Patent Grant
10895151
The present invention relates to apparatus, systems and methods for oil and gas operations, in particular to apparatus, systems and methods 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 sampling apparatus, systems and methods 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.
WO2013/121212 describes an apparatus and system for accessing a flow system such as a subsea tree, which addresses drawbacks of choke-mounted flow access, by providing a flow access apparatus which can be used at a variety of access points away from the choke and optionally away from the subsea tree. The apparatus and methods of WO2013/121212 enable a range of fluid intervention operations, including fluid sampling, fluid diversion, fluid recovery, fluid injection, fluid circulation, fluid measurement and/or fluid metering.
When a sampling hydrocarbons during production operations, there are various technical challenges associated with obtaining a representative sample of hydrocarbons from the production flow.
It is known to use a Venturi device to creates a pressure differential to cause fluid to be driven through a sampling circuit and into sampling chambers. However, Venturi devices in this application are sensitive to production flow. During the production cycle, production flow varies according to the production curve, which causes the performance of the Venturi to vary. If the Venturi is configured to operate at a peak production rate, then as the production rate drops, there may be insufficient pressure to drive the sampling circuit. Conversely, if the Venturi is configured to operate at a reduced production rate, during periods of peak production, the sampling circuit may be overdriven, resulting in poor collection parameters and prevent representative samples from being collected.
It has also been proposed to use differential pressure, for example, across a choke of a subsea tree, to drive a sampling circuit. However, differential pressures which are too high may result in freezing of the pipework and other flow system components.
It is amongst the objects of the invention to address the drawbacks and deficiencies of the prior art sampling methods and apparatus.
It is amongst the aims and objects of the invention to provide a method and/or apparatus for driving a subsea sampling circuit in a hydrocarbon production system.
An aim of at least one aspect of the invention is to provide an improved sampling apparatus for oil and gas operations and methods of use. Other aims and objects of the invention include providing an improved sampling test circuit, sampling tools, and/or methods for fluid intervention which are improved with respect to sampling apparatus and method of the prior art. A further aim of at least one aspect of the invention is to provide a sampling apparatus and method of use which facilitates the use of novel flow system access methods and fluid intervention operations.
Further aims and aspects of the invention will become apparent from the following description.
According to a first aspect of the invention there is provided a valve apparatus for a flow system in a subsea oil and gas production installation, the valve apparatus comprising:
an inlet for production flow from the subsea oil and gas production installation;
an outlet for production flow;
a flow control valve disposed between the inlet and the outlet;
a first flow line in communication with a sampling circuit, the first flow line disposed between the inlet and the flow control valve;
a second flow line in communication with a sampling circuit, the second flow line disposed between the outlet and the flow control valve;
wherein the flow control valve is operable to be partially closed to create a pressure differential between the first and second flow lines, and thereby drive a production fluid into the sampling circuit.
According to a second aspect of the invention there is provided a valve apparatus for a flow system in a subsea oil and gas production installation, the valve apparatus comprising:
an inlet for production flow from the subsea oil and gas production installation;
an outlet for production flow;
a flow control valve disposed between the inlet and the outlet;
a first flow line in communication with a sampling circuit, the first flow line disposed between the inlet and the flow control valve;
a second flow line in communication with a sampling circuit, the second flow line disposed between the outlet and the flow control valve;
wherein the flow control valve is operable to drive a production fluid into the sampling circuit.
The valve apparatus may be configured to be coupled into a production flowline located downstream of a subsea tree.
Alternatively, the valve apparatus may be configured to be directly mounted on the subsea tree. The valve apparatus may be a modified subsea valve, and may be modified valve of a subsea tree.
The valve apparatus may be integrated into a metering apparatus, which may be a flowmeter module.
The flow control valve may be operable to be partially closed to create a pressure differential between the first and second flow lines, and thereby drive a production fluid into the sampling circuit.
Alternatively, or in addition, the sampling circuit may be contained within a sampling apparatus and the valve apparatus may be integrated into the sampling apparatus.
The flow control valve may be a first flow control valve, and the sampling apparatus may comprise a second flow control valve. The second flow control valve may be disposed in the sampling circuit, and/or the first and/or second flow lines to the sampling circuit. Preferably, the second flow control valve is operable to regulate the flow of fluid through the sampling circuit, which may therefore regulate the flow of fluid into the sampling circuit. The second flow control valve may be operable to choke the flow in the sampling circuit. Preferably, the second flow control valve is operable to be partially closed to regulate the flow of fluid through the sampling circuit. The sampling apparatus may also comprise a further flow control valve which is operable to be partially closed to regulate the flow of fluid through the sampling circuit. In one embodiment, the second flow control valve is disposed in an inlet flow line to the sampling circuit. Alternatively, the second flow control valve and/or a further flow control valve is disposed in an outlet flow line from the sampling circuit.
