Patent Grant
10738557
The present invention relates to methods and apparatus for oil and gas operations, in particular to methods and apparatus for fluid intervention in oil and gas production or injection systems. The invention has particular application to subsea oil and gas operations, and aspects of the invention relate specifically to methods and apparatus for fluid intervention in subsea oil and gas production and injection infrastructure.
In the field of oil and gas exploration and production, it is common to install an assembly of valves, spools and fittings on a wellhead for the control of fluid flow into or out of the well. A Christmas tree is a type of fluid manifold used in the oil and gas industry in surface well and subsea well configurations and have a wide range of functions, including chemical injection, well intervention, pressure relief and well monitoring. Christmas trees are also used to control the injection of water or other fluids into a wellbore to control production from the reservoir.
There are a number of reasons why it is desirable to access a flow system in an oil and gas production system. In the context of this specification, the term “fluid intervention” is used to encapsulate any method which accesses a flow line, manifold or tubing in an oil and gas production, injection or transportation system. This includes (but is not limited to) accessing a flow system for fluid sampling, fluid diversion, fluid recovery, fluid injection, fluid circulation, fluid measurement and/or fluid metering. This can be distinguished from full well intervention operations, which generally provide full (or near full) access to the wellbore. Full well intervention processes and applications are often technically complex, time-consuming and have a different cost profile to fluid intervention operations. It will be apparent from the following description that the present invention has application to full well intervention operations. However, it is an advantage of the invention that full well intervention may be avoided, and therefore preferred embodiments of the invention provide methods and apparatus for fluid intervention which do not require full well intervention processes.
International patent application numbers WO00/70185, WO2005/047646, and WO2005/083228 describe a number of configurations for accessing a hydrocarbon well via a choke body on a Christmas tree.
Although a choke body provides a convenient access point in some applications, the methods of WO00/70185, WO2005/047646, and WO2005/083228 do have a number of disadvantages. Firstly, a Christmas tree is a complex and carefully-designed piece of equipment. The choke performs an important function in production or injection processes, and its location on the Christmas tree is selected to be optimal for its intended operation. Where the choke is removed from the choke body, as proposed in the prior art, the choke must be repositioned elsewhere in the flow system to maintain its functionality. This compromises the original design of the Christmas tree, as it requires the choke to be located in a sub-optimal position.
Secondly, a choke body on a Christmas tree is typically not designed to support dynamic and/or static loads imparted by intervention equipment and processes. Typical loads on a choke body in normal use would be of the order of 0.5 to 1 tonnes, and the Christmas tree is engineered with this in mind. In comparison, a typical flow metering system as contemplated in the prior art may have a weight of the order of 2 to 3 tonnes, and the dynamic loads may be more than three times that value. Mounting a metering system (or other fluid intervention equipment) on the choke body therefore exposes that part of the Christmas tree to loads in excess of those that it is designed to withstand, creating a risk of damage to the structure. This problem may be exacerbated in deepwater applications, where even greater loads may be experienced due to thicker and/or stiffer components used in the subsea infrastructure.
In addition to the load restrictions identified above, positioning the flow intervention equipment on the choke body may limit the access available to large items of process equipment and/or access of divers or remotely operated vehicles (ROVs) to the process equipment or other parts of the tree.
Furthermore, modifying the Christmas tree so that the chokes are in non-standard positions is generally undesirable. It is preferable for divers and/or ROV operators to be completely familiar with the configuration of components on the Christmas tree, and deviations in the location of critical components are preferably avoided.
Another drawback of the prior art proposals is that not all Christmas trees have chokes integrated with the system; approaches which rely on Christmas tree choke body access to the flow system are not applicable to these types of tree.
It is amongst the objects of the invention to provide a method and apparatus for accessing a flow system in an oil and gas production system, which addresses one or more drawbacks or disadvantages of the prior art. In particular, it is amongst the objects of the invention to provide a method and apparatus for fluid intervention in an oil and gas production system, which addresses one or more drawbacks of the prior art. An object of the invention is to provide a flexible method and apparatus suitable for use with and/or retrofitting to industry standard or proprietary oil and gas production manifolds, including Christmas trees.
It is an aim of at least one aspect or embodiment of the invention to provide an apparatus which may be configured for use in both a subsea fluid injection operation and a production fluid sampling operation.
