Back pressure control device

Abstract

The invention relates to a back pressure control device which comprises a nitrogen supply device and a back pressure control manifold, and the nitrogen supply device is used for conveying gas required by back pressure to the back pressure control manifold; the back pressure control manifold comprises a back pressure compensation pipeline, one end of the back pressure compensation pipeline is connected with the nitrogen supply device, the other end of the back pressure compensation pipeline is connected with one end of a first manifold, and the other end of the first manifold is connected with one end of a back pressure relief pipeline. The first manifold is provided with at least one wellhead back pressure compensation interface connected with a wellhead casing valve or a blowout preventer, and the other end of the back pressure relief pipeline is connected to a mud pit; the return pressure compensation pipeline is used for feeding gas conveyed by the nitrogen supply device into a wellhead casing valve or a blowout preventer to compensate return pressure, and the return pressure release pipeline is used for releasing the gas to reduce the return pressure when the return pressure exceeds a target value. The back pressure control device is fast in pressure control response and accurate in pressure control, and has a good application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of ground well control equipment for oil and gas well cementing, and particularly relates to a back pressure control device. Background Art

[0002] With the expansion and deepening of oil and gas development, the geological conditions of oil and gas reservoirs are becoming more and more complex. The narrow density window formations have put forward higher and more precise pressure control requirements for the entire cementing process to avoid uncontrolled well leakage, well kick accidents or cementing quality accidents.

[0003] At present, precision pressure-controlled cementing adopts pressure balance cementing technology. Since the cementing process involves stopping the circulation of drilling fluid to install the cement head and switching to inject different densities of pre-fluid, cement, post-fluid, displacement fluid, and drilling fluid, once the drilling fluid slows down or stops circulating, the dynamic pressure in the well decreases or disappears, which is likely to cause a well kick or blowout. This requires timely and accurate application of appropriate back pressure at the wellhead to maintain the bottomhole pressure within a narrow density window. Although there are back pressure compensation devices that use mud circulation throttling, first of all, their response is slow and the compensation pressure range is limited. In addition, the throttle valve will experience flow fluctuations at low flow rates, and the flow fluctuations of the throttle valve will cause back pressure fluctuations. Secondly, during the replacement of the wellhead device and the waiting period for solidification, the continuously running back pressure pump will cause energy waste. Finally, if the back pressure skid fails during this period, it will cause pressure imbalance, leading to cementing accidents.

[0004] In view of the functional defects, large size, high energy consumption and other reasons of the back pressure control device of the above-mentioned fine pressure controlled cementing, as well as the demand for fine pressure controlled cementing construction on offshore platforms, there is an urgent need for a back pressure control device with smaller size, faster back pressure adjustment and larger adjustment range. Summary of the Invention

[0005] In order to solve all or part of the above problems, the purpose of the present invention is to provide a back pressure control device. The back pressure control device of the present invention has a fast pressure control response and precise pressure control; it does not require the long-distance arrangement of back pressure slurry circulation pipelines and continuous operation of circulation pumps, which correspondingly reduces energy consumption; it is practical in both land and marine cementing and has good application prospects.

[0006] According to one aspect of the present invention, there is provided a back pressure control device, comprising a nitrogen supply device and a back pressure control manifold connected to the nitrogen supply device, wherein the nitrogen supply device is used to deliver gas required for back pressure to the back pressure control manifold;

[0007] The back pressure control manifold includes a back pressure compensation pipeline, one end of which is connected to the nitrogen supply device, the other end of which is connected to one end of the first manifold, the other end of which is connected to one end of the back pressure relief pipeline, the first manifold is provided with at least one wellhead back pressure compensation interface connected to a wellhead casing valve or a blowout preventer, and the other end of the back pressure relief pipeline is connected to the mud pit; the back pressure compensation pipeline is used to deliver the gas delivered by the nitrogen supply device into the wellhead casing valve or the blowout preventer to compensate for the back pressure, and the back pressure relief pipeline is used to release the gas to reduce the back pressure when the back pressure exceeds a target value.

[0008] Furthermore, the nitrogen supply device includes several first gas cylinders, each of which is used to store gas, and each of which is connected to a second manifold, the outlet of which is connected to a gas supply connector, which is connected to one end of the back pressure compensation pipeline; a first air pressure transmitter and a first valve are provided on the second manifold.

