WO2007027080A2

WO2007027080A2 - Control system for seabed processing system

Info

Publication number: WO2007027080A2
Application number: PCT/MY2006/000006
Authority: WO
Inventors: David Appleford; Brian William Lane
Original assignee: Alpha Perisai Sdn. Bhd.; Alpha Thames Limited
Priority date: 2005-08-29
Filing date: 2006-08-28
Publication date: 2007-03-08
Also published as: WO2007027080A3; MY140159A; CN101253307A

Abstract

A control system of modular seabed processing unit (100) using one of a process module as a test separator comprising a system-module (110) to which external lines are connected, the system-module (110) includes a first portion (31) of the system-module isolating and connecting means (30), for acting on received fluid. At least one inlet flow line (21) and at least one outlet flow line (81) being connected to the first portion (31) of the system-module isolating and connecting means (30) for selective isolation of system-module from, or connection of the system-module to the external flow lines by means of a second complementary portion (32) of a manifold (130). The system-module includes control means (60) for controlling operation of the system-module characterized in that the system-module (110) includes at least one actuating means (121) connected to a control means (60) wherein the actuating means (121) of the system-module (110) associated with diverter valve (131) situated at a manifold (130). The diverter valve (131) is connectable and disconnectable to fluid carrying conduits from production well (160, 170) and is enabled to control the direction of fluid flow into the system-module.

Description

CONTROL SYSTEM FOR SEABED PROCESSING SYSTEM

FIELD OF INVENTION

The present invention relates to a control system of fluid carrying conduits for seabed processing system. More particularly the control system is suitable for use in subsea location where it is necessary to connect and disconnect oil and/or gas carrying conduits between a system-module and a manifold used in a subsea field. The control system includes equipments to well test and/or other platform based applications.

BACKGROUND OF INVENTION

A conventional underwater oil/gas field may include controllable underwater equipment between the subsea wells and host facility both connected by a number of flowlines. When producing hydrocarbons from a number of distributed subsea wells, the simplest method would be to collect well produce locally at manifold before transporting combine fluids through a single flowline to a host surface facility, which could be several kilometres away (In this description the term 'host' and 'host surface facility' are used interchangeably).

In this configuration, all output from wells is transported to the host as a single, multiphase flow. However, in most cases it is desirable to have the capability to determine the performance of each individual well. A common method to achieve this is to install a second flowline from the manifold to the host. Flow from a selected well is then diverted into second flowline by means of remotely actuated valves incorporated in the manifold.

The flow from the flowline is then collected at the host. The phases are then separated and analysed to access the individual well produce and performance. Once the analytical process has been completed, another well may be selected and the process repeated until every well has been tested. As a certain amount of separation usually takes place in the flowline during transportation the test results suffer from some inaccuracies. In practice the well and the host are separated by several kilometres. As used there is a significant time lag between time of production at well and time of testing of output well. There is no real time analysis. There can be a substantial costs involved in the installation of the second flowline and the associated riser to the host. Furthermore, in order to ensure that the next test is carried out only on fluid produced from the selected well, there is a considerable delay whilst the flowline is given time to run clear of fluid from the previous test.

Another method of well testing is to test by "differential" or by "deduction". This is achieved by ceasing the flow from each well and analysing the combined flow from the remaining wells. The produce and performance of each individual well is therefore obtained by computation of data resulting from the testing and analysis of the combined flow of the remaining wells. This method is not very accurate as when the flow from the selected well is closed, it has an effect on the flow characteristics of the remaining wells because there is less resistance to the flow.

Recent technology developments have enabled multiphase meter to be introduced into service. They would normally be fitted to each tree and are able to monitor and transmit flow information of each phase but are not capable of determining the compositional analysis of the produce hydrocarbon. Although the accuracy of these meters is slowly improving but they are very expensive and require occasional recalibration.

