BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The present invention pertains to a method and apparatus for controlling wells situated in offshore marine environments. More particularly, the present invention pertains to a method and apparatus for deploying certain intervention components in wells including, without limitation, subsea wells. More particularly still, the present invention pertains to a method and apparatus for packaging modular components in a structurally sound manner that does not impart excessive loads on said modular components.

2. Brief Description of the Prior Art

[0002] Oil and gas wells are currently being drilled in increasingly challenging environments. For example, wells drilled in marine environments are often situated in water depths of several thousand feet. In many cases, offshore wells situated in marine environments are maintained using floating vessels such as semi-submersible drilling rigs, drill ships or the like, while wellheads and related equipment such as subsea trees are situated at or near the sea floor.

[0003] Currently, there are two primary conventional methods for performing intervention or workover operations on wells in marine environments, and particularly wells in water depths of 1 ,000 feet or deeper: (1) a Thru-Blowout Preventer Intervention Riser System (or “TBIRS”); and (2) an Open-Water Intervention Riser System (or OWIRS”). [0004] With a conventional “TBIRS” (that is, the Thru-BOP Intervention Riser System), a relatively large-diameter pipe known as a riser (also commonly referred to as a drilling riser, marine riser or marine drilling riser) is used as a conduit to connect subsea assemblies at or near the sea floor, including a blowout preventer (or “BOP”), to a floating offshore drilling rig or drill ship at the water surface. Thereafter, pipe and/or well-control valves and downhole equipment used for interventions or workovers can be lowered from said floating vessel through said riser and BOP, and ultimately into the subsea wellbore itself. One important advantage of TBIRS systems is that tension and bending loads imparted by the vessel and sea currents are resisted by the marine or drilling riser and the BOP - and not exclusively by the TBIRS components positioned within said components.

[0005] Although dimensions can vary, commonly used bore diameter for the marine or drilling riser is 19-inches, constricting to 18-3/4-inches in the BOP stack and other subsea components. Smaller riser and BOP combinations exist as well; for example, 16- 3/4-inch-bore risers are sometimes used. Conventional TBIRS components have an outer diameter or “OD” that allows such components within the inner diameter of a riser and BOP through which they will be deployed. Because the OD of components must fit within the riser, and because said components are generally not required to resist large bending and tension loads induced by a vessel and the sea, TBIRS components can be relatively compact and lightweight.

[0006] Another common method for performing intervention or workover operations in marine wells is commonly referred to as an Open-Water Intervention Riser System, also known more simply as OWIRS. With an OWIRS, there is no marine or drilling riser. Instead, equipment is lowered to the bottom of the sea, typically on drill pipe or casing, which essentially forms a subsea riser system. The bore of OWIRS riser is typically the same bore as that of an underlying subsea tree. Although dimensions can vary, the diameter of the bore often ranges between 4-inches and 7-inches.

[0007] Intervention and/or workover equipment lowered on an open-water riser is frequently installed directly on a subsea tree at the sea floor. Such equipment typically comprises two primary components: a Well Control Package (or “WCP”) and an Emergency (Dis)connect Package (or “EDP”). The WCP typically lands directly on a subsea tree, while the EDP lands directly on the WCP.

[0008] A conventional OWIRS WCP roughly mimics the way in which a BOP stack is used in TBIRS applications. When a need arises, such as in an emergency, the WCP can cut coiled tubing or wireline in the production bore and seal the wellbore against uncontrolled flow/well pressure. This is typically accomplished with miniature BOP-style rams, or in some cases, cutting and sealing valves.

[0009] A conventional OWIRS EDP roughly mimics a blowout preventer's Lower Marine Riser Package or “LMRP”. When a need arises, such as in an emergency, the EDP can disconnect, as well as seal the contents of the open-water riser from spillage into the surrounding environment, such as the sea.

[0010] Because of the relatively small bore of open-water riser, TBIRS-style well- control valves cannot be raised or lowered through conventional open-water risers. Any well-control rams or valves must therefore be integral to the WCP and EDP of a conventional OWIRS. Tension and bending loads imparted by sea currents and/or floating vessel are imparted directly through the open-water riser into the EDP/WCP assembly (sometimes referred to as a “stack-up”). Thus, an EDP/WCP open-water stack- up must typically be designed to be structurally robust. As result, such open-water stack- ups are generally relatively large and heavy in order to handle anticipated forces/loads, as well as to isolate the integral well control rams or valves from these loads.

[0011] Conventional 15,000-psi EDP/WCP combinations used in open water applications can often weigh 200,000 pounds or more. The robust and large nature of this conventional open-water equipment requires a large deep-water drilling rig, full-sized drillship or slightly smaller intervention vessel for transportation and deployment of such conventional equipment; such vessels typically command a high day rate, are very expensive and are often of limited availability.

