CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 62/095,828, filed December 23, 2014, which is incorporated herein by reference.

BACKGROUND

[0002] The present disclosure relates generally to methods of abandoning a well.

More specifically, in certain embodiments the present disclosure relates to subsea abandonment apparatuses and associated methods and systems.

[0003] In order to provide adequate well control and to satisfy the statutory safety requirements of many jurisdictions around the world, most operating companies adopt the principle of ensuring that at least two independently verified barriers are in place at all times during the construction or suspension of wells. Conventional methods of suspending the well may involve the use of a Mobile Offshore Drilling Unit (MODU) to install completions through a marine riser and subsea blowout preventer (BOP) conduit. Typically these conventional methods require an enclosed conduit between the wellhead and the deployment unit to maintain primary well control and monitor fluid levels in the wellbore. Using these methods may require the MODU on-site throughout the completion installation or well suspension period when it could be better utilized drilling wells or performing other operations.

[0004] Other methods of suspending a well are discussed in U.S. Patent No. 7,438,135, the entirety of which is hereby incorporated by reference. Briefly, U. S. Patent No. 7,438,135 describes method of suspending a well that do not require the use of a BOP stack to supplement well control. Disadvantages of such method are that the barrier systems described therein may not be suitable for use in open water environments. In addition, the methods described therein include intensive high risk wireline operations to install and verify the barriers with no means to isolate the wellbore at the mudline in the event of downhole failure.

[0005] Improved methods of suspending, completing, and/or working over a well are described in PCT/US2014/058786, the entirety of which is hereby incorporated by reference.

[0006] While the methods described above may be applicable for, suspending, completing, and/or working over a well, it is desirable to develop a method of abandoning a well that is suitable for open water installation and does not require the use of a marine

SUMMARY

[0007] The present disclosure relates generally to methods of abandoning a well. More specifically, in certain embodiments the present disclosure relates to subsea abandonment apparatuses and associated methods and systems.

[0008] In one embodiment, the present disclosure provides a subsea abandonment assembly comprising: a well isolation module and a well abandonment module, wherein the well abandonment module is connected to the well isolation module.

[0009] In another embodiment, the present disclosure provides a subsea abandonment assembly system comprising: a subsea abandonment assembly, wherein the subsea abandonment assembly comprises a well isolation module and a well abandonment module, wherein the well abandonment module is connected to the well isolation module and a subsea well head, wherein the subsea abandonment assembly is installed on the subsea well head.

[0010] In another embodiment, the present disclosure provides a method comprising: providing a well isolation module; connecting the well isolation module to a subsea well head; providing a well abandonment module; and installing the well abandonment module on the well isolation module.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] A more complete and thorough understanding of the present embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings.

[0012] Figure 1 illustrates a subsea abandonment assembly comprising a well isolation module, according to aspects of the present disclosure.

[0013] Figure 2 illustrates a subsea abandonment assembly comprising a first abandonment module connected to a well isolation module, according to aspects of the present disclosure.

[0014] Figure 3 illustrates a subsea abandonment assembly comprising a first abandonment module connected to a well isolation module and a second abandonment module connected to the first abandonment module, according to aspects of the present disclosure.

[0015] Figure 4 is a cross-sectional view of a subsea abandonment assembly with a drill string passing through the subsea abandonment assembly, according to aspects of the present disclosure. [0016] Figure 5 illustrates an example subsea abandonment assembly comprising a casing cleaning module, according to aspects of the present disclosure.

[0017] The features and advantages of the present disclosure will be readily apparent to those skilled in the art. While numerous changes may be made by those skilled in the art, such changes are within the spirit of the disclosure.

DETAILED DESCRIPTION

[0018] The description that follows includes exemplary apparatuses, methods, techniques, and/or instruction sequences that embody techniques of the inventive subject matter. However, it is understood that the described embodiments may be practiced without these specific details.

[0019] The present disclosure relates generally to methods of abandoning a well. More specifically, in certain embodiments the present disclosure relates to subsea abandonment apparatuses and associated methods and systems.

