CN112832749B - Underwater wellhead oil sleeve ring air pressure control system and method - Google Patents
Underwater wellhead oil sleeve ring air pressure control system and method Download PDFInfo
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- CN112832749B CN112832749B CN202110310265.1A CN202110310265A CN112832749B CN 112832749 B CN112832749 B CN 112832749B CN 202110310265 A CN202110310265 A CN 202110310265A CN 112832749 B CN112832749 B CN 112832749B
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B47/00—Survey of boreholes or wells
- E21B47/06—Measuring temperature or pressure
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B34/00—Valve arrangements for boreholes or wells
- E21B34/02—Valve arrangements for boreholes or wells in well heads
- E21B34/04—Valve arrangements for boreholes or wells in well heads in underwater well heads
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B41/00—Equipment or details not covered by groups E21B15/00 - E21B40/00
- E21B41/0007—Equipment or details not covered by groups E21B15/00 - E21B40/00 for underwater installations
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/01—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells specially adapted for obtaining from underwater installations
Abstract
The invention relates to the field of oil extraction, and discloses an underwater wellhead oil sleeve ring air pressure control system and method, which comprises the following steps: the production pipeline can communicate the oil pipe with the water storage terminal, is connected with the first valve and the second valve in series, and is also provided with a first internal pressure detection piece for detecting the pressure of the production pipeline; a first storage tank for storing a first antifreeze; an injection pump communicable with the first tank; an injection line capable of communicating the injection pump with the production line between the first valve and the second valve; the emptying pipeline can communicate the oil sleeve annulus with the atmosphere, and a third valve and a fourth valve are connected to the emptying pipeline in series; the injection pump can be communicated with a vent pipeline between the third valve and the fourth valve, and a second internal pressure detection piece for detecting the annular pressure is arranged on the vent pipeline; and a first communication line capable of communicating the vent line between the third valve and the fourth valve with the production line between the first valve and the second valve. The invention has simple operation and low cost, can reduce the annular pressure and ensure the safe production.
Description
Technical Field
The invention relates to the technical field of oil extraction, in particular to an underwater wellhead oil sleeve ring air pressure control system and method.
Background
With the continuous development of economy in China, the demand for new energy is also increased, and natural gas is an important representative of clean energy as a novel energy. The natural gas resources in the ocean deepwater area are very rich, and in recent years, the exploitation of the deepwater natural gas in China is developed in a crossing manner in order to ensure the supply of the natural gas.
The exploitation of the deepwater natural gas and the exploitation of diving or land have different exploitation modes, an underwater production system is mostly adopted in the deepwater natural gas exploitation, a Christmas tree is arranged at the seabed of a deepwater area, the exploitation of well flow is controlled by the underwater Christmas tree, and the well flow is conveyed to an offshore platform in the deepwater area through a submarine pipeline to be processed and then is boosted and conveyed to a land terminal. The production tree is more intelligent than the production tree on water when the design under water, and all valves on the production tree under water all can carry out long-range opening and closing through the hydraulic oil in the umbilical cable, and all instruments on the tree all have the teletransmission function, have all designed well opening methyl alcohol injection pipeline and oil jacket unloading pipeline the same with the production tree on water simultaneously.
No matter the production tree on water or under water all is provided with the oil jacket annular space pressure detecting system of the underwater well head, under normal conditions the completion fluid that the oil jacket ring is full of in the sky is sealed in the annular space by oil jacket packer and oil jacket isolating valve, when the pit shaft temperature changes in the production process, because completion fluid in the heat-conduction annular space receives temperature effect, inflation effect to make annular space pressure rise, the evacuation flow that general accessible annular space set up is with pressure control in safety range, guarantees safety in production. However, when the annular packer fails, the oil pipe joint leaks or the oil pipe punctures, the overwater Christmas tree can adopt various means such as continuous emptying, casing production or inert gas injection in the annular space to control the annular pressure or prevent the casing corrosion, and more preparation time is strived for well repair.
When the underwater Christmas tree is adopted for natural gas exploitation, when the annular pressure caused by packer failure is abnormally increased, the sleeve pressure cannot be effectively controlled within a safety range due to the limitation of small size, long distance and the like of an emptying pipeline, and at the moment, only well closing measures can be taken to wait for well repair. In the face of expensive workover cost of the subsea tree, gas wells with small gas amount cannot pass economic benefit evaluation and can only be closed permanently.