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 flowmeter apparatus for a flow system in a subsea oil and gas production installation, the flowmeter apparatus comprising:
an inlet for production flow from the subsea oil and gas production installation;
an outlet for the production flow;
a flow control valve disposed between the inlet and the outlet;
a first flow line in communication with a sampling circuit, the first flow line disposed between the inlet and the flow control valve;
a second flow line in communication with a sampling circuit, the second flow line disposed between the outlet and the flow control valve;
wherein the flow control valve is operable to drive a production fluid into the sampling circuit.
The flow control valve may be operable to be partially closed to create a pressure differential between the first and second flow lines, and thereby drive a production fluid into the sampling circuit.
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 a method of sampling fluid from a flow system in a subsea oil and gas installation, the method comprising:
providing a sampling circuit;
providing a valve apparatus comprising:
using the flow control valve of the valve apparatus to drive a production fluid into the sampling circuit.
The method may comprise partially closing the flow control valve to create a pressure differential between the first and second flow lines, and thereby drive a production fluid into the sampling circuit.
The method may comprise collecting fluid in one or more sampling bottles or vessels.
The method may comprise removing and/or retrieving one or more sampling bottles or vessels from the sampling circuit and/or the sampling apparatus.
The sampling bottles or vessels may be disposed in a collection module, which may be removable and/or retrievable from a part of the sampling apparatus.
The method may comprise partially closing the flow control valve to create a pressure differential sufficient to create a turbulent and/or mixed flow of fluid in the sampling circuit.
The flow control valve may be a first flow control valve, and the sampling apparatus may comprise a second flow control valve. Where a second flow control valve is provided, the method may comprise regulating the flow of fluid through and/or into the sampling circuit. The method may comprise choking the flow through sampling circuit.
Thus the method may comprise partially closing the flow control valve to create a pressure differential in excess of that required or desired to drive a sufficient portion of fluid passing through the sampling apparatus into the sampling circuit, in order to create a turbulent and/or mixed flow of fluid in the sampling circuit. The second flow valve regulates the turbulent and/or mixed flow of fluid back to the required flow rate for sampling of the fluid.
The sampling apparatus may comprise a further flow control valve. Where a further flow control valve is provided, the method may comprise regulating the flow of fluid through the sampling circuit using the second flow control valve and/or the further flow control valve.
The method may comprise partially closing the second flow valve and/or the further flow control valve to regulate a turbulent and/or mixed flow of fluid back to the required flow rate for sampling of the fluid.
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 valve apparatus, the valve apparatus comprising:
an inlet;
an outlet;
a flow control valve disposed between the inlet and the outlet;
a first flow line in communication with a sampling circuit, the first flow line disposed between the inlet and the flow control valve;
a second flow line in communication with a sampling circuit, the second flow line disposed between the outlet and the flow control valve;
wherein the flow control valve is operable to drive a fluid into the sampling circuit.
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 a method of sampling fluid from a flow system, the method comprising:
providing a sampling circuit;
providing a valve apparatus comprising:
using the flow control valve of the valve apparatus to drive a fluid into the sampling circuit.
The method may comprise partially closing the flow control valve to create a pressure differential between the first and second flow lines, and thereby drive a fluid into the sampling circuit.
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 flow system in a subsea oil and gas production installation comprising the valve apparatus of the first, second or fifth aspects of the invention
The flow system may comprise a sampling apparatus having one or more sampling bottles or vessels.
The flow system may comprise a sampling apparatus having one or more sampling bottles or vessels which are removable and/or retrievable from a part of the sampling apparatus.
The sampling bottles or vessels may be disposed in a collection module, which may be removable and/or retrievable from a part of the sampling apparatus.
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 a further aspect of the invention, there is provided a valve apparatus for a flow system in a subsea oil and gas production installation substantially as described herein with reference to the appended drawings.
According to a further aspect of the invention, there is provided a method of sampling fluid from a flow system in a subsea oil and gas installation substantially as described herein with reference to the appended drawings.
Referring firstly to
The flow access bores 315, 317 extend from the interface 310 to the flow bores 314, 316 and provide a fluid intervention path between the interface and the production system to which the valve apparatus is connected. In each of the flow access bores 315, 317 there is located a pair of isolation valves 322a, 322b and 324a, 324b, respectively. In this case, the isolation valves 322a, 322b, 324a, 324b are ROV operated isolation valves and enable the flow access bores 315, 317 and flowlines 314, 316 to be isolated, for example, during connection and disconnection of equipment to the interface 310. ROV hot stab connectors 330 and associated ROV operated valves 332 are connected to each of the flow access bores 315, 317 between their respective isolation valves 322a, 322b, 324a, 324b. Together, the hot stabs 330 and valves 332 enable controlled provision of hydraulic or system fluids, for example for the flushing of internal lines.