[0020] Referring now to Figure 1, a well isolation module 110 is shown connected to a wellhead 105 via a wellhead connector 107. In certain embodiments, well isolation module 110 may comprise any subsea isolation device described in PCT/US2014/058786, the entirety of which is hereby incorporated by reference.

[0021] The well isolation module 110 may comprise a bottom wellhead connection point (not shown) structured and arranged to couple with and/or connect to the wellhead connector 107. A support vessel may deploy the well isolation module 110 on the wellhead 105 using a remotely operated vehicle (ROV) 112, for example. In certain embodiments, a battery 120 may be connected to the well isolation module 110. In certain embodiments, a subsea accumulator module (SAM) 125 may be connected to the well isolation module 110. The well isolation module 110 may comprise one or more transponders 114 to communicate with subsea modules, such as the SAM 125 and/or communicate with the support vessel. In certain embodiments, the SAM 125 may communicate with the support vessel through a crane wire 127 connecting the SAM 125 to the support vessel.

[0022] The well isolation module 110 may isolate contents within the well from surrounding environment. The well isolation module 110 may comprise one or more blowout preventer rams to control the pressure within the well. The well isolation module 110 may comprise a top module connection point 140 structured and arranged to receive and connect to a bottom module connection point located on a subsequent abandonment module.

[0023] Referring now to Figure 2, a subsea abandonment assembly 200 is shown comprising a well isolation module 201 and a well abandonment module 210. The well abandonment module 210 may be connected to the well isolation module 201 via a bottom module connection point 220 structured and arranged to connect to the top module connection point (not shown in Figure 2, shown as item 140 in Figure 1) on the well isolation module 201. The well abandonment module 210 may comprise a top module connection point 225, similar to the top module connection point located on the well isolation module 201. The well abandonment module 210 may accept and connect to another subsequent well abandonment module.

[0024] The well isolation module 201 may comprise a controller 215. The well abandonment module 210 may be connected to the controller 215 via a control jumper 217. As such, the well abandonment module 210 may be controlled through control signals sent to the well abandonment module 210 and/or by control signals sent to the controller 215 by the support vessel (wirelessly or through the water).

[0025] The well abandonment module 210 is shown in Figure 2 as an isolation and testing module. However, the well abandonment module 210 may comprise any module tools desired for the abandonment operation. For example, in certain embodiments, the well abandonment module 210 may be an isolation and testing module, a circulating module, an annular isolation module, a temporary plug removal module, a casing hanger seal retrieval module, a wellbore logging module, a casing retrieval module, a casing cleaning module, a downhole multifunctional tool string module, a casing perforating module, an emergency quick disconnect (EQD) module, and/or a mud recovery module.

[0026] Each well abandonment module 210 may comprise the same or similar top module connection point 225 and a bottom module connection point 220. As such, each well abandonment module 210 may accept and be capable of connecting with any other well abandonment module 210 in any order desired by the needs of the abandonment operation.

[0027] Accordingly, the subsea abandonment assembly 200 may comprise one or more well abandonment modules 210 connected vertically with one another, where a bottom well abandonment module 210 may be connected to the well isolation module 201 and a second well abandonment module 210 may be connected to the bottom well abandonment module 210. In certain embodiments, each well abandonment module 210 may comprise a mandrel located at the top of the well abandonment module 210 and a connector located at the bottom of the well abandonment module. The well abandonment modules 210 may be connected together using the mandrel at the top of the lower well abandonment module 210 which interfaces with a connector at the bottom of the upper module well abandonment module 210.