Therefore, the underwater wellhead oil collar air pressure control system and method have the advantages of being simple in principle, simple to operate, low in cost, high in return, capable of effectively reducing the air pressure, reducing the well repairing times and guaranteeing the safe production of the underwater Christmas tree.
Disclosure of Invention
The invention aims to provide an underwater wellhead oil sleeve ring air pressure control system which is simple in principle, simple to operate, low in cost and high in return, can effectively reduce annular pressure, reduces well repairing times and ensures safe production of an underwater Christmas tree.
In order to achieve the purpose, the invention adopts the following technical scheme:
an underwater wellhead oil casing annulus pressure control system for controlling the pressure of an oil casing annulus between an oil pipe and a casing, comprising:
the inlet of the production pipeline is communicated with the oil pipe, the outlet of the production pipeline is communicated with the above-water storage terminal, a first valve and a second valve are sequentially connected in series on the production pipeline along the conveying direction of the production pipeline, and a first internal pressure detection piece for detecting the pressure of the production pipeline is arranged between the second valve and the outlet of the production pipeline;
the first storage tank is used for storing a first antifreezing agent;
an injection pump having an inlet selectively communicating with the first reservoir;
an injection line having an inlet selectively in communication with an outlet of the injection pump, the injection line selectively in communication with the production line between the first valve and the second valve;
an inlet of the emptying pipeline is used for being communicated with the oil sleeve annulus, an outlet of the emptying pipeline is used for being communicated with the external atmosphere on the water, a third valve and a fourth valve are sequentially connected in series on the emptying pipeline from the inlet of the emptying pipeline to the outlet of the emptying pipeline, an outlet of the injection pump is selectively communicated with the emptying pipeline between the third valve and the fourth valve, and a second internal pressure detection piece for detecting the annulus pressure is arranged on the emptying pipeline;
and one end of the first communication pipeline is communicated with an emptying pipeline between the third valve and the fourth valve, the other end of the first communication pipeline is communicated with a production pipeline between the first valve and the second valve, and a fifth valve is connected in series on the first communication pipeline.
Optionally, the method further comprises:
a second storage tank for storing a second antifreeze agent having a lower density than the first antifreeze agent, the second storage tank being selectively in communication with the inlet of the injection pump.
Optionally, a sixth valve is connected in series between the second storage tank and the inlet of the injection pump.
Optionally, an outlet of the injection pump is communicated with the vent line between the third valve and the fourth valve through a second communication line, and a seventh valve is connected in series to the second communication line.
Optionally, a third internal pressure detection element is disposed at an end of the seventh valve, which communicates with the outlet of the injection pump.
Optionally, the method further comprises:
and one end of the third communication pipeline is configured to be communicated with a plug closed space formed between two plugs at the end part of the oil pipe, the other end of the third communication pipeline is communicated with an inlet of the fourth valve, and the third communication pipeline is connected with an eighth valve in series.
Optionally, a ninth valve above the water and a tenth valve below the water are connected in series on the injection line in the injection direction of the injection line.
Optionally, an eleventh valve is connected in series between the first storage tank and the inlet of the injection pump.
Optionally, a twelfth valve is further connected in series to the production line, the twelfth valve is located between the first valve and the second valve, and the injection line and the first communication line are selectively communicated with the production line between the first valve and the twelfth valve respectively.
The invention also aims to provide an underwater wellhead oil collar air pressure control method which has the advantages of simple principle, simple operation, low cost and high return, can effectively reduce the annular pressure, reduce the well repairing times and ensure the safe production of the underwater Christmas tree.
In order to achieve the purpose, the invention adopts the following technical scheme:
the method for controlling the air pressure of the oil collar of the underwater wellhead is based on the system for controlling the air pressure of the oil collar of the underwater wellhead, and comprises the following steps:
s1, detecting and judging whether the annular pressure is higher than a safe pressure range or not in a well opening state, if so, judging whether the annular pressure is larger than the pressure of a production pipeline or not, and if so, executing a step S2;
s2, opening a third valve and a fourth valve to enable the oil sleeve annulus to be subjected to torch emptying through an emptying pipeline, and closing the fourth valve when the annulus pressure is reduced by a first preset value;
s3, injecting the first antifreezing agent in the first storage tank into the oil jacket annulus through a vent pipeline until the pressure of the annulus rises to a pressure value before flare venting, and stopping injection;
s4, closing the first valve and the second valve after the oil sleeve annulus and the emptying pipeline are subjected to well stewing for a first preset time; then, enabling the oil sleeve annulus to be communicated with the production pipeline through the first communication pipeline, and opening a second valve to discharge the pressure of the oil sleeve annulus to the production pipeline;
s5, when the annular pressure is reduced by a second preset value, disconnecting the first communication pipeline from the production pipeline, and opening the first valve and the second valve to enable the production pipeline to be in a well opening and conveying state;
and S6, judging whether the annular pressure is equal to the pressure of the production pipeline, if not, returning to execute the step S3, and if so, ending.
