1. Field of the Invention
The present invention is generally directed to the field of offshore well drilling, and, more particularly, to a lightweight, reusable temporary abandonment cap that can be placed on and retrieved from an open pipe of a subsea well.
2. Description of the Related Art
Drilling of offshore oil and gas wells is a very expensive and time-consuming activity. Moreover, when drilling and/or completing such wells, there may be many occasions, both planned and unexpected, where it is desirable to temporarily suspend drilling or completion activities at a well. As part of this process, a temporary abandonment cap is installed to aid in protecting the wellhead during this period of inactivity. Typically, a portion of the well bore will be filled with a liquid corrosion inhibitor to displace the seawater within the bore such that certain surfaces, e.g., sealing surfaces, are not corroded by the seawater or otherwise subjected to the formation of undesirable marine growth, e.g., algae. The temporary cap is used in an effort to keep the corrosion inhibitor fluid in the bore until such time as it is desired to resume drilling and/or completion activities at the well.
Some prior art temporary caps were locked to the wellhead by a plurality of sacrificial pins. See, for example, U.S. Pat. No. 5,107,931 (Valka et al.) for an example of such a temporary cap. Some prior art temporary abandonment caps were comprised of a relatively heavy steel body and they were deployed from a surface vessel or rig via a drill string. The cap 12 depicted in
In operation, to run the temporary cap 12 down to the well, the tool 10 is secured to the temporary cap 12 of the Valka patent by positioning the stem 22 (see
In other cases, the running and retrieve tool 10 shown in
U.S. patent application Ser. No. 2002/0000322A1 (Bartlett et al., Jan. 3, 2002) depicts a situation in which a debris cap 460 is used in conjunction with an internal tree cap 458. See, e.g., FIGS. 13, 16 and 17 and the associated discussion thereof The debris cap performs a variety of functions. For example, the debris cap 460 is used to protect various sealing surfaces on the exposed end of the Christmas tree. The debris cap 460 also serves to prevent debris from collecting in the annular area between the internal tree cap and the tree bore.
Despite prior efforts, there still exists a need for temporary abandonment caps that may be readily deployed by means of an ROV. Moreover, such a temporary cap should provide means for supplying desired fluids to the well bore in a timely and efficient manner.
The present invention is directed to an apparatus for solving, or at least reducing the effects of, some or all of the aforementioned problems.
The present invention is directed to a lightweight, reusable temporary abandonment cap that can be placed on and retrieved from an open pipe of a subsea well. In one illustrative embodiment, the present invention is directed to a well cap comprised of a body, a pressure-retaining top portion extending across the body, and a plurality of locking pins coupled to the body and a single moveable handle, the plurality of locking pins adapted to be moved from an engaged position to a disengaged position by movement of the single moveable handle.
In another illustrative embodiment, the well cap is comprised of a body, a pressure-retaining top portion extending across the body, a plurality of locking pins coupled to the body and a single moveable handle, wherein the plurality of locking pins are adapted to be moved from an engaged to a disengaged position by movement of the single moveable handle. The well cap further comprises a plurality of check valves coupled to the top portion of the cap and a hot stab manifold coupled to the top portion of the cap, wherein the hot stab manifold is coupled to at least one of the valves such that a fluid may be introduced into a well via the hot stab manifold and the valve, and a conical portion coupled to the body at an end opposite the top portion.
In yet another illustrative embodiment, the well cap is comprised of a body, a pressure-retaining top portion extending across the body, a plurality of locking pins coupled to the body and a single moveable handle, the plurality of locking pins adapted to be moved from an engaged to a disengaged position by movement of the single moveable handle. The cap is further comprised of a plurality of check valves coupled to the top portion, a hot stab manifold releasably coupled to the top portion, wherein the hot stab manifold is coupled to at least one of the valves such that a fluid may be introduced into a well via the hot stab manifold and the valve, and a pipe extension in fluid communication with one of the check valves, wherein the pipe extension has an open end that is positioned below the top portion.
The invention may be understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements, and in which:
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.
The cap 50 further comprises two lock pins 68 that are operatively coupled to the movable handle 60. The lock pins 68 are positioned within a housing 70 having a groove 72 (see
The components of the cap 50 are generally comprised of carbon steel. For example, the cylindrical body 54 and the conical portion are comprised of ⅜″ or ½″ plate steel rolled, welded and cut to the desired size. The top portion 56 may be comprised of approximately ⅛″-{fraction (3/16)}″ steel plate. The temporary cap 20 is not exposed to well pressures, thus the top portion 56 may be relatively thin. In operation, a differential pressure of less than approximately 0.33 psi will be applied across the top portion 56. This differential pressure is due to the presence of the lighter, anti-corrosive fluid in the well bore. The movable handle 60 and the fixed handle 61 may be made of ¾″ bar stock material that is formed as desired. The physical size of the temporary cap 50 may vary depending upon the application. In one embodiment, the body of the cap 50 has a height 71 of approximately 8 inches, a diameter 73 of approximately 27.4 inches and an overall footprint as defined by a first dimension 75A of approximately 37.5 inches and a second dimension 75B of approximately 32.5 inches.
