Patent Application
20170254148
The invention generally relate to mobile offshore drilling units. More particular, the invention relates to an offshore system comprising a mobile offshore drilling unit and for performing concurrent well-processing tasks.
Mobile offshore drilling units and offshore production platforms are widely used in the exploration and exploitation of hydrocarbon reservoirs under the sea floor.
The various types of mobile offshore drilling units include so-called bottom-supported rids which rest on the seafloor. Jack-up drilling units are typical examples of bottom-supported units; they comprise a hull and a number of legs adapted to be lowered towards the sea floor. Such jack-up units may thus be towed towards their desired off shore location with the legs in a raised position. Once the unit is at its intended position the legs are lowered and brought into contact with the sea floor. Further lowering of the legs relative to the hull causes the hull to be elevated out of the water. Many jack-up drilling units have the drill floor and well centre positioned on a cantilever system that can be extended horizontally outwards relative to the hull of the jack-up unit, thus allowing the well centre to be positioned outside the periphery of the unit defined by the hull of the unit.
Offshore production platforms used for extracting oil or gas from a production well are frequently fixedly installed during longer periods. They frequently operate a plurality of wells.
When an oil or gas well is no longer economical or if there is some problem with the well which means that production is no longer possible or that well integrity has been compromised in some way, or for other reasons, the well may be abandoned. It is common practice to plug the well before abandoning it, e.g. to prevent seepage of hydrocarbon product from the well. This can also apply to water injectors, i.e. bores which have been drilled in order to pump water into a reservoir to increase bottom-hole pressure. Similar processes may also be relevant for drilling new wells, or so-called “slot-recovery” where the upper part of the well is re-used by plugging the lower part and side-tracking thus creating a new well using same “slot” on the production platform.
Commonly, plugging may be achieved by injecting a settable substance or medium, e.g. cement, into the well. A well will normally have production perforations, that is to say apertures in a well liner or casing through which hydrocarbon product enters from the rock formation and travels to the surface. During plug and abandonment operations it is common to seal (“squeeze”) production perforations with cement or another settable medium which may then form a permanent barrier to prevent flow through the perforations and/or across the zones and potentially out of the well. Alternatively or additionally, at least a part of the downhole equipment, such as casings, production tubing, etc., is often pulled from the well.
The process may further involve pumping mud or other high-density fluids into the well in order to stabilize or “kill the well” and, in particular to provide sufficient pressure so as to prevent carbohydrates from rising out of the well.
The process may further involve pumping a surfactant liquid, known as a “spacer”, into the well. The purpose of the spacer is to remove oil residues from the internal surface of the well casing and/or liner and rock matrix making them “water wet” (allowing better adhesion by cement) in addition to limiting cross-contamination between liquids/cement. Commonly, immediately following the spacer, cement is pumped down the well to occupy the part of the well casing and/or liner where perforations are to be squeezed. When sufficient cement has been pumped down, more spacer liquid and possibly other liquids may be pumped down the well in order to place the cement at its final designed location.
The plug and abandonment process may be a complex and costly process, and it is generally desirable to reduce the time required for performing the process, in particular when multiple wells are to be processed at the same site.
WO 2012/144952 discloses a multi-functional jack-up for decommissioning an offshore platform. In particular, this prior art jack-up unit comprises a mobile crane and a tubular-handling crane mounted to a cantilever platform of the jack-up unit and arranged to be operable independently from each other. This prior art jack-up unit aims to introduce flexibility during the well plugging and abandonment by utilizing the multifunctional jack up as a tender assist vessel which assists the offshore platform during the plugging and abandonment operation. In addition to providing assistance to the offshore platform, the multifunctional jack-up is able to perform decommissioning of the offshore platform itself.
However, it remains desirable to further improve the efficiency of the plug and abandonment process or similar processes performed on multiple wells.
According to a first aspect, disclosed herein are embodiments of do offshore well-processing system for performing one or more well-processing tasks on one or more wells of an off-shore all or gas reservoir. Embodiments of system comprise a mobile offshore drilling unit and a remote well-processing device. The mobile offshore drilling unit defines at least one well centre and comprises at least one primary drill rig comprising at least one drill floor and at least one hoisting system for raising and/or lowering tubular equipment through the at least one well centre from and/or into a well in the seafloor.