The invention has the beneficial effects that:
the pressure of an oil sleeve annulus between an oil pipe and a sleeve can be controlled by a worker through the underwater wellhead oil sleeve annulus pressure control system. Firstly, detecting and judging whether the annular pressure is higher than a safe pressure range or not in a well opening state; when the annular pressure is greater than the pressure of the production pipeline, the third valve and the fourth valve can be opened, so that the oil sleeve annulus can be subjected to torch emptying through an emptying pipeline, and when the annular pressure is reduced by a first preset value, the fourth valve is closed; then, injecting the first antifreezing agent in the first storage tank into the oil jacket annulus through a vent pipeline until the pressure of the annulus rises to a pressure value before flare venting, and stopping injection; then, after the oil sleeve annulus and the emptying pipeline are subjected to well stewing treatment for a first preset time, closing the first valve and the second valve; then, enabling the oil sleeve annulus to be communicated with the production pipeline through the first communication pipeline, and opening a second valve to discharge the pressure of the oil sleeve annulus to the production pipeline; then, when the annular pressure is reduced by a second preset value, disconnecting the first communication pipeline from the production pipeline, and opening the first valve and the second valve to enable the production pipeline to be in a well opening and conveying state; and finally, judging whether the annular pressure is equal to the pressure of the production pipeline, if not, injecting the first antifreezing agent into the oil sleeve annular space through the emptying pipeline and the subsequent steps are carried out again until the annular pressure is equal to the pressure of the production pipeline.
Therefore, the underwater wellhead oil sleeve ring air pressure control system and the underwater wellhead oil sleeve ring air pressure control method based on the underwater wellhead oil sleeve ring air pressure control system have the advantages of being simple in principle, simple to operate, low in cost and high in return, the annular pressure can be effectively reduced, the well repairing times are reduced, and the safety production of an underwater Christmas tree is guaranteed.
Drawings
FIG. 1 is a schematic diagram of an underwater wellhead oil collar air pressure control system provided by the present invention.
In the figure:
100-oil pipe; 200-a cannula; 300-oil jacket annulus; 400-plug closed space;
1-a production line; 2-a first valve; 3-a second valve; 4-a first storage tank; 5-an injection pump; 6-an injection line; 7-an emptying pipeline; 8-a third valve; 9-a fourth valve; 10-a first internal pressure detection member; 11-a second internal pressure detecting member; 12-a first communication line; 13-a fifth valve; 14-a second reservoir; 15-a sixth valve; 16-a second communication line; 17-a seventh valve; 18-a third internal pressure detecting member; 19-a third communication line; 20-an eighth valve; 21-ninth valve; 22-tenth valve; 23-eleventh valve; 24-a twelfth valve; 25-a thirteenth valve; 26-a fourteenth valve; 27-a fourth internal pressure detecting member; 28-fifth internal pressure detecting element.
Detailed Description
In order to make the technical problems solved, the technical solutions adopted and the technical effects achieved by the present invention clearer, the technical solutions of the present invention are further described below by way of specific embodiments with reference to the accompanying drawings.
In the description of the present invention, unless expressly stated or limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, e.g., as meaning permanently connected, removably connected, or integral to one another; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or may be connected through the use of two elements or the interaction of two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.
In the description of the present embodiment, the terms "upper", "lower", "left", "right", and the like are used based on the orientations and positional relationships shown in the drawings, and are only for convenience of description and simplicity of operation, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used only for descriptive purposes and are not intended to have a special meaning.
Production tree wide application in the exploitation of natural gas compound, no matter production tree all is provided with underwater well head oil jacket annular space pressure detecting system on water or under water, the completion fluid that is full of in the oil jacket annular space is sealed in the annular space by oil jacket packer and oil jacket isolating valve under the normal condition, when well bore temperature variation in the production process, because the completion fluid in the heat-conduction annular space receives the temperature effect, the inflation effect makes annular space pressure rise, the emptying flow of general accessible annular space setting is with pressure control in safety range, guarantee safety in production. However, when the annular packer fails, the oil pipe joint leaks or the oil pipe punctures, the overwater Christmas tree can adopt various means such as continuous emptying, casing production or inert gas injection in the annular space to control the annular pressure or prevent the casing corrosion, and more preparation time is strived for well repair.
