Downhole safety valve assembly having sensing capabilities

An apparatus that is usable with a subterranean well includes a safety valve assembly and a pressure/temperature sensor. The safety valve assembly is controllable to selectively isolate a formation of a well from the surface of the well. The pressure/temperature sensor is located in the safety valve assembly to measure a pressure/temperature near the safety valve assembly.

BACKGROUND

The invention relates generally to a downhole safety valve assembly that has sensing capabilities, such as, for example, a safety valve assembly that has at least one temperature and/or pressure sensor.

A typical subterranean well includes a formation isolation valve, or safety valve, for purposes of providing a failsafe mechanism to isolate one or more downhole formations from the surface of the well. A typical safety valve may be formed from a flapper element that is located inside a tubular string and is biased to close off a central passageway of the string. The flapper element may be opened by a flow tube.

More specifically, a conventional safety valve assembly may include a flapper valve element and a hydraulically-actuated flow tube. When communication is desired between the surface and the formation(s) below the safety valve, the flow tube is actuated to force the flapper valve element open. However, when this communication is no longer desired, the flow tube is actuated to retract, a retraction that allows the flapper element to return to its normally closed position to isolate the formation(s) from the surface of the well.

A difficulty in using the above-described arrangement is that downhole seals, such as seals associated with hydraulic control lines that control movement of the flow tube, may potentially fail. Although safety valve assemblies have been designed to accommodate potential seal failure, an operator at the surface of the well may be unaware of such a failure or the specific type of failure, as the safety valve assembly typically is located far (approximately 10,000 feet or more downhole, for example) from the surface of the well.

SUMMARY

In an embodiment of the invention, an apparatus that is usable with a subterranean well includes a safety valve assembly and a pressure sensor. The safety valve assembly is controllable to selectively isolate a formation of the well from the surface of the well. The pressure sensor is located in the safety valve assembly to measure a pressure near the safety valve assembly.

In another embodiment of the invention, an apparatus that is usable with a subterranean well includes a safety valve assembly and a temperature sensor. The safety valve assembly is controllable to selectively isolate a formation of the well from the surface of the well. The temperature sensor is located in the safety valve assembly to measure a temperature near the safety valve assembly.

Advantages and other features of the invention will become apparent from the following description, drawing and claims.

DETAILED DESCRIPTION

Referring toFIG. 1, an embodiment of a subterranean well10in accordance with the invention includes a tubular string, such as a production tubing string14, that extends downhole into the well10. As depicted inFIG. 1, in some embodiments of the invention, the well10may be cased, and thus, the production tubing string14may extend downhole inside a casing string12that lines a borehole of the well10.

The tubing string14includes a safety valve assembly18that may be remotely operated from the surface of the well10for purposes of selectively isolating one or more formations below the valve18from the surface of the well10. In some embodiments of the invention, the safety valve assembly18may be located miles (more specifically, 5,000-10,000 feet or more, for example) from the surface of the well10. Due to this distance from the surface, an operator of the well10may only speculate as to the condition of the well at the depth of the safety valve assembly18, if not for the features of the present invention.

More specifically, in accordance with an embodiment of the invention, the safety valve assembly18includes one or more pressure sensors20that are integrated into the safety valve assembly18and are constructed to measure various pressures downhole. For example, in some embodiments of the invention, some of the pressure sensors20may measure pressures connected with hydraulic control lines22and24that are used to operate the safety valve assembly18.

As another example, in some embodiments of the invention, one or more of the pressure sensors20may measure a pressure present in an annulus15of the well20. As used herein, the term “annulus” means the region of the well that surrounds the tubing string14and is generally defined between the outer region surrounding the safety valve assembly18and the interior wall of the casing string12(assuming the well10is cased).

As yet another example, in some embodiments of the invention, one or more of the pressure sensors20may measure the pressure of fluid flowing through a central passageway, of the tubing string14. Thus, the safety valve assembly18contains one or more pressure sensors20that allow an operator at the surface of the well20to monitor potentially many different fluid pressures at the depth of the safety valve assembly18.