The valve apparatus 300 is configured to be used in a subsea production system in a number of different configurations, as will be apparent from the following description. In a production mode, production flow is received into the flow bore 314, is directed through the bypass bore 318 through the flow control valve 320 in its open condition, and is directed out of the flow bore 316. The flow access bores 315, 317 facilitate a range of fluid intervention operations and the benefits of the invention and its features will be illustrated with reference to the exemplary implementations described below.
Referring now to
In this embodiment, the flow access interface of the valve apparatus 400 is connected to a sampling apparatus, generally depicted at 360. The sampling apparatus comprises a pair of flowlines 361, 362 connected respectively to the flow access bores 415, 417 of the valve apparatus. Sampling isolation valves 364 and valves 368a, 368b are provided in the flowlines 361, 362. The flowlines 361, 362 respectively provide an inlet and an outlet to a sampling circuit, generally depicted at 370. In this case, the sampling circuit contains a pair of sampling bottles which are connected into the sampling circuit via ROV operated isolation valves. A first bottle is arranged with its sampling volume substantially vertically below the sampling flowline, to facilitate collection of liquid phase hydrocarbons. Gaseous phase hydrocarbons tend to pass and are collected in the second sampling bottle, which is arranged substantially above the flowline.
A bypass line 363 connects first and second flowlines and is provided with a pressure gauge and a ROV actuated valve 365. The ROV actuated valve 365, in conjunction with the sampling isolation valves 364 and valves 368a, 368b, enable fluid entering the sampling apparatus to be bypassed from the sampling circuit if required. ROV hot stab connectors 367 are provided on the sampling module along with ROV operated valves, and together the hot stabs and valves enable controlled delivery of hydraulic or system fluids, for example for flushing of the sampling circuit and/or flowlines.
In a production mode, isolation valves 422b, 424b and optionally isolation valves 422a and 424a are closed. The flow control valve 420 is fully open such that production fluid flows through the bypass bore 418, and exits the valve apparatus 400 through the second flow bore 416 to a flowline towards the production manifold.
In sampling mode, the flow control valve 420 is operated to initiate sampling. With the isolation valves 422, 424 open, the sampling isolation valves 364 open, and valves 368a, 368b also open, the flow control valve 420 is partially closed such that the valve member (in this case, the valve gate) partially impinges into the production flow. This flow disruption creates a hydrodynamic pressure differential between the flow access bores 415, 417 which is sufficient to drive fluid from the first flow bore into the flowline of the sampling apparatus.
The inventors have appreciated that only a small pressure differential, of the order of 1 bar (0.1 MPa) is desirable in order to drive the sampling circuit without creating excessive flow of the fluid into the sampling bottles. By use of a flow control valve, the pressure differential can be adjusted by using an ROV (or in shallow water, a diver) to control the extent to which the valve is used to create a flow restriction. This simple adjustability means that the valve position can be modified to maintain the desired pressure differential in a range of different flow conditions. The control provided by the valve adjustment enables the pressure differential to be optimised to the production flow. In particular, the valve position can be adjusted in dependence on the flow rate to ensure that the pressure differential of the right magnitude can be selected regardless of the flow rate. Therefore, adjustment can be performed by the ROV to enable sampling at different stages of production, in which production rates differ markedly. The ability to maintain a small pressure differential facilitates application to a wide range of flow regimes, including for example wet gas production wells.
The flow control valve can be a conventional flow control valve of the type commonly used in subsea applications, which are readily available, have known reliability, and which are easily adjusted with conventional subsea tools.
It will be appreciated that the valve apparatus, while providing particular advantages in sampling applications, may also be used for alternative flow access applications.
Referring now to
Referring now to
In the foregoing embodiments, the valve apparatus 400 is configured to be connected into a flowline such as a jumper flowline in the production flow system, downstream of the subsea tree and upstream of the production manifold. However, it will be appreciated that the invention may also be implemented in a valve apparatus which forms a part of a subsea tree itself. Referring now to
However, the valve apparatus is directly mounted into the subsea tree 540, and provides a flow access interface at the production wing of the tree, in this case to a sampling apparatus 360.
In a normal production mode, the valve apparatus 550 functions as a conventional production wing valve, with the isolation valves 552a, 552b, 554a, 554b closed. However, the production wing valve 555 can also be operated to initiate sampling. With the isolation valves 552a, 552b, 554a, 554b open, the sampling isolation valves 364 open, and valves 368a, 368b also open, the valve 555 is partially closed such that the valve member (in this case, the valve gate) partially impinges into the production flow. This flow disruption creates a hydrodynamic pressure differential between the flow access bores 515, 517 which is sufficient to drive fluid from the first flow bore into the flowline of the sampling apparatus.
