BACKGROUND
The present invention relates to subterranean operations and, more particularly, to a method and system for opening and closing a subsurface valve used in conjunction with such operations.
Hydrocarbons, such as oil and gas, are commonly obtained from subterranean formations that may be located onshore or offshore. The development of subterranean operations and the processes involved in removing hydrocarbons from a subterranean formation are complex. Typically, subterranean operations involve a number of different steps such as, for example, drilling a wellbore at a desired well site, treating the wellbore to optimize production of hydrocarbons, and performing the necessary steps to produce and process the hydrocarbons from the subterranean formation.
When performing subterranean operations, it may be desirable to close off a well in the event of an uncontrolled condition that may damage property, injure personnel or cause pollution. One of the mechanisms used to close off a well is a Surface Controlled Subsurface Safety Valve (“SCSSV”). An SCSSV typically includes a flapper. The flapper is a closure member that may be pivotally mounted such that it is rotatable between a first “open” position and a second “closed” position. When in the closed position, the flapper may close off the well. However, SCSSVs are often made with many small, specialized parts that are costly to implement and/or replace.
It would be advantageous to have a fail-safe SCSSV that may be installed without the use of small, specialized parts. This would reduce costs and increase efficiency.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 depicts a general view of an SCSSV installed in a wellbore in accordance with an illustrative embodiment of the present disclosure;
FIGS. 2A and 2B show an SCSSV in accordance with an illustrative embodiment of the present disclosure;
FIGS. 3A and 3B show a flapper valve assembly in accordance with an illustrative embodiment of the present disclosure where the flapper is in an open position;
FIGS. 4A and 4B show a flapper valve assembly in accordance with an illustrative embodiment of the present disclosure where the flapper is in a closed position; and
FIG. 5 shows an exemplary wave spring that may be employed in any of the embodiments of the present disclosure.
While embodiments of this disclosure have been depicted and described and are defined by reference to examples set forth in the disclosure, such references do not imply a limitation on the disclosure, and no such limitation is to be inferred. The subject matter disclosed is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those skilled in the pertinent art and having the benefit of this disclosure. The depicted and described embodiments of this disclosure are examples only, and not exhaustive of the scope of the disclosure.
DETAILED DESCRIPTION
The terms “couple” or “couples,” as used herein are intended to mean either an indirect or a direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect mechanical connection via other devices and connections. The terms “up” or “uphole” as used herein means along the drillstring or the hole from the distal end toward the surface, and “down” or “downhole” as used herein means along the drillstring or the hole from the surface toward the distal end. Further, the terms “up”, “uphole”, “down” and “downhole” are merely used to denote the relative location of different components and are not meant to limit the present disclosure to only a vertical well. Specifically, the present disclosure is applicable to horizontal, vertical, deviated or any other type of well.
It will be understood that the term “well” is not intended to limit the use of the equipment and processes described herein to developing an oil well. The term also encompasses developing natural gas wells or hydrocarbon wells in general. Further, such wells can be used for production, monitoring, or injection in relation to the recovery of hydrocarbons or other materials from the subsurface.
Referring now to FIG. 1, oil well drilling equipment used in an illustrative drilling and completion environment is shown. A cross-sectional view of a wellbore 116 that has been drilled with casing 128 and tubing 126 in accordance with certain embodiments of the present disclosure is denoted generally with reference numeral 100. A drilling platform 102 supports a derrick 104 having a traveling block 106 for raising and lowering a drill string (not shown), wireline, slickline, or coiled tubing. An annulus 132 is formed between the casing 128 and the formation 130. Cement 118 is pumped down the wellbore 116, e.g., through the interior of the casing 128 and up through the annulus 132 where it sets and holds the casing 128 in place. The cement 118 may be directed downhole using a cement pumping unit (not shown) or other types of rig pumping equipment (not shown), as appropriate. The casing 128 and tubing 126 may be concentric tubes inside the wellbore 116. An SCSSV 120 may be installed in the wellbore 116 with tubing 126 coupled to each side as shown in FIG. 1. In such embodiments, the SCSSV 120 would be semi-permanently installed in the wellbore 116. In order to remove the SCSSV 120, the entire string of tubing 126 may be removed from the wellbore 116. In other embodiments, not shown in FIG. 1, the SCSSV 120 may be installed in the wellbore 116 on wireline, coiled tubing, or some other semi-flexible work string. In such embodiments, the SCSSV 120 may be installed in a profile that is communicatively coupled to a control line (not shown) that runs to the surface of the wellbore 116.