As depicted inFIG. 1, in some embodiments of the invention, the safety valve assembly18may communicate the measure pressure(s) with a monitoring circuit46that is located at the surface (surface may refer to a sea floor mounted system) of the well10. The monitoring circuit46may, for example, display the measured pressure(s), further process the measured pressure(s) and/or communicate the measured pressures to another location, as just a few examples.

The communication between the monitoring circuit46and the pressure sensor(s)20may occur, for example, via one or more telemetry lines47that extend between the safety valve assembly18and the surface of the well10. However, in other embodiments of the invention, other telemetry techniques may be used for purposes of establishing communication between the pressure sensors20and the monitoring circuit46.

For example, depending on the particular embodiment of the invention, electromagnetic communication (via formation-communicated waves or waves communicated via the production tubing string14or casing string20, for example); fluid pulse communication (via fluid in the annulus15or fluid in a column of fluid present in a control passageway of the production tubing string14, for example); or acoustic communication (communication via the well of the production tubing string14, for example) may be used. Thus, many different telemetry techniques may be used to communicate the measured pressure(s) between the sensor(s)20of the safety valve assembly18and the monitoring circuit46, in accordance with the many possible embodiments of the invention.

In some embodiments of the invention, the state (open or closed) of the safety valve assembly18may be controlled by the hydraulic control lines22and24. More specifically, the hydraulic control line22communicates hydraulic fluid between the surface of the well10and the safety valve assembly18. As described below, the hydraulic fluid in the hydraulic control line22exerts a control pressure (called Pc) that, when at the appropriate level (relative to a Pbbalance pressure described below), places the safety valve assembly18in its open state. The control pressure Pcis controlled by a hydraulic source42that is located at the surface of the well10, for example.

The hydraulic control line24also communicates hydraulic fluid between the surface of the well10and the safety valve assembly18. As described below, the hydraulic fluid in the hydraulic control line24exerts a balance pressure (called Pb). The balance pressure Pbis exerted (and thus, is controlled by) a hydraulic source44that is located at the surface of the well10.

The open and closed states of the safety valve assembly18are controlled by the Pband Pcpressures. More specifically, when the Pccontrol pressure exceeds the Pbbalance pressure by a certain threshold, the safety valve assembly18is placed in its open state. Otherwise, the safety valve assembly18is in its closed state.

As further described below, in some embodiments of the invention, the safety valve assembly18may have various failsafe aspects to accommodate the scenario in the control hydraulics for the valve assembly18fail. In other words, these failsafe aspects ensure that the safety valve assembly18is closed if one or more seals of the safety valve or control system assembly18should fail.

Still referring toFIG. 1, among the other features of the well10, in some embodiments of the invention, a wellhead40may be coupled to the upper end of the production tubing string14for purposes of directing well fluid from the string14to a pipeline, well processing equipment, etc. Furthermore, in some embodiments of the invention, the well10may include one or more lateral wellbores, such as a lateral wellbore32in which a horizontal liner30laterally extends from the casing string12.

Thus, as depicted inFIG. 1, in some embodiments of the invention, the production tubing string14may extend into this lateral wellbore and may include, for example, a “smart” production control valve38that includes sensors and at least one valve for purposes of controlling production from the associated zone. As depicted inFIG. 1, in some embodiments of the invention, this zone may be created via a packer34that seals off an annulus between the string14and the corresponding liner30.

In some embodiments of the invention, the well10may include additional packers, such as, for example, a packer17that is located near the safety control valve assembly18.

