through the use of Steps 621, 623 and 625. The operation of the controller with respect to such steps can be generally as previously described with respect to Steps 521, 523 and 525 of FIGS. 5A-5B.

As those of ordinary skill in the art having the benefit of this disclosure will appreciate, in the embodiment associated with FIGS. 4A-1, 4A-2 and 4B, because the control process is implemented based on periodic determination of the TV_Speed throughout at various points throughout a single pump stoke, the speed of the system is subject to change within and during each individual pump stroke. In the alternative embodiments of FIGS. 5A-5C and 6A-6C, however, because the control process is based on a determination of the TV_Speed at a single point in each pump stroke (specifically at the estimated point of contact between the TV and the fluid or gas in the pump) the speed setting of the system will not dynamically change throughout a given pump stroke, but generally will be subject to change only once each pump stroke (or every series of X strokes if Stroke Delay functionality is implemented).

In certain embodiments, all adjustments should be small (on the order of 5 Hz or, in some examples, 2.5 Hz) to keep the unit running smoothly. In such embodiments, if the PF % causes the TV to vary drastically, the controller can reduce the speed one step, 5 Hz and reevaluate. The controller can then continuously sense and adjust, either decrease or increase in increments of 2.5 Hz, the Maximum operating sleep to prevent the system from being continuously impacted with drastic TV changes from the time TV is measured to the next stroke.

In such embodiments, or in further alternate embodiments, the controller can limit the speed adjustments, so as PF % varies from one stroke to the next, the difference between the measure speed and the target should not surpass a certain defined amount. In such embodiments, this speed adjustment limitation process can occur within, or in connection with, the previously described steps 526 or 626 in which the speed setpoint is adjusted. FIG. 9 illustrates one exemplary process 904 that may be implemented by the controller for a speed adjustment limitation process.

Referring to FIG. 9, in the illustrated example, the controller will first determine in step 904-1 whether the difference between the measured and the proposed new target max speed is greater than the max speed increase (which in the example is 12.5 Hz.) If the answer is NO, the controller will then determine at step 904-8 if the difference between the proposed new target max speed is less than the max speed decrease (10 Hz. in the example). If YES, then the controller will proceed to the appropriate speed setting step (526 or 646) and set the new target speed as the proposed new speed.

If the controller determines at step 904-1 that the proposed new max target speed would result in a speed increase above the max speed increase, the controller will determine at step 904-2 whether the proposed new speed max is above the min speed. If not, then the controller will proceed to the appropriate speed setting step (526 or 646) and set the new target max speed as the proposed new speed.

If the proposed new max speed is greater than the min speed, then the controller will proceed through a series of steps 904-3 to 904-6 to reduce the proposed target speed in 5 Hz. steps. Similarly, if the controller determines at step 904-8 that a limited increase in the speed is warranted, the controller will proceed through steps 904-9 to 904-11 to increase the speed in 2.5 Hz. steps.

Additionally, the present inventor has recognized that downhole dynamometers only sense fluid load, its inertia effects, and the friction of components below them. In other words, rod fiction against tubing, stuffing box friction, rod friction against fluid, and especially buoyant rod weigh cannot be sensed by a downhole dynamometer installed right above the pump. Moreover, because the downhole dynamometers measure negatives loads when compressed and positive loads when stretched, and because the only friction component below the pump is pump friction, the calculated downhole dynagraph should not display other negatives loads other that those that can be justified by pump friction or the difference between buoyant pump weigh and pump friction. As seen in downhole dynamometer measurements, dynagraphs derived from downhole dynamometers display little negative loads, normally approximately a few hundred pounds, which come from pump friction.

Unlike measured downhole dynamometer dynagraphs, the calculated downhole dynagraph is derived from load and position measurements at the surface, and since all components of the system are below the load and position sensors at surface, all load and friction in the system are captured at the surface. As a result, the calculated downhole dynagraph, unless removed, ends up with all load and friction in the system.

Although the calculated downhole dynagraph initially includes all the friction components listed above, the inventor of the embodiments disclosed herein has determined that it is possible to center the calculated downhole dynagraph in the same manner as the downhole dynamometer. By separating fluid load from friction in the calculated downhole dynagraph in the downstroke a controller constructed in accordance with the teachings of the present disclosure can determine where to center the calculated downhole dynagraph.

As previously discussed, the travelling valve decelerates and then accelerates once the fluid load level is reached, and this load is transferred from the traveling valve to the standing valve. This point of inflection in which the slope of the travelling speed transition from negative to positive to establish the low fluid load line.