EP 1555387 Al discloses a retrievable module for a subsea processing system and its use for exploiting oil/gas fields in underwater. The system uses a module isolating and connecting means which enable easy diverless module replacement within a short period of time for modification, or repair or change the way a field is exploited to take account of changes in the field characteristic. However, the increasing use of modularised processing systems in deepwater has been brought about by the need to reduce the subsea installation and maintenance time. The use of interchangeable modules in a subsea system requires the need for suitable connecting system which will enable the module to be lowered into position, and connected up to the gas/oil supply and also to be removed therefrom by means operated from the surface of the sea. GB 2261271 discloses a modularised processing system which is used to separate a mixture of oil, gas and water from the wells into its individual components. The system comprises an offshore installation in which interchangeable modules are individually supported in a support framework located on the seabed, the module being used to separate the mixture. Two-part connectors enable modules to be lowered from the surface of the sea into the framework and be connected up to the wells. The module can also be retrieved from the system so that the maintenance can be carried out at the surface.

A system module and an installation are disclosed in published PCT specification No. WO 0216734. The installation comprises the steps of fixing docking unit to the foundation via a single connection. The flowline is connected to the said docking unit and the retrievable autonomous module is lowered from the surface to the docking unit which includes actuating isolation means. The system can be reconfigured or replaced by part of the underwater equipment without having to shut down or to significantly reduce production from the field.

The present invention takes advantage of above-mentioned modular seabed processing system architecture. It uses one of the process modules as a test separator whilst production from the remaining wells is put through the other process modules.

By this means swift and accurate results are produced as there is no long flowline to clear each time a different well is selected for testing and the use of high-cost multiphase meters is avoided. For a better understanding of the system, reference figures and the accompanying descriptive matter to preferred embodiments of the present invention will be described thereof in the detailed description.

SUMMARY OF INVENTION

A control system of modular seabed processing unit using one of a process module as a test separator comprising a system-module to which external lines are connected, the system-module includes a first portion of the system-module isolating and connecting means, for acting on received fluid. At least one inlet flow line and at least one outlet flow line connected to the first portion of the system-module isolating and connecting means for selective isolation of the system-module from, or connection of the system-module to the external flow lines by means of a second complementary portion of a manifold.

The connecting means with which the first portion of the system-module isolating and connecting means is adapted to engage wherein the system-module includes control means for controlling operation of the system-module. The system- module includes at least one actuating means connected to a control means wherein the actuating means of the system-module associated with diverter valve situated at a manifold. The actuating means of system-module is preferably an electrically operated actuator controlled by a programmable logic controller located in the control means. The actuating means of system-module may be a hydraulic system. The actuating means of system-module is in seating engagement with the diverter valve.

The diverter valve is a three-way valve whereby it is connectable and disconnectable to fluid carrying conduits from production well and is enabled to control the direction of fluid flow into the system-module. The three-way diverted valves have a third port to divert the fluid enter from the production wells to other process module or host facility via outlet lines at the docking-manifold. The control means is in communication with a master control station. The diverter valve is activated by actuator means when said actuator means receives commands from master control station via the control means. The control means is adapted to receive control signal from master control station on host platform via communication line and to transmit signals to host platform via umbilical. The communication mode between diverter valves, actuator means master control station and control means can be wired and/or wireless lines.

The temperature and/or pressure measuring means and valves are connected to control means by control line, which is adapted to transmit process values to a host platform and receive the control signals from the host platform via umbilical through a power connector. The measuring means are temperature and/or pressure measuring devices or can be any other operating parameter. Sensing means for measuring measure pressure and temperature parameter may be allocated at control valve wand the sensing means to measure flow parameter may be allocated at venturing- flowmeter. All sensing means is connected to the control unit by the control lines. The pump means in the system-module is use to boost the produce fluid to host via outlet flow line. The master controller station enables production well to be shut down when process values show undesired throughput.

BRIEF DESCRIPTION OF DRAWINGS In the appended drawings:

FIGS. 1 and 2 show diagrammatically the installation of first system-module to a seabed processing system according to the present invention.

FIG. 3 shows diagrammatically a seabed processing system use for well test according to the present invention. FIG. 4 shows a schematic diagram of a selective input system of a system-module according to present invention.