When the underwater Christmas tree is adopted for natural gas exploitation, when the annular pressure caused by packer failure is abnormally increased, the sleeve pressure cannot be effectively controlled within a safety range due to the limitation of small size, long distance and the like of an emptying pipeline, and at the moment, only well closing measures can be taken to wait for well repair. In the face of expensive workover cost of the subsea tree, gas wells with small gas amount cannot pass economic benefit evaluation and can only be closed permanently.
In order to solve the above problems, as shown in fig. 1, the present embodiment provides an underwater wellhead oil casing annulus pressure control system for controlling the pressure of an oil casing annulus 300 between an oil pipe 100 and a casing 200, which includes a production line 1, a first valve 2, a second valve 3, a first tank 4, an injection pump 5, an injection line 6, a blow-down line 7, a third valve 8, a fourth valve 9, a first internal pressure detecting member 10, a second internal pressure detecting member 11, and a first communication line 12.
Wherein, the inlet of the production pipeline 1 is used for communicating the oil pipe 100, the outlet of the production pipeline 1 is used for communicating an above-water storage terminal (not shown in the figure), along the conveying direction of the production pipeline 1, a first valve 2 and a second valve 3 are connected in series on the production pipeline 1 in sequence, and a first internal pressure detection piece 10 for detecting the pressure of the production pipeline 1 is arranged between the second valve 3 and the outlet of the production pipeline 1; the first storage tank 4 is used for storing a first antifreezing agent; an inlet of the injection pump 5 is selectively communicated with the first storage tank 4, and specifically, an eleventh valve 23 is connected in series between the first storage tank 4 and the inlet of the injection pump 5, so that on-off control is realized. The inlet of the injection line 6 is selectively communicated with the outlet of the injection pump 5, and the outlet of the injection line 6 is selectively communicated with the production line 1 between the first valve 2 and the second valve 3; an inlet of the emptying pipeline 7 is used for being communicated with the oil sleeve annulus 300, an outlet of the emptying pipeline 7 is used for being communicated with the external atmosphere on the water, the third valve 8 and the fourth valve 9 are sequentially connected in series on the emptying pipeline 7 from the inlet of the emptying pipeline 7 to the outlet of the emptying pipeline 7, the outlet of the injection pump 5 is selectively communicated with the emptying pipeline 7 between the third valve 8 and the fourth valve 9, specifically, the outlet of the injection pump 5 is communicated with the emptying pipeline 7 between the third valve 8 and the fourth valve 9 through a second communication pipeline 16, and a seventh valve 17 is connected in series on the second communication pipeline 16, so that on-off control over the second communication pipeline 16 is achieved. A second internal pressure detection piece 11 for detecting the annular pressure is arranged on the emptying pipeline 7; one end of the first communicating pipeline 12 is communicated with the emptying pipeline 7 between the third valve 8 and the fourth valve 9, the other end of the first communicating pipeline 12 is communicated with the production pipeline 1 between the first valve 2 and the second valve 3, and the fifth valve 13 is connected in series on the first communicating pipeline 12 to realize on-off control.
It should be noted that, in fig. 1, the direction of the arrow on the production line 1 is the conveying direction of the production line 1, and the direction of the arrow on the injection line 6 is the injection direction; the direction of an arrow on the emptying pipeline 7 is the emptying direction of the emptying pipeline 7, the left side of the drawing is the pipeline arrangement of the underwater wellhead oil collar air pressure control system, and the right side of the drawing is the pipeline arrangement of the underwater wellhead oil collar air pressure control system on water.
This embodiment is through production pipeline 1, first storage tank 4, the injection pump 5, injection pipeline 6, unloading pipeline 7, first intercommunication pipeline 12, the intercommunication control of second intercommunication pipeline 16, can realize in a flexible way the notes liquid of oil jacket annulus 300, pressure release control, also can realize in a flexible way the on-off control of production pipeline 1 and oil pipe 100, open the well and close the well control promptly, a structure is simple, both can carry out annular injection to oil jacket annulus 300 through injection pipeline 6 cooperation first intercommunication pipeline 12 and unloading pipeline 7, also can carry out annular injection to oil jacket annulus 300 through second intercommunication pipeline 16 cooperation unloading pipeline 7, and can also carry out the torch of oil jacket annulus 300 through unloading pipeline 7, and also can carry out the unloading of oil jacket annulus 300 through production pipeline 1 cooperation first intercommunication pipeline 12 and unloading pipeline 7, it has the principle simply, the operation is simple, low cost, high advantage, can effectively reduce pressure, reduce the annular number of times of workover, guarantee the safe production return of subsea tree. The specific control method will be described in detail later in the subsea wellhead oil collar air pressure control.