Integrating pressure measurements with the safety valve assembly18provides real data to the surface of the well10to enhance the operator's ability to “know-the-well.” Thus, the collection of the pressure data at the surface of the well aids in selecting well operations for enhanced production, as well as providing knowledge as to the operation of the hydraulics at the safety valve setting depth location. The use of this technique greatly simplifies the typical “guess work” of troubleshooting well performance properties, by providing valid in-the-well-data upon which decisions may be based. Additionally, the ability to measure the pressures above and below the closure mechanism offers better controls over the application of pressures to equalize the loading on the closure mechanism to allow free movement of the closure thereby minimizing the forces required for this action. Therefore, the time and cost of such operations are minimized.

As a more specific example,FIG. 2depicts a possible embodiment of the safety valve assembly18. As depicted inFIG. 2, in some embodiments of the invention, the safety valve assembly18may be a “flapper valve” assembly, in that the safety valve assembly18typically includes a flapper valve closure element74to control communication between a central passageway78(of the safety valve assembly18) above the flapper valve element74and a central passageway79(of the safety valve assembly18) below the flapper valve element74. The central passageway78and79are concentric with the portions of the tubing string14immediately above and below the safety valve assembly18.

In its closed state (the state depictedFIG. 2), the flapper valve element74blocks communication between the central passageways78and79. This is the normal state of the safety valve assembly18in that in some embodiments of the invention the flapper valve element74is biased to remain closed. Although biased to remain closed, the flapper valve element74is constructed to pivot about a pivot connection76in a counterclockwise direction to open communication between the central passageways78and79(and thus, open the safety valve assembly18) when a flow tube64(of the safety valve assembly18) exerts a downward force on the flapper element74.

More particularly, as described below, to open the safety valve assembly18, hydraulics of the assembly18move the flow tube64in a downward direction so that the flow tube64pushes the flapper valve element74downwardly (and thus, pivots the flapper valve element74in a counterclockwise direction about the pivot point76) to open communication between the central passageways79and78. In some embodiments of the invention, the flow tube64may be formed from sections of different diameters so that the flow tube64is a telescoping tube.

For purposes of moving the flow tube64in a downward direction to open the flapper valve element74, the safety valve assembly18includes a first input control port70that is connected to the hydraulic line22(to receive the Pccontrol pressure) and a second input control port72that is connected to the hydraulic control line24(to receive the Pbbalance pressure). The ports70and72may be extend through a housing62(formed from one or more connected pieces) of the safety valve assembly18.

The difference between the Pccontrol pressure and the Pbbalance pressure controls operation of a flow tube actuator60of the safety valve assembly18. Thus, depending on the relationship between the Pcand Pbpressures, the flow tube actuator60either keeps the flow tube64in the position depicted inFIG. 2(to keep the safety valve assembly18closed) or moves the flow tube64in a downward direction to pivot the flapper valve element74(to open the safety valve assembly18).

As depicted inFIG. 2, in some embodiments of the invention, the safety valve assembly18may include the housing62that generally houses the flow tube actuator60(disposed in a side pocket65of the housing62) as well as the flow tube64that is concentric with the central passageway of the housing62. Furthermore, the pivot point76may attached to the housing62.

As shown inFIG. 2, in some embodiments of the invention, the pressure sensor(s)20may be located in a side pocket65of the safety valve assembly18. Thus, in some embodiments of the invention, the pressure sensor(s)20may be located in close proximity (within 5 feet, for example) to the valve closure element of the safety valve assembly18, such as the flapper valve element74. As depicted inFIG. 2, in some embodiments of the invention, the pressure sensor(s)20may be located in the housing62near the one or more pistons that drive the flow tube64of the safety valve assembly18. However, the pressure sensor(s)20may be located in other parts of the safety valve assembly18, in other embodiments of the invention. Thus, many variations are possible and are within the scope of the appended claims.

It is noted that other types of safety valves may be used in other embodiments of the invention. For example, althoughFIG. 2depicts a flapper-type safety valve assembly, in other embodiments of the invention, a safety valve that uses a ball valve as a valve element may be used. Furthermore, in some embodiments of the invention, the safety valve assembly18may include multiple valve elements (multiple flapper valve or ball valve elements, for example) to provide redundancy for the safety valve assembly18. Thus, many variations are possible and are within the scope of the appended claims.