[0028] For example, referring now to Figure 3, a subsea abandonment assembly

300 is shown comprising a well isolation module 301 connected to a wellhead connector 304 on a wellhead 302. A first well abandonment module 310 and a second well abandonment module 312 connected vertically in series with the well isolation module 301. The second well abandonment module 312 may comprise a top module connection point 325 and a bottom module connection point 327. The first well abandonment module 310 may also comprise a top module connection point (now shown) and a bottom module connection point 328. As shown by example in Figure 3, the first abandonment module 310 may comprise an isolation and testing module and the second abandonment module 312 may comprise a case cleaning and containment module. A first control jumper 320 may connect the first well abandonment module 310 to the well isolation module 301 and a second control jumper 322 may connect the second well abandonment module 312 to the well isolation module 301. The control jumpers 320, 322 may supply each respective well abandonment module 310, 312 with electric and/or hydraulic control from the well isolation module 301. As mentioned above, the well isolation module 301 may comprise a controller, which may control one or both of the well abandonment modules 310, 312 via the respective control jumper 320, 322. In certain embodiments, the subsea abandonment assembly 300 may comprise a fluid supply line 340 connected to the well isolation module

301 to supply fluid to the well isolation module 301. In certain embodiments, the well isolation module 301 may circulate fluid received by the fluid supply line 340 to one or more of the well abandonment modules 310, 312 via the control jumper 320, 322 and/or through a separate abandonment module circulation line (now shown)

[0029] Referring now to Figure 4, a cross-sectional view of the subsea abandonment assembly 400 is shown comprising a well isolation module 401 and a first well abandonment module 410 and a second well abandonment module 412, where a drill string 405 is extended through an inner pathway 420 defined by the subsea abandonment assembly 400. The well isolation module 401 and the first and second well abandonment modules 410, 412 may each comprise an inner pathway 420 through each respective module 401, 410, 412, such that the inner pathway 420 has a substantially uniform diameter throughout the subsea abandonment assembly 400. As such, the drill string 405 may be extended through the subsea abandonment assembly 400 and into a subsea well 450. In certain embodiments, the drill string 405 may comprise a drill bit, a well scraper, a logging tool, a mud motor, a multifunction tool module, a perforation gun, and/or any other drill string tools for use within the subsea well 450.

[0030] Similarly, once an abandonment cementing operation has been completed and a casing from the subsea well 450 is ready to be retrieved from the subsea well 450, the casing may be pulled through the inner pathway 420. In certain embodiments, one of the well abandonment modules 410, 412 may comprise a casing cleaning module, as shown by example in Figure 5 and discussed further below. Residual well fluids may be washed from the exterior of the casing as it is pulled through a wash zone within at least a portion of the inner pathway 420 within the casing cleaning module.

[0031] It will be noted that the subsea abandonment assembly 400 may allow a drill string to be extended into the subsea well 450 and recovery of casing from the subsea well 450 without the use of a riser to separate sea water and other environmental elements from interacting with subsea well fluids.

[0032] It should also be noted that Figure 4 shows a cross-sectional view of one embodiment of how a first top module connection point 430 of the first well abandonment module 410 may connect and lock within a second bottom module connection point 435 of the second well abandonment module 412. In addition, the second bottom module connection point 435 may comprise at least one seal 437. The connection made between the first well abandonment module 410 and the second well abandonment module 412 is similar to the connection made between the well isolation module 401 and the first well abandonment module 410.

[0033] As mentioned above, the subsea abandonment assembly may comprise one or more well abandonment modules. Each well abandonment module may comprise a set of tools for a specific operative step needed to complete the abandonment operation. In certain embodiments, the subsea abandonment assembly may comprise a plurality of well abandonment modules, which are capable of completing each of the steps in the abandonment operation without needing to remove or replace well abandonment modules. In other embodiments, the abandonment modules may be removed and/or replaced during the course of the abandonment operation as needed. As such, each abandonment module may be configured to complete at least one specific operative step, as will now be discussed. Although each type of abandonment module is discussed as separate modules, an abandonment module may also comprise tools capable of completing two or more steps and/or functions required by the abandonment operation.