Furthermore, the respective delivery pressure is known for the purpose of supplying the first antifreeze agent by the injection pump 5 to the second connecting line 16. As shown in fig. 1, a third internal pressure detecting member 18 is provided on one end of the seventh valve 17 communicating with the outlet of the injection pump 5, and the third internal pressure detecting member 18 detects the delivery pressure on the second communication line 16.
Further, as shown in fig. 1, in the present embodiment, the subsea wellhead oil collar air pressure control system further comprises a second storage tank 14. The second storage tank 14 is used to store a second antifreeze agent having a lower density than the first antifreeze agent, and the second storage tank 14 is optionally in communication with the inlet of the injection pump 5. Specifically, a sixth valve 15 is connected in series between the second storage tank 14 and the inlet of the injection pump 5, thereby realizing on-off control. In this embodiment, the first antifreeze is ethylene glycol, the second antifreeze is methanol, and the concentration of ethylene glycol is generally 80% to 100% (mass fraction). Due to the design of the second storage tank 14, the subsea wellhead oil collar air pressure control system of the present embodiment can also perform methanol injection operation through the injection line 6 during normal well-opening production.
Further, as shown in fig. 1, in the present embodiment, the subsea wellhead oil collar air pressure control system further comprises a third communication line 19. One end of the third communication pipeline 19 is configured to be communicated with a plug closed space 400 formed between two plugs at the end of the oil pipe 100, the other end of the third communication pipeline 19 is communicated with an inlet of the fourth valve 9, and the eighth valve 20 is connected in series to the third communication pipeline 19, so that when the pressure in the plug closed space 400 in the oil pipe 100 on the seabed leaks and rises, the third communication pipeline 19 can be communicated with the inlet of the fourth valve 9, so as to perform emptying and pressure relief. Specifically, in this embodiment, since the vent line 7 is long, the vent line 7 is further connected in series with a thirteenth valve 25 and a fourteenth valve 26, the thirteenth valve 25 and the fourteenth valve 26 are located between the fourth valve 9 and the third valve 8, the outlet of the eighth valve 20 is communicated with the inlet of the thirteenth valve 25, the first communication line 12 is communicated with the vent line 7 between the third valve 8 and the thirteenth valve 25, and the second communication line 16 is communicated with the vent line 7 between the fourteenth valve 26 and the fourth valve 9. It is contemplated that in other embodiments, the thirteenth valve 25, the fourteenth valve 26 may not be provided, or other control valves may be additionally provided, to realize the segmented on-off control of the blow line 7 according to the control requirement.
Further, as shown in fig. 1, a ninth valve 21 located above the water and a tenth valve 22 located below the water are connected in series on the injection line 6 in the injection direction of the injection line 6, so as to control the on/off of the injection line 6. The ninth valve 21 and the tenth valve 22 are provided in the present embodiment, and it is contemplated that in other embodiments, one or three or even more control valves may be provided.
In addition, as shown in fig. 1, in the present embodiment, a twelfth valve 24 is further connected in series on the production line 1, the twelfth valve 24 is located between the first valve 2 and the second valve 3, and the injection line 6 and the first communication line 12 are selectively communicated with the production line 1 between the first valve 2 and the twelfth valve 24, respectively. The twelfth valve 24 and the first valve 2 are isolation valves, and the second valve 3 is a throttle valve, so that the second valve 3 can be controlled in opening degree, the twelfth valve 24 and the first valve 2 can only be opened and closed, and the flexible control of the production pipeline 1 is realized through the second valve 3. Therefore, in this embodiment, the well opening operation of the production pipeline 1 is to open the first valve 2, the twelfth valve 24 and the second valve 3, and the well closing operation is to close the first valve 2, the twelfth valve 24 and the second valve 3.