Further objects and aims of the invention will become apparent from the following description.
According to a first aspect of the invention there is provided an apparatus for accessing a flow system in a subsea oil and gas production system, the apparatus comprising:
a body defining a conduit therethrough;
a first connector for connecting the body to the flow system;
a second connector for connecting the body to an intervention apparatus;
wherein, in use, the conduit provides an intervention path from the intervention apparatus to the flow system.
The apparatus is preferably a fluid intervention apparatus, which may be a fluid intervention apparatus for fluid sampling, fluid diversion, fluid recovery, fluid injection, fluid circulation, fluid measurement and/or fluid metering.
Preferably, the apparatus is an access hub which is configured for connection to the flow system. The access hub may be configured to be connected to an external opening on the flow system. For example, the access hub may be configured to be connected to a flange of the flow system. The flow system may comprise a blind flange, removal of which provides a flange connection point for the access hub.
Where the flow system comprises a subsea Christmas tree, the external opening may be downstream of a wing valve of the Christmas tree.
The external opening may be a flowline connector, such as a flowline connector for a jumper flowline. The apparatus may comprise a third connector for connecting the apparatus to a downstream flowline such as a jumper flowline. Therefore the apparatus may be disposed between a flowline connector and a jumper flowline, and may provide a flow path from the flow system to the jumper flowline, and may also establish an access point to the flow system, via the conduit and the first connector.
A flowline connector for a jumper flowline is a preferred location for the connection of the access hub. This is because it is displaced from the Christmas tree sufficiently to reduce associated spatial access problems and provides a more robust load bearing location compared with locations on the Christmas tree itself (in particular the choke body). However, it is still relatively near to the tree and the parts of the flow system to which access is required for the intervention applications.
The apparatus may provide a further connector for connecting the body to an intervention apparatus, which may be axially displaced from the second connector (in the direction of the body). Therefore the apparatus may provide a pair of access points to the flow system, which may facilitate certain applications including those which require fluid circulation and/or sampling.
In one embodiment, the access hub is configured for connection to an external opening of a choke body, which may be on a side of the choke body. Preferably in this embodiment, the access hub is configured to be connected to the choke body without interfering with the position or function of the choke (i.e. the choke may remain in situ in the choke body).
Preferably, the access hub is configured to be connected to a flowline at a location displaced from a choke of the flow system. The access hub may be configured to be connected to the flow system at a location selected from the group consisting of: a jumper flowline connector; downstream of a jumper flowline or a section of a jumper flowline; a Christmas tree; a subsea collection manifold system; subsea Pipe Line End Manifold (PLEM); a subsea Pipe Line End Termination (PLET); and a subsea Flow Line End Termination (FLET).
In embodiments of the invention, the apparatus is configured to provide access to the production bore or the annulus of Christmas tree directly (i.e. without relying on access through the production wing or annulus wing). In one such implementation, the apparatus comprises a tree cap hub, and the first connector connects the body to a production bore of a Christmas tree. Preferably, the intervention apparatus comprises a fluid injection apparatus.
The tree cap hub may comprise an axial bore extending from an opening to the production bore to a top opening of the tree cap hub. The apparatus may be provided with a pressure cap, which may seal the top opening. The apparatus may comprise a debris cap and/or insulation cap. Conveniently, the apparatus may be deployed and left in situ on the subsea Christmas tree.
Alternatively, the apparatus may comprise a tree mandrel hub, and the first connector is configured to be connected to an annulus bore of a Christmas tree. The tree mandrel hub may comprise a bore extending from an opening to the annulus bore to a top opening of the tree mandrel hub. The bore may comprise a first axial portion extending from the opening to the annulus bore, a second axial portion extending from the top opening, and a radial portion joining the first and second axial portions. The apparatus may be provided with a pressure cap, which may seal the top opening. The apparatus may comprise a debris cap and/or insulation cap. Conveniently, the apparatus may be deployed for a subsea intervention operation or series of operations and recovered to surface. Preferably, the intervention apparatus comprises a fluid injection apparatus.
According to a second aspect of the invention, there is provided a subsea oil and gas production system comprising:
a subsea well and a subsea flow system in communication with the well; and an access hub;
wherein the access hub comprises a first connector connected to the subsea flow system;
a second connector configured to be connected to an intervention apparatus; and wherein a conduit between the first and second connectors provides an intervention path from the intervention apparatus to the subsea flow system.