FIG. 3depicts one out of many possible embodiments for the flow tube actuator60in accordance with an embodiment of the invention. Referring toFIG. 3, the flow actuator60includes a piston160that is attached to the flow tube64through a mechanical connection (not shown) through an opening184in the housing62. The piston160is constructed to move (and thus, move the flow tube64) in response to a difference between the Pccontrol pressure (appearing in a control pressure chamber170) and the Pbbalance pressure (appearing in a balance pressure chamber180).

More specifically, in some embodiments of the invention, when the Pccontrol pressure exerts a force (on a top surface161of the piston160) that is greater than the weight of the piston160and the force that is exerted by the Pbbalance pressure (on the bottom surface162of the piston160), the piston160moves in a downward direction to open the flapper valve element74(seeFIG. 2). Conversely, when the Pccontrol pressure exerts a force on the piston160, which is less than the combined weight of the piston160and the force that is exerted on the piston160by the Pbbalance pressure, the piston160moves in an upward direction to permit the flapper valve element74to close. In some embodiments of the invention, the flow actuator60may include a spring and or a gas accumulator acting as a spring (not shown) to exert an upward force on the piston160to allow the flapper valve element74to close if the forces that are exerted on the piston160are otherwise balanced.

As depicted inFIG. 3, in some embodiments of the invention, the flow actuator60includes a passageway122in the housing62to communicate the Pccontrol pressure to the control pressure chamber170and a passageway124in the housing62to communicate the Pbbalance pressure to the balance pressure chamber180. The flow actuator60may also include a failsafe passageway130that is in fluid communication with the passageway124to control the movement of the piston60in the event of a seal failure, as further described below.

In some embodiments of the invention, the flow actuator60includes a first seal140, a second seal150, and a third seal163around the piston60. The seals140,150,163isolate the control chamber170, balance chamber180and the central passageway of the production tubing string14from each other. The piston60is exposed to the central passageway of the string14at the opening184so that a mechanical connection may be made between piston60and the flow tube64. The opening184is positioned between the second seal150and the third seal163. The failsafe passageway130is located between the first seal140and the third seal163.

With this particular configuration, if the second seal150fails, then fluid from inside the tubing string14travels past the second seal150and exerts equal and opposite forces on the first and third seals140and163. Furthermore, fluid from inside the tubing string14travels directly to the third seal163and exerts an upward force on the seal163to exert a net upward force on the piston60. By decreasing the control pressure to Pcthat acts on piston60at the upper surface161, the piston60moves upward, causing the flapper valve element34to close.

If the third seal163were to fail, then fluid from the production tubing string14travels past the third seal163, through the failsafe passageway130and into the passageway124to exert an upward force on the piston60via the lower surface162by virtue of the second seal150. Furthermore, fluid from the production tubing string14travels past the third seal163and exerts an upward force on the first seal140, thereby exerting a net upward force on the piston60to allow valve closure member30to close when the Pccontrol pressure decreases.

If the first seal140were to fail, then fluid from the hydraulic control line22travels past the first seal140and acts equally and oppositely on second and third seals150and163, as would fluid from the hydraulic control line24. As such, the net forces on piston60due to control pressure Pcand balance pressure Pbare zero. In some embodiments of the invention, a spring and or a gas accumulator acting as a spring (not shown) that keeps the flapper valve element34closed when the net forces on the piston60are otherwise zero lifts the flow tube64to close the safety valve assembly18.

If both first and third seals140and163were to fail, then fluid from the production tubing string14flows through the failsafe passageway130and into the passageway124to exert an upper force on the piston60. Fluid from the production tubing string14exerts a downward force on the piston60against the second seal150. Furthermore, fluid from the hydraulic control line24flows through failsafe passageway130and exerts a downward force on the second seal150, as well as exerts an upward force on second seal150in the normal manner through the control line24. Similarly, fluid from the control line22exerts both upward and downward forces on the second seal150. As such, the net forces due to fluid pressure on the piston60are zero and a spring (not shown) lifts the flow tube64to close the safety valve assembly18.

