BOREHOLE CLAMPING SYSTEMS AND METHODS OF OPERATING THE SAME

Abstract

A borehole clamping system is provided. The borehole clamping system includes: (a) a pressure actuated clamp for clamping a sensor assembly in a borehole; (b) a fluid control unit configured for use within the borehole, the fluid control unit providing a fluid to the pressure actuated clamp, and controlling a pressure of the fluid; and (c) a surface electrical control unit for controlling flow of the fluid.

Description

TECHNICAL FIELD

This invention relates generally to the field of sensing systems, and more particularly, to improved transducers, accelerometers, and improved sensing systems.

BACKGROUND OF THE INVENTION

Clamping mechanisms are required to ensure that seismic monitoring tools (such as accelerometers and geophones) that are used for oil, gas and geothermal energy monitoring applications are well coupled, mechanically, to a borehole. The terms “borehole” and “wellbore” are used herein interchangeably Traditional clamps include: mechanical bow-spring, motor-driven arms, fixed magnet, and pneumatically-driven arms.

Existing clamping methods suffer from limitations, such as: (1) high friction (i.e., drag) throughout the installation/retrieval which increases loads on cables and lifting hardware (e.g., crane, workover rig, etc.), and exacerbates cable torque due to constant resistance to twist at the casing; (2) high temperature limitations of electronics, for example, to 150° C. and less over extended periods of time; and (3) tangling of ancillary control lines (e.g., pneumatic lines) along the lead cable on structures such as blowout preventers, potentially resulting in control line damage.

Thus, it would be desirable to provide improved borehole clamping systems to address these and other issues.

BRIEF SUMMARY OF THE INVENTION

According to an exemplary embodiment of the present invention, a borehole clamping system is provided. The borehole clamping system includes: (a) a pressure actuated clamp (e.g., a hydraulically activated clamp) for clamping a sensor assembly in a borehole; (b) a fluid control unit (e.g., a hydraulic control unit, such as a hydraulic control module) configured for use within the borehole, the fluid control unit providing a fluid to the pressure actuated clamp, and controlling a pressure of the fluid; and (c) a surface electrical control unit (e.g., surface electronics 106 shown in FIG. 1) for controlling flow of the fluid, for example, through the operation of one or more valves (e.g., such as solenoid valves).

According to another exemplary embodiment of the present invention, a method of operating a clamping system within a borehole is provided. The method includes: (a) providing a pressure actuated clamp for clamping a sensor assembly in a borehole; (b) providing a fluid to the pressure actuated clamp, and controlling a pressure of the fluid, via a fluid control unit included within the borehole; and (c) controlling, via a surface electrical control unit, flow of the fluid from the fluid control unit to the pressure actuated clamp.

According to yet another exemplary embodiment of the present invention, a borehole clamping system is provided. The borehole clamping system includes a pressure actuated clamp (e.g., a hydraulically activated clamp) for clamping a sensor assembly in a borehole, the pressure actuated clamp configured to be operated using wellbore (i.e., borehole) pressure.

According to yet another exemplary embodiment of the present invention, a method of operating a clamping system within a borehole is provided. The method includes: (a) providing a pressure actuated clamp for clamping a sensor assembly in a borehole; and (b) operating the pressure actuated clamp via wellbore pressure.

It is to be understood that both the foregoing general description and the following detailed description are exemplary, but are not restrictive, of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is best understood from the following detailed description when read in connection with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity purposes. Included in the drawings are the following figures:

FIG. 1 is a block diagram of a borehole clamping system in accordance with an exemplary embodiment of the present invention;

FIG. 2 is a perspective view of a fluid control unit of a borehole clamping system in accordance with an exemplary embodiment of the present invention;

FIGS. 3A-3B are block diagram views of a sensing assembly of a borehole clamping system in accordance with an exemplary embodiment of the present invention; and

FIGS. 4 is a block diagram schematic illustrating fluid flow of a borehole clamping system in accordance with an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

According to certain exemplary embodiments, the present invention relates to passive energizing and release of clamps arms included in sensor assemblies. Only increased ambient (e.g., wellbore or borehole) pressure is used. Motors, pumps or other motive force producers may be avoided through the use of ambient pressure increased using a pressure converter. Because motors, pumps, etc. are avoided in the clamping operations, standard hybrid (e.g., electrical/optical) cable may be used to control the clamping action. Thus, ancillary lines (e.g., carrying hydraulic fluid) to the surface may be avoided in the lead cable. Rather, such ancillary lines may be included in the short lengths of interconnect cable. In certain exemplary embodiments of the present invention, passive electronics may be utilized that are typically reliable at temperatures above 200° C. including solenoid valves. Check valves may be utilized to ensure that clamps remain released during installation, when large excursions of pressure and temperature are experienced by the system.

