IN-WELL MULTIPLE INLET GAS AVOIDING APPARATUS

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Great Britain Patent Application No. 2412244.2 filed on 20 Aug. 2024, the disclosure of which is incorporated by reference herein in its entirety.

FIELD

The invention relates generally to oil wells and, more specifically, to a system and method to prevent gas from entering an artificial lift production system.

BACKGROUND

Generally, artificial lift systems are used in wellbore applications for pumping production fluids, such as water and petroleum. Insufficient well reservoir pressure can be overcome with artificial lift systems such as electrical submersible pumps, sucker rod pumps, progressive cavity pumps, gas lift, plunger lift, or the like. An artificial lift system reduces bottom hole pressure and increases the rate of production.

The presence of gas, a gas surge or a gas slug within a wellbore is intricately influenced by a multitude of fluid and wellbore characteristics. Parameters such as reservoir pressure, wellbore exploitation duration, reservoir gas pockets, fluid density, viscosity, the ratio of gas to liquid volume, in conjunction with wellbore properties like wellbore inclination, tubular dimensions, and overall length collectively orchestrate the dynamics of gas and liquid flow along the wellbore's trajectory.

The gas in well fluid will remain in solution until the pressure decreases or temperature increases, at which time it may break out of solution to become free gas. The pressure at which the gas starts to be released from the oil is referred to as the bubble point pressure. A reduction in well bore pressure below the bubble point results in free gas which is gas released from the oil. The lower the pressure is below the bubble point, the more free gas is present. It is desirable to reduce the well bore pressure to maximize the produced fluid from a reservoir, however this may result in free gas being ingested inside the artificial lift system interfering with its operation.

For an artificial lift system that includes a single intake passage, all production fluids migrate along the wellbore to reach the intake so that the production fluids can be lifted to the surface. In the case of horizontal wells having single or multiple individual production zones distributed along the length of the well, production zones located closest to the intake deliver fluids with less resistance to the artificial lift system. Production zones further away from the intake deliver fluids less effectively because of increased flow resistance between the production zone and the intake. Such drawbacks reduce the production rate and the total recovery of resources from the well, although methods are available to minimize these drawbacks.

There are solutions available to minimize the impact of free gas on the artificial lift system. In the case of an electrical submersible pump system, either a static or dynamic gas separator may be employed rather than a conventional intake. Static gas separators have demonstrated limited efficiency, especially in high volume applications. Dynamic gas separators employ a rotating paddle to separate the gas from the fluid or employ an arrangement to induce a vortex or separate liquid from gas by applying centrifugal forces. These devices have moving parts which negatively impact reliability and can direct solids to the housing inner surface resulting in erosive wear. Its efficiency depends on how the gas and liquid mixture enters the pump, such as the homogeneity of bubbles in the liquid, gas slugging or other types of fluid patterns.

SUMMARY

The primary aim of the present invention is to provide a fluid control system and method to more efficiently prevent gas from entering an artificial lift system. Other objects and advantages of the invention may become apparent upon reading the following detailed description and upon reference to the accompanying drawings.

According to the present invention, there is provided a system according to the independent claims.

The system takes advantage of the buoyancy effect of the gas, channeling the liquid inside the gas avoiding device at a speed low enough to minimize the dragging of the gas into the system, and preferentially ingesting oil and water from the lower side of the casing in a non-vertical well section. It is further desirable that this system operate in a vertical to near horizontal well section orientation. It is yet further desirable that this system employs multiple intake ports in series to reduce the ingested fluid velocity per intake port and thus accommodate higher total rates of flow.

Free gas naturally migrates upwards by buoyancy when mixed with a liquid. A deployed device in a well bore will most likely not be centered, and in the case of a non-vertical well section, the gas tends to accumulate on the upper side of the casing and the liquid on the lower side of the casing.