[0009] Furthermore, the nitrogen supply device also includes several second gas cylinders, each of which is used to store gas, each of which is connected to a third manifold, the outlet of the third manifold is connected to the gas supply connector, and the third manifold is provided with a second air pressure transmitter and a second valve; the second manifold and the third manifold are connected by a bypass pipe, and the bypass pipe is provided with a gas booster pump.

[0010] Furthermore, the back pressure compensation pipeline includes at least one automatic control pipeline and at least one manual adjustment pipeline, one end of all the automatic control pipelines and one end of all the manual adjustment pipelines are connected to one end of the gas inlet pipeline, the other end of the gas inlet pipeline is connected to the nitrogen supply device, the other end of all the automatic control pipelines and the other end of all the manual adjustment pipelines are connected to one end of the outlet pipeline, the other end of the outlet pipeline is connected to one end of the first manifold, the manual adjustment pipeline is provided with a first switch ball valve, and the automatic control pipeline is provided with a second switch ball valve, a pressure reducing valve and a first proportional control valve.

[0011] Furthermore, the automatic control pipeline is divided into two lines, and the manual adjustment pipeline is divided into one line; a one-way valve and a pressure transmitter are provided on the outlet pipeline.

[0012] Furthermore, the back pressure relief pipeline includes a proportional pressure relief pipeline and a safety overflow pipeline. The other end of the back pressure compensation pipeline is connected to a vertical pipe. The upper end of the vertical pipe is connected to one end of the first manifold. The other end of the first manifold is connected to one end of the proportional pressure relief pipeline. The lower end of the vertical pipe is connected to one end of the safety overflow pipeline. The other end of the proportional pressure relief pipeline and the other end of the safety overflow pipeline are both connected to the mud pool. The safety overflow pipeline is used for overpressure overflow and emergency pressure relief, and the proportional pressure relief pipeline is used for pressure relief.

[0013] Furthermore, a safety overflow valve and a pneumatic switch valve are provided on the safety overflow pipeline; a first back pressure relief interface is provided at the lower end of the vertical pipe, and the first back pressure relief interface is connected to one end of the safety overflow pipeline.

[0014] Furthermore, the back-pressure relief pipeline includes a proportional pressure relief pipeline and a manual back-pressure relief branch. The other end of the back-pressure compensation pipeline is connected to a vertical pipe. The upper end of the vertical pipe is connected to one end of the first manifold. The other end of the first manifold is connected to one end of the proportional pressure relief pipeline. The lower end of the vertical pipe is connected to one end of the manual back-pressure relief branch. The other end of the proportional pressure relief pipeline and the other end of the manual back-pressure relief branch are both connected to the mud pool. A first manual switching valve is provided on the manual back-pressure relief branch. The proportional pressure relief pipeline is used for pressure relief.

[0015] Furthermore, a second back pressure relief interface is provided at the other end of the first manifold, and the second back pressure relief interface is connected to one end of the proportional pressure relief pipeline; a gas supply interface is provided on the vertical pipe, and the other end of the back pressure compensation pipeline is connected to the gas supply interface; a pressure transmitter interface is provided on the first manifold or the vertical pipe.

[0016] Furthermore, the proportional pressure relief pipeline includes at least one pressure relief branch, each of the pressure relief branches is provided with a second manual switch valve and a second proportional regulating valve, one end of all the pressure relief branches is connected to one end of the pressure relief main line, and the other end of all the pressure relief branches is connected to the mud pool, the pressure relief main line is provided with an electric switch valve, and the other end of the pressure relief main line is connected to the other end of the first manifold; or, the proportional pressure relief pipeline is provided with a third manual switch valve and a third proportional regulating valve.

[0017] Furthermore, there are three wellhead back pressure compensation interfaces, and each wellhead back pressure compensation interface is provided with a switch valve.

[0018] Furthermore, it also includes a skid and a control host, the control host is used to control the nitrogen supply device and the back pressure control manifold, and the control host, the nitrogen supply device and the back pressure control manifold are all arranged in the skid.