FIG. 5 shows a schematic diagram of a retrievable system-module use for well test according to present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring to FIG. 1 and FIG. 2 of the accompanying drawing, figures show an installation of a seabed processing system (100). The seabed processing system (100) generally has a host platform (140), which may be, for example, onshore or on a fixed or floating rig. The host platform (140) has a master control station (150) connected to a first system-module (110) by communication lines (141). The first system-module (110) comprises of control unit (60) connected to an actuating means (121) by a control line (122). The first system-module (110) is lowered onto a docking-manifold (130) by means of installation tools such as remote operating vehicles (ROVs) or by a ship or direct from a host platform (140). The first system-module (110) is then connected to docking-manifold (130) by a multibore fluid connector. The actuating means (121) at the system-module (110) is aligned and in seating engagement with the diverter valve (131) located at docking-manifold (130). Referring to FIG. 3, the figure shows a second system-module (120) is lowered onto docking manifold (130). The docking-manifold (130) is connected to production wells (160, 170) by flow lines (161, 171) and enabling fluid from production wells (160, 170) entering into the system-module (110, 120). The system- module (110, 120) may be of the general type forming part of a modular system for subsea use designed by Alpha Thames limited of Essex, United Kingdom, and referred to as AlphaPRIME.

Referring now to FIG. 4, the system-module (110) is shows with a selective input system for high/low pressure or heavy/light fluid diversion. Any required means of the system-module (110) for well test has been omitted for the purposes of clarity and will be described in details later in the description. The system-module (110) shown in FIG. 4 is connected to the docking-manifold (130) by a multibore fluid isolation connector (30) in which installation tools can be operated by remote operating vehicles (ROVs) or direct from ship or from host platform (140) as mentioned earlier. The connection between the system-module (110) and docking- manifold (130) by the multibore fluid connector (30) is described in GB 2261271 and is adopted herein. The multibore fluid connector (30) has two complementary portions (31, 32) of which one portion (31) forms part of the system-module (110) and the other portion (32) is on the docking-manifold (130). The portions each have a plurality of bores (33, 34, 35, 36, 37), which are aligned when the complementary portions (31, 32) are engaged. Each said bore (33, 34, 35, 36, 37) has an associated isolation valve. The said isolation valve includes valves (38, 39, 40, 41, 42) for system-module portion (31) and valves (43, 44, 45, 46, 47) for docking-manifold portion (32) are closed when the complementary two portions (31, 32) are to be disengaged.

The system-module (110) in FIG. 4 is shown with a booster pump (50). A number of conduits or flowlines (51, 52) lead from the first portion (31) of the multibore fluids isolation connector (30) towards the booster pump (50), each conduit

(51, 52) having an associated valve (38, 39) for controlling the commingling of fluid flowing from the wells through the docking-manifold (130) into the system-module (110). Each valve (38, 39) is connected to a control unit (60) by control line (65). A check valve (43, 44) is provided at each conduit (51, 52), which is also known as nonreturn valve. The flow from conduits (51, 52) passes through the valve (38, 39) and the check valve (43, 44) into the booster pump (50) via a single inlet conduit (56). A pressure-measuring device (61) and a temperature-measuring device (62) are provided to measure pressure and temperature downstream of the single inlet conduit (56) before entering to the booster pump (50). Each measuring device is connected to the control unit (60) by control line (65). Similarly, the outlet of the booster pump (50) is provided with a pressure-measuring device (63) and a temperature-measuring device (64) to measure the pressure and temperature at outlet flow line (57). All the pressure and temperature measuring devices are connected to control unit (60) by control line (65). The fluid from production well is pumped to interconnecting pipework (132), or to other process module by booster pump (50) at the system-module (110) via an outlet line (81).

The booster pump (50) is powered by high voltage power supply wherein it is connected to a power connector (70) by a power line (66) located at the docking- manifold (30). The control unit (60) receives information from pressure and temperature measuring device and adapted to transmit the data or information to the host facility via umbilical (80). The control unit (60) preferably comprises a pod divided into two compartments respectively housing solid-state control electronics and power distribution switchgear. The control unit (60) is housed in a pressure vessel known as a control pod, wherein the pod has penetrators for cables from outside the pod to connect to the power and control lines. The host platform (140) provides the power to the module via umbilical (80) and is in communication with the control unit (60) via a communication line (67). As the control unit (60) controls the normal running of the module, it may, for example, be controlled, be programmed or be instructed to shut down the module by the host facility via umbilical (80). The system-module (110) further comprises actuators (121) connected to the control unit (60) by control line (122) and the docking-manifold (130) contains diverter valves (131), which will be described later in the description. Referring now to FIG. 5, the figure illustrates a system-module (110) used for well test in which loaded onto the docking-manifold (130). The system-module (110) contains a three-phase separator vessel (300) wherein the separator vessel (300). has a level sensor (302) for detecting the position of the interface between the oil, water and gas in the separator vessel (330) linked to a control unit (60). A first inlet conduit (56) of the three-phase separator (300) is connected by fluid conduit (51, 52) containing an isolation valve (48, 49) downstream to an actuation fail-safe valve (57). The actuation fail-safe valve (57) is linked to a control unit (60) in which the system-module will be shutdown when unusual events occurred. The fluid flow from production wells (160, 170) is enters into the three-phase separator (300) by inlet flow line (21, 22) to fluid conduit (51, 52) via the multibore fluid connector (30).