The remote well-processing device is configured to be positioned on an offshore platform different from the mobile offshore drilling unit, and to perform at least a first well-processing task when positioned on said offshore platform at a position displaced from the at least one well centre defined by the mobile offshore drilling unit. The mobile offshore drilling unit and the remote well-processing device are configured to be operationally coupled to each other when the remote well-processing device is positioned on said offshore platform; and the mobile offshore drilling unit is configured to assist in performing two or more concurrent well-processing tasks performed concurrently on respective wells, including the first well-processing task performed by the remote well-processing device on a first well and a second well-processing task concurrently performed by the offshore well-processing system on a second well.
Hence, embodiments of the well-processing system described herein allow plug and abandonment process or other well-processes to be performed in an efficient manner as multiple wells may be processed concurrently and independently of each other. In particular, the remote well-processing device may be moved from well to well and perform one or more first well-processing tasks while the drill rig of the mobile offshore drilling unit and/or another remote well-processing device may concurrently, i.e. parallel in time, be moved from well to well and perform one or more second well-processing tasks. Consequently, a batch processing of multiple wells may be performed where certain tasks may be moved away from the critical path of the overall process, thus speeding up the overall process.
The first well-processing task may be different from the second well-processing tasks and may require different types of equipment. Hence, the remote well-processing device may be specifically configured to perform a selected set of one or more first well-processing tasks while the drill rig of the mobile offshore drilling unit or a second remote well-processing device may be specifically configured to perform the one or more second well-processing task. For example, the drill rig may perform tasks that require a high lifting capacity and/or high torque to be imparted on a string of tubular and/or a high-throughout pipe handling; while a lower-rated remote well-processing device may perform tasks that do not require the heavy and efficient equipment of a drill rig.
Consequently, the well-processing tasks may be performed on multiple wells in parallel and by equipment specifically configured for the respective tasks, thus allowing for a more efficient overall utilisation of the equipment.
The first and second well-processing tasks may be respective sub-tasks of a process. In some embodiments the first and the second well-processing tasks are each to be performed on multiple wells, e.g. on all wells associated with the offshore platform. In some embodiments, they even have to be performed in predetermined sequence, e.g. the second well-processing task before the first well-processing task or vice versa. In other embodiments, the first and/or the second well-processing task may only need to be performed on one or some, but not on all wells. For example, some wells may only require the first well-processing task while some wells may only require the second well-processing task to be performed.
Generally, the mobile offshore drilling unit may comprise one or more drill rigs, each comprising a drill floor defining a well centre. Alternatively or additionally, the mobile offshore drilling unit may comprise a multi-activity drill rig, such as a dual-activity drill ring, defining two or more well centers and comprising one, two or more hoisting systems for raising or lowering tubulars through the respective well centres. In any event, the remote well-processing device is configured to be positioned independently from, and at a position different from, the position of the well centre(s) defined by any drill rig mounted on the mobile offshore drilling unit. As the remote well-processing device may be positioned above respective wells independently of the positioning of the drill rig, re-positioning of the remote well-processing device may be performed efficiently and without necessarily requiring cantilever operations of the mobile offshore drilling unit.
Embodiments of the drill rig of the mobile offshore drilling unit may comprise a derrick, a tower, a mast or another suitable drilling support structure. The hoisting system may be a drawworks based hoisting system, a hydraulic hoisting system or another suitable type of hoisting system. The hoisting system of the mobile offshore drilling unit may have a rated capacity sufficiently high to allow raising tubular equipment, such as production tubing or casing, out of a well. The drill rig may comprise a top drive or another suitable device for imparting sufficient torque on a drill string that extends into a wellbore for performing drilling or similar operations.
In some embodiments, the mobile offshore drilling unit comprises a mud handling system including one or more mud pumps and a manifold allowing mud or other well fluids to be pumped into the well, out of the well or circulated in and out of the well. The mobile offshore system may further comp a blow-out-preventer which may be located below the drill floor.