Referring now to the drawings, FIG. 1 illustrates a borehole clamping system 100 installed in connection with a borehole 104. That is, a borehole (i.e., a wellbore) 104 is formed in earth 102. Sensor assemblies 112a, 112b, . . . , 112n (e.g., where the sensor assemblies may be provided in an array such as the illustrated sensor assembly string including assemblies 112a, . . . , 112n) are lowered into borehole 104 to sense vibration information within borehole 104. In a specific example, borehole 104 may be provided in connection with gas and oil exploration, reservoir monitoring and production monitoring activities, and sensor assemblies 112a, 112b, . . . , 112n include sensors for sensing information related to such activities. Such sensors may be fiber optic sensors (e.g., fiber optic transducers, fiber optic accelerometers, etc.), electronic sensors, etc.

Each of the sensor assemblies is desirably securely positioned within borehole 104. For example, sensor assembly 112a includes a clamp arm 112a1 (e.g., a pressure actuated clamp) for securely pressing sensor assembly 112a against a wall (e.g., a casing wall) 104a of borehole 104. The remaining sensor assemblies (e.g., sensor assembly 112n including clamp arm 112n1) are also securely positioned within borehole 104.

In the example shown in FIG. 1, system 100 also includes surface electronics 106 (e.g., interrogation electronics for interrogating sensors in sensor assemblies 112a, . . . , 112n and hydraulic control/monitoring electronics), lead cable 108, fluid control unit 110 (e.g., a hydraulic fluid control unit for operating and controlling hydraulically actuated clamps 112a1, . . . , 112n1, etc.), and interconnect cables 114. In an exemplary application including fiber optic sensing of the sensor assemblies, lead cable 108 may include optical fibers for sending and receiving optical signals to fiber optic sensors within the sensor assemblies 112a, . . . , 112n1. Lead cable 108 may also include, for example, electrical conductors, etc. for performing operations in connection with fluid control unit 110 (e.g., operating solenoid valves in fluid control unit 110). Depending on the application, interconnect cables 114 may carry, for example, fiber optic signals, hydraulic fluid, etc.

FIG. 2 illustrates an example of fluid control unit 110 from FIG. 1. In certain exemplary embodiments of the present invention, fluid control unit 110 may be a hydraulic fluid control unit for controlling hydraulic fluid used to operate the various sensor assembly clamps. FIG. 2 illustrates an end of lead cable 108 entering into cable shroud 110e1 of control unit 110. Control unit 110 also includes a pressure relief module 110c (including pressure relief valves 110c1, 110c2, and one or more electronic or optical fiber pressure transducers 116 for monitoring fluid pressure at one or more locations shown in FIG. 4), a solenoid valve manifold 110d (including solenoid control valves 110d1, 110d2, 110d3 and hydraulic lines to control the flow of hydraulic fluid for clamping and release functions), a pressure converter (e.g., a pressure intensifier) 110a, an isolation device 110b, and another cable shroud 110e2 leading to interconnect cable 114. Exemplary functions of certain of the elements of control unit 110 are explained below in connection with the example shown in FIG. 4.

FIGS. 3A-3B illustrate an exemplary operation of clamp 112a1 of sensor assembly 112a (in an exemplary embodiment of the present invention where clamp 112a1 of sensor assembly 112a is hydaulically actuated and controlled). Referring specifically to FIG. 3A, sensor assembly 112a is securely positioned in borehole 104 such that feet 112d of assembly 112a are pressed against one wall 104a of borehole 104, and clamp arm 112a1 is pressed against another wall 104a of borehole 104. Fluid 116a (e.g., an incompressible fluid, such as an incompressible hydraulic fluid) is injected through a hydraulic line into cylinder 112e on the left side of piston 112f (and fluid 116b is likewise forced out on the right side of piston 1120. The addition of fluid 116a creates a positive differential across piston 112f, and therefore moves piston 112f to the right, compressing spring 112h and driving piston rod 112g to the right, thereby actuating clamp arm 112a1 (which is coupled and/or linked to piston rod 112g), and pressing clamp arm 112a1 against wall 104a as shown in FIG. 3A. In this position, the sensing to be done by sensor 112c (e.g., a fiber optic sensor including a fiber optic transducer and/or fiber optic accelerometer) included in sensor assembly 112a may be accomplished in connection with surface electronics 106.