In addition to, or as an alternative to, implementing beneficial control processes, embodiments of a controller 110 constructed in accordance with the present disclosure may provide an enhanced display of the downhole dynamometer card that provides information not readily available from conventionally displayed downhole dynamometer cards. Specifically, in certain embodiments of the present disclosure, the controller 110 can display a downhole dynamometer card where the card is positioned to reflect the fluid load line as the zero load of the system. In general, such a display can be generated by the controller 110 by: (a) calculating the downhole dynagraphic card from the surface data available to the system for a given pump stroke; (b) determining the downstroke fluid load line for the system for such pump stroke; (c) scaling the load values for the determined downhole dynamometer card such that the fluid load line corresponds to a zero load on the system.

Aspects of this embodiment are generally illustrated in FIGS. 7A, 7B, 7C and 7D.

Referring first to FIG. 7A, an unadjusted determined downhole card for the pumping system is illustrated. As reflected in the figure, the unadjusted downhole dyno card may display a downstroke fluid load line having a value of −1478 lbs. FIG. 7B shows an adjusted downhole dyno card generated in accordance with certain teachings of the present disclosure. As reflected in FIG. 7B, each of the load values has been adjusted by adding the difference been 0 lbs and the value of the downstroke fluid load line from the unadjusted downhole dyno card to the load value for each load, position data point. Specifically, in the example, 1478 (which=0 minus−1478) has been added to each data point scale or shift the displayed downhole dyno card.

FIG. 7C illustrates a process 700 that may be implemented by the controller to display an adjusted downhole dynamometer card in accordance with certain teachings of the present disclosure.

In Step 702 the controller will calculate downhole card data based on received surface measurements. In Step 704, the controller 110 will use the calculated downhole data to determine the downstroke fluid load line.

In Step 706, the controller will calculate a load adjustment factor based on the difference between zero and the load value determined for the fluid load line in Step 704.

In Step 708 the controller will adjust the calculated load values for each position point by adding to the unadjusted load values, the load adjustment factor and in Step 710, the controller will display an adjusted downhole card, with the fluid load line corresponding to the zero condition using the adjusted values.

In embodiments where the pump weight and pump friction are known the zero load line value used in the process described can be further refined by adding in the buoyant weight of the pump (or an estimate of the pump weight) and subtracting the pump friction (or an estimate of pump friction, e.g., 200 lbs along the pump barrel).

While the artificial lift system illustrated in FIG. 1 can be used with a controller 110 constructed in accordance with the present disclosure, other forms of artificial lift systems can be used as well.

FIG. 8 illustrates an alternative exemplary artificial lift system 800 that may be used to implement the under-pumping mitigation functionality described in this disclosure. Like the embodiment of FIG. 1, the system 800 includes a controller 810 and a beam pumping unit 814 that includes a pump 802 and a rod 804. In the example of FIG. 8, the pump 802 and rod 804 are positioned within an annulus defined, in the example, by a casing string 106. As with the example of FIG. 1. a fluid, having a fluid level 108, resides in the annulus.

Unlike the exemplary system of FIG. 1, the system 800 of FIG. 7 includes a prime mover 850 that is coupled to the beam pumping unit through a mechanical coupling 860. In the illustrated example, the prime mover 850, operating under the control of the controller 810 and through the mechanical coupling 860, operate the beam pumping unit 814 such the pump 802 can operate at different pumping speeds to implement the under-pumping mitigation functionality described herein.

In the example of FIG. 8, the prime mover 850 can take many different forms. Exemplary embodiments are envisioned where the prime mover takes the form of an electric, gas or hydraulic motor. In certain embodiments, the prime mover 850 is such that it can be controlled by the controller 810 to operate across a range of various speeds. Alternate embodiments are envisioned wherein the prime mover 850 is capable of being operated by the controller 810 at only certain defined speeds. Still alternate embodiments are envisioned wherein the prime move 850 is capable of operating at only a single speed, or across a speed range, and where the mechanical coupling 860 is adjusted during operation to vary the pumping speed of the pump 102.

In the example of FIG. 8, the mechanical coupling 860 can likewise take different forms. In one embodiment, the mechanical coupling 860 can include a gear reducer, with sheaves and belts. In an alternate embodiment, the mechanical coupling 860 can include a transmission-like element under the control of the controller 810 such that adjustment of the transmission element can adjust the operating speed of the pump 102. In still further embodiments, the prime mover 850 can take the form of a permanent magnet motor that is mounted directly onto a high-speed shaft/gear of a gear reducer within the mechanical coupling 860. In such an embodiment, the mechanical coupling 860 need not include any sheaves or belts.