As the mobile offshore drilling unit is operationally coupled to the remote well-processing device, the remote-well processing device utilises one, some or all of the facilities of the mobile offshore unit, such as power, pumping capacity, pipe handling capacity, process control equipment etc. These facilities thus perform one or more auxiliary functions. Assisting in performing a well-processing task is thus intended to comprise supplying one or more auxiliary functions that facilitate the performance of the well-processing task. The actual well-processing task may also be performed by the mobile offshore drilling unit; alternatively the actual well-processing task may be performed by a device that may be positioned on, and be structurally supported by, the offshore platform. In particular, assisting in performing a well-processing task may include performing one or more auxiliary functions that may be performed remotely from the well head, e.g. horizontally displaced from the well-centre and/or vertically displaced from a well head located on the offshore platform. In some embodiments, the horizontal and/or vertical displacement may be more than 2 m, such as more than 5 m away, such as more than 10 m. To this end, the equipment of the mobile offshore drilling unit that provides the auxiliary function is connected to the device positioned at or above the well head via the operational coupling, e.g. a supply line and/or a communication line and/or flow line.
Consequently, the offshore platform on which the remote well-processing device is placed needs to be able to provide structural support only to the remote well-processing device while further auxiliary equipment assisting the remote well-processing device in the operation performed by the remote well-processing device is structurally supported by the mobile offshore drilling unit. Moreover, such auxiliary equipment may require considerable space which may be available on the mobile offshore drilling unit while the offshore platform may not have sufficient free space available for accommodating the auxiliary equipment. Examples of such auxiliary equipment may include pumps and/or pits and/or mixing devices and/or manifolds for mud, cement and/or other fluid media, devices for storing and/or processing and/or controlling solids, drums/reels for coiled tubing, etc.
To this end, in some embodiments, the operational coupling comprises at least one connection chosen from:
For example the power and communication lines may be provided as one or more umbilical cables between the offshore drilling unit and the remote well-processing device.
The mobile offshore drilling unit may comprise a pipe setback associated with the primary drilling rig and/or other pipe handling apparatus for handling pipes on the drill floor or off the drill floor. Off-drill-floor pipe handling may include all pipe handling for moving tubulars to/from the drill floor as well as all pipe handling other than connecting the pipes to the hoisting system and/or to an existing string of tubulars and other than alignment of the pipes with the hoisting system and the well centre.
In some embodiments, the system comprises a pipe transfer apparatus configured to transport tubulars between the mobile offshore drilling unit and the remote well-processing device when said remote well-processing device is positioned on said offshore platform. The pipe transfer apparatus may comprise a pipe handling apparatus and/or a catwalk machine, a chute, a crane, or similar pipe transport apparatus for transporting pipes across the offshore platform and/or between the offshore platform and the mobile offshore drilling unit. The pipe transport apparatus may be configured to transport individual pipes and/or multiple pipes at the same time. Once tubulars are transferred to the mobile offshore drilling unit, the pipe handling and/or storage facilities of the mobile offshore drilling unit may be utilised for efficient handling and storage of pipes.
In some embodiments, the mobile offshore drilling unit comprises a pump system including one or more pumps for transferring fluids such as mud, chemicals, cement between the mobile offshore drilling unit and a well; wherein the remote well-processing device is connectable to said pump system via a flow line. The remote well-processing device may further be connectable to a conductor extending from the offshore platform to the first well. In some embodiments the mobile offshore drilling unit comprises a pump system configured to selectively or concurrently transfer fluids between the mobile offshore drilling unit and the first well via the remote well-processing device and between the mobile offshore drilling unit and the second well via the primary rig. More particular, in some embodiments, the mobile offshore drilling unit comprises a first manifold connected to the pump system id operable to facilitate pumping fluids, such as mud or other well fluids, into or out of the second well via the primary drill rig, e.g. through a conductor extending from the offshore platform or from the mobile offshore drilling unit to the second well; and wherein the mobile offshore drilling unit comprises a second manifold connected to the pump system and operable to facilitate pumping fluids into or out of the first well through said flow line and a conductor extending from the offshore platform to the first well. Hence, the control of transferring fluids between the mobile offshore drilling unit and multiple wells, selectively via the remote well-processing device, may be performed in an efficient manner.
The mobile offshore drilling unit and the offshore platform are each configured to be positioned relative to the seafloor independently of each other and with a gap them. In particular, they may each be configured to support the weight equipment positioned on them Hence, the offshore platform only needs to support the weight of the remote well-processing device, while the drill rig, mud and/or cement and/or other pumps, energy, pipe handling and storage capacity is provided by the mobile offshore drilling unit. The mobile offshore drilling unit, the offshore platform, or both may be bottom-supported.