Turning now to FIG. 2A, an SCSSV in accordance with an illustrative embodiment of the present disclosure is denoted generally with reference numeral 200. In the embodiment shown in FIG. 2A, the flapper 206 is shown in a first open position. The SCSSV 200 includes a rod piston 202 disposed within a housing 204. For illustrative purposes, SCSSV 200 of FIG. 2A may have a first distal end 202A, a middle portion 202B and a second distal end 202C. The rod piston 202 may be coupled to a tubing member 216. A seat 214 in a valve housing (not shown) may surround the tubing member 216. A flapper 206 may be pivotally mounted to a first connector beam 210 such that the flapper 206 is rotatable between an open position and a closed position. In the embodiment shown in FIG. 2A, the flapper 206 is shown in an open position.
In operation of the SCSSV 200, a control line 220 may be coupled to the rod piston 202. The control line may deliver pressure to the rod piston 202 from the surface or from a desirable subsurface location. Pressure from the rod piston 202 may hold the tubing member 216 in place and in engagement with the flapper 206. Thus, when the flapper 206 is in the open position, it may be held in contact with the tubing member 216. The flapper 206 is shown in further detail in FIGS. 2A-2B and FIGS. 3A-3B. If it is desirable to close the flapper 206, the pressure applied to the rod piston 202 may be reduced or eliminated. In some embodiments, pressure may be applied to the control line 220 which communicates with the rod piston 202 at surface or from a desirable subsurface location prior to deployment of the SCSSV 200. Pressure may be maintained throughout deployment to verify integrity of the control system and SCSSV 200. Thus, in order to close the flapper 206, the operator may alter the pressure applied to the control line at the surface. In other embodiments, the flapper 206 may be mechanically propped open during installation. Thus, in order to close the flapper 206 in those embodiments, the operator may retract the mechanical prop to the surface. Either of these scenarios may allow the spring 202B to partially decompress, allowing the tubing member 216 to move uphole. The tubing member 216 thus may be disengaged from the flapper 206. This in turn may allow a wave spring 318 to partially decompress, causing the flapper 206 to close. Thus, the wave spring 318 may rotate the flapper between its open and closed positions. This is shown in further detail in FIGS. 2B, 3A, and 3B. An exemplary wave spring 500 is shown in further detail in FIG. 5.
The wave spring 318 may be made from flat wire, and may include waves that are in contact with each other, as shown in further detail by the exemplary wave spring 500 in FIG. 5. The waves may deflect during compression. A coiled spring, by contrast, may be manufactured from round or square wire that is coiled into a desired shape. As a coiled spring is compressed, the coils get closer together. There are several advantages associated with using the wave spring 318 rather than a coiled spring in an SCSSV application. First, the shorter size of the wave spring 318 compared to a coiled spring that is able to deliver the same operating load makes the wave spring 318 more desirable because of the limited space available in the SCSSV and in the wellbore 116. In other words, the wave spring 318 may be able to provide the same operating loads as a coiled spring but using a shorter design. Thus, the wave spring 318 may provide a greater operating load than a coiled spring of the same length and diameter. Second, use of a wave spring 318 allows the motion of the flapper 206 to be more controlled and adjustable as compared to using a coiled spring. The wave spring 318 may be of any length, so that the speed and motion of the flapper 206 closure may be controlled as desired. Third, an SCSSV that includes a wave spring 318 as provided in the present disclosure requires fewer components than previous SCSSVs that included a coiled spring. Therefore, the SCSSV is less expensive to replace and manufacture.
