CROSS-REFERENCE TO RELATED APPLICATIONS

None. FIELD

The present disclosure relates to remedial well operations in oil and gas wells. The present disclosure relates generally to a wellbore intervention system, and more specifically to a deployment of a well intervention system having a micro-coiled tubing. More particularly, embodiments of the present disclosure relates to methods of performing wellbore interventions on subsea wells having riserless completions.

BACKGROUND

Offshore hydrocarbon drilling and producing operations can be conducted from a drilling rig located either on a bottom-supported offshore platform or on a floating platform. A bottom-supported platform extends from the seafloor upwardly to a deck located above the surface of the water, and at least a portion of the weight of the platform is supported by the seafloor. In contrast, a floating platform is a ship, vessel, or other structure, such as a tension- leg platform, for example, in which the weight of the platform is supported by water buoyancy.

Exploration and production of offshore hydrocarbon reservoirs has expanded into ever- deeper waters. With increasing water depths, operations conducted from moored or dynamically positioned floating platforms have become more prevalent since economic and engineering considerations discourage the use of bottom-supported platforms commonly used in shallow water.

Regardless of whether a bottom-supported or floating platform is used, once the well is drilled, typically a subsea wellhead is placed at or near the seabed. A riser can then be set providing a casing from the subsea wellhead to a platform at the surface. Another option that is used in most deep water completions is a subsea riserless completion wherein the subsea wellhead is not permanently connected to a platform at the surface. Well intervention refers to any operation carried out on an oil or gas well during or at the end of its productive life, which alters the state of the well or well geometry, provides well diagnostics, or manages the production of the well. Such an operation is referred to herein as a well intervention operation. One of the most complex types of well intervention is a workover operation, wherein the present condition of the well and/or the present condition of the reservoir or surrounding formation make the current completion presently unsuitable for its intended purpose. For instance, oil and gas wells can require subsurface maintenance and remediation to maintain adequate flow or production. Workover operations may include perforating, gravel packing, production stimulation, injection of treatment fluids and repair to a downhole completion. In one example of a workover operation, specialized tools can be lowered into the well by means of a wireline and winch. This wireline winch is typically positioned on the surface and the workover tool is lowered into the well through a lubricator and blowout preventer (BOP). Workover operations on subsea wells can require specialized intervention equipment to pass through the water column and to gain access to the well. Well treatments of an oil or gas well can involve the injection of a fluid into the wellbore, such as to stimulate production from the well by injecting acid into the formation or performing chemical treatments such as the injection of corrosion or scale treatments.

A commonly used method for accessing a subsea well first requires installation of a BOP with a lubricator for connection with the well. The BOP/lubricator is lowered from a derrick that is mounted on a surface vessel such as a drill ship or semi-submersible platform. The BOP/lubricator can be lowered on a segmented length of pipe, coiled tubing or wireline. After the BOP/lubricator is connected to the wellhead, a workover tool can be lowered into the well through the lubricator and BOP. The lubricator provides a sealing system at the entrance of the wireline that maintains the pressure and fluids inside the well and the workover tool deployed by the wireline.

Well intervention in deep water environments can involve the use of a remotely operated vehicle (ROV) to facilitate the connection and deployment of tools into the wellhead. The ROV can be used to guide the BOP/lubricator package into position and attach it to the wellhead. A control umbilical, attached to the BOP/lubricator package can then be used to operate the various functions required to access the well. The workover tool can then be lowered on a wireline winch and the ROV can be utilized to install the tool in the lubricator so that workover operations can be accomplished. Wireline well intervention can be performed on riserless well completions in the manner discussed above with minimal interference from the flow of water such as currents, due to the wirelines small cross-sectional area. But at times there is a desire to inject fluids into the well, such as corrosion inhibitors or solvents to cut paraffin buildup. Well intervention involving fluids such as the common stimulation technique of acidizing on riserless well completions can be made with a workstring, such as jointed tubing or coiled tubing, but the increased cross-sectional area of tubing as opposed to wireline will result in the forces from water currents to have a strong effect on the tubing. These effects can result in complications with tubing bending and accuracy in the depth within the wellbore and can result in ultimate tubing failure.