In some embodiments the offshore platform is a production platform, e.g. with facilities to extract and process oil and natural gas, and to temporarily store product until it can be brought to shore for refining and marketing. The production platform may be a production platform with dry well heads. In many cases, the platform contains facilities to house the workforce as well. Depending on the circumstances, the offshore platform may be fixed to the sea floor, e.g. by a jacket, may consist of an artificial island, may be a compliant tower, or may otherwise float. The production platform may operate on a plurality of wells e.g. arranged in a grid of wells. From each well, a conductor pipe may extend between the production platform and the seafloor.
The mobile offshore drilling unit and/or the offshore platform may comprise accommodation for personnel.
In some embodiments, the mobile offshore drilling unit is configured to stand on the sea floor, to float in the water, to perform drilling operation while floating and being moored and/or to perform drilling operations while resting on the seafloor. In some embodiments the mobile offshore drilling unit is a jack-up unit or a semi-submersible unit or a drillship. A jack-up unit is a floatable, self-elevating platform which is bottom-supported by legs. In some embodiments, the mobile offshore drilling unit comprises a cantilever mounted on the unit. The primary drill rig including the drill floor is mounted on a drill operation end of the cantilever. The cantilever mat be arranged to allow two-dimensional movement of the primary drill rig. The cantilever may be moveable in a longitudinal direction of the cantilever such that the drill operation end of the cantilever extends beyond the platform, whilst the drill floor may be moveable on the cantilever in a direction transverse to the longitudinal direction. Hence, the cantilever may allow the well center of the primary drill rig to be located within an area described by the longitudinal and transverse movement of the cantilever and/or the drill rig. When the mobile offshore drilling unit is configured to extend the cantilever above the offshore platform, the well centre of the primary drill rig may be positioned above selected wells associated with an existing offshore production platform. The cantilever may provide a counterweight to the cantilever such that the cantilever can extend above the offshore platform without resting the cantilever on the offshore platform. In some embodiments, the that well-processing task and/or the second well processing task is/are performed on a well that is positioned outside a perimeter defined by the cantilever, i.e. on a well that is not positioned underneath the cantilever. In some embodiments, only the first well-processing task is performed (e.g. by the remote well-processing device) on a well that is positioned outside a perimeter defined by the cantilever, while the second well-processing task is performed on a well above which the cantilever extends.
In some embodiments, the offshore mobile drilling unit transports the remote well-processing device, e.g. in assembled form or as several modules, to an existing offshore platform and positions the remote well-processing device—or modules of the device—the offshore platform. The transfer may be performed by a crane of the mobile offshore drilling unit or the offshore platform. Alternatively or additionally, in some embodiments, the mobile offshore drilling unit is configured to attach at least a part of the remote well-processing device to the cantilever and to position at least the part of the remote well-processing device onto the offshore platform. Hence, the cantilever may be operable to carry and position a relatively large structure in one piece en the offshore platform. To this end, the cantilever may comprise connectors—e.g. hooks, beams, or the like, for detachably connecting and carrying the remote well—processing device or one or more modules thereof.
The connectors may be positioned at the longitudinal end of the cantilever extending away from the hull. Alternatively, the connectors may be positioned along the lateral sides of the cantilever e.g. so that the remote well-processing device, when connected to the cantilever, does not substantially extend the dimensions of the mobile offshore drilling unit during transit. It may sit over or on the main deck when the cantilever is retracted so as to allow maintenance and/or configuration of the remote well-processing device, e.g. during transit.
Alternatively, or in combination, the remote well-processing device may be assembled on the offshore platform. Optionally the remote well-processing device may remain on the platform for further operations when the mobile offshore drilling unit is moved away or to be ready for a later operation in conjunction with the same or another mobile offshore drilling unit. This may require the addition of utilities to the offshore platform and/or connections to the systems existing on the offshore platform if any.
In some embodiment the offshore platform may comprise a first well-processing device and the offshore mobile drilling unit may transport a further well-processing device, e.g. a drill rig, a mast, and/or the like, to the offshore platform and position the further well-processing device—or modules of the device—on the offshore platform. The offshore mobile drilling unit may then be operationally coupled to one or both of the first well-processing device and the further well-processing device so as to assist one or both of the well-processing devices in performing the respective well-processing tasks performed by the respective well-processing devices.