A gas avoiding intake directs gas to bypass the inlets ports and travel upwards per the forces of buoyancy thus minimizing the ingestion of gas. A reverse flow gas avoiding intake directs the fluid to a nearly 180-degree change in direction favoring the releasing of gas from liquid due to difference of densities. The forces of buoyancy direct the free gas away from the intake and travel up the casing. An intake which favors the ingestion of fluid from the lower side of the well casing in this non-vertical section of the well will further avoid the ingestion of the free gas congregating on the upper side of the casing. A pivoting eccentric baffle will orientate the inlet of the gas separator towards the bottom section of the casing and favoring the ingestion of fluid from the lower side of the casing in a non-vertical well section. An increasing rate of fluid entering a single intake will drag more free gas into the intake. Multiple intakes in series reduce the rate of fluid in each intake. Thus, the ingestion of free gas is reduced, because the dragging effect is less.

There is a need for a fluid control device with no or minimal moving parts which efficiently removes gas slugs enhancing the performance of artificial lift systems.

During the normal production of subterranean fluid with or without gas, the fluid enters the wellbore from a reservoir or aquifer, then travels to the flow control system.

In accordance with one exemplary embodiment, a flow control system with one or a multitude of pivoting, baffled gas avoiding intakes is located below the artificial lift system. The flow control system may be hanging from the artificial lift system via tubing which conveys the conditioned fluid to the artificial lift system's intake or suspended in the well with a packer, tubing hanger or swab cup or other wellbore sealing or suspension device. The avoided free gas migrates to surface via the annular volume between the artificial lift system and the casing, and the annular volume between the tubing and casing. The artificial lift system may be a progressing cavity pump, electrical submersible pump, sucker rod pump, gear pump, or other type.

A secondary embodiment includes a well packer. Well packers isolate regions of well casing typically with elastomers contacting a well casings inner diameter. Tubing passes through the packer and devices deployed above or below the packer. The flow control system containing a pivoting, baffled gas avoiding intake preferentially ingests fluid from the lower side of the casing region. The avoided free gas bypasses the artificial lift system traveling to the surface within vent tubing.

In a third embodiment the flow control system may control the gas with or without being connected to an artificial lift system.

While many of the drawings and descriptions may depict the flow control device being operated in a vertical or horizontal well section its usefulness can be considered in any well section orientation from vertical to horizontal.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention will now be described with reference to the drawings, of which:

FIG. 1 is a diagram illustrating a typical ESP system;

FIG. 2 is a diagram illustrating a typical ESP system with the flow control device deployed separately hanging from a packer;

FIG. 3 is a diagram illustrating a typical ESP system with flow control devices in series with multiple intakes;

FIGS. 4A and 4B are diagrams illustrating an ESP system connected to a gas avoiding intake device;

FIGS. 5A, 5B, and 5C are cross-sectional diagrams of the well with a gas avoiding device deployed in a horizontal well section and views of the main components;

FIG. 5D-5G are sectional views taken through FIG. 5C along lines A-A, B-B, C-C and D-D, respectively, showing the integration of the tubing, baffle, vent tube, intake area, and closed base within the well casing;

FIG. 5H shows detail of the vent tube and vent ports;

FIG. 5I is s sectional view taken through FIG. 5H along lines E-E;

FIG. 6A is a diagram illustrating an alternative baffle arrangement;

FIG. 6B-6C are sectional views taken through FIG. 6A along lines A-A, B-B, respectively, showing the concentric arrangement of inner tube within casing and baffle, and the interface between tubular sections and their relationship to the inner tube and surrounding casing;

FIGS. 7A, 7B, and 7G are diagrams illustrating a different baffle and vent ports arrangement;

FIG. 7C-7F are sectional views of FIG. 7A taken along lines A-A, B-B, C-C and D-D, respectively, showing the integration of the tubing, intake area, baffle and closed base within the well casing;

FIG. 8 is a cross-sectional diagram of the well and gas avoiding device with well fluid and gas;

FIG. 9A is a longitudinal section diagram of the pivoting baffle of the gas avoiding device;

FIG. 9B is a cross section view taken along line A-A showing the relationship between the inner tube, inlet ports and baffle;

FIG. 10A shows a side view of the gas avoiding device inside a perforated tube;

FIG. 10B shows a side view of the perforated tube alone; and

FIG. 11 illustrates two gas avoiding devices connected in series.

DETAILED DESCRIPTION

One or more embodiments of the invention are described below. It should be noted that these and any other embodiments described below are exemplary and are intended to be illustrative of the invention rather than be limiting.

