Data Transfer Method and Apparatus

Description

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to patent application GB 2413320.9 filed on Sep. 11, 2024. The contents of that application are incorporated herein in their entirety.

FIELD OF THE INVENTION

This invention relates to a data transfer method and apparatus and in particular relating to the transfer of sensed data from down a well (at a rod well pumping unit) to the surface.

BACKGROUND OF THE INVENTION

It is known to use sensors which are sensitive to distinguishing characteristics of the properties of well and the well fluids and of the surrounding geological formation. Such information may be acquired during any type of production. The acquired data may include measurements of pressure and temperature, Gamma ray, resistivity, porosity, and density are examples of the sensors that can be used to acquire data downhole. The skilled person will be aware of other types of data. This data is required to be transmitted back to surface for analysis to assist with the management of the production process and the equipment involved.

The rotating rod well pumping unit is a mechanical system that is quite elastic in structure. Such a system includes a string of small diameter connecting rods extending long distances the surface of the earth to an impeller and rotated by a motor located at the surface.

These are to be distinguished from beam pumps to sucker rods attached to a plunger pump which is actuated by suitable surface equipment comprising a walking beam, counterweights, a rotating crank arm, a pitman connecting said crank arm with said walking beam, a prime mover, and driving means connecting said crank arm with said prime mover. Although sucker rod and rotating rod pumping units have been employed in oil fields for many years, due to the elasticity of the system, satisfactory methods of dynamic analysis have not been available which can serve to predict the numerous possibilities as to variance in peak and average loads with regard to pumping speed or viscosity or the fluid being pumped.

Progressive cavity pumps are a form of positive displacement pumps based on the Moineau principle. They are often used for the extraction of water and oil from underground reservoirs. They are installed downhole and driven from surface by a rotary drive mechanism that is connected to the pump by slender rotating rods. The speed of rotation of the pump controls the flow rate and the differential pressure across the pump.

Positive displacement pumps work well with liquid but can be damaged, or can wear prematurely, if a gaseous medium gets into the flow stream, or if abrasive particles are entrained in the fluid. Either of these events can damage the pump and make it less efficient, or cause it to fail completely due to wear.

Even under normal usage, with no gas or entrained solids, the sealing elements of the pump will eventually fail, and the pump will need to be replaced. Typically this might be after a period of two years constant usage but this lifetime is very variable and difficult to predict. Replacing the pump involves retrieving the drive rods and then retrieving the pump on the bottom of the tubing. This can be expensive and time consuming. It is activity that is best postponed as long as possible and over the years, pump manufacturers have found ways to adjust the sealing dimensions of the pump to provide the best lifetime without impairing pump efficiency.

Although the rotation speed of the pump can be used to control pressure and flow rate down hole, it can be difficult to adjust pressure with any degree of precision without making a direct pressure measurement.

SUMMMARY OF THE INVENTION

It is therefore an object of the present invention is to provide an apparatus and method of transmitting sensed data back to surface which avoids the problems with existing methods.

According to the present invention there is provided a data transfer apparatus and method as defined in the attached claims.

BRIEF DESCRIPTION OF THE FIGURES

Embodiments of the present invention will now be described in more detail, with reference to the attached drawings in which:

FIG. 1 shows a side elevation of a production well with the well fluid extraction system of the invention installed,

FIG. 2 shows an enlarged side elevation view of the pump portion,

FIG. 3 shows an enlarged side elevation view of the drive head,

FIG. 4 shows a perspective view of the torque sensor in the installed position,

FIG. 5 shows a side elevation of the production well of FIG. 1 with torque inducing means included,

FIG. 6 shows an enlarged perspective view of the pump of FIG. 5,

FIG. 6a shows an enlarged side elevation of the well drive head with a further embodiment of the sensor housing and sensor housing support of the invention

FIG. 7 shows a block diagram of the data processing steps,

FIG. 8 shows a block diagram of the data transmission steps,

FIG. 9 is a graph showing a typical output of an induced torque reading,

FIG. 10 shows an enlarged view of a further embodiment of the sensor housing support of the invention,

FIG. 11 shows an enlarged view of the sensor housing and top part of the sensor housing support of the embodiment of FIG. 10 of the invention,

FIG. 12 shows an enlarged underside view of a sensor housing of FIG. 11,

FIG. 13 shows a longitudinal cross section of the sensor housing of FIG. 12,

FIG. 14 shows an enlarged cross sectional view of the torque inducing aspect of the invention,

FIG. 15 shows a cross sectional view of an embodiment of the downhole components, and