[0019] It can be seen from the above technical solution that the back pressure control device provided by the present invention has the following beneficial effects:

[0020] The backpressure control device of the present invention can replace conventional slurry backpressure compensation skids during precision pressure-controlled cementing. Specifically, the backpressure control device of this embodiment can be used to replace conventional slurry backpressure compensation skids during the period when the wellbore's liquid circulation is about to cease. The backpressure control device of the present invention offers rapid and precise pressure control. Compared to existing technologies, the backpressure control device of the present invention eliminates the need for remotely deployed backpressure slurry circulation piping and continuous operation of circulating pumps, resulting in corresponding energy savings and cost reductions. The backpressure control device of the present invention is practical for both terrestrial and offshore cementing applications and has promising application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the composition of a nitrogen supply device according to an embodiment of the present invention;

[0022] Figure 2 Schematic diagram of a back pressure control manifold according to an embodiment of the present invention;

[0023] Figure 3 yes Figure 2 AA view of the middle back pressure compensation pipeline;

[0024] Figure 4 Schematic diagram of a back pressure control manifold according to another embodiment of the present invention;

[0025] Figure 5 Schematic diagram of the planar layout of the skid body according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to better understand the purpose, structure and function of the present invention, a back pressure control device of the present invention is further described in detail below with reference to the accompanying drawings.

[0027] like Figure 1 、 Figure 2As shown, it shows a back pressure control device according to an embodiment of the present invention, comprising a nitrogen supply device 1 and a back pressure control manifold 2 connected to the nitrogen supply device 1, wherein the nitrogen supply device 1 is used to deliver the gas required for back pressure to the back pressure control manifold 2; the back pressure control manifold 2 comprises a back pressure compensation pipeline 202, one end of the back pressure compensation pipeline 202 is connected to the nitrogen supply device 1, the other end of the back pressure compensation pipeline 202 is connected to one end of a first manifold 201, and the other end of the first manifold 201 is connected to one end of a back pressure relief pipeline 203, the first manifold 201 is provided with at least one wellhead back pressure compensation interface 2012 connected to a wellhead casing valve or a blowout preventer, and the other end of the back pressure relief pipeline 203 is connected to a mud pit; the back pressure compensation pipeline 202 is used to deliver the gas delivered by the nitrogen supply device 1 to the wellhead casing valve or the blowout preventer to compensate for the back pressure, and the back pressure relief pipeline 203 is used to release the gas to reduce the back pressure when the back pressure exceeds a target value.

[0028] Specifically, the nitrogen supply device 1 is used to deliver the gas required for back pressure to the back pressure control manifold 2; the back pressure control manifold 2 includes a back pressure compensation pipeline 202, a first manifold 201 and a back pressure relief pipeline 203. The back pressure compensation pipeline 202 is used to deliver the gas delivered by the nitrogen supply device 1 to the wellhead back pressure compensation interface 2012. The wellhead back pressure compensation interface 2012 is connected to the wellhead casing valve or blowout preventer (not shown in the figure) through an on-site pipeline, so that the back pressure compensation pipeline 202 delivers the gas delivered by the nitrogen supply device 1 to the wellhead casing valve or blowout preventer through the wellhead back pressure compensation interface 2012 to compensate for the back pressure to the target value, thereby achieving the purpose of controlling the pressure; the back pressure relief pipeline 203 is used to release gas to reduce the back pressure when the back pressure exceeds the target value, so as to play a corresponding protective role.

[0029] The backpressure control device of the present invention can replace the traditional slurry backpressure compensation skid during fine pressure-controlled cementing. Specifically, it can be used to replace the traditional slurry backpressure compensation skid during the period when the wellbore's liquid circulation is about to stop. The backpressure control device of this embodiment offers fast and precise pressure control. Compared to existing technologies, it eliminates the need for remotely deployed backpressure slurry circulation piping and continuous operation of the circulation pump, resulting in corresponding energy savings and consumption reductions. The backpressure control device of this embodiment is practical for both terrestrial and offshore cementing applications and has promising application prospects.

[0030] Among them, Figure 1 As shown, the nitrogen supply device 1 includes a plurality of first gas cylinders 101, each of which is used to store gas. Each of the first gas cylinders 101 is connected to a second manifold 102, the outlet of the second manifold 102 is connected to a gas supply connector 108, and the gas supply connector 108 is connected to one end of a back pressure compensation line 202; a first air pressure transmitter 106 and a first valve 105 are provided on the second manifold 102.