The access hub may be connected to the flow system at a location selected from the group consisting of: a jumper flowline connector; downstream of a jumper flowline or a section of a jumper flowline; a Christmas tree; a subsea collection manifold system; a subsea Pipe Line End Manifold (PLEM); a subsea Pipe Line End Termination (PLET); and a subsea Flow Line End Termination (FLET).
Where the flow system comprises a subsea Christmas tree, the external opening may be downstream of a wing valve of the Christmas tree.
The external opening may be a flowline connector, such as a flowline connector for a jumper flowline. The apparatus may comprise a third connector for connecting the apparatus to a downstream flowline such as a jumper flowline. Therefore the apparatus may be disposed between a flowline connector and a jumper flowline, and may provide a flow path from the flow system to the jumper flowline, and may also establish an access point to the flow system, via the conduit and the first connector.
Embodiments of the second aspect of the invention may include one or more features of the first aspect of the invention or its embodiments, or vice versa.
According to a third aspect of the invention there is provided a method of performing a subsea intervention operation, the method comprising:
providing a subsea well and a subsea flow system in communication with the well;
providing an access hub on the subsea flow system, the access hub comprising a first connector connected to the subsea flow system and a second connector for an intervention apparatus;
connecting an intervention apparatus to the second connector;
accessing the subsea flow system via an intervention path though a conduit between the first and second connectors.
Preferably the access hub is pre-installed on the subsea flow system and left in situ at a subsea location for later performance of a subsea intervention operation. The intervention apparatus may then be connected to the pre-installed access hub and the method performed.
Preferably the method is a method of performing a fluid intervention operation. The method may comprise fluid sampling, fluid diversion, fluid recovery, fluid injection, fluid circulation, fluid measurement and/or fluid metering.
The method may be a method of performing a well scale squeeze operation.
The method may comprise performing a well fluid sampling operation. A preferred embodiment of the invention comprises: (a) performing a fluid injection operation; and (b) performing a well fluid sampling operation. Preferably the fluid injection operation and the well fluid sampling operation are both carried out by accessing the subsea flow system via the intervention path of the access hub.
Embodiments of the third aspect of the invention may include one or more features of the first or second aspects of the invention or their embodiments, or vice versa.
According to a fourth aspect of the invention there is provided an access hub for a flow system in a subsea oil and gas production system, the access hub comprising:
a body defining a conduit therethrough;
a first connector for connecting the body to a jumper flowline connector of the flow system;
a second connector for connecting the body to an intervention apparatus;
and a third connector for connecting the apparatus to a jumper flowline;
wherein, in use, the conduit provides an intervention path from the intervention apparatus to the flow system.
Preferably, the subsea flow system comprises a Christmas tree, and the jumper flowline connector is production wing flowline connector of the Christmas tree.
Embodiments of the fourth aspect of the invention may include one or more features of the first to third aspects of the invention or their embodiments, or vice versa.
According to a fifth aspect of the invention there is provided a subsea oil and gas production system comprising:
a subsea well; a subsea Christmas tree in communication with the well; a jumper flowline and an access hub;
wherein the access hub comprises a first connecter connected to a flowline connector of the Christmas tree, a second connector for connecting the body to an intervention apparatus, and a third connector connected to the jumper flowline; and wherein a
a conduit between the first and second connectors provides an intervention path from the intervention apparatus to a production bore of the subsea Christmas tree.
Embodiments of the fifth aspect of the invention may include one or more features of the first to fourth aspects of the invention or their embodiments, or vice versa.
According to a sixth aspect of the invention there is provided an access hub for a subsea Christmas tree, the access hub comprising:
a tree cap comprising a tree cap connector configured to be connected to a production bore of the subsea Christmas tree and an upper connector for connecting the tree cap to an intervention apparatus;
wherein, in use, a conduit between the tree cap connector and the upper connector provides an intervention path from an intervention apparatus to the production bore of the subsea Christmas tree.
Preferably, the tree cap comprises a pressure cap. The tree cap may therefore be pre-installed on the Christmas tree and left in situ at a subsea location for later performance of a subsea intervention operation.