FIG. 16 shows an enlarged view of the downhole components of FIG. 15.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 to 6a, a well fluid extraction system 1 using a progressive cavity pump 7 is shown; wherein the progressive cavity pump 7 comprises: a stator 8, a rotor 9, a drive rod 3, and a drive motor 6. The stator 8 has an internal uniform tubular surface; the rotor 9 is installed in the stator 8 and has an external threaded curved surface 5. The rotating drive rod 3 is connected to the rotor 9. The drive motor 6 and the rotating rod 3 are connected via a drive head 6a; a fluid outlet 9b is connected to an input end of a tank or a fluid pipeline; the external threaded curve surface 5 is a tapered spiral structure with equal tapers which urges the fluid upwards as the rotating rod 3 rotates inside the tubing 4 through inlet 9a. The well fluid extraction system 1 further comprises a monitoring and control system 10, and the monitoring and control mechanism 10 comprises a controller 11 and a torque sensor housing 12. The controller 11 is electrically connected to the torque sensor housing 12. A torque sensor 15 in the torque housing 12 monitors the torque in the rotating rod 3; and the torque housing 12 comprises a housing portion 13 which includes support means 14 to locate the torque sensor housing 12 in a desired non-contacting position in relation to the rotating rod 3, whilst permitting the rotating rod to rotate. The housing 13 is attached by the support means 14 to a frame, which in this embodiment forms part of the mounting frame of the drive head 6a. In this embodiment the support means 14 are in the form of elongate springs which support the housing in the desired location surrounding the drive rod 3 in a non-contact way and serve to continuously restore and maintain the housing in a central position adjacent to the rotating rod 3. At the end adjacent the drive head 6a the rotating rod 3 includes a polished portion 2 around which the torque sensor housing 12 is located in a non-contacting manner. The spring supports 14 protect the torque sensor(s) by preventing vibration in the system during use being transmitted to the torque sensor(s). Incidental contact with the polished portion 2 may occur as the system vibrates during use, but contact is not required for the torque sensor to detect the torque within the rod 3.

At the end adjacent the drive head 6a the rotating rod 3 includes a polished portion 2 around which the torque sensor housing 12 is located. A suitable torque sensor can be selected to measure the torque pulses induced in the drive rod 3.

Referring now to FIGS. 5 and 6 torque pulse inducing means 38 are shown enclosed in a further housing which holds the torque pulse inducing means in non-contacting proximity to the rotating rod 3 and which enables the data transfer method for transferring data from below the surface in a well to the surface. The data transfer method comprising the following steps:

• • a) receiving power from a power source 41,
  • b) receiving sensed data from a downhole sensor 40 located down the well,
  • c) inducing a series of torque pulses 42 in the drive rod 3, by means of the torque inducing means 38,
  • d) coding the torque pulses using the sensed data preserving the data integrity,
  • e) sensing the torque pulse by means of a torque sensor supporting in a torque sensor housing adjacent the rotating rod at the surface,
  • f) decoding the sensed data from the torque pulses by means of a demodulator and processer 30,
  • g) providing an output 31 of the sensed data at surface.

The power source is provided by harvesting energy from movement of the rotating drive rod 3 by means of an electric generator which is not shown, but is familiar to persons in the art. Generally, only about 0.25% of the pump power in the rotating rods 3 is required to be harvested to provide sufficient power to generate the torque pulses 42.

The harvested energy is stored in an energy storage device, (not shown) which acts as the power source when the rotating rod is not rotating. The energy storage device can be a battery or super capacitor so that short, intermittent, high-power pulses can be applied to energise the pulse inducing means. The torque pulses are provided by an electrically controlled electromagnetic brake acting intermittently on the drive rod 3. Other types of electrically controlled brakes could be used. In one embodiment the torque pulses 42 are between 0.01 and 0.3 seconds in duration and are between 0.01-10 Newton meters (Nm). Other ranges of values that are detectable by the torque sensor are possible.

By this means an apparatus is provided for transferring data from below surface in a well to the surface, adapted for a well fluid extraction system using a drive rod, comprising, located in the well, a power source, sensed data receiving means for receiving sensed data from a well sensor located down the well, torque pulse inducing means for inducing a series of torque pulses in the rod, pulse coding means for coding the torque pulses using the sensed data preserving the data integrity, and comprising, located at surface, a torque sensor for sensing the torque pulses, and a decoder for decoding the sensed data from the torque pulses to provide an output of the sensed data at surface. This data could be used to identify changes in performance in order to inform preventative maintenance strategies.