[0031] In this embodiment, each first gas cylinder is used to store gas. For example, each first gas cylinder is a nitrogen cylinder with a gas storage pressure of 14 MPA, so that nitrogen can be used for pressure control. Nitrogen has the advantages of being easily available and cheap, and does not increase pollution after use. Using nitrogen for pressure control saves costs and is not harmful to the environment. Each first gas cylinder is connected to the gas supply connector 108 through the second manifold 102, so that the gas in the first gas cylinder can enter the back pressure compensation pipeline 202 through the second manifold 102 and the gas supply connector. The first air pressure transmitter 106 here is used to detect the gas pressure of the manifold where it is located, and the first valve 105 is used to control the on and off of the gas.

[0032] In one embodiment, if Figure 1 As shown, the nitrogen supply device also includes a plurality of second gas cylinders 107, each of which is used to store gas. Each second gas cylinder 107 is connected to a third manifold 104, the outlet of the third manifold 104 is connected to a gas supply connector 108, and a second air pressure transmitter 1061 and a second valve 1051 are provided on the third manifold 104; the second manifold 102 and the third manifold 104 are connected by a bypass pipe, and a gas booster pump 103 is provided on the bypass pipe.

[0033] For this embodiment, each second gas cylinder is, for example, also a nitrogen cylinder with a gas storage pressure of 14 MPA, so that nitrogen can be used for pressure control; each second gas cylinder is connected to the gas supply connector 108 through the third manifold 104, so that the gas in the gas cylinder can enter the back pressure compensation pipeline 202 through the third manifold 104 and the gas supply connector; the second air pressure transmitter 106 is used to detect the gas pressure of the manifold where it is located, and the second valve 105 is used to control the on and off of the gas.

[0034] Again, for the embodiment in which the first gas cylinder and the second gas cylinder are provided, for example, the first gas cylinder is used as a conventional cylinder group and the second gas cylinder is used as a high-pressure cylinder group.

[0035] When supplying gas, first open the first valve 105 connected to the second manifold 102 to allow the conventional bottle group to supply gas. When the pressure of the bottle group is lower than the maximum pressure requirement of the pressure control, switch to the high-pressure bottle group to supply gas. When the pressure of the two groups of gas cylinders is lower than the maximum pressure requirement of the pressure control, start the gas booster pump 103 to boost the pressure and then supply gas.

[0036] With respect to the gas booster pump 103, the second manifold 102 is connected to the air inlet of the gas booster pump 103, and the third manifold 104 is connected to the air outlet of the gas booster pump 103. The gas booster pump 103 is preferably, but not limited to, a pneumatic booster pump, the pressure of which after boosting should reach above 10 MPa, and the maximum compression flow rate should be not less than 30 liters / minute (when the input is 1 MPa); the gas booster pump 103 can use the compressed air in the on-site air compressor as power to boost the gas in the conventional bottle group and store it in the high-pressure bottle group for use. Obviously, it can also compress the remaining gas in the conventional bottle group into one or more second gas cylinders in the high-pressure bottle group before inflating the nitrogen supply device 1 to save the use of gas source.

[0037] During specific implementation, the nitrogen supply device can be fixed on the support structure as needed. The form of the support structure is not limited, as long as it can be used to fix and support the first gas cylinder, the second gas cylinder, the second manifold 102, the third manifold 104 and the gas booster pump 103, and facilitate the connection of the gas line and the replacement of the gas cylinder.

[0038] In one embodiment, if Figure 2 、 Figure 3 and Figure 4 As shown, the back pressure compensation pipeline 202 includes at least one automatic control pipeline 2022 and at least one manual adjustment pipeline 2028. One end of all the automatic control pipelines 2022 and one end of all the manual adjustment pipelines 2028 are connected to one end of the gas inlet pipeline 2021, and the other end of the gas inlet pipeline 2021 is connected to the nitrogen supply device 1. The other end of all the automatic control pipelines 2022 and the other end of all the manual adjustment pipelines 2028 are connected to one end of the outlet pipeline 2023, and the other end of the outlet pipeline 2023 is connected to one end of the first manifold 201. A first switching ball valve 2024 is provided on the manual adjustment pipeline 2028, and a second switching ball valve 20241, a pressure reducing valve 2025 and a first proportional control valve 2026 are provided on the automatic control pipeline 2022.