Embodiments of the sixth aspect of the invention may include one or more features of the first to fifth aspects of the invention or their embodiments, or vice versa.
According to a seventh aspect of the invention, there is provided a subsea oil and gas production system comprising:
a subsea well; a subsea Christmas tree in communication with the well; and an access hub;
wherein the access hub comprises a tree cap having a tree cap connector connected to production bore of the subsea Christmas tree and an upper connector configured to be connected to an intervention apparatus;
and wherein a conduit between the tree cap connector and the upper connector provides an intervention path from an intervention apparatus to a production bore of the subsea Christmas tree.
Embodiments of the seventh aspect of the invention may include one or more features of the first to sixth aspects of the invention or their embodiments, or vice versa.
According to an eighth aspect of the invention there is provided an access hub for a subsea Christmas tree, the access hub comprising:
a mandrel cap comprising a mandrel cap connector configured to be connected to an annulus bore of the subsea Christmas tree and an upper connector for connecting the mandrel cap to an intervention apparatus;
wherein, in use, a conduit between the mandrel cap connector and the upper connector provides an intervention path from an intervention apparatus to the annulus bore of the subsea Christmas tree.
Embodiments of the eighth aspect of the invention may include one or more features of the first to seventh aspects of the invention or their embodiments, or vice versa.
According to a ninth aspect of the invention, there is provided a subsea oil and gas production system comprising:
a subsea well; a subsea Christmas tree in communication with the well; and an access hub;
wherein the access hub comprises a mandrel cap having a mandrel cap connector connected to an annulus bore of the subsea Christmas tree, and an upper connector configured to be connected to an intervention apparatus;
and wherein a conduit between the mandrel cap connector and the upper connector provides an intervention path from an intervention apparatus to an annulus bore of the subsea Christmas tree.
Preferably, the tree comprises one or more pressure barriers and may comprise a dust and/or debris cap. The mandrel cap is preferably deployed for a particular subsea intervention operation or series of operations and recovered to surface, although it may alternative be pre-installed on the Christmas tree and left in situ at a subsea location for later performance of a subsea intervention operation.
Embodiments of the ninth aspect of the invention may include one or more features of the first to eighth aspects of the invention or their embodiments, or vice versa.
According to a tenth aspect of the invention there is provided a combined fluid injection and sampling apparatus for a subsea oil and gas production flow system, the apparatus comprising:
a body defining a conduit therethrough;
a first connector for connecting the body to the flow system;
a second connector for connecting the body to a fluid injection apparatus;
wherein, in use, the conduit provides an injection path from the intervention apparatus to the flow system;
and wherein the apparatus further comprises a sampling subsystem for collecting a fluid sample from the flow system.
Preferably the sampling chamber is in fluid communication with the flow system via the first connector.
The apparatus preferably comprises a third connector for connecting the apparatus to a downstream flowline such as a jumper flowline. Therefore the apparatus may be disposed between a flowline connector and a jumper flowline, and may provide a flow path from the flow system to the jumper flowline, and may also establish an access point to the flow system, via the conduit and the first connector.
The second connector may comprise a hose connector. The apparatus may comprise a hose connection valve, which may function to shut off and/or regulate flow from a connected hose through the apparatus. The hose connection valve may comprise a choke, which may be adjusted by an ROV (for example to regulate and/or shut off injection flow).
Preferably the apparatus comprises an isolation valve between the first connector and the second connector. The isolation valve preferably has a failsafe close condition, and may comprise a ball valve or a gate valve. The apparatus may comprise a plurality of isolation valves.
The sampling subsystem may comprise an end effector, which may be configured to divert flow to a sampling chamber of the sampling subsystem of the apparatus, for example by creating a hydrodynamic pressure.
An inlet to the sampling chamber may be fluidly connected to the first connector. An outlet to the sampling chamber may provide a fluid path for circulation of fluid through the chamber and/or exit to a flowline.
Preferably, the sampling subsystem comprises a sampling port, and may further comprise one or more sampling needle valves. The sampling subsystem may be configured for use with a sampling hot stab.
The sampling subsystem may be in fluid communication with the flow system via a flow path extending between the first and third connectors. Alternatively or in addition the sampling subsystem may be in fluid communication with the flow system via a flow path extending between the first and second connectors.