Referring to FIG. 1, there is shown a typical electrical submersible pump (ESP) system in a subterranean well. ESP system 120 is installed in wellbore 150, inside well casing 160, and above well perforations 140. Downhole ESP system 120 consists of electric motor 121, seal section 122, and multistage centrifugal pump 123. Power cable 112 conveys power provided by variable speed drive 110. Power cable 112 connects to motor 121. Motor 121 rotates seal section 122 and multistage centrifugal pump 123. Pump 123 pushes the fluid up production tubing 130. Seal section 122 component may also be referred to as an equalizer or protector.

Referring to FIG. 2, there is shown a typical ESP system with a flow control device. The flow control device is a gas slug directing device requiring a gas avoiding intake such as the one described below. Flow control device 250 typically resides below ESP system 220 and above well perforations 240. Flow control device 250 may incorporate further flow control apparatus such as a gas slug storage and metering. The pump could alternatively be a surface driven pump, linear actuated pump, conventional rod pump, gear pump, progressing cavity pump, gas lift or other. Alternatively, ESP system 220 shown could be an electrical submersible progressing cavity pump, gear pump, a linear actuated pump, or similar.

Referring to FIG. 3, there is shown a typical ESP system with multiple flow control devices. Flow control devices 250 typically resides below ESP system 220 and above well perforations 240. Alternatively, there are a multitude of flow control devices 250.

Referring to FIGS. 4A and 4B, there is shown a cross-sectional diagram of the well with a gas avoiding device below an encapsulated ESP system. FIG. 4A shows flow control device 450 connected to encapsulated ESP system 460 by tubing 465. FIG. 4B shows the same configuration with encapsulation housing 435 sectioned. Liquid 470 and gas 480 enter fluid control device 450 with gas 485 exiting the top of device 450. Liquid 470 travels inside connecting tubing 465 to encapsulation housing 435. Fluid 470 travels in the annular space between ESP system 430 and encapsulation housing 435 entering pump 437 which pushes liquid 470 to the surface. The pump could alternatively be a surface driven pump, linear actuated pump, conventional rod pump, gear pump, progressing cavity pump, gas lift or other. Alternatively, ESP system 220 shown could be an electrical submersible progressing cavity pump, gear pump, a linear actuated pump, or similar.

Referring to FIGS. 5A, 5B, and 5C, there are shown a cross-sectional diagrams of the well with a gas avoiding device deployed separately from the artificial lift system and the major components. FIG. 5A is a cross-section of the well bore with gas avoiding device shown. Device 512 is shown attached to well packer 520 which adheres to well casing 510. Device 512 consists of one module or a multitude of modules each consisting of round tube 530 to convey the fluid, and pivoting baffle 540 attached to vent tube 550. Tubing 530 is supported within centralizers 560 that allows free rotation around tubing 530. Bearings 570 facilitate the rotation of baffle 540 and tube 550. Packer 520 accommodates tubing 530 to convey liquid and tubing 580 to vent the avoided gas. FIG. 5B provides a longitudinal cross-section of the gas avoiding apparatus. Tubing 530 is provided with inlet ports 531 at the base of baffle 540. Intake 541 of the gas avoiding apparatus is at the top of baffle 540. As a result of the free rotation, intake 541 biases towards the lower surface of casing 510. The free rotation results from the eccentricity of baffle 540 with respect to the center line of tubing 530. Vents 551 face downwards and upwards because of the free rotation. Counterweight 543 assures free rotation of baffle 540 and vent tube 550. Free rotation is further enhanced by bearings 570 which allow baffle 540 and vent tube 550 to rotate about tubing 530. FIG. 5C provides cross sections for further detail of the gas avoiding apparatus. FIG. 5D depicts Section A-A of FIG. 5C and provides further details of the integration of tubing 530 and baffle 540 within well casing 510. FIG. 5E depicts Section B-B of FIG. 5C and provides further details of the integration of tubing 530 and vent tube 550 within well casing 510. FIG. 5F depicts Section C-C of FIG. 5C and provides further details of intake area 541 in baffle 540, vent tube 550 and tubing 530 within well casing 510. FIG. 5G depicts Section D-D of FIG. 5C and provides further details of closed base 542 of baffle 540 and tubing 530 within well casing 510. Closed base 542 blocks the fluid from entering the baffle from the bottom and directing the fluid to enter intake 541. FIG. 5H shows detail of vent tube 550 which is attached by welding, adaptor, threading, or other mechanical fastening to baffle 540. FIG. 5I, which depicts Section E-E of FIG. 5I, shows a cross section of vent tube 550 and vents 551. If gas enters intake 541, then vent tube 550 will direct the gas to exit through vent holes 551 to the annular volume between casing 510 and vent tube 550, otherwise the efficient movement of the fluid within vent tube 550 will be blocked by the congregating gas on the upper side of the annular volume between inner tube 530 and vent tube 550.