[0039] In this embodiment, the back-pressure compensation pipeline 202 includes at least one automatic control pipeline 2022 and at least one manual adjustment pipeline 2028. The automatic control pipeline 2022 and the manual adjustment pipeline 2028 are connected in parallel, with one end of the parallel structure connected to the gas inlet pipeline 2021 and the other end to the outlet pipeline 2023. The automatic control pipeline 2022 is equipped with a second on-off ball valve 20241, a pressure reducing valve 2025, and a first proportional control valve 2026. These valves are arranged sequentially along the direction of gas flow, forming a pipeline with throttling and pressure reduction functions. The manual adjustment pipeline 2028 is equipped with only the first on-off ball valve 2024 to facilitate manual emergency adjustment in the event of a failure of the electric or pneumatic power supply, achieving comprehensive manual pressure control.

[0040] As a simplified implementation scheme, for example, the automatic control pipeline 2022 is set as one channel, and the manual adjustment pipeline 2028 is set as one channel, such as Figure 4 As an alternative, the automatic control pipeline 2022 can be set to two lines and the manual adjustment pipeline 2028 can be set to one line, as shown in FIG. Figure 2 shown.

[0041] Again in this embodiment, a one-way valve 2027 and a pressure transmitter are provided on the outlet pipe 2023. The one-way valve 2027 is provided to prevent gas from flowing in the desired direction, and the pressure transmitter is used to detect the gas pressure in the manifold where it is located.

[0042] In one embodiment, if Figure 2 As shown, the back pressure relief pipeline 203 includes a proportional pressure relief pipeline 205 and a safety overflow pipeline 204. The other end of the back pressure compensation pipeline 202 is connected to a vertical pipe 2017. The upper end of the vertical pipe 2017 is connected to one end of the first manifold 201. The other end of the first manifold 201 is connected to one end of the proportional pressure relief pipeline 205. The lower end of the vertical pipe 2017 is connected to one end of the safety overflow pipeline 204. The other end of the proportional pressure relief pipeline 205 and the other end of the safety overflow pipeline 204 are both connected to the mud pool. The safety overflow pipeline 204 is used for overpressure overflow and emergency pressure relief, and the proportional pressure relief pipeline 205 is used for pressure relief.

[0043] Specifically, the back pressure relief pipeline 203 includes a proportional pressure relief pipeline 205 and a safety overflow pipeline 204. The proportional pressure relief pipeline 205 is used to relieve pressure when the back pressure exceeds the target value, and the safety overflow pipeline 204 is used for overpressure overflow and emergency pressure relief.

[0044] The high-pressure nitrogen supplied by the nitrogen supply device 1 enters the vertical pipe 2017 through the back pressure compensation pipeline 202. The vertical pipe 2017 of this embodiment plays the role of gas-liquid separation. The gas moves up along the vertical pipe 2017 to the first manifold 201, and then enters the wellhead casing valve or blowout preventer through the wellhead back pressure compensation interface 2012 on the first manifold 201, thereby playing the role of compensating for the back pressure. The separated liquid enters the mud pool through the safety overflow pipeline 204 at the lower end of the vertical pipe 2017.

[0045] Among them, a safety overflow valve 2034 and a pneumatic switch valve 2035 are provided on the safety overflow pipeline 204. The air source of the pneumatic switch valve 2035 comes from the on-site air compressor. The air is controlled by the pneumatic switch valve 2035. It mainly utilizes the advantage of faster pneumatic speed than electric valves to facilitate overpressure overflow and emergency pressure relief during grouting.

[0046] Among them, a first back pressure relief interface 2016 is provided at the lower end of the vertical pipe 2017, and the first back pressure relief interface 2016 is connected to one end of the safety overflow pipeline 204.