Alternatively or in addition the sampling subsystem may be in fluid communication with the flow system via at least a portion of an injection bore.
Embodiments of the tenth aspect of the invention may include one or more features of the first to ninth aspects of the invention or their embodiments, or vice versa. In particular, apparatus or systems of the first to ninth aspects of the invention may be configured with a sampling subsystem as described (to be used with in a sampling operation) and/or an injection flow path (for use in an injection operation), and the apparatus or systems of the first to ninth aspects of the invention may be configured for just one of sampling or injection.
According to an eleventh aspect of the invention there is provided a subsea oil and gas production system comprising:
a subsea well; a subsea Christmas tree in communication with the well; and a combined fluid injection and sampling unit;
wherein the a combined fluid injection and sampling unit comprises a first connector connected to the flow system and a second connector for connecting the body to an intervention apparatus;
wherein, in use, the conduit provides an injection path from an injection apparatus to the flow system;
and wherein the apparatus further comprises a sampling subsystem for collecting a fluid sample from the flow system.
The system may further comprise an injection hose, which may be connected to the combined fluid injection and sampling unit. The hose may comprise an upper hose section and a subsea hose section. The upper and subsea hose sections may be joined by a weak link connector. The weak link connector may comprise a first condition, in which the connection between the upper hose and the subsea hose is locked, and a second (operable) condition, in which the upper hose is releasable from the subsea hose.
Embodiments of the eleventh aspect of the invention may include one or more features of the first to tenth aspects of the invention or their embodiments, or vice versa.
According to a twelfth aspect of the invention there is provided a method of performing a subsea intervention operation, the method comprising:
providing a subsea well and a subsea flow system in communication with the well;
providing a combined fluid injection and sampling apparatus on the subsea flow system, the combined fluid injection and sampling apparatus comprising a first connector for connecting the apparatus to the flow system and a second connector for connecting the apparatus to a fluid injection apparatus;
connecting an injection hose to the second connector;
accessing the subsea flow system via an injection bore between the first and second connectors.
Preferably the combined fluid injection and sampling apparatus is pre-installed on the subsea flow system and left in situ at a subsea location for later performance of a subsea intervention operation. The injection hose may then be connected to the pre-installed unit and the method performed.
Preferably the method is a method of performing a fluid intervention operation. The method may comprise fluid sampling, fluid diversion, fluid recovery, fluid injection, fluid circulation, fluid measurement and/or fluid metering.
The method may be a method of performing a well scale squeeze operation.
The method may comprise performing a well fluid sampling operation. A preferred embodiment of the invention comprises: (a) performing a fluid injection operation; and (b) performing a well fluid sampling operation. Preferably the fluid injection operation and the well fluid sampling operation are both carried out by accessing the subsea flow system via the intervention path of the access hub.
Embodiments of the twelfth aspect of the invention may include one or more features of the first to eleventh aspects of the invention or their embodiments, or vice versa.
There will now be described, by way of example only, various embodiments of the invention with reference to the drawings, of which:
Referring firstly to
The production bore 12 comprises hydraulically controlled valves which include a production master valve 18 and a production swab valve 20 (as is typical for a vertical subsea tree). The production bore 12 also comprises a branch 22 which in includes production choke valve 24, and which may be closed from the bore 12 via production wing valve 26. The production branch 22 also includes an outlet conduit 28 leading to a flowline connector 30, which in this case is an ROV clamp, but may be any industry standard design including but not limited to ROV clamps, collet connectors, or bolted flanges. In this example the flowline connector 30 is horizontally oriented, and would conventionally be used for connection of a horizontally or vertically deployed jumper flowline.
On the annulus side, the annulus bore 16 comprises an annulus master valve 32 located below an annulus branch 34, which includes an annulus wing valve 36 which isolates the annulus branch 34 and annulus choke valve 38 from the bore 16. An annulus outlet conduit 40 leads to a flowline connector 42 (which as above may be any industry standard design).