The safety valve assembly18is one out of many types of safety valve assemblies that may be used in accordance with embodiments of the invention. Thus, in accordance with the various embodiments of the invention, the safety valve assembly may or may not have the failsafe features that are described herein and may have different failsafe features than those that are described herein. Furthermore, in some embodiments of the invention, the safety valve assembly may not be hydraulically-actuated. Thus, although the safety valve assembly may take on various forms, the safety valve assembly includes at least one pressure sensor. More specific details regarding the basic operation of the safety valve assembly18in accordance with the embodiment that is depicted inFIGS. 2 and 3may be found in U.S. Pat. No. 6,513,594, entitled “Subsurface Safety Valve,” issued on Feb. 4, 2003.

As shown inFIG. 3, although pressure sensors may be located anywhere in the safety valve assembly18, in some embodiments of the invention, one or more pressure sensors20may be embedded in the flow actuator60. For example, in some embodiments of the invention, a pressure sensor20amay be located in the housing62near the chamber180for purposes of measuring, or sensing, the balance pressure Pb. As also depicted inFIG. 3, in some embodiments of the invention, a pressure sensor20bmay be located in the housing62near the chamber170to measure, or sense, the control pressure Pc. Likewise, in some embodiments of the invention, a pressure sensor20cmay be embedded in the housing62near the opening184for purposes of sensing, or measuring, pressure inside the tubing string14(seeFIG. 1).

Lastly, in some embodiments of the invention, a pressure sensor20dmay be located in the housing62and exposed to the annulus15(seeFIG. 1) for purposes of sensing, or measuring, annulus pressure. As shown inFIG. 3, in some embodiments of the invention, all of these various pressure sensors20a,20b,20cand20dmay electrically communicate with a telemetry circuit190. The telemetry circuit190may communicate with the monitoring circuit46(seeFIG. 1) via one or more telemetry lines193(as an example). Many variations are possible and are within the scope of the appended claims.

To summarize, in accordance with some embodiments of the invention, a technique250that is depicted inFIG. 4may be used to monitor downhole pressure. Pursuant to the technique250, one or more pressure sensors are embedded in a safety valve assembly, as depicted in block252. Pursuant to the technique250, the safety valve assembly is then run downhole and installed, as depicted in block254. The pressure sensor(s) are used (block258) to monitor at least one of the pressure of hydraulics of a safety valve, pressure inside a tubular string pressure and annulus pressure. Other variations are possible and are within the scope of the appended claims.

Sensors other than pressure sensors may be used in other embodiments of the invention. For example, referring toFIG. 5, in accordance with some embodiments of the invention, a safety valve assembly300has a similar design to the safety valve assembly18(seeFIG. 2, for example), with the exception that the safety valve assembly300includes one or more temperature sensors302. The temperature sensor(s)302may be located in various locations (i.e., control line, annulus and tubing temperatures) inside the safety valve assembly300, such as the pressure sensor locations (for example) that are described above. Furthermore, the temperature sensor(s)302may be in other locations to measure well fluid and hydraulic fluids (for example) within the well. The telemetry circuit190(FIG. 3) may be used to communicate measured temperature(s) from the temperature sensors302to the monitoring circuit46(FIG. 1) at the surface of the well.

Thus, depending on the particular embodiment of the invention, the safety valve assembly may include a combination of one or more pressure sensors and one or more temperature sensors; may include only one or more pressure sensors (and no temperature sensors); or may include only one or more temperature sensors (and no pressure sensors). Therefore, many variations are possible and are within the scope of the appended claims. It is noted that with the ability to measure temperature at the depth of the safety valve assembly, the operator at the surface of the well is provided with additional data to further “know-the-well” at this well depth.