It will be appreciated that although the described embodiment is a modified production wing valve, other valves which form a part of a conventional or horizontal subsea tree may be used to form a sampling drive valve and flow access interface, including any suitable production or annulus master or wing valve. In further alternative embodiments, any suitable valve forming a part of 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) may be used to form a sampling drive valve and flow access interface in accordance with principles of the invention.
Referring now to
In a metering mode, production flow is passed through the flowline 619 and flowmeter 618 and returned to the production flowline 616 via the open valve 620. However, in a sampling mode, the valve 620 is operated to initiate sampling: the valve 620 is partially closed such that the valve member (in this case, the valve gate) partially impinges into the production flow. This flow disruption creates a hydrodynamic pressure differential between the flowlines 621, 622 which is sufficient to drive fluid from the flowline 619 into the sampling circuit of the module 606.
Injection module 608 enables a subsea injection operation, and in particular a well scale and squeeze operation, to be performed by delivering injection fluid from a hose to the production bore via the sampling flowline 631, the flowline 619, and the flow bore 614. It will be appreciated that in an alternative embodiment, the injection and sampling functions of the system may be performed by a single, combined injection and sampling module, rather than the two separate modules shown in
In addition to the primary flow control valves, which function to drive fluid into a sampling circuit, the foregoing embodiments comprise additional valves for additional flow control, the operation of which will be described with reference to
In some modes of operation, the flow control valve 420 may be partially closed to create an increased pressure differential, greater than that required or desired to drive a sufficient portion of fluid into the sampling circuit. This pressure differential produces a turbulent and/or mixed flow on the inlet side of sampling circuit 370. Valves 368a, 368b, or both, are adjusted to provide a restriction which regulates the fluid flow passing into the sampling circuit 370, and returns the flow to a desired sampling flowrate. Therefore, valves 420, 368a and 368b may be operated together to enable mixing of the fluid before it enters the main portion of the sampling circuit 370, and then regulating the resulting flow to a desired rate. The combination of valve 420 with valves 368a and/or 368b mitigates the unrepresentative sampling which could occur if an unmixed and unrepresentative flow regime were to enter the sampling bottles.
The flow control valves 368a, 368b may be conventional flow control valves of the type commonly used in subsea applications, which are readily available, have known reliability, and which are easily adjusted with conventional subsea tools. It will be appreciated that valves 368a, 368b may not be present in an application where flow mixing is not required. It will also be appreciated that only one of the valves 368a, 368b may be provided.
The embodiments described with reference to
Referring now to
Referring now to
The retrievable collection module 801 contains upper and lower sampling bottles 802, 804. In contrast with previous embodiments, the sampling bottles 802, 804 are configured such that the inlet and the outlet flowlines of each sampling bottle are disposed on either side of a single valve 810, respectively above and below the sampling flowline 812. The inlet and the outlet of upper bottle 802 are placed at the same height. The vertically displaced configuration of upper and lower sampling bottles 802, 804 respectively within collection module 801 may facilitate the preferential collection of liquid phase hydrocarbons in lower bottle 804, whilst gaseous phase hydrocarbons are preferentially collected in the upper sampling bottle 802. This configuration may therefore aid separation during sampling.
The separable nature of the collection module 801 from the primary sampling module 860 enables sampling bottles 802, 804 to be retrieved to surface or changed out for replacement bottles without retrieving the sampling system as a whole.
It will be appreciated that one or more separable, retrievable, sampling bottles or vessels may be used in alternative configurations, in other embodiments of the invention. An example of such a system is shown in
It will be appreciated that valve types other than gate valves may be used in alternative embodiments of the invention, including (for example) ball valves.
The invention provides a valve apparatus for a flow system in a subsea oil and gas production installation and a method of use. The valve apparatus comprises an inlet for production flow from the subsea oil and gas production installation, an outlet for production flow, and a flow control valve disposed between the inlet and the outlet. A first flow line in communication with a sampling circuit is disposed between the inlet and the flow control valve, and a second flow line in communication with a sampling circuit is disposed between the outlet and the flow control valve. The flow control valve is operable to be partially closed to create a pressure differential between the first and second flow lines, and thereby drive a production fluid into the sampling circuit.
Embodiments of the invention provide a range of flow access solutions 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. 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 flow line 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 flow line or a section of a jumper flow line; 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
| Number | Date | Country | Kind |
|---|---|---|---|
| 1506266.4 | Apr 2015 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/GB2016/051036 | 4/13/2016 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2016/166534 | 10/20/2016 | WO | A |
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