[0034] In certain embodiments, one or more of the well abandonment modules may comprise an Emergency Quick Disconnect (EQD) module. The EQD module may allow quick isolation of the well if an issue with the abandonment process (e.g., kick or excess inflow) or an issue with the support vessel (DP drift or drive off) develops. The EQD module may comprise the controls and one or more isolation valves to isolate the well and/or well annulus from the surrounding environment. In order to disconnect the drill pipe or casing from the well, the EQD module may sever the drill pipe or casing at the subsea well and isolate the well and/or well annulus with a severed portion remaining in the well. The severed portion may then be retrieved later using a retrieval tool. In certain embodiments, the drill pipe or casing may be pulled from the well through the EQD module prior to isolating the well.

[0035] In certain embodiments, the EQD module may be operated from the surface using a control signal. The control signal may be transmitted to the EQD module through a cable connecting the EQD with the surface vessel, through acoustic telemetry, or any other type of signal used to carry control information to the EQD module. The EQD module may comprise a controller connected to the one or more isolation valves. To initial a quick disconnect process, EQD control commands transmitted from the surface may be received by the controller. In response to the EQD control commands, the controller may actuate one or more isolation valves and/or shear the casing or drill pipe to close and seal the well from the environment.

[0036] In certain embodiments, the EQD module may comprise a backup control.

In certain embodiments, the EQD control may comprise the backup control. The backup control may comprise an EQD battery and a backup EQD controller connected to the one or more isolation valves. An independent source of stored hydraulic power in a SAM may also be included in the back up control. The backup EQD controller may store shutdown functions to be executed autonomously without a signal from the surface. The EQD module may allow the abandonment process to proceed without the need for a lower marine riser package (LMRP) for connecting and/or disconnecting risers to a blowout preventer (BOP). [0037] In certain embodiments, one or more of the well abandonment modules may comprise a casing cleaning module 512 and/or a circulation module 510, as shown by example in Figure 5. The casing cleaning module 512 may comprise a supply line 520 and a return line 522. In certain embodiments, a surface pump may direct fluid through the supply line 520 toward the circulation module 510. The return line 522 may direct fluid from the circulation module 510 toward the surface. In certain embodiments, fluid received from the return line 522 at the surface may be redirected by the surface pump into the supply line 520. In certain embodiments, the supply line 520 and/or the return line 522 may comprise coiled tubing.

[0038] The circulation module 510 may comprise an inlet valve 525 and/or an outlet valve 527. The inlet valve 525 may control the flow of fluid from the supply line 520 into the casing cleaning module 512 and the outlet valve 527 may control the flow of fluid from the casing cleaning module 512 to the return line 522. The inlet valve 525 and/or the outlet valve 527 may be actuated by a circulation module controller and/or a control jumper 530 connected to the well isolation module 501 to control fluid flow within the casing cleaning module 512.

[0039] The circulation module 510 may be in a circulation mode, a testing mode, or a shutoff mode. In the circulation mode, the inlet valve 525 and the outlet valve 527 may be open to circulate fluid from the supply line 520, through the circulation module 510, and into the return line 522. In a testing mode, the outlet valve 527 may be closed to prevent fluid flow into the return line 522 and back to the surface. As such, in the testing mode, a surface pump may direct fluid into the circulation module 510 to increase the pressure within the circulation module 510, the subsea abandonment assembly 500, and/or the well 505. In a shutoff mode, the inlet valve 525 may be closed to prevent fluid flow from the supply line 520 to the circulation module 510.

[0040] In certain embodiments, one or more of the well abandonment modules may comprise an annular isolation module. The annular isolation module may separate fluid in the well from the surrounding environment. As such, the annular isolation module may create a seal on a pipe and/or bottom-hole assembly (BHA) within the well to prevent fluid located within a well annulus from entering the surrounding environment. The pressure within the well may be increased, for example using the circulation module discussed above. The annular isolation module may maintain the pressure within the well. In certain embodiments, the annular isolation module may comprise a stripping annular blow-out preventer (BOP), a variable bore ram, and/or a pressure control device. In certain embodiments, the annular BOP may have a sealing rubber which can be adjusted to suit various diameters of BHAs. BHAs can therefore be run into an annular BOP while it is subsea. The pressure control devise has fixed rubber elements which can adjust to a limited range of BHAs diameters. The pressure control device may be a rotating control head or a system with multiple sealing elements. The pressure control device is installed on the BHA on the surface, run with the BHA and latched on the upper module subsea.