[0012] Thus, there is a need for light weight, compact modular equipment embodying the benefits of TBIRS systems while permitting use in open water applications, such as an OWIRS. The system should be smaller, lighter and less expensive than conventional OWIRS systems, and could be deployed from smaller, less expensive and more readily available Multi-Service Vessels (or “MSVs”) or other similarly configured moonpool-style boats.

SUMMARY OF THE INVENTION

[0013] The present invention comprises a well-control assembly for use on subsea wells for intervention or workover operations performed through a subsea tree. The well- control assembly of the present invention provides certain benefits associated with conventional OWIRS systems, while being smaller, lighter and capable of being deployed not only from full-size or intervention rigs, but also from MSVs or Multi-Service Vessels or other similarly configured moonpool-style boats. Further, the well-control assembly of the present invention can optionally comprise additional beneficial components such as cutting and sealing valves; by packaging said components into compact, yet structurally robust load housings (or “LH”), relatively large tension and bending moments can be transmitted without excessive loads being imparted to modular components disposed within said load housings.

[0014] In a preferred embodiment, the present invention comprises EDP and WCP subassemblies, each of which can utilize its own load housing. The WCP load housing can comprise a single housing configured with a connector assembly (typically on the bottom of the housing) to connect to a subsea tree (typically on the upper portion of the subsea tree). Said connector can comprise an 18-3/4-inch H4-style connector, but the size and configuration may vary depending upon the type and size of the subsea tree to which said housing must be connected. The WCP load housing connector can optionally be integral, or a separate subcomponent attached via studs and nuts, bolts or other fastening means or direct threaded connection.

[0015] In a preferred embodiment, the EDP of the present invention can optionally be equipped with its own load housing, or with an integral valve block. The EDP load housing can be a single housing configured with a connector assembly (typically on the bottom of the housing) to connect to WCP (typically on the upper portion of the WCP). Said connector is typically a 13-5/8-inch H4-style connector, but the size and connection style may vary depending upon anticipated loading. Said EDP load housing connector can optionally be integral, or a separate subcomponent attached via studs and nuts, bolts or other fastening means or direct threaded connection. [0016] In a preferred embodiment, multiple TBIRS or similar modular components are stacked upon each other in a compact manner, with structural and pressure sealing connections between components, and forming a subassembly called the Valve Pack or “VP”. Key VP components can comprise a tree stab, a circulation sleeve, a cutting/sealing valve and a sealing valve. Additionally, adapter components to allow structural connections and pressure sealing can be included. One such component with a full-bore seal can be inserted between the circulation sleeve and the cutting/sealing valve, and this full-bore seal can isolate the well annulus from the well production bore or other pressure connections.

[0017] Said valve pack is installed into the load housing subassemblies. The load housing subassemblies then can be installed within a structure containing accumulators, a controls system, a remote operated vehicle (“ROV”) control panel, as well as other desired OWIRS components.

[0018] In a preferred embodiment, an EDP valve pack subassembly further comprises a retainer valve and is packaged into and installed within a structure containing accumulators, a controls system, an ROV control panel as well as other conventional OWIRS EDP features.

BRIEF DESCRIPTION OF DRAWINGS/FIGURES

[0019] The foregoing summary, as well as any detailed description of the preferred embodiments, is better understood when read in conjunction with the drawings and figures contained herein. For purposes of illustrating the invention, the drawings and figures show certain preferred embodiments. It is understood, however, that the invention is not limited to the specific methods and devices disclosed in such drawings or figures. [0020] FIG. 1 depicts a side view of a conventional subsea well connected to a floating vessel via a riser.

[0021] FIG. 2 depicts conventional deep-water TBIRS components landed out in a subsea BOP at the well.

[0022] FIG. 3 depicts a perspective view of a VP within a WCP LH subassembly installed into structure with accessories to form a WCP, as well as an EDP (above) and a subsea tree (below).

[0023] FIG. 4 depicts a side view of the well control assembly depicted in FIG. 3.

[0024] FIG. 5 depicts a side sectional view of the well control assembly depicted in

FIG. 4 along line 5-5.

[0025] FIG. 6 depicts a detailed view of the highlighted portion (labeled “6”) of the well- control assembly of the present invention depicted in FIG. 5.

[0026] FIG. 7 depicts a detailed view of the highlighted portion (labeled “7”) of the well- control assembly of the present invention depicted in FIG. 5.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION [0027] While the present invention will be described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the present invention not be limited to the particular embodiments disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments (and legal equivalents thereof). In the drawings, certain features well established in the graphics may be omitted in the interest of descriptive clarity; such features may include weld lines, threaded fasteners, surface finishes and the like.