After the sensing is complete, and sensor assembly 112a is to be withdrawn from borehole 104 (e.g., along with other sensor assemblies in an array), the situation in FIG. 3B occurs. That is, fluid 116b (e.g., an incompressible fluid) is injected into cylinder 112e on the right side of piston 112f (and fluid 116a is likewise forced out on the left side of piston 112f, for example, to substantially equalize fluid pressure on each side of cylinder 112e and likewise across piston 112f), allowing spring 112h to naturally extend, thereby pushing piston 112f to the left and pulling piston rod 112g to the left, thereby retracting clamp arm 112a1 such that clamp arm 112a1 does not press against wall 104a. With clamp arm 112a1 in the retracted position shown in FIG. 3B, sensor assembly 112a may be withdrawn from borehole 104. While sensor assembly 112a is shown in FIGS. 3A-3B alone in borehole 104, it is understood that sensor assembly 112a may be part of a sensor array including a plurality of sensor assemblies, such as is shown in FIG. 1.

FIGS. 4 is a block diagram fluid schematic of an exemplary configuration of fluid control unit 110 in a hydraulic fluid control configuration. Also shown are simplified sensors assemblies 112a, 112b, . . . , 112n (shown in more detail in FIGS. 3A-3B) included in borehole clamping system 100 (see FIG. 1). In the example shown in FIG. 4, fluid control unit 110 includes a pressure converter 110a (e.g., a pressure intensifier) for operating the clamp arms of sensor assemblies 112a, 112b, . . . , 112n, where pressure converter 110a includes piston 110a1 within cylinder 110a2. In the example shown in FIG. 4, pressure converter 110a (intensifier) includes two coupled dissimilar diameter cylinder/piston assemblies for creating a higher pressure output compared to an input pressure.

Unit 110 also includes an isolation device 110b (e.g., a device for isolating the active fluid for driving pistons, such as piston 112f, from wellbore fluid, such as a mud piston system, etc.) having a piston 110b1 in a cylinder 110b2. Cylinder 110b2 of isolation device 110b separates borehole fluid (at wellbore pressure) from working (clean) fluid with no pressure difference and serves as a reservoir to accommodate changes in overall system fluid volume. Unit 110 also includes: pressure relief valves 110c1, 100c2; check valves 110c3, 110c4; and solenoid valves 110d1, 110d2, and 110d3 (controlled by surface electronics 106).

During installation of the sensor assemblies 112a, 112b, . . . , 112n into borehole 104, the hydraulics may be considered to be at surface ambient pressure. Solenoid operated valves 110d1, 110d2, and 110d3 are closed (e.g., using surface electronics 106), such that the clamp arms 112a1, etc. are in a retracted position for lowering into borehole 104. During the installation, check valves 110c3, 110c4 desirably ensure that both sides of clamp pistons (e.g., such as piston 112f shown in FIGS. 3A-3B) are at approximately wellbore pressure.

After the sensor assemblies are lowered into borehole 104, the wellbore pressure increases with hydrostatic pressure (or applied pressure, or both), resulting in an increase (amplification) in the pressure on the high pressure side (with the smaller piston/cylinder diameter) of pressure converter 110a (e.g., a pressure intensifier). With solenoid valves 110d1 and 110d3 now in an open position (controlled using electrical signals from surface electronics 106), the resulting fluid movement causes the clamping pistons (e.g., piston 112f shown in FIGS. 3A-3B) to drive the clamp arms (e.g., clamp arm 112a1) into an extended position (e.g., through the piston rods such as rod 112g), such as the position shown in FIG. 3A. Solenoid valves 110d1 and 110d3 are then closed electrically (controlled using electrical signals from surface electronics 106) to ensure that the clamp arms remain extended for long periods of time.

In order to release the clamp arms, solenoid valve 110d1 is closed (via electrical signals from surface electronics 106), and solenoid valves 110d2 and 110d3 are in an open position. In this configuration, both sides of clamp pistons (e.g., piston 112f shown in FIGS. 3A-3B) have substantially equal pressure (i.e., wellbore pressure). A mechanical spring force from spring 112h is used to retract the clamp aims, for example, as shown in FIG. 3B.

In order to retrieve the sensor assemblies from borehole 104, each of solenoid valves 100d1, 110d2, and 110d3 are then closed. The well pressure decreases with depth as the sensor assemblies are lifted to a reduced depth. A positive pressure across the clamp pistons (e.g., piston 112f shown in FIGS. 3A-3B) works with the retraction springs (e.g., spring 112h in FIGS. 3A-3B). The pressure relief valve on release side is set to a slightly higher cracking pressure than the check valve on the clamping side, thereby providing a slightly higher pressure on the release side of the clamps throughout the entire retrieval to ensure that the clamps remain released.