Thus, there is a need for improved methods of treating wells having riserless well completions.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying views of the drawing are incorporated into and form a part of the specification to illustrate aspects and examples of the present invention. The figures are only for the purpose of illustrating examples of how the various aspects of the invention can be made and used and are not to be construed as limiting the invention to only the illustrated and described examples.

Figure 1 is an elevation view of a semi-submersible offshore rig installation according to one or more embodiments disclosed.

Figure 2 is an elevation view of a subsea well according to one or more embodiments disclosed.

Figure 3 is an elevation view of a subsea well with a lubricator according to one or more embodiments disclosed. Figure 4 is an elevation view of a subsea well intervention operation that may be performed in accordance with certain embodiments of the present disclosure.

Figure 5 is an elevation view of a subsea well intervention operation that may be performed in accordance with certain embodiments of the present disclosure. Figure 6 is a photo of a micro-coiled tubing spool in accordance with embodiments of the present disclosure.

DETAILED DESCRIPTION

The present disclosure includes well intervention methods using a special type of hollow fluid delivery conduit referred to herein as micro-coiled tubing (defined below) for treating a subsea riserless well completion. The method includes running a micro-coiled tubing, in lieu of slickline or e-line. The micro-coiled tubing may also be run without the aid of a coiled tubing injector. For example, grease head equipment may be used in lieu of a coiled tubing injector, with the proper flow tubes to handle the small OD of the micro-coiled tubing. Grease head equipment is typically used to control well pressure while running a slickline or e-line in a well. The grease head uses a series of very small pipes, called flow tubes, to decrease the pressure head of the well. Grease is injected at high pressure into the bottom portion of the grease head to counteract the remaining well pressure. The grease head equipment can control well pressure by sealing around a micro-coiled tubing string in a manner similar to how it is typically used while running a slickline or e-line in a well. In an example application, the micro-coiled tubing can be spooled and run on a slickline or e-line drum unit, i.e. using the micro-coiled tubing in place of a conventional slickline or e-line. The method may further include using slickline tools coupled to a working (lower) end of the micro-coiled tubing. The drum can be fitted with a high-pressure swivel to allow for pumping while selectively deploying the micro-coiled tubing into the well for intervention operations. The method can be particularly effective in treating wells or formations with treatment fluids transported through the micro-coiled tubing.

The term micro-coiled tubing herein refers to a coiled tubing having less than 20 mm outer diameter (OD) and having an inner diameter (ID). Non-limiting examples would include coiled tubing having 20 mm OD and 10 mm ID; 15 mm OD and 7 mm ID; 12 mm OD and 6 mm ID; 10 mm OD and 4 mm ID; and 8 mm OD and 3 mm ID.

The term well intervention operation refers to any operation carried out on an oil or gas well, such as during or at the end of its productive life, which alters the state of the well or well geometry, provides well diagnostics, or manages the production of the well. Non-limiting examples of well intervention operations include: re-perforating, acidizing, scale inhibitor injection, corrosion inhibitor injection, water control additive injection, addition of gas lift or other fluid lightening methods, injection of paraffin solvents, and injection of relative permeability modifiers.

Referring to Figure 1, illustrated is an elevation view of a semi-submersible offshore rig installation 100 in a body of water 101 that can be centered over a submerged oil and gas formation 130 located below the sea floor 102. A marine riser 104 extends from the deck 106 of the offshore rig installation 100 through the body of water 101 to a wellhead installation 108 established at the sea floor 102. The wellhead installation 108 may include one or more blowout preventers 110 to prevent, stop, or contain otherwise uncontrolled flow. The offshore rig installation 100 has a hoisting apparatus 112 and a derrick 114 for raising and lowering a pipe string 116. The term "pipe string," as used herein, may refer to pipe or tubing segments connected end to end, and may include, for example, segments of drill string, production tubing, or casing.