[0028] FIG. 1 depicts a side view of a conventional subsea well installation. Subsea wellhead assembly 10 having blowout preventers 11 and blowout-preventer support structure 14 is disposed on sea floor 20 on a wellhead 12 positioned at the upper end of a well extending into the earth’s crust. Subsea wellhead assembly 10 is operationally connected to a floating vessel 30 situated at water surface 40 via riser conduit 50; upper end 52 of riser 50 is operationally connected to floating vessel 30 while lower or distal end 51 of riser 50 is operationally connected to subsea wellhead assembly 10. It is to be understood that the water depth (that is, the distance between sea floor 20 and water surface 40) can vary for different installations, but in some cases can be 1 ,000 feet or more. Tension and bending loads imparted by the vessel and sea currents are frequently imparted on drilling riser 50, particularly in the vicinity of end 51 of riser where said riser connects to subsea wellhead assembly 10. Said imparted loads are then resisted by bodies of blowout preventers 11 and blowout preventer structure 14.

[0029] FIG. 2 depicts conventional deep-water TBIRS assembly 60 which is at least partially disposed within a subsea BOP assembly. Subsea BOP assembly generally comprises a plurality of blowout preventers 11 in stacked relationship operationally attached to wellhead 12 via blowout preventer connector 13. Said blowout preventers 11 typically comprise a combination of pipe rams and shear rams well known to those having skill in the art. Blowout-preventer connector 13 is mounted on the upper end of wellhead 12. Conventional TBIRS assembly 60 is concentrically disposed within the aligned central through bores of said blowout preventers 11 and associated equipment. [0030] Although components and arrangement can vary depending upon structural and operational considerations, conventional TBIRS assembly 60 depicted in FIG. 2 comprises cut and seal valve(s) 61 , accumulator(s) 62, latch assembly 63 and shear joint 64.

[0031 ] FIG. 3 depicts a perspective view of a well-control assembly 100 of the present invention, while FIG. 4 depicts a side view of said well control assembly 100 depicted in FIG. 3. Well-control assembly 100 of the present invention can be utilized in connection with subsea wells for various operations including, without limitation, intervention or workover operations performed through a subsea tree. By way of illustration, said intervention or workover operations can be conducted using wireline or coiled tubing. [0032] Referring to FIG. 3, in a preferred embodiment well control assembly 100 of the present invention comprises EDP subassembly 160 and WCP subassembly 110, each of which can include its own LH (Load Flousing) as described in more detail herein. Said EDP subassembly 160 and WCP subassembly 110 are disposed in a generally stacked configuration upon a subsea tree assembly 150.

[0033] Still referring to FIG. 3, riser 50 can be connected to EDP load housing 165 using bolted flange 161. In the configuration depicted in FIG. 3, EDP subassembly 160 generally comprises base support structure 162 and said EDP load housing 165. At least one accumulator 163, as well as ROV control panel 166, are disposed on said base support structure 162, generally in proximity to said EDP load housing 165. EDP subassembly 160 is operationally attached to WCP subassembly 110 using EDP subassembly connector 164.

[0034] Still referring to FIG. 3, WCP subassembly 110 generally comprises top plate 111 and base plate 112 disposed in substantially parallel orientation relative to each other. A plurality of rigid support posts 113 extend between said top plate 111 and base plate 112. It is to be understood that the said components generally provide a protective support structure for WCP subassembly 110; however, the specific shape and configuration of said protective components can be different than depicted in the appended drawings without departing from the scope of the present invention.

[0035] WCP load housing 120 is disposed between said top plate 111 and base plate 112. At least one accumulator 118 is disposed on said base plate 112. Said WCP subassembly 110 further comprises ROV control panel 114, as well as hydraulic flying lead 115 and electric flying lead 116 having connector 117. Flying lead 115 is operationally connected to ROV control panel 114 using connection member 115a. WCP subassembly 110 is operationally attached to subsea tree assembly 150 using WCP subassembly connector 119.

[0036] Subsea tree assembly 150 comprises upper plate 151 and support posts 153, as well as ROV control panel 154. Hydraulic flying lead 115 is operationally attached to ROV control panel 154 using connection member 115b. Hydraulic flying lead 155 is operationally connected via connection member 155a, and electric flying lead 156 having connector 157. [0037] Referring to FIG. 4, in a preferred embodiment well control assembly 100 of the present invention comprises EDP subassembly 160 and WCP subassembly 110, each of which can include its own LH (Load Housing) 165 and 120, respectively. Said EDP subassembly 160 and WCP subassembly 110 are disposed in a generally stacked configuration and mounted upon a subsea tree assembly 150.