The sensing assemblies/tools described herein may include, for example, tools for sensing mechanical and/or acoustic vibration . Such tools may include electronic sensing elements (e.g., geophones), fiber optic sensing elements, among others. Exemplary fiber optic sensing elements include fiber optic transducers and accelerometers. Exemplary fiber optic transducers and accelerometers are disclosed in U.S. Patent Application Publication No. 2012/0257208, titled “FIBER OPTIC TRANSDUCERS, FIBER OPTIC ACCELEROMETERS AND FIBER OPTIC SENSING SYSTEMS”, which is hereby incorporated by reference in its entirety.

Exemplary applications for the sensing assemblies/tools (e.g., electronic sensing elements, fiber optic sensing elements, etc.) include vertical seismic profiling (VSP), three dimensional sub-surface mapping, microseismic monitoring, machine vibration monitoring, civil structure (e.g., dams, bridges, levees, etc.) monitoring, tunnel detection, perimeter/border security, earthquake monitoring, borehole leak detection, amongst others.

Although illustrated and described above with reference to certain specific embodiments, the present invention is nevertheless not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the spirit of the invention.

Claims

1. A borehole clamping system comprising: a pressure actuated clamp for clamping a sensor assembly in a borehole;a fluid control unit configured for use within the borehole, the fluid control unit providing a fluid to the pressure actuated clamp, and controlling a pressure of the fluid;a surface electrical control unit for controlling flow of the fluid.

2. The borehole clamping system of claim 1 wherein the fluid is an incompressible fluid.

3. The borehole clamping system of claim 1 wherein the fluid is a hydraulic fluid.

4. The borehole clamping system of claim 1 wherein the surface electrical control unit controls flow of the fluid through the operation of one or more valves included in the fluid control unit.

5. The borehole clamping system of claim 1 wherein pressure used to operate the pressure actuated clamp is provided via wellbore pressure.

6. The borehole clamping system of claim 1 wherein the fluid control unit includes a pressure converter for increasing a pressure used to actuate the pressure actuated clamp.

7. A method of operating a clamping system within a borehole, the method comprising the steps of: (a) providing a pressure actuated clamp for clamping a sensor assembly in a borehole;(b) providing a fluid to the pressure actuated clamp, and controlling a pressure of the fluid, via a fluid control unit included within the borehole; and(c) controlling, via a surface electrical control unit, flow of the fluid from the fluid control unit to the pressure actuated clamp.

8. The method of claim 7 wherein the surface electrical control unit controls flow of the fluid from the fluid control unit to the pressure actuated clamp through the operation of one or more valves included in the fluid control unit.

9. The method of claim 7 wherein pressure used to operate the pressure actuated clamp is provided via wellbore pressure.

10. The method of claim 7 wherein the fluid control unit includes a pressure converter for increasing a pressure used to actuate the pressure actuated clamp.

11. A borehole clamping system comprising: a pressure actuated clamp for clamping a sensor assembly in a borehole, the pressure actuated clamp configured to be operated using wellbore pressure.

12. The borehole clamping system of claim 11 further comprising a fluid control unit configured for use within the borehole, the fluid control unit providing a fluid to the pressure actuated clamp, and controlling a pressure of the fluid.

13. The borehole clamping system of claim 12 wherein the fluid control unit includes a pressure converter for increasing a pressure used to actuate the pressure actuated clamp.

14. The borehole clamping system of claim 12 further comprising a surface electrical control unit for controlling flow of the fluid.

15. The borehole clamping system of claim 14 wherein the surface electrical control unit controls flow of the fluid through the operation of one or more valves included in the fluid control unit.

16. The borehole clamping system of claim 12 wherein the fluid is an incompressible fluid.

17. The borehole clamping system of claim 12 wherein the fluid is a hydraulic fluid.

18. A method of operating a clamping system within a borehole, the method comprising the steps of: (a) providing a pressure actuated clamp for clamping a sensor assembly in a borehole; and(b) operating the pressure actuated clamp via wellbore pressure.

19. The method of claim 18 further comprising the step of providing a fluid to the pressure actuated clamp, and controlling a pressure of the fluid, via a fluid control unit included within the borehole.

20. The method of claim 19 further comprising the step of controlling, via a surface electrical control unit, flow of the fluid from the fluid control unit to the pressure actuated clamp.

21. The method of claim 20 wherein the surface electrical control unit controls flow of the fluid from the fluid control unit to the pressure actuated clamp through the operation of one or more valves included in the fluid control unit.

22. The method of claim 19 wherein the fluid control unit includes a pressure converter for increasing a pressure used to actuate the pressure actuated clamp.