A wellbore 118 extends below the wellhead installation 108 and has been drilled through various earth strata 120, including one or more oil and gas formations 130. A casing string 122 is cemented within the wellbore 118. The term "casing" is used herein to designate a tubular string used to line a wellbore. Casing may actually be of the type known to those skilled in the art as "liner" and may be made of any material, such as steel or composite material.

Operatively disposed at the sea floor 102, and within the wellhead installation 108, is a hanger 124 anchored to the pipe string 116 and a wear bushing 126 complementarily engaged by the hanger 124. The cooperative engagement of the hanger 124 and the wear bushing 126 may be configured to generally suspend the pipe string 116 within the wellbore 118 and/or otherwise support the pipe string 116 within the marine riser 104 as it extends from the deck 106. One or more centralizers 128 (three are shown) may be arranged at strategic locations along the pipe string 116 in order to maintain the pipe string 116 centrally disposed within the marine riser 104 and/or the wellhead installation 108.

Figure 2 is an elevation view of a subsea well 108 which is a riserless completion on which a well treatment method may be performed according to the teachings of the present disclosure. A string of production tubing 116 may extend from the wellhead 108 to the oil and gas formation 130 to transport production fluid from the formation to the seafloor 102. A packer 132 may be set between the production tubing 116 and the casing 122 to isolate an annulus 134 formed between the production tubing 116 and the casing 122 from production fluid.

Figure 3 is an elevation view of a subsea well 108 which is a riserless completion on which a well treatment method may be performed according to the teachings of the present disclosure. A lubricator 136 has been attached to the subsea production wellhead 108. A support vessel 200 may be deployed to a location in the vicinity of the subsea well. The support vessel 200 is not limiting, for example may be a light, medium or heavy intervention vessel and include a dynamic positioning system compensator (not shown) to maintain position of the vessel 200 over the wellhead 108 and a heave compensator (not shown) to account for vessel heave due to wave action of the sea 101. Alternatively, the vessel 200 may be a mobile offshore drilling unit (MODU). The vessel 200 may further include a tower 202 located over a moonpool 204 and a winch 206. The winch 206 may include a drum having wire rope, slickline, or wireline 210 wrapped around it and a motor for winding and unwinding the wire rope, thereby raising and lowering a distal end of the wireline 210 relative to the tower. A remote operated vehicle (ROV) 220 may be deployed into the sea 101 from the vessel

200. The ROV 220 may be an unmanned, self-propelled submarine that includes a video camera, an articulating arm, a thruster, and other instruments for performing a variety of tasks. The ROV 220 may be controlled and supplied with power from vessel 200. The ROV 220 may be connected to the support vessel 200 by an umbilical 222. The umbilical 222 may provide electrical (power), hydraulic, and/or data communication between the ROV 220 and the support vessel 200. An operator on the support vessel 200 may control the movement and operations of ROV 220. The umbilical 222 may be wound or unwound from a drum 224.

The ROV 220 may be deployed to the wellhead 108 and may transmit video to the ROV operator for inspection of the wellhead 108 and assist in the landing of the lubricator 136 on the wellhead 108. The subsea production wellhead 108 with the lubricator 136 is now capable of receiving a well intervention.