[0038] Riser 50 is connected to EDP load housing 165 using bolted flange 161. In the configuration depicted in FIG. 4, EDP subassembly 160 generally comprises base support structure 162 and said EDP load housing 165. At least one accumulator 163, as well as ROV control panel 166, are disposed on said base support structure 162, generally in proximity to said EDP load housing 165. In a preferred embodiment, said load housing 165 has an internal bore having an inner diameter of approximately 18.75”; although this dimension can vary, it is to be observed that said inner diameter can be beneficially larger than the inner diameter of subsea tree assembly 150. EDP subassembly 160 is operationally attached to WCP subassembly 110 using EDC subassembly connector 164.

[0039] Still referring to FIG. 4, WCP subassembly 110 comprises parallel top plate 111 and base plate 112, while a plurality of rigid support posts 113 extend between said top plate 111 and base plate 112. WCP load housing 120 is disposed between said top plate 111 and base plate 112; at least one accumulator 118 is disposed on said base plate 112. WCP subassembly 110 further comprises ROV control panel 114, as well as hydraulic flying lead 115 and electric flying lead 116 having connector 117. Flying lead 115 is operationally connected to ROV control panel 114 using connection member 115a. WCP subassembly 110 is operationally attached to subsea tree assembly 150 using WCP subassembly connector 119. Subsea tree assembly 150 comprises upper plate 151 and support posts 153, as well as ROV control panel 154. Hydraulic flying lead 115 is operationally attached to ROV control panel 154 using connection member 115b.

[0040] Still referring to FIG. 4, WCP subassembly 110 can beneficially comprise a load housing 120 configured with a connector assembly 119 (typically on the bottom of the housing) to connect to a subsea tree assembly 150 (typically on the upper portion of the subsea tree). Said connector can comprise an 18-3/4-inch H4-style connector, but the size and configuration may vary depending upon the type and size of the subsea tree assembly to which said housing must be connected. Said WCP LH connector 119 can optionally be integral, or a separate subcomponent attached via studs and nuts, bolts or other fastening means or direct threaded connection. In a preferred embodiment, said load housing 120 has an internal bore having an inner diameter of approximately 18.75”; although this dimension can vary, it is to be observed that said inner diameter can be beneficially larger than the inner diameter of subsea tree assembly 150.

[0041] Referring to FIG. 5, EDP subassembly 160 of the present invention can be installed within a structure containing accumulators, a controls system, an ROV control panel and other typical OWIRS EDP features. FIG. 5 depicts a side sectional view of an EDP (depicted in highlighted section “6”) on a WCP (depicted in highlighted section “7”) along line 5-5 of FIG. 4. Riser 50 is connected to EDP load housing 165 using bolted flange 161 via bolts 159. In the configuration depicted in FIG. 5, EDP subassembly 160 generally comprises base support structure 162 and EDP load housing 165. At least one accumulator 163 is disposed on said base support structure 162. EDP subassembly 160 is operationally attached to WCP subassembly 110 using EDC subassembly connector 164.

[0042] WCP subassembly 110 comprises parallel top plate 111 and base plate 112, while a plurality of rigid support posts 113 extend between said top plate 111 and base plate 112. WCP load housing 120 is disposed between said top plate 111 and base plate 112; at least one accumulator 118 is disposed on said base plate 112. WCP subassembly 110 is operationally attached to subsea tree assembly 150 using WCP subassembly connector 119 and bolts 121 . Subsea tree assembly 150 comprises upper plate 151 and support posts 153, as well as ROV control panel 154.

[0043] Referring to FIG. 6, EDP subassembly 160, in a preferred embodiment, contains a TBIRS retainer valve 70 packaged into its own LH 165 (Load Housing), or with an integral valve block. The EDP LH 165 can be a single housing configured with a connector assembly 80 (typically on the bottom of the housing) to connect to WCP 110 (typically on the upper portion of the WCP). Said connector is typically a 13-5/8-inch H4- style connector, but the size and connection style may vary depending upon anticipated loading. Said EDP LH connector can optionally be integral, or a separate subcomponent attached via studs and nuts, bolts or other fastening means or direct threaded connection. It is to be observed that the internal components of EDP subassembly 160 form an internal bore 200 that can form an unobstructed pathway through said EDP subassembly 160; although dimensions can vary, in a preferred embodiment said internal bore 200 has an inner diameter of at least 6.25 inches. Further, said EDP subassembly 160 can selectively allow disconnection of lower end 51 of riser 50 from well control assembly 100, while also sealing the contents of internal bore 200 from escaping into the surrounding environment