The counterweight may be constructed from a dissolvable material such that the inner volume of the device increases after deployment.

Liquid within inner tube 530 travels to a surface driven pump, linear actuated pump, conventional rod pump, progressing cavity pump, or other, whereas the gas from bypass tubing 580 is directed above the pump inlet. Alternatively, ESP system 460 shown could be an electrical submersible progressing cavity pump system, gear pump, submersible sucker rod system, or other artificial lift system.

Referring to FIGS. 6A, 6B, and 6C, there is an alternative embodiment to the embodiment shown in FIG. 5A-5I. Baffle 610 is composed of longitudinally sectioned tubulars 611 and 612 which are attached with welding or other mechanical fastening means. The rest of the components are as described in FIG. 5A-5I.

Referring to FIGS. 7A, 7B, and 7F, there are shown a further alternative embodiment to the embodiment shown in FIG. 5A-5I. FIG. 7A shows vent tube 550 replaced with a longitudinally extended baffle 740. Intake 541 is an opening on the outer round surface of baffle 740. Gas within baffle 740 vents outwards thru vent ports 743. Bearings 770 allow baffle 740 to rotate around inner tube 530.

FIG. 7C-7F provides cross section views at key locations of FIG. 7B. FIG. 7C (through Section A-A of FIG. 7B) shows the integration of tubing 530 and baffle 740 within well casing 510. FIG. 7D (through Section B-B of FIG. 7B) shows the integration of intake area 741 within well casing 510. FIG. 7E (through Section C-C of FIG. 7B) shows the integration of tubing 530 and baffle 740 within well casing 510. FIG. 7F (through Section D-D of FIG. 7B) shows closed base 742 at the bottom of baffle 740 and tubing 530 within well casing 510. Closed base 742 blocks the fluid from entering the baffle from the bottom and directing the fluid to enter intake 741. FIG. 7G shows an alternative embodiment with baffle 740 angled having an eccentric base and concentric top relative to the center line of inner tube 530. The increased gap between baffle intake 741 and well casing 510 allows the liquid to enter baffle 740 with less resistance.

Referring to FIG. 8, there is shown a cross-sectional diagram of the well and gas avoiding device with well fluid and gas. Well fluid 870 and free gas 880 travel inside well casing 810 traveling from the well perforations to the pump. Due the effects of buoyancy and gravity, free gas 880 accumulates on the upper side of casing 810 and well fluid 870 accumulates on the lower side. Baffle 840 and intake port 841 direct well fluid 870 and free gas 880 to reverse flow direction 885. Avoided free gas 880 continues traveling upwards thru the annulus. Well fluid 870 without free gas 880 enters the inner diameter of tubing 830 thru inlet ports 831 before traveling upwards to the artificial lift system. When the gas avoiding device resides in a non-vertical orientation pivoting baffle 840 will position the intake port 841 such that more liquid rich fluid 870 is preferentially ingested from the lower side of the casing and free gas 880 on the higher side of the casing is preferentially avoided from ingestion. Gas 881 entering thru intake port 841 escapes to the annulus by traveling within vent tube 850 to vent ports 851.

Referring to FIG. 9A, there are shown a cross-sectional diagram of the well with a module of the gas avoiding device with multiple inner tube ports and a depiction of the multiple positions of the baffle. FIG. 9A shows the flow control device residing inside well casing 910 and comprising inner tube 930 and baffle 940. This embodiment has multiple inner tube ports 951. FIG. 9B (through Section A-A of FIG. 9A) shows a sectioned view of tubing 930 and a multitude of positions of baffle 940 within well casing 910. Upon final deployment in a non-vertical well section the force of gravity acts upon the eccentric mass of baffle 940 resulting in the preferential ingestion of well fluid from the lower section of the well casing and more efficient gas avoidance.