It will be appreciated from consideration of FIG. 1 and FIG. 8 that the teachings of the present disclosure are not limited to any specific artificial lift system arrangements.

In addition to the control approaches discussed above, advanced control processes may be implemented by an embodiment of a controller constructed and configured to the teachings of the present disclosure. Such advanced control techniques may include, for example, advanced control techniques wherein control processes are implemented based, at least in part, on the determined acceleration/deceleration of the TV. Such advanced control processes may be explained, in part, through reference to FIG. 14.

FIG. 14 illustrates various data items received or determined by the controller including: load vs position data plot 1400 of data received by the controller; TV speed vs position data plot 1402 determined by the controller; a slope of load data plot 1403 determined by the controller; an acceleration of the load data plot 1404 as determined by the controller; and an acceleration of the TV plot 1406 as determined by the controller.

Referring to FIG. 14, it will be noted from data plot 1402 that the speed of the TV will (moving from right to left) experience a first inflection point (designated 1402-1) where the speed of the TV changes such that its speed ceases to accelerate and begins to decelerate. As reflected by the designation of this inflection point on the TV Acceleration Plot 1406 indicates, at this inflection point the acceleration of the TV will (exactly or approximately) be zero. NOTE that the actual data points used by the exemplary controller may—depending on when load vs position data is provided—not correspond precisely to the point where the acceleration of the TV is equal to zero. However, the controller can operate based on the data point closest to the zero acceleration point or to an interpolated value equal to the zero-acceleration point.

Continuing to refer to FIG. 14, it will be understood that—in addition to determining the first speed inflection point 1402-1 discussed above, the exemplary controller will also determine (moving from right to left) a second inflection point wherein the speed of the TV stops decreasing and begins to increase (in the negative direction) again. This point is designated (on both the TV speed and the TV acceleration plots) as 1402-2. As with the point 1402-1, this second inflection point will correspond to a point where the TV Acceleration again reaches zero.

The present inventor has discovered that an assessment of the difference between the two inflection points 1402-1 and 1402-2 provides meaningful information that the controller can use to determine the operating state of the pump such that it can operate the pump in the most efficient manner. This is at least because it has been discovered that consideration of these points, and the acceleration values of the TV, is both an excellent way to sense energy transfer and a way to sense highly pressurized gas inside the pump, providing a sense for high versus low intake. For example, if the controller determines that there is a relatively large gap between the first inflection point 1402-1 and the second inflection point 1402-2, it can assess that the pump is experiencing a meaningful amount of gas compression such that it can potentially continue to operate the pumping system at a relatively high speed. Conversely, if the gap between the first and second described inflection points is small, the controller can assess that the pump is at or approaching pump off and can thus control the speed of the pump to avoid a pump-off condition.

In other words, by considering the actual or determined zero crossings of the TV acceleration plot, a controller constructed and configured in accordance with teachings of the present disclosure can evaluate the determined deceleration/acceleration of the TV to assess the extent to which the pumping system is experiencing gas interference (as opposed to pump off). Because there is relatively low gas compression when the intake is low, a higher deceleration value will generally correlate to pump-off condition (as opposed to a gas interference condition). Alternatively, a lower deceleration value will generally suggest a level of gas interference.

In addition to the above, the present inventor has discovered that the second inflection point 1402-2 corresponds to the pump fillage percentage (PF %) because it is at that point that the TV has made contact with fluid and begins to open and receive fluid into the pump.

Continuing to refer to FIG. 14, it will be noted from an inspection of the TV Acceleration plot 1406 that (moving from right to left) following the points 1402-1 and 1402-2, the system will reach a point where there is an inflection in the acceleration values of the TV, such that the acceleration changes from a point of increasing acceleration to a point of decreasing acceleration. This acceleration inflection point is designated in the TV acceleration plot as point 1406-1. The present inventor has discovered that this inflection point is an indication that the fluid load on the pump has, or has very nearly, reached zero, such that it corresponds to, or is close to, the true fluid load line. As such the controller can use this point to determine the fluid load line for presentation of the downhole pump card as described above. The controller can make the fluid load line determination by, for example, assessing the slope of the load (plot 1403) beginning at point 1406-1 and determine the point where the load is no longer changing or, in some embodiments, using the point 1406-1 as the fluid load line.