[0044] Referring to FIG. 7, in a preferred WCP embodiment, multiple TBIRS or similar modular components are stacked upon each other in a compact manner, with structural and pressure sealing connections between components, and forming a subassembly in this embodiment referred to as a Valve Pack or “VP” 85. Said VP components can comprise a tree stab 69, a circulation sleeve 70, and/or a cutting/sealing valve and a sealing valve 80. In a preferred embodiment, said cutting and sealing valve 80 is capable of selectively cutting wireline and/or coiled tubing disposed through said cutting and sealing valve 80. Additionally, adapter components 90 to allow structural connections and pressure sealing can be included; one such component with a full-bore seal 108 can be inserted between the circulation sleeve and the cutting/sealing valve, and this full-bore seal can isolate the well annulus from the well production bore or other pressure connections.

[0045] Still referring to FIG. 7, said VP is installed into the WCP subassembly 110. The VP and LH subassembly are then installed within a structure containing accumulators, a controls system, a remote operated vehicle (“ROV”) control panel, as well as other desired components. Further, the well control assembly 100 of the present invention can optionally comprise certain conventional components such as cutting and sealing valves 80; by packaging said components into compact, yet structurally robust Load Flousings (or “LH”), relatively large tension and bending moments can be transmitted without excessive loads being imparted to modular components packaged within said LH. It is to be observed that the internal components of WCP subassembly 110 (including, without limitation, valve pack 85) form an inner bore 200, aligned with inner bore 200 of EDP subassembly 160 that can form an unobstructed pathway through said WCP subassembly 110 (and aligned EPD subassembly 160). Although dimensions can vary, in a preferred embodiment said aligned internal bores 200 have an inner diameter of at least 6.25 inches.

[0046] Well control assembly 100 comprises a light weight, compact, and modular system providing the benefits of conventional TBIRS systems (including, without limitation, an inner diameter larger than that of an underlying subsea tree, said diameter being approximately 18.75” and capable of accommodating conventional TBRIS tools such as a valve pack 85) while permitting use in open water applications. In operation, well control assembly 100 can be deployed from rigs or drill ships or smaller, less expensive and more readily available Multi-Service Vessels (or “MSVs”) or other similarly configured moonpool-style boats that are not capable of deploying conventional OWIRS equipment. EDP subassembly 160 and WCP subassembly 110 are disposed in a generally stacked configuration upon a subsea tree assembly 150, while riser 50 provides an operational conduit extending from said well control assembly 100 to said floating vessel.

[0047] Intervention operations (such as for example, wireline and/or coiled tubing operations) can be conducted through riser 50 and aligned inner bores 200 of said well control assembly 100. If required, such as in an emergency, WCP subassembly 110 (and, more specifically, cutting/sealing valve and a sealing valve 80 of valve pack 85) can selectively cut coiled tubing or wireline extending through bore 200, and seal said bore 200 (and the wellbore below) against uncontrolled flow/well pressure. Similarly, if required, EDP subassembly 160 can selectively allow disconnection of lower end 51 of riser 50 from well control assembly 100, while sealing the contents of bore 200 from escaping into the surrounding environment. By way of illustration, but not limitation, EDP subassembly 160 can permit selective disconnection of riser 50 from well control assembly 100 such as during severe weather or other emergency event.

[0048] Unlike conventional TBIRS assemblies, tension and bending loads imparted by sea currents and/or a floating vessel can be resisted by the robust design of well control assembly 100 (and, in particular, EDP load housing 165 and WCP load housing 120). Unlike conventional open-water stack-ups, well control assembly 100 is light weight, compact, and modular and, thus, is much more versatile and can be deployed from rigs or drill ships or much smaller vessels.

[0049] The well control assembly of the present invention can be more quickly recovered and repaired or refurbished than conventional OWIRS systems or components thereof. Further, due to its modular nature, Valve Pack 85 can be removed from the inner bore of WCP load housing 120 in order to replace or repair only worn or malfunctioning individual components thereof, then reinstalled

[0050] Dimensions and material selections disclosed herein are illustrative only and are not intended to be, and should not be construed as, limiting in any way.

[0051] The above-described invention has a number of particular features that should preferably be employed in combination, although each is useful separately without departure from the scope of the invention. While the preferred embodiment of the present invention is shown and described herein, it will be understood that the invention may be embodied otherwise than herein specifically illustrated or described, and that certain changes in form and arrangement of parts and the specific manner of practicing the invention may be made within the underlying idea or principles of the invention.