The production system 10 is provided with a flow jumper hub assembly, generally shown at 50, and process equipment 60. An enlarged sectional view of the flow jumper hub assembly 50 is provided at
By providing intervention access points in the flowline jumper, a number of advantages are realised compared with the prior art proposals which rely on access via choke bodies on the tree. Firstly, the production choke valve 24 remains in its originally intended position and therefore may be accessed and controlled using conventional techniques. Secondly, the flowline jumper hub assembly 50 may be engineered to support dynamic and/or static loads imparted by a wide range of fluid intervention equipment and processes, and is not subject to the inherent design limitations of the choke body of the tree. Thirdly, while there are spatial limitations around the choke body of the tree, the flowline jumper hub assembly may be located in a position which allows larger items and/or different configurations of process equipment to be positioned, and may also provide improved access of ROVs and/or divers to the process equipment or other components of the tree (such as the choke). In addition, the described configuration has application to a wide-range of production manifolds, including those which do not have integrated choke bodies (as is the case for example with some designs of subsea tree).
The system 10
The hub 70 may be used in combination with another access hub described herein, for example the hub assembly 50. In this latter case, the hub 70 may provide an inlet to process equipment for a fluid intervention operation and one of the openings of the hub 50 (conveniently the opening 58 which is downstream of the valve 54) may provide an inlet for re-entry of the processed fluid from the process equipment to the production flowline.
Although the hub assembly 50 and the hub 70 are described above with the context of a production system, and are shown to provide access points for the production wing of the tree, it will be appreciated that the hubs 50 and 70 may also be used in other modes and in particular can be connected to the annulus wing, for example to provide similar functionality in an injection process. The same applies to other embodiments of the invention unless the context specifically requires otherwise. Although the hub 70 is shown connected to an external opening of a choke body, other locations on the flow system may be used to provide access to the flow system via the hub. For example, the hub may be configured to be connected to any flange point in the flow system, the removal a blind flange providing a flange connection point for the hub 70. In particular the hub may be connected via any external opening may be downstream of a wing valve of the Christmas tree.
Referring now to
The system 100 differs from the system 10 in that it is provided with an alternative jumper hub 150, which comprises a single hub opening 151 on a main flowline bore 153. An enlarged view of the jumper hub 150 is shown in
The hub 150 may be used in combination with another access hub described herein, for example the hub assembly 50 or the hub 70. In the latter case, the hub 70 may provide an inlet to process equipment for a fluid intervention operation and the hub 150 may provide an inlet for re-entry of the processed fluid from the process equipment to the production flowline.
Referring now to
The system 200 differs from the systems 10 and 100 in the nature of the jumper hub assembly 250 and its connection to the tree 211. In this case the hub assembly 250 comprises a first hub 251 connected to a vertically-oriented flowline connector 230 on the production outlet conduit 228, and a second jumper hub 252 connected to the first jumper hub 251. Each hub 251, 252 comprises an opening (256, 258 respectively) for facilitating access to process equipment 60, and functions in a similar manner to the hub assembly 50 of system 10. In this case, the hub 251 does not include a valve, and instead directs all of the fluid to the outlet and into the process equipment 60. However, in this embodiment the first jumper hub 251 comprises a vertically-oriented spool piece 260 with a perpendicular bend 262 into a horizontal section 264 on which the openings 256, 258 are located. The second hub 252 is connected to a vertically oriented ‘U’ spool jumper flowline 266. This embodiment provides a convenient horizontal section for access to the production flow for fluid intervention in a vertical ‘U’ spool configuration.
Referring now to
The hub 350 may be used in combination with another access hub described herein, for example the hub assembly 50 or the hub 70. In the latter case, the hub 70 may provide an inlet to process equipment for a fluid intervention operation and the hub 350 may provide an inlet for re-entry of the processed fluid from the process equipment to the production flowline. Alternatively or in addition, the configuration 300 may be modified to include a double hub assembly similar to the hub 50 in place of the hub 350, which may or may not include a valve in the main flowline bore.
The above-described embodiments provide a number of configurations for accessing a flow system in an oil and gas production system, which are flexible and suitable for use with and/or retrofitting to industry standard or proprietary oil and gas production manifolds. The invention extends to alternative configurations which provide access points through modified connections to the cap or mandrel of the tree, as described below.