Turning now to FIG. 2B, the flapper 206 of FIG. 2A is shown in the closed position. When the flapper 206 is in the closed position, it may engage with the seat (not shown in FIG. 2B), creating a seal in the wellbore.
Turning now to FIGS. 3A and 3B, a flapper valve assembly in accordance with an illustrative embodiment of the present disclosure is denoted generally with reference numeral 300. FIG. 3B depicts a cross-sectional view. In the embodiment shown in FIGS. 3A and 3B, the flapper 206 is shown in the open position. In certain illustrative embodiments, a collapsible member 308 may be coupled to the flapper 206. The connector beam 210 may be coupled to the collapsible member 308. The collapsible member 308 is shown in a collapsed position. A wave spring housing 312 may be coupled to the connector beam 210. The wave spring housing 312 includes a wave spring 318, which may be in an at least partially compressed position when the flapper 206 is in the open position. In other words, the wave spring housing 312 may surround or contain the wave spring 318. The wave spring 318 may be in a compressed position, and therefore may exert force on the connector beam 210 and the collapsible member 308. However, the tubing member 216 may be engaged with the flapper 206 and may prevent it from closing. Thus, the tubing member 216 is engaged with the flapper 206 when the flapper 206 is in the open position, as shown in FIGS. 3A and 3B.
In operation of the system 300, when a well operator desires to shut off the well, pressure may be removed from the rod piston 202 at the surface. Thus, the tubing member 216 may move uphole, allowing the tubing member 216 to disengage from the flapper 206 and thus removing support from the flapper 206. This may allow the wave spring 318 to partially decompress and the flapper 206 to close, engaging with the seat 214.
Turning now to FIGS. 4A and 4B, a flapper valve assembly in accordance with another illustrative embodiment of the present disclosure is denoted generally with reference numeral 400. FIG. 4B depicts a cross-sectional view. In the embodiment shown in FIGS. 4A and 4B, pressure has been removed from the rod piston 202, allowing the tubing member 216 to disengage from the flapper 206. Thus, the force exerted from the wave spring 318 on the connector beam 210 and the collapsible member 308 may allow the collapsible member 308 to extend, pushing the flapper 206 into a closed position. Thus, in FIGS. 4A and 4B, the wave spring 318 is shown in a partially decompressed position, the collapsible member 308 is shown in an extended position, and the flapper 206 is shown in a closed position such that it is engaged with the seat 214.
In existing SCSSVs, debris may prevent the flapper closure mechanism from functioning properly and may have prevented flapper 206 from engaging with the seat 214 and closing completely. In contrast, in the improved design disclosed herein, the wave spring housing 312 and wave spring 318 may be located uphole of the flapper 206. As a result, unlike typical prior art SCSSV designs, the flapper closure mechanism disclosed herein is located outside of the direct debris path of the wellbore 116 because the wave spring housing 312 and wave spring 318 may be located uphole of the flapper 206.
As would be appreciated by those of ordinary skill in the art, the methods and systems disclosed herein may be applicable to more than just SCSSVs. Accordingly, any reference to a “tubing member” is made for illustrative purposes only and is intended to generically refer to a part of a tool that is actuated by a rod piston of a control system.
The present invention is therefore well-adapted to carry out the objects and attain the ends mentioned, as well as those that are inherent therein. While the disclosure has been depicted, described and is defined by references to examples of the disclosure, such a reference does not imply a limitation on the disclosure, and no such limitation is to be inferred. The disclosure is capable of considerable modification, alteration and equivalents in form and function, as will occur to those ordinarily skilled in the art having the benefit of this disclosure. The depicted and described examples are not exhaustive of the disclosure. Consequently, the disclosure is intended to be limited only by the spirit and scope of the appended claims, giving full cognizance to equivalents in all respects.
Patent Application
20160222757