FIG. 15 illustrates an enlarged version of the acceleration plot 1406 if FIG. 14 and highlights the region between points 1402-1 and 1402-2 (designated as 1502) and the region between points 1402-2 and 1406-2 (designated 1501). As described above in accordance with the teachings of the present disclosure, the controller can evaluate the relative value of region 1502 to determine the extent to which the pump is experiencing gas interference and/or the margin to pump off under which the pump is operating. Moreover, as discussed herein, the controller can use the point 1402-2 to determine the point of fluid contact (and thus pump fillage percentage (PF %)) and point 1406-1 to determine the true fluid load line. Further, because the approach disclosed herein can discriminate between the point of fluid contact (the pump filliage percentage PF %) 1402-2 and the true fluid-load line (where the fluid load is zero) a controller operating according to teachings of the present disclosure can, by considering the displacement corresponding to region 1501, more accurately determine the overall displacement of the pump system during operation than systems that equate the fluid load line with the pump fillage percentage. Further, because pump fillage in such an embodiment is more accurately determined, and because the system in such an embodiment is controlled based on pump fillage percentage, the overall control of the system is enhanced.

FIG. 16 illustrates an exemplary HMI that may be provided by a controller constructed and configured in accordance with certain teachings of the present disclosure. As reflected in the figure, the exemplary HMI includes a region 1602 depicting downhole a pump card and region (unlabeled) reflecting various operating parameters for the system (e.g., TV_Max; Low PF %; Max_Speed_at_Low PF). It will be appreciated that in the example of FIG. 16, the pump card is show with real (i.e., detected) load values. Alternate embodiments are envisioned wherein the pump card is positioned on the fluid load line (as described above).

The exemplary HMI of FIG. 16 also includes a further region that shows several significant data items. First, it shows in a solid vertical line 1604 that corresponds to the pump fillage percentage (PF %) (in other words, the point where the pump makes contact with the fluid). Second, the exemplary HMI reflects, by point 1606, the first speed inflection point (e.g., point 1402-1 in FIG. 14). Thus, by inspecting this exemplary HMI, a user can be provided with a graphical indication for gas interference and pump intake pressure (PIP). This is because the farther point 1606 is from the PF % line the higher the gas is pressurized, and the closer it is the lower the gas is pressurized inside the pump, indicating low intake.

In the exemplary examples provided above, the described artificial lift system includes a sucker rod pump stroked by a beam pumping unit that is driven by a variable speed motor riven by a variable speed drive (or the alternate arrangement described in connection with FIG. 8). It will be appreciated that the operating processes described here is not limited to such an embodiment and that one could utilize the teachings of this disclosure in connection with an artificial lift system using different forms of pumping apparatus and/or different apparatus for driving such pumps.

For example, the pumping apparatus can be any form of pumping apparatus that can be subject to varying fillage percentage levels.

Additionally, the apparatus driving the pump need not be a variable speed motor driven by a variable speed drive. Any suitable driving apparatus (or prime mover) can be used, and embodiments are envisioned wherein the driving apparatus (or prime mover) takes the form of a gas engine, a diesel engine, or a pneumatically or hydraulicly driven apparatus. In certain alternate embodiments, the rod driving the pump may be integrated into the prime mover such that no separate driving apparatus is required. For example, the rod may be threaded and form the stator of an inside out electric motor having a rotor with a threaded interior bore that mates with the threaded exterior of the rod, such that activation of the motor will cause the stator to rotate (and cause the rod to move up or down).

In addition, the present disclosure can be implemented using artificial systems that do not involve beam pumping units. For example, linear pumping units can be utilized without departing from the teachings of this disclosure.

Other and further embodiments utilizing one or more aspects of the inventions described above can be devised without departing from the spirit of Applicant's invention. Further, the various methods and embodiments of the methods of manufacture and assembly of the system, as well as location specifications, can be included in combination with each other to produce variations of the disclosed methods and embodiments. Discussion of singular elements can include plural elements and vice-versa.

The order of steps can occur in a variety of sequences unless otherwise specifically limited. The various steps described herein can be combined with other steps, interlineated with the stated steps, and/or split into multiple steps. Similarly, elements have been described functionally and can be embodied as separate components or can be combined into components having multiple functions.

The inventions have been described in the context of preferred and other embodiments and not every embodiment of the invention has been described. Obvious modifications and alterations to the described embodiments are available to those of ordinary skill in the art. The disclosed and undisclosed embodiments are not intended to limit or restrict the scope or applicability of the invention conceived of by the Applicants, but rather, in conformity with the patent laws, Applicants intend to protect fully all such modifications and improvements that come within the scope or range of equivalent of the submitted claims.