Figure 4 is an elevation view of a subsea well 108 which is a riserless completion on which a well treatment method may be performed according to the teachings of the present disclosure. Deployment of a lubricator 136 has been made to a subsea production wellhead 108. (In the present context, operations performed from the support vessel 200 may be described as being peformed from "surface" in the sense that the equipment and rig personnel conduct operations from the vessel near or above the water's surface, or at least from above the subsea well completion. In a land-based operation, "surface" might refer to the general location of equipment and personnel on land, performing operations on a subterranean well, i.e. performing operations below surface.) The support vessel 200 may deploy a micro-coiled tubing 300 from the vessel 200 to the subsea production wellhead 108. The winch 206 may include a drum 310 having micro-coiled tubing 300 wrapped around the drum as shown in Figure 6. In one implementation, the drum may be a slickline/e-line drum, specially adapted as described herein by omitting any slickline/e-line and by using the micro-coiled tubing 300 in lieu of a conventional slickline or e-line. A motor (not shown) may be provided for controllably rotating the drum, for winding and unwinding the micro-coiled tubing 300, thereby raising and lowering to selectively position a distal end 302 of the micro-coiled tubing 300 relative to the tower. As shown in Figure 4 the micro-coiled tubing 300 extends from the vessel 200, proceeds through the lubricator 136, wellhead 108, into production tubing 116 located within the casing 122 of the well. Fluids pumped from the surface through the micro- coiled tubing 300 are thus discharged through the distal end 302 at the selected position. For example, the micro-coiled tubing 300 is capable of delivering treatment fluids such as paraffin solvents, corrosion inhibitors, etc. for use within the subsea well. Further the micro-coiled tubing 300 is capable of delivering treatment fluids such as acids, relative permeability modifiers, etc. for use to treat a subterranean formation zone. In certain embodiments the micro-coiled tubing can be run with a typical wireline, slickline or e-line deploying apparatus, including both surface equipment, such as a slickeline/e-line drum. In certain embodiments the micro-coiled tubing can be run with additional components deployable subsea and downhole, such as slickline/e-line tools 304 that can be coupled to the distal end 302 of the micro-coiled tubing 300 as shown in Figure 5. A non-limiting listing of slickline/e-line tools that could be utilized are: pressure sensors, temperature sensors, flow indicators, expandable tools, packoff tools, and sample collectors. Moreover, the micro-coiled tubing can be deployed utilizing open water slickline equipment that is currently able to work with riserless subsea completions. The micro-coiled tubing can be deployed without the need for a typical coiled tubing injector because the micro-coiled tubing can be deployed from the drum using the micro-coiled tubing in lieu of a conventional slickline or e-line, such as drum 310 as shown in Figure 6. A typical coiled tubing injector bends the coiled tubing to take out the curvature of the spool from which it is being deployed and make the coiled tubing a straight run for it to be deployed within a wellbore. For instance, the micro-coiled tubing can be deployed using typical grease head type lubricator, as commonly used with a typical slickline or e-line, in lieu of any coiled tubing injector. The drum may also be fitted with a high pressure swivel, as is commonly known in the art, to allow for the pumping of fluid through the micro-coiled tubing as it is run in and out of the well. Embodiments can be run in conjunction with a separate slickline or e-line having tools attached to perform well services. For example an e-line can be run in conjunction with a micro-coiled tubing such that a logging tool on the e-line can be operated while a treatment fluid can be injected within the well through the micro-coiled tubing. In an embodiment a slickline can be run having a hydraulically actuated tool attached in conjunction with a micro- coiled tubing, wherein the micro-coiled tubing provides the hydraulic conduit to the surface vessel such that an operator on a surface vessel can actuate the hydraulically actuated tool on the slickline by means of exerting hydraulic pressure through the micro-coiled tubing.

An embodiment of the present disclosure is a method for intervention of a well that includes inserting a micro-coiled tubing into the well. Embodiments of the method can include deploying the micro-coiled tubing from a drum having the micro-coiled tubing wrapped around the drum. Embodiments of the method can include passing the micro-coiled tubing through a wireline lubricator attached to a wellhead.

Embodiments of the method can include passing the micro-coiled tubing through a tubing string disposed within the well. Embodiments of the method can include applying hydraulic pressure through the micro-coiled tubing, and can include actuating a hydraulically actuated tool utilizing the micro-coiled tubing.

Embodiments of the method can include placing a treatment fluid in at least a portion of the well. Embodiments of the method can include placing a treatment fluid in at least a portion of the well wherein the treatment fluid is chosen from the group consisting of corrosion inhibitors, scale inhibitors, acids, surfactants, emulsion inhibitors, and combinations thereof. Embodiments of the method can include the well being a riserless subsea well.

An embodiment of the present disclosure is a method for riserless intervention of a subsea well including lowering a micro-coiled tubing from a vessel to a subsea wellhead. Embodiments of the method can include deploying the micro-coiled tubing from a drum having the micro-coiled tubing wrapped around. Embodiments of the method can include passing the micro-coiled tubing through a wireline lubricator attached to the subsea wellhead. Embodiments of the method can include passing the micro-coiled tubing through a tubing string disposed within the subsea well.