The remote well-processing device may be configured perform single type of tasks or a variety of tasks. Accordingly, the remote wall-processing device may range from relatively simple equipment to a complex drill rig with its own hoisting system and top drive.
Some embodiments of the remote well-processing device comprises one or more of
For example, in one embodiment the remote well-processing device merely comprises a device for transferring cement and/or mud and/or other well fluids into or out of a well. To this end, the remote well-processing device may comprise a connector or manifold for connecting a flow line extending from a pump of the mobile offshore drilling unit to a conductor extending from the offshore platform to the seafloor.
When the remote-processing device further comprises a work platform, personnel may easily access the connector and/or manifold and/or other equipment of the remote well-processing device.
When the remote well-processing device further comprises a device for wireline operation and/or coiled tubing operation, the remote well-processing device may further perform monitoring and testing operations and/or other operations that do not require the handling of pipes. In some embodiments, a reel or drum for accommodating a wireline or coiled tubing may be positioned on the mobile offshore drilling unit and be fed from said drum to a well-processing device on the offshore platform which well-processing device is configured to advance the wireline or coiled tubing into the well.
Alternatively or additionally, when tare remote-processing device comprises a heisting system, the remote well-processing device may also be used to pull equipment e.g. production tubing from the well. To this end remote-processing device may further comprise pipe-handling equipment, break-out tongues and/or shearing devices and/or a blow-out preventer (BOP), such as a wireline BOP or stripping BOP. Nevertheless, in some embodiments, a pipe transfer apparatus and on- and/or off-drill-floor pipe handling apparatus of the mobile offshore drilling unit may perform some or even all off-drill-floor pipe handling associated with the first well-processing task performed by the remote well-processing device. In some embodiments, the pipe handling may be assisted by a crane of the offshore platform.
In some embodiments, the remote-processing device may even comprise a top drive.
In any event, the type of the equipment, its rated capacity and capabilities may be adapted to the nature of the well-processing tasks to be performed by the remote well-processing device. In some embodiments, the remote well-processing device has a lower rated lift capacity and/or a lower rated torque capacity and/or a lower pipe handling throughput capacity as the primary drill rig.
The remote well-processing device may be movable between well locations. It will be appreciated that the mechanism for moving the remote well-processing device may depend on the size and type of the device. In some embodiments, the remote well-processing device is arranged skiddable on the offshore platform, e.g. on one or more skid beams traversing a grid of well slots and supported by skid beams extending along said grid, or fitted on one or more trolleys for parallel movement; and/or via other forms of skid beams, tracks and/or the like; and/or by means of wheels on the remote well-processing device.
In some embodiments, the system may comprise multiple remote well-processing devices, each configured to perform one or more well-processing tasks (e.g. respective sub-tasks of a sequence of sub-tasks) when positioned on said offshore platform at respective positions displaced from each other and from the at least one well centre defined by the mobile offshore drilling unit; and wherein the mobile offshore drilling unit is configured to be operationally coupled (e.g. by respective flow lines, utility lines, communications lines and/or the like, as described herein) to each of the remote well-processing devices when the respective remote well-processing devices are positioned on said offshore platform; and wherein the mobile offshore drilling unit is configured to assist in performing concurrent well-processing tasks performed concurrently on respective wells, including a first well-processing task performed by a first remote well-processing device on a first well and a second well-processing task concurrently performed by a second remote well-processing device on a end well. The remote well-processing devices may each have the same ability and equipment or they may have different capabilities and equipment, e.g. so as to tailor respective remote well-processing devices for respective specific well-processing tasks. Additionally or alternatively, the remote well-processing device and/or the primary drilling rig may be configured to operate concurrently on multiple wells. Hence, generally embodiments of the system described herein is configured to perform two or more concurrent well-processing tasks on respective two or more wells, wherein at least one task is performed by the remote well-processing device and another task is concurrently performed by a remote well-processing device or the primary drilling rig.
The present disclosure relates to different aspects including the system described above and in the following, corresponding methods, devices, and/or product means, each yielding one or more of the benefits and advantages described in connection with the first mentioned aspect, and each having one or more embodiments with all or just the additional features corresponding to the embodiments described in connection with the first-mentioned aspect and/or disclosed in the appended claims.