Further, as shown in fig. 1, in the present embodiment, the subsea wellhead oil collar air pressure control system further includes a fourth internal pressure detecting member 27 and a fifth internal pressure detecting member 28. The fourth internal pressure detecting element 27 is configured to detect a pressure in the production pipeline 1 between the twelfth valve 24 and the second valve 3, and the fifth internal pressure detecting element 28 is configured to detect a pressure in the production pipeline 1 between the first valve 2 and the twelfth valve 24, so as to flexibly monitor the pressure, which is not described in detail again.
Further, based on the underwater wellhead oil collar ring air pressure control system of this embodiment, this embodiment still provides an underwater wellhead oil collar ring air pressure control method, and it includes following steps:
step S1, detecting and judging whether the annular pressure is higher than a safe pressure range (the safe pressure range is a known existing value according to different underwater production systems) in a well opening state, if so, judging whether the annular pressure is higher than the pressure of a production pipeline 1, and if so, executing a step S2; specifically, the second internal pressure detection element 11 detects the annular pressure of the oil jacket annular space 300, and the first internal pressure detection element 10 detects the pressure of the production line 1 for comparison and judgment. Wherein, the fifth valve 13, the sixth valve 15, the seventh valve 17, the ninth valve 21, the tenth valve 22 and the eleventh valve 23 are in a normally closed state to ensure normal production when the well is opened.
And S2, opening the third valve 8 and the fourth valve 9 to enable the oil sleeve annulus 300 to be subjected to flare emptying through an emptying pipeline 7. In this embodiment, the thirteenth valve 25 and the fourteenth valve 26 are also opened synchronously, so as to ensure that the vent line 7 is used for flare venting, and when only the third valve 8 and the fourth valve 9 are arranged, the third valve 8 and the fourth valve 9 are directly opened to vent. When the annular pressure is reduced by a first preset value (in the embodiment, the value is 15-20 bar), the fourth valve 9 is closed;
s3, injecting a first antifreezing agent (namely ethylene glycol) in the first storage tank 4 into the oil jacket annulus 300 through the emptying pipeline 7 until the annulus pressure rises to a pressure value before the flare is emptied, and stopping injecting; specifically, in this embodiment, the fourth valve 9 is closed, and the eleventh valve 23, the seventh valve 17, the fourteenth valve 26, the thirteenth valve 25 and the third valve 8 are opened, so that the injection pump 5 sequentially delivers the first antifreeze agent in the first storage tank 4 to the oil jacket annulus 300 through the second communication line 16 and the emptying line 7. The input of the first antifreeze agent is used for realizing the unfreezing treatment of the frozen position in the oil casing annulus 300 so as to perform the pressure relief of the oil casing annulus 300 in the following step.
And S4, after the oil jacket annulus 300 and the emptying pipeline 7 are subjected to stewing for a first preset time (in the embodiment, the value is 2 hours), the stewing is performed to fully thaw. Then, the first valve 2 and the second valve 3 on the production pipeline 1 are closed, and the twelfth valve 24 is also synchronously closed in the embodiment, so that the production pipeline 1 is in a shut-in state; then, the oil jacket annulus 300 is put into communication with the production line 1 through the first communication line 12 (i.e. the fifth valve 13 is opened) and the second valve 3 is opened to bleed the pressure of the oil jacket annulus 300 to the production line 1;
step 5, after the annular pressure is reduced by a second preset value (in the embodiment, the value is 15-20 bar), disconnecting the first communication pipeline 12 from the production pipeline 1 (namely, closing the fifth valve 13), and opening the first valve 2 and the second valve 3, wherein the twelfth valve 24 is also opened at the same time, so that the production pipeline 1 is in a well-opening conveying state;
and S6, judging whether the annular pressure is equal to the pressure of the production pipeline 1, if not, returning to the step S3, and if so, ending.
In this embodiment, through steps S1 to S6, when the annular pressure is greater than the pressure of the production pipeline 1, the pressure relief control of the annular pressure in the open-hole state can be realized, and then the annular pressure falls back into the safe pressure range, wherein steps S1 to S3 can be performed in the open-hole state without affecting the normal operation of the open-hole, and the operation is simple and the cost is low, so that the annular pressure can be effectively reduced, and the safe production of oil recovery is ensured.
Further, the present embodiment also provides a method for controlling the annulus pressure in the shut-in state when the annulus pressure is greater than the pressure of the production line 1. Taking the underwater wellhead oil collar air pressure control system of the embodiment as an example, the system specifically comprises the following steps:
step 1, closing the second valve 3, the twelfth valve 24 and the first valve 2 in sequence according to a normal shut-in procedure, and further closing the production pipeline 1; wherein the fifth valve 13, the sixth valve 15, the seventh valve 17, the ninth valve 21, the tenth valve 22, and the eleventh valve 23 are normally closed.