Embodiments of the method can include applying hydraulic pressure through the micro-coiled tubing and can include actuating a hydraulically actuated tool with the micro- coiled tubing. Embodiments of the method can include placing a treatment fluid in at least a portion of the well. The treatment fluids can be a treatment fluid chosen from the group consisting of corrosion inhibitors, scale inhibitors, acids, surfactants, emulsion inhibitors, and combinations thereof.

An embodiment of the present disclosure is a method for riserless intervention of a subsea well including lowering an adaptive device from a vessel to a subsea wellhead, fastening the adaptive device to the subsea wellhead, lowering an end of a micro-coiled tubing from the vessel to the adaptive device and inserting the micro-coiled tubing into the subsea well through the adaptive device. Embodiments of the method can include deploying the micro-coiled tubing from a slickline unit. Embodiments of the method can include placing a treatment fluid in at least a portion of the well.

The treatment solutions and methods of the present invention are applicable in both newly-drilled formations and in formations requiring re-stimulation. The solutions and methods of the present invention are particularly useful for formation re-stimulations where hydrocarbons will be present in the formation zones. The various embodiments of the present invention can be joined in combination with other embodiments of the invention and the listed embodiments herein are not meant to limit the invention. All combinations of various embodiments of the invention are enabled, even if not given in a particular example herein.

A treatment fluid may be used in a variety of subterranean operations, such as for use as a completion, workover, and/or preventive maintenance treatment fluid. As used herein, the term "subterranean operation" is defined to mean any operation that requires the performance of some action or procedure below the surface of the earth, including, but not limited to, actions or procedures performed in the course of recovering oil, gas, and/or other substances from a formation below the surface of the earth. As used herein, the term "treatment," or "treating," does not imply any particular action by the fluid or any particular component thereof, but instead refers to any use related to a subterranean operation in conjunction with a desired function and/or for a desired purpose.

While illustrative embodiments have been depicted and described, modifications thereof can be made by one skilled in the art without departing from the scope of the disclosure. All numbers and ranges disclosed above may vary by some amount. Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range is specifically disclosed. In particular, every range of values (of the form, "from about a to about b," or, equivalently, "from approximately a to b," or, equivalently, "from approximately a-b") disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. Moreover, the indefinite articles "a" or "an", as used in the claims, are defined herein to mean one or more than one of the element that it introduces. If there is any conflict in the usages of a word or term in this specification and one or more patent or other documents, the definitions that are consistent with this specification should be adopted. While compositions and methods are described in terms of "comprising," "containing," or "including" various components or steps, the compositions and methods can also "consist essentially of or "consist of the various components and steps. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee.

Depending on the context, all references herein to the "invention" may in some cases refer to certain specific embodiments only. In other cases it may refer to subject matter recited in one or more, but not necessarily all, of the claims. While the foregoing is directed to embodiments, versions and examples of the present invention, which are included to enable a person of ordinary skill in the art to make and use the inventions when the information in this patent is combined with available information and technology, the inventions are not limited to only these particular embodiments, versions and examples.

Numerous other modifications, equivalents, and alternatives, will become apparent to those skilled in the art once the above disclosure is fully appreciated. While embodiments of the invention have been shown and described, modifications thereof can be made by one skilled in the art without departing from the teachings of this disclosure. The embodiments described herein are exemplary only, and are not intended to be limiting. Many variations and modifications of the invention disclosed herein are possible and are within the scope of the invention. Use of the term "optionally" with respect to any element of a claim is intended to mean that the subject element is required, or alternatively, is not required. Both alternatives are intended to be within the scope of the claim. It is intended that the following claims be interpreted to embrace all such modifications, equivalents, and alternatives where applicable. Other and further embodiments, versions and examples of the invention may be devised without departing from the basic scope thereof and the scope thereof is determined by the claims that follow.