According to yet another aspect, disclosed herein are embodiments of a method of performing one or more well-processing tasks en one or more wells of an offshore oil or gas reservoir, the method comprising:
In some embodiments, the method comprises:
The well-processing tasks may be respective sub-tasks of a decommissioning task and, in particular, a plug and abandoning task including stabilizing or “killing” and sealing a well in preparation for temporarily or permanent abandonment. In some embodiments, the well-processing tasks may be sub-tasks of the process of drilling new wells, or of a so-called “slot-recovery” process where the upper part of a well is re-used by plugging the lower part and by side-tracking, thus creating a new well using an existing “slot” on the production platform.
I some embodiments, the first well-processing task comprises one or more of: killing a well, sealing, logging, testing and/or monitoring tasks in the well, and/or the like. Killing the well may comprise injecting a fluid or medium, e.g. mud, into the well, where the fluid or medium has a density sufficiently high to create a pressure high enough to prevent oil or gas from exiting the well. Sealing the well may comprise injecting a settable substance or medium, e.g. cement, into the well. Sealing may further comprise injecting other chemicals such as a spacer. Testing and monitoring tasks may include lowering a wireline or coiled tubing into the well.
In some embodiments, the second well-processing task comprises one or more of: pulling production tubing from a well, removing casing from a well, drilling a side track, milling, logging, and/or the like. These tasks may require a relatively high lifting capacity and/or torque and may thus advantageously be performed by a drilling rig or by a remote processing unit having a sufficient lift and/or torque rating.
It will be appreciated, that other divisions of the first and second well-processing tasks between the remote well-processing device and the primary drill rig or another remote well-processing device may be used. For example, some of the killing, sealing, and monitoring tasks may be performed by the drill rig, while only one or some of the killing, sealing and monitoring operation is performed by the remote well-processing device.
In some embodiments, the well-processing tasks may be respective sub-tasks of a drilling and completion task.
Generally, when a remote well-processing device assisted by a mobile offshore drilling unit performs concurrent operations (e.g. in parallel to operations performed by another remote well-processing device and/or by the mobile offshore drilling unit), this may take time off the critical path of the mobile offshore drilling unit for operations that would otherwise have to be performed by the mobile offshore drilling unit. A well processing task typically comprises sub-tasks that only impose, relatively few requirements on the equipment while others impose many requirements. Accordingly, the selection of which sub-tasks may advantageously be performed by a remote well-processing device of the offshore platform and merely assisted by the mobile offshore drilling unit and which sub-tasks are rather performed by the mobile drilling unit depends on the available space, structural support and facilities available on the offshore drilling unit, and by the requirements imposed on the remote-well processing device that is present or positioned on the offshore platform. For example, if a full BOP stack is installed at the remote well-processing device, the remote well-processing device may run and pull tubing, perform scraper run and/or possibly mill and drill tasks. This may be applicable for a remote well-processing device configured to perform plug and abandonment operations or for a remote well-processing device configured to perform well construction/completion tasks. Even without having a full BOP stack installed, a remote well-processing device may perform tasks such as slickline wireline and, coil tubing operations and other minor handling jobs.
In some embodiments, the well processing task comprises a drilling and completion task that comprises multiple sub-tasks. Some sub-tasks, such as slikline completion tasks, X-mas tree tasks and/or post-completion jobs, only require e.g. a slickline drum, sheaves, a crane, a pump. Some or all of these sub-tasks may thus be performed by a relatively simple remote well-processing device and assisted by the mobile offshore drilling unit. As these tasks ace typically performed at the final stages of a drilling and completion task, these may be performed by a remote well-processing device after some or all the previous sub-tasks of the drilling and completion task have been performed by a mobile offshore drilling unit. Some or all of these sub-tasks may thus be performed by relatively simple a remote well-processing device and assisted by the mobile offshore drilling unit. Concurrently, the mobile offshore drilling unit may be used to perform other subtasks, e.g. drilling tasks, on another well.