A first outlet (304) of the separator vessel (300) is connected by an oil conduit (306) to a dedicated oil pipeline (82) to the host facility via the multibore fluid connector (30). A second outlet (308) of the separator vessel (300) is connected by a water conduit (310) to the water pipeline (83) via the multibore fluid connector (30).

The water pipeline may be routed to the host facility or to a dedicated water disposal well. A third outlet (312) of the separator vessel (300) is connected by a gas conduit (314) to a dedicated gas pipeline (81) to the host facility via the multibore fluid connector (30).

The oil conduit (306) and the water conduit (310) each have a booster pump (320, 322), a flow control valve (330, 332), a venturi-flowmeter (324, 326) and a check valve (354, 356) downstream of the booster pump (320, 322) to an oil pipeline (81) and water pipeline (83) respectively. Between the oil booster pump (320) and the oil flow control valve (330) is a junction (340) in the oil conduit (306) from which an oil return line (344) connects the oil conduit (306) to the fluid inlet (56) via a check valve (350), which is known as non-return valve. Also, between the water booster pump (322) and the water flow control valve (332) is a junction (342) in the water conduit (310) from which a water return line (346) connects the water conduit (310) via a check valve (352) to the oil return line (344) downstream back to the separator vessel (300). The gas conduit (314) has a pressure control valve (360), a venturi- flowmeter (362) and a check valve (364) downstream to the dedicated gas pipeline (81) via the multibore fluid connector (30). All above-mentioned pumps, venturi- flowmeters, flow control valves and pressure control valves are connected and control by the control unit (60). Connection between the control unit (60), pumps, venturi- flowmeters, flow control valves and pressure control valves have been omitted for clarity.

The system-module (110) further comprises of at least two preferably electrically operated actuators (121) connected to the control unit (60) by control lines (122). In the prior art, actuator is described in EP 0596900 whereby the actuator comprises a stem extending through the actuator body for coupling to a valve such that axial movement of the stem open and closes the valve. Such prior art has an outer shaft arranged coaxial around, and in threaded engagement with the stem and is coupled to an electric motor for conveying rotational drive to the shaft and thus axial movement of the shaft relative to the stem a spring bias. The shaft is releasably retained in a predetermined position by a solenoid-actuated latching mechanism with the spring in a compressed stage, such that further rotation of the shaft cause axial movement of the stem relative to the shaft to actuate the valve.

The actuator (121) used in the system is rotary actuator whereby it is connected to three-way diverter valves (131) located at the docking-manifold (130). The actuator (121) is aligned and seating engagement with the diverter valve (131) when the system-module (110) is being lowered to the docking manifold (130). The three-way diverter valve (131) is activated by preferably electrically operated actuator (121) and is enabled to control the direction of fluid flow into the system-module (110). The interconnecting pipework (132) within the docking-manifold (130) is provided to connect the production wells (160, 170) (FIG. 3) to the second portion (32) of the multibore fluid connector (30) via inlet flow line (21, 22). The interconnecting pipework (132) is closed by isolation valves (43, 44, 45, 46, 47) when the two portions (31, 32) are to be disengaged and/or the system-module (110) is retrieved for maintenance or reconfiguration in response to changing field characteristics. The three-way diverted valves (131) have a third port to divert the fluid enter from the production wells (160, 170) to other process module or host facility via outlet lines (84, 85) at the docking-manifold (30).

The actuator (121) is connected to control unit (60) by the control line (122).

The control unit (60) of the system-module (110) is built up as a network of programmable logic controllers (PLCs) in the power and control pod and in a master control station (MSC) (150) on the host platform (140). The control unit (60) receives commands from master control station (150) via a communication line (141) and the signal is transmitted to actuator (121) by control line (122). Thus, three-way diverter valve (131) is actuated by actuator (121) when commands from master control station (150) are received.