Step 2, recording annular pressure data measured by the second internal pressure detection piece 11, opening a third valve 8, a thirteenth valve 25, a fourteenth valve 26 and a fourth valve 9, and reducing the annular pressure by 15-20bar; the thirteenth valve 25 is then closed, and a preliminary flare vent pressure relief is performed via vent line 7.
And 3, opening the eleventh valve 23, the tenth valve 22, the ninth valve 21 and the fifth valve 13, keeping the first valve 2, the twelfth valve 24, the thirteenth valve 25 and the seventh valve 17 closed, further conveying the first antifreeze in the first storage tank 4 to the emptying pipeline 7 through the injection pipeline 6 and the first communication pipeline 12 by the injection pump 5, and finally conveying the first antifreeze to the oil jacket annulus 300 to realize the injection of the oil jacket annulus 300, wherein one purpose of the injection is to unfreeze the frozen position in the oil jacket annulus 300.
And 5, recording the annular pressure measured by the second internal pressure detection piece 11, opening the thirteenth valve 25 again, and performing annular pressure relief through the emptying pipeline 7 to reduce the annular pressure by 15-20bar.
And 6, closing the thirteenth valve 25, opening the fifth valve 13, starting the injection pump 5 to inject the annular liquid into the oil sleeve annulus 300 again, and repeating the steps until the annular pressure is reduced to the safety range. And after the injection is finished, the states of the valves after the well is closed are recovered, specifically, the fifth valve 13, the sixth valve 15, the seventh valve 17, the ninth valve 21, the tenth valve 22 and the eleventh valve 23 are normally closed, and the injection pump 5 stops working.
And 7, opening the well to produce according to the well opening program. Specifically, the first valve 2, the twelfth valve 24 and the second valve 3 are opened in sequence; keeping the fifth valve 13, the third valve 8, the ninth valve 21, the tenth valve 22 and the eleventh valve 23 normally closed.
In the process, the change of the annular pressure is observed, the annular pressure is in a slow descending trend, the annular injection success of the oil sleeve annular 300 is indicated, the annular pressure relief can be gradually realized, and the problem that the pressure in the oil sleeve annular 300 is abnormally too high is solved.
As described above, the present embodiment provides two different steps of injecting and depressurizing in the two different environments of the shut-in state and the open-hole state when the annular pressure measured by the second internal pressure detecting element 11 is greater than the pressure of the production line 1 measured by the first internal pressure detecting element 10.
Further, when the annulus pressure is lower than the pressure of the production line 1 and the annulus pressure is higher than the safe pressure range, in order to realize the pressure control of the oil jacket annulus 300, a control method in a shut-in state when the annulus pressure is higher than the pressure of the production line 1 may also be adopted. Therefore, the description thereof is omitted.
In conclusion, by adopting the method and the system for controlling the air pressure of the oil jacket ring of the underwater wellhead, on one hand, the normal operation of injecting the methanol can be performed through the injection pipeline 6; on the other hand, the ethylene glycol can be injected into the oil jacket annulus 300 through the injection pipeline 6 or the second communication pipeline 16 and the emptying pipeline 7, the flare emptying of the emptying pipeline 7 can be realized through the emptying pipeline or the pressure relief can be realized through the production pipeline 1, the problem of overhigh pressure of the different annulus can be simply and flexibly solved, the expensive workover cost of the underwater Christmas tree is effectively saved, the annulus pressure relief processing in the open-hole state is realized when the annulus pressure is greater than the pressure of the production pipeline 1 in the steps, the shut-in time can be shortened, the normal oil production effect cannot be influenced, and the safe production is ensured.
The above description is only a preferred embodiment of the present invention, and for those skilled in the art, the present invention should not be limited by the description of the present invention, which should be interpreted as a limitation.