Another group of subtasks of a drilling and completion task include the running and pulling of tubing. These sub-tasks may require one or more of the following: a mast, a topdrive and/or power swivel, a rotary table, fluid circulation, a control system, a BOP and associated control system, a manifold and pipe handling equipment. Some or all of these sub-tasks may thus be performed by a remote well-processing device and assisted by the mobile offshore drilling unit. In such an embodiment, the remote well-processing device may thus comprise one or more of the following: a mast, a BOP, a topdrive, power swivel or similar device for imparting torque, a rotary table.
Yet another group of subtasks of a drilling and completion task include the running and pulling of drill pipe. These sub-tasks may further require an increased hoisting capacity and increased torque, pipe storage and handling facilities. Some all of these sub-tasks may thus still be performed by a remote well-processing device and assisted by the mobile offshore drilling unit, provided that the remote well-processing device has sufficiently rated hoisting equipment. Nevertheless, in some embodiments, these sub-tasks may advantageously be performed by a mobile offshore drilling unit.
Finally, yet another group of subtasks of a drilling and completion task includes the drilling, running casing and cementing of a top/surface section and of one or more intermediate sections of the well and the drilling of a reservoir section of a well. These sub-tasks may further require solids control, additional pumps and sufficient pit space. Some or all of these sub-tasks may thus still be performed by a remote well-processing device and assisted by the mobile offshore drilling unit provided that the remote well-processing device has sufficiently rated hoisting equipment. Nevertheless, in some embodiments, these sub-tasks may advantageously be performed by a mobile offshore drilling unit.
In some embodiments, the first and/or the second well processing task may be a task requiring a BOP. In such an embodiment, it may be particularly advantageous for the mud handling functionality to be performed on and by the mobile offshore drilling unit, as the operation of mud pits, mud pumps and mixing equipment requires considerable space. Hence, in some embodiments, the offshore drilling unit assists in a well-processing task that requires operation of a BOP by providing one or more facilities chosen from the following: a mud pump, a mud pit, mud mixing equipment, equipment for controlling solids.
In some embodiments, the offshore drilling unit assists in a well-processing task that requires operation of a BOP by further providing one or more facilities chosen from the following: a choke-and-kill manifold, a standpipe manifold, a cement manifold. However, in alternative embodiments, one, some or all of these functions may be provided by equipment of or on the offshore platform. In some embodiments, when a well-processing task requiring a BOP is performed by a well-processing device positioned on the offshore platform, a trip tank or other well monitoring equipment may be provided on the offshore platform.
According to yet another aspect, disclosed herein is a mobile offshore drilling unit comprising a primary drill rig comprising a drill floor and a hoisting system for raising and lowering tubular equipment from/into a well in the seafloor through a well centre defined by the mobile offshore drilling unit; and wherein the mobile offshore drilling unit is configured to establish an operational coupling with a remote well-processing device positioned on an offshore platform different from the mobile offshore drilling unit and at a position different from the well centre defined by the mobile offshore drilling unit; and to assist in performing two or more concurrent well-processing tasks performed on respective wells of an offshore oil or gas reservoir; wherein at least a first one of said well-processing tasks is performed by said remote well-processing device.
The cantilever may further comprise a hoisting system supported by a drilling support structure, such as a mast or derrick, extending upwards from the cantilever. The hoisting system is configured to raise and lower tubulars through the well centre and from/to the seabed. The drilling rig may further comprise a top drive or other device operable to rotate the tubulars that are lowered car raised through the well centre.
The above and/or additional objects, features and advantages of embodiments and aspects of the present invention, will be further elucidated by the following illustrative and non-limiting detailed description with reference to the appended drawings, wherein:
In the following description, reference is made to the accompanying figures, which show by way of illustration how the invention may be practiced.
The drill rig 132 is configured to perform drilling of other well-processing operations, e.g. through a BOP stack installed below or inside the cantilever and through a conductor pipe extending from the BOP stack downwards towards the seabed.
The offshore production platform 101 is configured for production of oil or gas offshore. The offshore platform 101 of
For example, an offshore platform may have a grid of several well slots 103. These well slots may be located between skid beams 104.
The offshore well-processing system of
The offshore jack-up rig 114 is positioned adjacent the existing fixed offshore platform which serves as a grid, over which the cantilever 117 of the jack-unit is extended. The offshore platform remains at some distance from the jack-up unit such that a gap exists between the two structures. While the jack-up unit is positioned next to the existing offshore platform, no weight is transferred between the jack-up unit and the offshore platform, other than placement of the remote well-processing device 106 on the offshore platform.