All control loops work locally without any need for fast transmission of large data quantities to and from the master control station (150) on the host platform (140).

Commands are sent from master control station (150) and the process values are sent to the master control station (150) via the communication lines (141) and umbilical

(80) without interrupting the production process. By this means, the seabed system is monitored and controlled continuously, sending data to a topside master control station (150) and only needing topside staff manual control of unusual events.

Claims

1. A control system of modular seabed processing unit (100) using one of a process module as a test separator comprising a system-module (110) to which external lines are connected, the system-module (110) includes a first portion (31) of the system-module isolating and connecting means (30), for acting on received fluid, and at least one inlet flow line (21) and at least one outlet flow line (81) connected to the first portion (31) of the system-module isolating and connecting means (30) for selective isolation of the system-module from, or connection of the system-module to the external flow lines by means of a second complementary portion (32) of a manifold (130) and connecting means (30) with which the first portion (31) of the system-module isolating and connecting means (30) is adapted to engage, and wherein the system-module includes control means (60) for controlling operation of the system-module characterized in that the system-module (110) includes:

at least one actuating means (121) connected to a control means (60); wherein the actuating means (121) of the system-module (110) associated with diverter valve (131) situated at a manifold (130);

diverter valve (131) is connectable and disconnectable to fluid carrying conduits from production well (160, 170) whereby enabled to control the direction of fluid flow into the system-module;

control means (60) is in communication with a master control station (150);

measuring means (61, 62, 63, 64) and valves (38, 39) connected to control means (60) by control line (65) which is adapted to transmit process values to a host platform (140) and to receive the control signals from the host platform (140) via umbilical (80) through a power connector (70);

sensing means to measure pressure, temperature and flow parameter; and

pump means (50, 320, 322) to boost the fluid to host facility.

2. A control system of modular seabed processing unit as claimed in claim 1, wherein the system may be used for high/low pressure or heavy/light fluid diversion or for well testing.

3. A control system of modular seabed processing unit as claimed in claim 1, wherein the actuating means (121) can be an electrically operated or a hydraulic system.

4. A control system of modular seabed processing unit as claimed in claim 3, wherein the actuating means (121) is preferably electrically operated.

5. A control system of modular seabed processing unit as claimed in claim 1, wherein the actuating means (121) is in seating engagement with the diverter valve (131).

6. A control system of modular seabed processing unit as claimed in claim 1, wherein the actuating means (121) is controlled by a programmable logic controller located in the control means (60).

7. A control system of modular seabed processing unit as claimed in claim 1, wherein the diverter valve (131) is activated by actuator means (121) when said actuator means (121) receives commands from master control station (150) via the control means (60).

8. A control system of modular seabed processing unit as claimed in claim 5, wherein the communication mode between diverter valve (131), actuator means (121) master control station (150) and control means (60) is a wired and/or wireless lines.

9. A control system of modular seabed processing unit as claimed in claim 1, wherein the diverter valve (131) is a three-way valve.

10. A control system of modular seabed processing unit as claimed in claim 9, wherein the diverter valve (131) have a third port to divert fluid enter from the production wells (160, 170) to other process module or host facility.

11. A control system of modular seabed processing unit as claimed in claim 1, wherein the control means (60) is adapted to receive control signal from master control station (150) on host platform (140) via communication line (141) and to transmit signals to host platform (140) via umbilical (81).

12. A control system of modular seabed processing unit as claimed in claim 1, wherein measuring means (61, 62, 63, 64) are temperature and/or pressure measuring devices or can be any other operating parameter.

13. A control system of modular seabed processing unit as claimed in claim 1, wherein sensing means for measuring flow parameter may be allocate at venturing- flowmeter (324, 326, 362).

14. A control system of modular seabed processing unit as claimed in claim 1, wherein sensing means for measuring temperature and pressure parameter may be allocate at control valve (48, 49, 330, 332, 360).

15. A control system of modular seabed processing unit as claimed in claim 13 and 14, wherein said sensing means is connected to control means (60).

16. A control system of modular seabed processing unit as claimed in claim 1, wherein master controller station (150) enables production well to be shut down when process values show undesired throughput.