[0047] As an alternative, the safety overflow line 204 can be replaced with a manual back pressure relief branch to achieve emergency manual control of the entire back pressure control process. Figure 4 As shown, backpressure relief pipeline 203 includes a proportional pressure relief pipeline 205 and a manual backpressure relief branch. The other end of backpressure compensation pipeline 202 is connected to a vertical pipe 2017. The upper end of vertical pipe 2017 is connected to one end of first manifold 201, the other end of first manifold 201 is connected to one end of proportional pressure relief pipeline 205, and the lower end of vertical pipe 2017 is connected to one end of the manual backpressure relief branch. The other ends of proportional pressure relief pipeline 205 and manual backpressure relief branch are both connected to the mud pit. A first manual on-off valve 20321 is provided on the manual backpressure relief branch to relieve pressure on proportional pressure relief pipeline 205. In this solution, the provision of first manual on-off valve 20321 on the manual backpressure relief branch enables emergency manual control of the entire backpressure control process. Similarly, a first back pressure relief interface 2016 is provided at the lower end of the vertical pipe 2017, where the first back pressure relief interface 2016 is connected to one end of the manual back pressure relief branch.

[0048] Among them, a pressure transmitter interface 2014 is provided on the first manifold 201 or the vertical pipe 2017. The setting of the transmitter interface 2014 is used to install a pressure transmitter through an instrument valve for accurately measuring the pressure at the casing mouth. It should be further explained that the pressure transmitter installed at this location should have a built-in backup battery and a pressure display panel to facilitate manual operation and control of back pressure in the event of an abnormal power outage.

[0049] Among them, for the scheme of setting up a safety overflow pipeline 204, and for the scheme of setting up a manual back pressure relief branch: the other end of the first manifold 201 is provided with a second back pressure relief interface 2015, and the second back pressure relief interface 2015 is connected to one end of the proportional pressure relief pipeline 205; a gas supply interface 2011 is provided on the vertical pipe 2017, and the other end of the back pressure compensation pipeline 202 is connected to the gas supply interface 2011, and preferably the other end of the back pressure compensation pipeline 202 is detachably connected to the gas supply interface 2011.

[0050] Regarding the aforementioned proportional pressure relief pipeline 205: Figure 2As shown, the proportional pressure relief pipeline 205 includes at least one pressure relief branch, each pressure relief branch is provided with a second manual switch valve 2032 and a second proportional regulating valve 2033, one end of all the pressure relief branches is connected to one end of the pressure relief main line, and the other end of all the pressure relief branches is connected to the mud pool, an electric switch valve 2031 is provided on the pressure relief main line, and the other end of the pressure relief main line is connected to the other end of the first manifold 201.

[0051] In a specific implementation, for example, two pressure relief branches are provided, each equipped with a second manual on / off valve 2032 and a second proportional control valve 2033. The second manual on / off valve 2032 facilitates manual on / off control of the pressure relief branch, allowing selection of the appropriate pressure relief branch. The second proportional control valve 2033 controls the pressure relief rate. One end of each pressure relief branch is connected to one end of the main pressure relief line, and the other end of each pressure relief branch is connected to the mud pit. The other end of the main pressure relief line is connected to the other end of the first manifold 201. The electric on / off valve 2031 provided on the main pressure relief line provides overall control of the proportional pressure relief line 205.

[0052] As an alternative, the proportional pressure relief pipeline 205 is provided with only one path, that is, Figure 2 Compared with the proportional pressure relief pipeline 205 shown in FIG. 1 , which includes a pressure relief main line and a pressure relief branch line, in this embodiment, one pressure relief branch line is omitted and the electric switch valve 2031 is omitted, and the pressure relief control is directly completed by the third proportional regulating valve, that is, Figure 4 As shown, a third manual switch valve 20321 and a third proportional regulating valve 20331 are provided on the proportional pressure relief pipeline 205 .

[0053] In one embodiment, there are three wellhead back pressure compensation interfaces 2012 , and each wellhead back pressure compensation interface 2012 is provided with a switch valve 2013 .

[0054] The wellhead backpressure compensation interface 2012 is preferably connected to the switch valve 2013 via a flange. The wellhead backpressure compensation interface 2012 can be connected to the wellhead casing valve or blowout preventer (not shown) via on-site piping to control the casing pressure. The number of wellhead backpressure compensation interfaces 2012 can be one or more. When there is one, the interface can be connected to the wellhead casing valve or blowout preventer. When there are more than one, one interface can be connected to the wellhead casing valve or blowout preventer, and the others can serve as backup interfaces. If backup interfaces are present, one of them can be selected as the connection port for the on-site slurry backpressure compensation system. This connection port can be connected to the wellhead casing valve or blowout preventer to serve as the mud inlet and outlet.