In place of the conventional tree cap 17 used in the embodiments of
A dog leg 428 in the pressure test line aligns the line concentrically with the cap (from the offset position of the production bore). The pressure test line 418 is an axial continuation of the production pressure test line 430 from the position at which it extends radially through the tree cap, right through the cap and up to the top of the cap. However, the inner diameter of the pressure test line is significantly greater compared with the bore size of the conventional pressure test line 430 to facilitate fluid intervention through the cap 417. Typical dimensions would be of the order of around 40 mm to 80 mm inner diameter, compared with around 6 mm inner diameter for a typical pressure test line (which is therefore not suitable for fluid intervention).
Also shown in
Significantly, the above-described tree cap hub 417 provides a convenient and flexible way of carrying out fluid interventions which does not rely on the removal of or interference with choke valves. In addition, the tree cap itself is typically able to withstand static and dynamic loading far in excess of the choke bodies, which facilitates mounting of large and massive process equipment associated with the fluid intervention operations onto the tree.
Referring now to
An annulus bore 516 is in fluid communication with the production wing via a cross-over loop 519. The upper part of the tree 511 is closed by upper and lower plugs 523, 525 respectively.
Also shown in
The tree mandrel injection hub 550 provides another convenient means of performing fluid intervention, this time via the annulus of a horizontal style tree. This embodiment offers similar advantages to the embodiment of
It will be appreciated that the present invention provides a hub for access to a subsea flow system that facilitates a wide range of different subsea operations. One example application to a combined injection and sampling hub will be described with reference to
The system 600 also comprises an upper injection hose 670, deployed from a surface vessel (not shown). The upper injection hose 670 is coupled to a subsea injection hose 672 via a weak link umbilical coupling 680, which functions to protect the subsea equipment, including the subsea injection hose 672 and the equipment to which it is coupled from movement of the vessel or retrieval of the hose. The subsea injection hose 672 is terminated by a hose connection termination 674 which is configured to be coupled to the hub 650. The hub 650 is configured as a combined sampling and injection hub, and is shown in more detail in
As shown most clearly in
The hub 650 comprises an injection bore 682 which extends through the hub body 684 between an opening 686 from the main production bore 640 and the hose connection coupling 688. Disposed between the opening 688 and the hose connection coupling 688 is an isolation valve 690 which functions to isolate the flow system from injection flow. In this example, a single isolation valve is provided, although alternative embodiments may include multiple isolation valves in series. The isolation valve 690 is a ball valve, although other valve types (including but not limited to gate valves) may be used in alternative embodiments of the invention. The valve 690 is designed to have a fail-safe closed condition (in embodiments with multiple valves at least one should have a fail-safe closed condition).
The hub 650 is also provided with a sampling chamber 700. The sampling chamber comprises an inlet 702 fluidly connected to the injection bore 682, and an outlet 704 which is in fluid communication with the main production bore 640 downstream of the opening 686. The sampling chamber 700 is provided with an end effector 706, which may be pushed down into the flow in the production bore 640 to create a hydrodynamic pressure which diverts flow into the injection bore 682 and into the sampling chamber 700 via the inlet 702. Fluid circulates back into the main production bore via the outlet 704.
In an alternative configuration the inlet 702 may be fluidly connected directly to the production bore 640, and the end effector 706 may cause the flow to be diverted into the chamber 700 directly from the bore 640 via the inlet.
The sampling chamber 700 also comprises a sampling port 708, which extends via a stem 710 into the volume defined by the sampling chamber. Access to the sampling port 708 is controlled by one or more sampling needle valves 712. The system is configured for use with a sampling hot stab 714 and receptacle which is operated by an ROV to transfer fluid from the sampling chamber into a production fluid sample bottle (as will be described below with reference to
The operation of the system 600 in an application to a well squeeze operation will now be described, with reference to
The injection hose assembly 670/672 is prepared by setting the weak link coupling 680 to a locked position and by adjusting any trim floats used to control its buoyancy. The hose connection valve 675 is shut off and the hose is pressure tested before setting the hose pressure to the required deployment value. A second ROV 685 is deployed below the vessel (not shown) and the hose is deployed overboard to the ROV. The ROV then flies the hose connection 674 to the hub 650, and the connection 674 is clamped onto the hub and pressure tested above the isolation valve 690 via an ROV hot stab. The weak link 680 is set to its unlocked position to allow it to release the hose 670 from the subsea hose 672 and the hub 650 in the event of movement of the vessel from its location or retrieval of the hose.