The cantilever is extended above the existing platform 101 such that the well centre defined by the drill floor 135 of the drill rig is positioned above one of the well slots 103a and such that the drill rig can raise or lower a string of tubulars 121 from or into the well 103a, e.g. so as to pull production tubing or casings from a well. The pipes or other tubulars may then be efficiently handled by pipe handling apparatus of the jack-up unit (not explicitly shown in
The jack-up unit 114 assists the remote well-processing device 106 in performing the coiled tube operation. In particular, in the example of
It will be appreciated that, in alternative embodiments, the reel and/or other parts of the coiled tubing equipment may be placed in the production platform and/or on other parts of the jack-up unit. Moreover, alternative embodiments of a system may include one or more further remote well-processing devices which may each be positioned above respective well centres 103 and which may each perform respective tasks.
Hence,
It will be appreciated that, in addition or alternative to coiled tubing operation, a remote well-processing device may be configured to perform another type of secondary process, such as logging operation, a wireline operation, a pumping operation, e.g. for killing a well, and/or the like.
As in the example of
As in the example of
Hence, as in the previous example, a primary operation is performed on one well entirely by the drilling rig 132 of the mobile offshore drilling unit, while a parallel, secondary operation is performed by the remote well-processing device on the platform which provides structural support to the remote well-processing device, but where the secondary operation is otherwise facilitated by equipment on-board the mobile offshore drilling unit.
The system of
The other remote well-processing device 329 comprises a derrick or other support structure and a hoisting system configured to raise or lower tubulars through the well centre 103a. The remote well-processing device may further comprise a blow-out-preventer and further equipment such as break-out tongs and/or shearing devices, and/or a top drive. The remote-well processing device thus provides satellite drill floor in addition to the drill floor 135 of the drill rig of the jack-up unit. It will be appreciated that the drill rig of the remote well-processing device 329 may have the same rating or a different, e.g. a lower, rating compared to the drill rig 136. The remote well device 329 is skiddable mounted e.g. on skid beams 330 traversing the grid of well slots 103. The jack-up unit assists the remote well-processing device 329 e.g. via a flow line connection 319a which may be connected to manifold 320 or to a separate an fold of the jack-up unit. Hence, the remote well-processing device 329 may receive mud, cement and/or other fluids from the jack-up unit. Additionally or alternatively, the remote well-processing device 329 may receive hydraulic and/or electrical power from the jack-up rig. The remote well-processing device 329 may further be controlled from a driller's cabin or other control station of the jack-up unit via suitable communication lines. The remote well-processing device 329 may also utilise pipe storage and pipe handling facilities of the jack-up unit. For example, pipes may be transferred between a storage are 223 of the jack-up unit and a temporary storage area 327 of the offshore platform 101. This transfer may be performed by a crane 325 of the jack-up unit and/or by other pipe handling equipment of the jack-up unit and/or by a pipe handling apparatus extending between the jack-up unit and the platform 101. The pipe may be transferred individually or as stacks of multiple pipes.
Hence, as in the previous example a primary operation is performed on one well while a secondary operation is performed on another well. However, in this example, both operations are performed by respective remote well-processing devices. It will be appreciated, however, that the drill rig of the jack-up unit may be used to operate on a third well concurrently with the operation of the two remote well-processing devices.
As in the previous examples, the offshore platform 101 provides structural support to the remote well-processing devices, but where the operations performed by the remote well-operating devices arm assisted/facilitated by equipment on-board the mobile offshore drilling unit.
Although some embodiments have been described and shown in detail, the invention is not restricted to them, but may also be embodied in other ways within the scope of the subject matter defined in the following claims. In particular, it is to be understood that other embodiments may be utilised and structural and functional modifications may be made without departing from the scope of the present invention. For example, embodiments of the invention have mainly been described with reference to a jack-up unit. It will be appreciated, however, that embodiments of the system described herein may also be used in connection with other types of mobile offshore drilling units.
In device claims enumerating several features, several of these features can be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims or described in different embodiments does not indicate that a combination of these measures cannot be used to advantage.
It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| PA 2014 70712 | Nov 2014 | DK | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/DK2015/000048 | 11/20/2015 | WO | 00 |