Referring to FIGS. 10A and 10B there is shown an alternative gas avoiding device. Perforated housing 1070 encases and protects the flow control device. Well fluid uniformly passes the perforations 1071 in housing 1070 before being ingested by the gas avoiding device. Avoided gas inside housing 1070 will exit the perforations along the upper side.

Referring to FIG. 11, there is shown an alternative configuration with multiple gas avoiding devices in series with multiple inlet and vent ports. Gas avoiding devices 110 and 1120 are connected in series with multiple intake ports 1141 and multiple vent ports 1151. Alternatively, there are a multitude of gas avoiding devices in series.

Across the embodiments described herein, three distinct classes of ports are to be understood. a first class comprises baffle intake ports (typically a single aperture or open end of a tube) through which well fluid initially enters the baffle annulus; such intakes may be located at the upper end of a baffle, on a side wall of an extended baffle. A second class comprises inner tube ports, which communicate fluid from within the baffle annulus into the inner tubing for conveyance to the artificial lift system. a third class comprises venting ports, which discharge gas from the baffle annulus to the surrounding well annulus; venting ports may be provided in a separate vent tube or integrated into a baffle wall. these three port classes are consistently present in the disclosed embodiments, although their physical arrangement varies according to the particular configuration. A separate perforated housing having a plurality of perforations in the housing which communicate with the baffle intake port may additional be provided.

In the foregoing embodiments, it is further to be understood that the vent ports are disposed axially above the intake port in the production flow direction. The relative axial displacement between the intake and the vent ports influences the separation efficiency of the device. If the vent ports are positioned too close to the intake, for example at a displacement of less than about one to three feet, gas from the surrounding well annulus may travel through the vent ports into the buffer, thereby reducing separation efficiency. By contrast, positioning the vent ports at a displacement above the intake of at least approximately one foot, and more typically three feet or most ideally five feet or greater, provides sufficient travel distance for buoyant gas to migrate upward and be discharged via the vent ports without being re-ingested from the annulus. This arrangement has been found to reduce the risk of gas ingestion across different well orientations and operating conditions. The specified displacement values are therefore to be regarded as exemplary of the distances effective to achieve the intended gas separation, and are applicable to all of the embodiments described herein.

It is further to be understood that the vent ports may be located at any position or location around the top region of the rotating assembly, whether formed in a vent tube or in the upper portion of the baffle wall, and are not limited to a position diametrically opposite the intake. When formed in the vent tube especially, they can be arranged axially, circumferentially, and can be confined to one region or dispersed.

In some embodiments, a plurality of gas avoiding modules may be deployed in series. Each module may comprise an inner tube section and an associated baffle capable of rotating independently of the others, thereby allowing each intake to orient itself separately towards the liquid-rich lower side of the casing. In alternative embodiments, two or more modules may be mechanically linked such that their baffles are constrained to rotate together, effectively forming a single larger gas avoiding assembly. Both independent and mechanically linked arrangements are contemplated herein.

It will be understood that in practical manufacture and assembly of the gas avoiding device, small clearances or joints may exist between components, for example at welded seams, adaptor connections, or rotating interfaces. Such mechanical tolerances and manufacturing features may permit a minor degree of gas and/or liquid ingress into the baffle annulus in addition to the intended flow through the defined intake and vent ports. However, the primary separation of liquid and gas within the device is determined by the deliberate arrangement of the intake ports, inlet ports, and vent ports as described above.

In each of the foregoing embodiments, the device is installed with its fluid intake arranged to face in the direction of production flow towards the wellhead, rather than towards the reservoir. This orientation is consistent irrespective of whether the well casing is vertical, inclined, or horizontal at the point of installation, and is to be understood as applying to all embodiments described herein. Accordingly, references herein to one component being ‘above’ another are to be understood as meaning axially displaced towards the wellhead (i.e. in the production flow direction), irrespective of the absolute vertical orientation of the well section.