The torque sensor housing 12 comprises a least first a contactless torque sensor 15 in a first housing portion 17 and spaced circumferentially in relation to the cross section of the rotating drive rod 3 when the torque sensor housing 12 is located in a supported position in relation to the rotating drive rod 3, such that fluctuations in the torque being experienced in the rotating drive rod 3 whilst the rotating drive rod 3 is rotating can be measured.

The first contactless torque sensor 15, and a second contactless torque sensor or a torque inducer 39 are located in the housing 13 respectively in the diametrically opposed housing portions 17, 18 in relation to the cross section of the rotating drive rod 3.

In an alternative embodiment the third and fourth torque sensors are located in positions that are spaced circumferentially 90 degrees apart from the first and second torque sensors respectively.

In this embodiment the opening 16 is C-shaped to permit the housing 13 to be located laterally with respect to the rotating rod 3 and secured to an adjacent frame.

In an alternative embodiment the housing 13 is formed in a first housing portion 17 and a second housing portion 18 which are connected together such that the housing 13 surrounds the rotating rod 3 with the rotating rod 3 extending though the opening 16.

In this embodiment the sensor housing 13 is located around the rotating rod 3 at surface and connected to the controller by means of a cable 22.

Referring now to FIGS. 7 and 8 the data output of the torque sensor(s) is connected to a torque sensor interface 22a which in turn is connected to a demodulator and processor 30 which produces a system output 31 of data which may be used to control the motor or to manage the pumping activity in other ways.

FIGS. 10 to 13 show detailed views of a further embodiment of a mounting assembly 20 comprising a support plate 21 configured to support a pair of torque sensors 15 in a central and stable position relative to the rotating rod (not shown). The support plate 21 is U-shaped and includes a pair of wing arms 23 and each wing arm 23 is connected to an axial support 24 on an outside surface of each wing arm 23. Each axial support 24 extends radially and is connected at an opposite end to a lower support 25 which is in the form of a C-shaped bracket, and which is securely attachable to the drive head or casing. This lower support 25 ensures concentricity of the mounting assembly 30, and thus the torque sensors 15, in relation to the rotating rod and restrains the mounting assembly from rotating. The axial supports 24, which may be in the form of springs, as in the previous embodiment, or flat strips as shown in this embodiment, and extend axially from the support plate 21 to the lower support 25 and are used to support the offset the torque sensors 15 axially, and usually vertically as shown, allowing alignment with respect to the rotating rod without contact therewith. At the upper end of the mounting assembly 20, the sensor housing portions 17, 18 are attached to the support plate 24 by fixing means in the form of a socket 27 on each sensor housing portion 17, 18 and a corresponding tongue 28 on each wing arm 23. A pair bolts (not shown) finally secure the sensor housing portions 17, 18 to the support plate 21. The lower support 25 interfaces with the main drive head casing. This connection is achieved through a mechanical fixing method, such as bolting or by the resilient clips 26 which are arranged at the external circumferential edge of the lower support 25 as shown.

The individual supports may be joined through various conventional fastening methods, including welding or threaded fasteners, depending on material selection and required mechanical properties.

In an alternative embodiment one the torque sensors 15 can be a torque inducer 39. In a further alternative embodiment the torque sensors can be configured electronically to be either torque sensors or inducers or both.

Reference is now particularly made to FIGS. 9 to 13 in which further details of the first and second sensor housing portions 17, 18 are shown connected together to form an integral sensor housing 33 by means of a connecting plate 29. The first and second housing portions 17, 18 each comprise a cylindrical casing 32 and inner and outer end caps 36, 34 which are all comprised of a thick resilient material and which completely surround the disc-shaped torque sensors/inducers 15, 39. This provides ruggedised protection for the torque sensors/inducers 15, 39 to prevent physical or chemical damage at the well head environment. Circumferential seal means 35 are provided which ensure a sealed connection between the end caps 34, 36 and the internal surface of the cylindrical casing 32. Power and date conduits 37 pass from the sensor through the cylindrical casings 32 into a common connector (not show) on an exterior side of the connecting plate 29.

Reference is now made to FIGS. 14 to 16. In particular FIG. 14 is an enlarged view of an electromagnetic brake torque transducer 43 which induces pulses of torque in the lower rotating rod 3a by means of the electromagnetic coils 44 which are arranged at the circumference of a disc 46 and forms part of the rotating rod 3. The coils 44 and disc 46 are enclosed in a brake housing 45.