The size, shape and configuration of the openings 62 may vary. The purpose of the openings 62 is to reduce the overall weight of the cap 50 such that ROV deployment and retrieval may be easier. Thus, the particular size, shape and configuration of the openings 62 should not be considered a limitation of the present invention unless such limitations are expressly set forth in the appended claims. Moreover, the relative location of the valves 66A, 66B and the hot stab manifold assembly 76 may be varied depending upon the application. The hot stab manifold assembly 76 may be hard plumbed to, for example, the check valve 66A, although that is not depicted in the attached figures. The length 79 (see
In
In operation, the cap 50 may be lowered into the water by means of a cable (not shown) attached to the fixed handle 61 or the moveable handle 60 when it is in its upright position. The cap 50 is lowered until such time as an ROV is able to grasp the moveable handle 60 (in its upright position) and transport the cap 50 to the wellhead. The movable handle 60 is in its upright position (not shown) prior to being positioned on the well. With the movable handle 60 in the upright position, the lock pins 68 are in their retracted, non-extended, non-engaged position by virtue of the camming action resulting from the cam pins 74 moving within the grooves 72 when the movable handle 60 was raised to its upright position. The shape and configuration of the moveable handle 60 is such that it can accommodate the linear travel of the lock pins 68 associated with this camming action. The conical portion 58 of the cap 50 is used to assist in the positioning of the cap 50 over the wellhead. Once the temporary cap 50 is properly positioned on the well, the ROV may be used to move the movable handle 60 to the closed or locked position shown in
Once the temporary cap 50 is properly seated and locked on the well, the next operation involves injecting an anti-corrosion fluid into the well through the connections provided on the cap 50. More specifically, an injection probe of the ROV is mated with the hot stab manifold assembly 76 to allow injection of a quantity of the anti-corrosive fluid on board the ROV to be injected into the well. As mentioned previously, in one illustrative example, the hot stab manifold assembly 76 is hard plumbed to the check valve 66A. The anti-corrosive fluid is injected into the well via the hot stab manifold 76 and the check valve 66A, as indicated by the arrows 81 (see FIG. 4B). Since the anti-corrosive fluid is typically lighter than sea water, the injected fluid will tend to collect immediately under the cap 50. As more of the anti-corrosive fluid is injected, the sea water in the well is ejected out of the well via the pipe extension 63 and the check valve 66B, as indicated by the arrows 83. This process is continued until such time as substantially all of the sea water within the well for a depth corresponding to the length 79 of the pipe extension 63 is displaced by the anti-corrosive fluid. That is, the process may be continued until such time as the anti-corrosive fluid is observed exiting the well via the check valve 66B.
The length 79 of the pipe extension 63 is based upon the desired amount of coverage of the anti-corrosive fluid within the well. This is normally determined by the depth of the surfaces within the well that are desired to be protected. Moreover, it should be understood that the fluid injected into the well may be of any type. For example, in lieu of, or in addition to, the anti-corrosive fluid, a fluid may be injected for purposes of reducing marine growth on certain surfaces within the well.
To remove the cap 50, an ROV is used to grasp and move the moveable handle 60 from its closed position, shown in
The embodiments of the cap 50 depicted in
The present invention is generally directed to a temporary well abandonment cap. In one illustrative embodiment, the present invention is directed to a well cap comprised of a body, a pressure-retaining top portion extending across the body, and a plurality of locking pins coupled to the body and a single moveable handle, the plurality of locking pins adapted to be moved from an engaged position to a disengaged position by movement of the single moveable handle.
In another illustrative embodiment, the well cap is comprised of a body, a pressure-retaining top portion extending across the body, a plurality of locking pins rotatably coupled to the body and fixedly coupled to a single moveable handle, wherein the plurality of locking pins can be moved from an engaged to a disengaged position by movement of the single moveable handle. The well cap further comprises a plurality of check valves and a hot stab manifold coupled to the top portion, the hot stab manifold being coupled to at least one of the valves such that a fluid may be introduced into a well via the hot stab manifold and the valve, and a conical portion coupled to the body at an end opposite the top portion.
In yet another illustrative embodiment, the well cap is comprised of a body, a pressure-retaining top portion extending across the body, a plurality of locking pins coupled to the body and a single moveable handle, wherein the plurality of locking pins can be moved from an engaged to a disengaged position by movement of the single moveable handle. In this embodiment, the cap further comprises a plurality of check valves coupled to the top portion and a hot stab manifold releasably coupled to the top portion, the hot stab manifold being coupled to at least one of the valves such that a fluid may be introduced into a well via the hot stab manifold and the valve, a pipe extension in fluid communication with one of the check valves, the pipe extension having an open end that is positioned below the top portion, and a conical portion coupled to the body at an end opposite the top portion.
The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. For example, the process steps set forth above may be performed in a different order. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below.
Number | Name | Date | Kind |
---|---|---|---|
4405016 | Best | Sep 1983 | A |
4423983 | Dadiras et al. | Jan 1984 | A |
4544036 | Saliger | Oct 1985 | A |
4881597 | Hensley | Nov 1989 | A |
5107931 | Valka et al. | Apr 1992 | A |
5992526 | Cunningham et al. | Nov 1999 | A |
6494257 | Bartlett et al. | Dec 2002 | B2 |
6494266 | Rogala et al. | Dec 2002 | B2 |
20020000322 | Bartlett et al. | Jan 2002 | A1 |
20020088622 | Beall et al. | Jul 2002 | A1 |
Number | Date | Country |
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2 330 160 | Apr 1999 | GB |
WO 9516102 | Jun 1995 | WO |
WO 9928593 | Jun 1999 | WO |
Number | Date | Country | |
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20040040702 A1 | Mar 2004 | US |