[0041] In certain embodiments, the annular isolation module may engage the well isolation module. For example, the annular isolation module may engage the well isolation module using one or more slips. In certain embodiments, the annular isolation module may engage the wellhead connector.

[0042] In certain embodiments, one or more of the well abandonment modules may comprise a case cleaning module. The case cleaning module may comprise one or more internal jets to clean residual hydrocarbons from the casing as it is pulled from the well. The one or more internal jets may be supplied with fluid from the supply tube. In certain embodiments, the case cleaning module may comprise a pump to circulate fluid supplied by the supply tube through the one or more internal jets. In certain embodiments, the case cleaning module may redirect at least a portion of the fluid from the supply tube toward the one or more internal jets. In certain embodiments, the case cleaning module may engage the annular isolation module using one or more slips. In certain embodiments, the case cleaning module may engage the well isolation module using one or more slips.

[0043] In certain embodiments, one or more of the well abandonment modules may comprise a casing retrieval module. The casing retrieval module may comprise a casing jack. The casing jack may engage the casing and assist in pulling the casing out of the well. For example, the casing jack may engage the casing with one or more slips. In certain embodiments, the casing retrieval module may comprise a casing spear. The casing spear may engage with and/or latch into the inside of the casing. The support vessel may also pull the casing out of the well. As such, the casing jack may assist the support vessel and supply an additional amount of pulling force needed to remove the casing from the well.

[0044] In certain embodiments, one or more of the well abandonment modules may comprise a mud recovery module. The mud recovery module may comprise a submersible motor. In certain embodiments, the submersible motor may comprise an electric motor and/or a hydraulic motor. The submersible motor may be connected to and drive a mud pump. The mud pump may direct mud and/or a mud mixture containing solids from the well toward a mud return tube. The mud return tube may be fluidly connected to the surface vessel and direct fluid from the mud pump toward the surface vessel. In certain embodiments, the submersible motor may be capable of pumping fluid at a rate of up to 10 barrels per minute.

[0045] In certain embodiments, the submersible motor may be powered and/or controlled from the surface vessel through an umbilical control line connected to the mud recovery module. The mud recovery module may send at least one monitoring signal to the surface vessel through the umbilical control line and/or by wireless transmission. For example, the mud recovery module may send a monitoring signal comprising a pump motor speed (rpm), mud pump flow rate, and/or differential pressure across the mud pump to the surface vessel.

[0046] In certain embodiments, one or more of the well abandonment modules may comprise a downhole tool string module. In certain embodiments, the downhole tool string module may comprise a plurality of downhole tools for use within the well. The plurality of downhole tools may be disposed on and/or part of a drill pipe or bottom hole assembly. The plurality of downhole tools may be deployed within the well at the same time. The downhole tool string module may be used to perform a plurality of downhole operations successively without the need to pull a downhole tool to the surface to replace it with another downhole tool.

[0047] In certain embodiments, the downhole tool string module may comprise a temporary plug removal module and/or a case perforation module. The temporary plug removal module may comprise at least one cutter and at least one reamer. The at least one cutter and the at least one reamer may be configured to cut and ream cement and/or a drillable plug in the well. In certain embodiments, a portion of the cuttings generated by the at least one cutter may be returned to the surface vessel through a cuttings return tube. In certain embodiments, a portion of the cuttings generated by the at least one cutter may be dropped into the well. The temporary plug removal module may be used to remove a drillable plug before further operations are conducted within the well. In certain embodiments, the temporary plug removal module may be attached to a bottom hole assembly, where the bottom hole assembly may have other modules and/or tools for performing multiple downhole operations concurrently and/or successively. [0048] In certain embodiments, one or more of the well abandonment modules may comprise a wellbore logging module. The wellbore logging module may be used to survey the wellbore to provide wellbore information to the operator. For example, the operator may use the wellbore logging module to find the location and/or termination of cement located behind the casing. As such, the wellbore logging module may be used to determine a casing cut location. The wellbore logging module may be deployed on wireline in open water or through a drill pipe.