Reference is now made to FIGS. 15 and 16 in which it can be seen that the electromagnetic brake torque inducer 43 is arranged below the power generator 47 which generates electrical power from the lower rotating rod 3a. At the lower end of the well a tubing anchor 48 is provided between the production tubing 4 and the outer production casing 49 just above the pump section 7. The pump inlet 9a is provided at the lower end of the pump section 7. Below the pump inlet 9a a coupling section is provided that connects the pump 7 and rotating rod 3 to lower data acquisition section in a disengageable manner so that the pump can be retrieved to surface leaving the data acquisition section 54 behind and can be re-engaged at a later occasion when the pump is reintroduced into the well and automatically coupled with the data acquisition section 54. The coupling section includes a splined length 53 which provides a continuous rotating connection from the rotating rod 3 of the pump 7 to the lower rotating rod 3a of the lower data acquisition section. The coupling section includes the splined length 53 and a splined section housing 59 and a bearing 58 which bears against the internal surface of the lower production tubing 52 during the engagement of the rotating rod 3 and permits the splined section housing 59 to rotate and transmit the rotation to the lower rotating rod 3a so that it also rotates.

A rotary seal 50 is provided between the pump inlet 9a and the coupling casing 52. The data acquisition section 54 includes at least one sensor 55, such as a pressure transducer, which generates data that is processed in the processor and circuit board 56 which includes a circuit board that imparts a signal on the torque generated by the electromagnetic brake torque inducer that is transmitted along the lower rotating rod 3a, through the splined length 33, and the whole of the rotating rod 3 length back to the surface where the signal is sensed by the torque sensor 15 at surface and decoded. In this way data from the sensor 55 is reliably transmitted to surface without the need for a dedicated cable extending the entire length of the well. It will be appreciated that data from many other kinds of sensor such could be input and transmitted in the same way.

The entire data acquisition and transmission is self-contained and self-powered being powered by the power generator 47 which generates power from the lower rotating rod 3a, which powers the electromagnetic brake generator 43 and the sensors 55 and processor and circuit board 56. Charge storage means are also provided so that the sensors 55 and processor and circuit board 56 electromagnetic brake generator can be powered and the data transmission can still operate for periods when the rotating rod is not rotating.

A lower rotating seal 51 is provided to seal the data acquisition section from the contents of the well whilst also permitting the lower rotating rod 3 to rotate and perform other functions such as stirring the contents of the well by means of the rotating stirrer 57.

The method and apparatus disclosed herein may be used, in isolation or in conjunction with existing sensor technologies, to overcome these drawbacks and to provide high resolution transfer of data from anywhere in the well hole to the surface.

This invention provides real-time, high-resolution measurement whilst pumping allows the well operation to be more effectively managed, with the obvious consequential benefits of increases in production and decrease in equipment failure.

Components

• • 1. Well fluid extraction system
  • 2. Polished portion
  • 3. Rotating drive rod
  • 3a. Lower rotating rod
  • 4. Tubing
  • 5. External threaded surface
  • 6. Drive motor
  • 6a Drive head
  • 7. Progressive cavity pump
  • 8. Stator
  • 9. Rotor
  • 9a. Fluid inlet
  • 9b Fluid outlet
  • 10. Monitoring and control system
  • 11. Controller
  • 12. Torque sensor
  • 13. Housing
  • 14. Support means
  • 15. Contactless torque sensor
  • 16. Opening
  • 17. First housing portion
  • 18. Second housing portion
  • 19. Cable
  • 20. Mounting assembly
  • 21. Support plate
  • 22. Cable
  • 22a. Torque sensor interface
  • 23. Wing arm
  • 24. Axial support
  • 25. Lower support
  • 26. Resilient clips
  • 27. Socket
  • 28. Tongue
  • 29. Connecting plate
  • 30. Demodulator and processor
  • 31. System output
  • 32. Cylindrical casing
  • 33. Sensor housing
  • 34. End cap
  • 35. Seal
  • 36. End cap
  • 37. Conduit
  • 38. Torque pulse inducer
  • 39. Torque pulse inducer
  • 40. Downhole sensor
  • 41. Power supply
  • 42. Torque pulses
  • 43. Electromagnetic brake torque inducer
  • 44. Coil
  • 45. Brake housing
  • 46. Disc
  • 47. Power generator
  • 48. Tubing anchor
  • 49. Production casing
  • 50. Rotating seal
  • 51. Rotating seal
  • 52. Lower production tubing
  • 53. Splined section
  • 54. Data acquisition housing
  • 55. Downhole sensor
  • 56. Processor and circuit board
  • 57. Stirrer
  • 58. Bearing
  • 59. Splined section housing