The tree isolation valve is opened, and the injection hose 672 is pressurised to the desired injection pressure. The hose connection valve 675 is opened to the desired setting, and the isolation valve is opened. Finally the production wing isolation valve is opened to allow injection flow from the hose 672 to the production bore to commence and the squeeze operation to be performed. On completion, the sequence is reversed to remove the hose connection 674 and replace the pressure cap 668 and any debris/insulation caps on the hub 650.
It is a feature of this aspect and embodiment of the invention that the hub 650 is a combined injection and sampling hub; i.e. the hub can be used in an injection mode (for example a well squeeze operation as described above) and in a sampling mode as described below with reference to
The sampling operation may conveniently be performed using two independently operated ROV spreads, although it is also possible to perform this operation with a single ROV. In the preparatory steps, a first ROV (not shown) inspects the hub 650 with its pressure cap 668 in place (as shown in
The sampling LARS 720 subsequently used to deploy a sampling carousel 730 from the vessel (not shown) to depth and a second ROV 685 flies the sampling carousel 730 to the hub location. The pressure cap 668 is configured as a mount for the sampling carousel 730. The sampling carousel is located on the pressure cap locator, and the ROV 685 indexes the carousel to access the first sampling bottle 732. The hot stab (not shown) of the sampling bottle is connected to the fluid sampling port 708 to allow the sampling chamber 700 to be evacuated to the sampling bottle 732. The procedure can be repeated for multiple bottles as desired or until the bottles are used.
On completion, the sample bottle carousel 730 is detached from the pressure cap 668 and the LARS 720 winch is used to recover the sample bottle carousel and the samples to surface. The debris/insulation cap is replaced on the pressure cap 668, and the hub is left in the condition shown in
The invention provides an apparatus and system for accessing a flow system (such as a subsea tree) in a subsea oil and gas production system, and method of use. The apparatus comprises a body defining a conduit therethrough and a first connector for connecting the body to the flow system. A second connector is configured for connecting the body to an intervention apparatus, such as an injection or sampling equipment. In use, the conduit provides an intervention path from the intervention apparatus to the flow system. Aspects of the invention relate to combined injection and sampling units, and have particular application to well scale squeeze operations.
Embodiments of the invention provide a range of hubs and/or hub assemblies which facilitate convenient intervention operations. These include fluid introduction for well scale squeeze operations, well kill, hydrate remediation, and/or hydrate/debris blockage removal; fluid removal for well fluid sampling and/or well fluid redirection; and/or the addition of instrumentation for monitoring pressure, temperature, flow rate, fluid composition, erosion and/or corrosion. Aspects of the invention facilitate injection and sampling through a combined unit which provides an injection access point and a sampling access point. Other applications are also within the scope of the invention.
It will be appreciated that the invention facilitates access to the flow system in a wide range of locations. These include locations at or on the tree, including on a tree or mandrel cap, adjacent the choke body, or immediately adjacent the tree between a flowline connector or a jumper. Alternatively the apparatus of the invention may be used in locations disposed further away from the tree. These include (but are not limited to) downstream of a jumper flowline or a section of a jumper flowline; a subsea collection manifold system; a subsea Pipe Line End Manifold (PLEM); a subsea Pipe Line End Termination (PLET); and/or a subsea Flow Line End Termination (FLET).
Various modifications may be made within the scope of the invention as herein intended, and embodiments of the invention may include combinations of features other than those expressly described herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1202581.3 | Feb 2012 | GB | national |
This is a Continuation Application of U.S. Utility patent application Ser. No. 14/379,277, filed Aug. 15, 2014, which is a National Stage Application of PCT/GB2013/050364, filed Feb. 15, 2013, which designates the United States and claims the priority of GB patent application GB1202581.3, filed on Feb. 15, 2012; the entire disclosures of which are incorporated herein by reference.
| Number | Name | Date | Kind |
|---|---|---|---|
| 10174575 | Donald | Jan 2019 | B2 |
| 20030145998 | Langford | Aug 2003 | A1 |
| 20050070150 | Williams | Mar 2005 | A1 |
| 20050205262 | Reimert | Sep 2005 | A1 |
| 20060108120 | Saucier | May 2006 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 20190218881 A1 | Jul 2019 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14379277 | US | |
| Child | 16212415 | US |