[0049] A method of abandoning the subsea well according to aspects of the present disclosure may comprise connecting the well isolation module to the subsea wellhead, as shown with reference back to Figure 1. The well isolation module may be deployed onto the subsea wellhead using an ROV to connect the bottom wellhead connection point to the subsea wellhead. The SAM and/or the battery may be deployed by a crane from the support vessel and connected to the well isolation module by the ROV. Communication between the well isolation module and the surface vessel may be tested isolation valves on the well isolation module may be closed to pressure test the wellhead connector.

[0050] Next, a first abandonment module may be installed on well isolation module by connecting the bottom module connection point to the top well entry connection point. In certain embodiments, the abandonment module may be an isolation and testing module, as shown with reference back to Figure 2. The control jumper may be connected to the well isolation module and the abandonment module. In certain embodiments, the control jumper may electronically and/or hydraulically connect the well isolation module with the abandonment module. A pressure test may be conducted to test whether the connection between the abandonment module and the well isolation module maintains a seal at operation pressures. A fluid circulation line may be deployed from the surface and connected to the well isolation module using the ROV.

[0051] Next, in certain embodiments, a second abandonment module may be installed on the second abandonment module by connecting the bottom module connection point on the second abandonment module to the top module connection point on the first abandonment module, as shown with reference back to Figure 3. In certain embodiments, the second abandonment module may be a casing cleaning module. In certain embodiments, an ROV may be used to connect the well isolation module to the abandonment module. A second control jumper may be connected to the well isolation module and the second abandonment module. [0052] In certain embodiments, a third abandonment module may be installed on the third abandonment module by connecting and locking the bottom module connection point on the third abandonment module to the top module connection point on the second abandonment module.

[0053] A drill string may be extended through the inner pathway of the subsea abandonment assembly and into the subsea well. In certain embodiments, the drill string may drill, ream, scrape casing, and/or perform a cement bond log. Fluids may be circulated into the subsea well. For example, in certain embodiments, fluid may be circulated down to the well through the drill string and returned up to the surface through a fluid return line connected to an abandonment module (e.g., the casing cleaning module).

[0054] In certain embodiments, casing may be pulled from the subsea well through the subsea abandonment assembly comprising the casing cleaning module. In certain embodiments, the casing cleaning module may wash residual well fluids from the casing by circulating wash fluids from the supply line connected to the casing cleaning module through at least a portion of the inner pathway containing the casing, and toward a return line connected to the support vessel. As such, residual well fluid may be washed from the casing toward the return line as the casing passes through the casing cleaning module. When the drill string is pulled out of the subsea well and above the well isolation module, BOP rams in the well isolation module may close and shut-off the well from the one or more abandonment well modules and surrounding environment.

[0055] Once the abandonment operation (or a portion of the abandonment operation) is complete, the one or more abandonment modules may be recovered back to the surface. If a casing cleaning module is installed, the supply line and the return lines may be disconnected from the casing cleaning module and recovered to the surface. The each abandonment module may be unlocked and disconnected from lower abandonment modules and/or the well isolation module and respective jumpers connected each abandonment module to the well isolation module may be recovered to the surface. The SAM and the battery may then be recovered to the surface. Next the well isolation module may be recovered, leaving the subsea wellhead.

[0056] While the embodiments are described with reference to various implementations and exploitations, it will be understood that these embodiments are illustrative and that the scope of the inventive subject matter is not limited to them. Many variations, modifications, additions and improvements are possible. [0057] Plural instances may be provided for components, operations or structures described herein as a single instance. In general, structures and functionality presented as separate components in the exemplary configurations may be implemented as a combined structure or component. Similarly, structures and functionality presented as a single component may be implemented as separate components. These and other variations, modifications, additions, and improvements may fall within the scope of the inventive subject matter.