Claims (9)
1. The method for controlling the air pressure of the oil sleeve ring of the underwater wellhead is characterized by comprising an air pressure control system of the oil sleeve ring of the underwater wellhead and the following steps:
the oil jacket annulus pressure control system of subsea wellhead for the pressure of the oil jacket annulus between control oil pipe and the sleeve pipe, include:
the inlet of the production pipeline is communicated with the oil pipe, the outlet of the production pipeline is communicated with the above-water storage terminal, a first valve and a second valve are sequentially connected in series on the production pipeline along the conveying direction of the production pipeline, and a first internal pressure detection piece for detecting the pressure of the production pipeline is arranged between the second valve and the outlet of the production pipeline;
the first storage tank is used for storing a first antifreezing agent;
an injection pump having an inlet communicable with the first tank;
an injection line, an inlet of which is communicable with an outlet of the injection pump, the injection line being communicable with the production line between the first valve and the second valve;
an inlet of the emptying pipeline is used for being communicated with the oil sleeve annulus, an outlet of the emptying pipeline is used for being communicated with the external atmosphere on water, a third valve and a fourth valve are sequentially connected in series on the emptying pipeline from the inlet of the emptying pipeline to the outlet of the emptying pipeline, an outlet of the injection pump can be communicated with the emptying pipeline between the third valve and the fourth valve, and a second internal pressure detection piece for detecting the annulus pressure is arranged on the emptying pipeline;
a first communication pipeline, one end of which is communicated with the emptying pipeline between the third valve and the fourth valve, the other end of which is communicated with the production pipeline between the first valve and the second valve, and a fifth valve is connected in series on the first communication pipeline;
the steps include:
s1, detecting and judging whether annulus pressure is higher than a safe pressure range or not in a well opening state, if so, judging whether the annulus pressure is larger than the pressure of a production pipeline or not, and if so, executing a step S2;
s2, opening a third valve and a fourth valve to enable the oil sleeve annulus to be subjected to torch emptying through an emptying pipeline, and closing the fourth valve when the annulus pressure is reduced by a first preset value;
s3, injecting the first antifreezing agent in the first storage tank into the oil jacket annulus through a vent pipeline until the pressure of the annulus rises to a pressure value before flare venting, and stopping injection;
s4, closing the first valve and the second valve after the oil sleeve annulus and the emptying pipeline are subjected to well stewing for a first preset time; then, enabling the oil sleeve annulus to be communicated with the production pipeline through the first communication pipeline, and opening the second valve to discharge the oil sleeve annulus pressure to the production pipeline;
s5, when the annular pressure is reduced by a second preset value, disconnecting the first communication pipeline from the production pipeline, and opening the first valve and the second valve to enable the production pipeline to be in a well opening and conveying state;
and S6, judging whether the annular pressure is equal to the pressure of the production pipeline, if not, returning to execute the steps S3-S6, and if so, ending.
2. The subsea wellhead oil collar air pressure control method of claim 1, further comprising:
a second storage tank for storing a second antifreeze agent having a lower density than the first antifreeze agent, the second storage tank being communicable with the inlet of the injection pump.
3. The subsea wellhead oil collar air pressure control method of claim 2, wherein a sixth valve is connected in series between the second storage tank and the inlet of the injection pump.
4. The subsea wellhead oil collar air pressure control method according to claim 1, wherein an outlet of the injection pump is communicated with the vent line between the third valve and the fourth valve through a second communication line, and a seventh valve is connected in series to the second communication line.
5. The method for controlling the air pressure of the oil collar of the subsea wellhead as claimed in claim 4, wherein a third internal pressure detecting member is provided at an end of said seventh valve communicating with an outlet of said injection pump.
6. The subsea wellhead oil collar air pressure control method of claim 1, further comprising:
and one end of the third communicating pipeline is configured to be communicated with a plug closed space formed between two plugs at the end part of the oil pipe, the other end of the third communicating pipeline is communicated with an inlet of the fourth valve, and the eighth valve is connected to the third communicating pipeline in series.
7. The subsea wellhead oil collar air pressure control method according to claim 1, wherein a ninth valve located above water and a tenth valve located below water are connected in series to the injection line in the injection direction of the injection line.
8. The subsea wellhead oil collar air pressure control method of claim 1, wherein an eleventh valve is connected in series between the first storage tank and the inlet of the injection pump.
9. The method of claim 1, wherein a twelfth valve is connected in series to the production line, the twelfth valve being located between the first valve and the second valve, and the injection line and the first communication line are respectively communicable with the production line between the first valve and the twelfth valve.
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| CN108487882B (en) * | 2018-02-23 | 2020-05-01 | 中国石油大学(北京) | Christmas tree device and method for exploiting natural gas hydrate |
| CN110260161B (en) * | 2019-07-10 | 2024-01-26 | 美钻深海能源科技研发（上海）有限公司 | Automatic pressure relief system and automatic pressure relief device for marine oil field jumper |
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