[0055] In one embodiment, it further includes a skid and a control host, which is used to control the nitrogen supply device 1 and the back pressure control manifold 2. The control host, the nitrogen supply device 1 and the back pressure control manifold 2 are all arranged in the skid.

[0056] The control host consists of a PLC host, necessary expansion modules, a matching human-machine interface, and a power supply. It is placed in an explosion-proof housing and uses specially developed PLC application software to achieve at least the following functions:

[0057] 1) Set or modify basic computer communication parameters, gas source working pressure, gas source pressure low alarm value, etc. through the setting interface;

[0058] 2) It can receive the back pressure target value from the host computer, and according to the difference between the measured current back pressure and the back pressure target value, quickly adjust the opening of the first proportional control valve 2026 (manually select the channel and open the corresponding manual valve before starting the work), and timely control the back pressure within a safe range.

[0059] 3) Display of real-time parameters or curves and status, such as: current back pressure value, target pressure and back pressure history curve, display of valve working status, working channel display, normal and abnormal system operation alarm prompts and sound alarms, etc.

[0060] The skid is preferably a frame structure, which is used to carry the nitrogen supply device 1, the back pressure control manifold 2 and the control host, and is separated from the monitoring room and the electrical cabinet area. Figure 5 As shown, the skid is equipped with areas for back-pressure control manifolds, nitrogen supply devices, monitoring rooms, and electrical cabinets. The nitrogen supply device and back-pressure control manifold 2 are arranged in a three-dimensional space within the skid, conserving skid floor space while facilitating operation and maintenance. The skid should be equipped with appropriate supports and brackets to support and secure the nitrogen supply device 1, back-pressure control manifold 2, control unit, electrical cabinet, and monitors. Furthermore, the skid should be easy to hoist, transport, and install.

[0061] The backpressure control device of the present invention can replace the traditional slurry backpressure compensation skid during precision pressure-controlled cementing. When the wellbore's liquid circulation is about to cease, the device switches to the backpressure control device of the present invention, automatically controlling air supply or pressure relief to achieve automatic backpressure control. The backpressure control device of the present invention offers fast and precise pressure control. Nitrogen is readily available and inexpensive, and its use does not increase pollution. The device is compact and eliminates the need for remotely deployed backpressure slurry circulation piping and continuous operation of a circulating pump. This approach saves energy and reduces consumption, making it practical for both land and offshore cementing applications, and has promising application prospects.

[0062] It should be noted that, unless otherwise specified, the technical or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0063] In addition, the terms "one", "two", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. In the description of the present invention, the meaning of "multiple" is more than two, unless otherwise clearly and specifically limited.

[0064] In this application, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they may refer to fixed or detachable connections, or integration; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and description of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A back pressure control device, characterized in that: It comprises a nitrogen supply device (1) and a back pressure control manifold (2) connected to the nitrogen supply device (1), wherein the nitrogen supply device (1) is used to deliver gas required for back pressure to the back pressure control manifold (2); The back pressure control manifold (2) comprises a back pressure compensation pipeline (202), one end of which is connected to the nitrogen supply device (1), the other end of which is connected to one end of a first manifold (201), the other end of which is connected to one end of a back pressure relief pipeline (203), the first manifold (201) being provided with at least one wellhead back pressure compensation interface (2012) connected to a wellhead casing valve or a blowout preventer, and the other end of the back pressure relief pipeline (203) being connected to a mud pool; the back pressure compensation pipeline (202) is used to deliver the gas delivered by the nitrogen supply device (1) into the wellhead casing valve or the blowout preventer to compensate for the back pressure, and the back pressure relief pipeline (203) is used to release the gas to reduce the back pressure when the back pressure exceeds a target value.

2. The back pressure control device according to claim 1, characterized in that: The nitrogen supply device (1) comprises a plurality of first gas cylinders (101), each of the first gas cylinders (101) is used to store gas, each of the first gas cylinders (101) is connected to a second manifold (102), the outlet of the second manifold (102) is connected to a gas supply connector (108), and the gas supply connector (108) is connected to one end of the back pressure compensation pipeline (202); a first gas pressure transmitter (106) and a first valve (105) are provided on the second manifold (102).

3. The back pressure control device according to claim 2, characterized in that: The nitrogen supply device further comprises a plurality of second gas cylinders, each of which is used to store gas, and each of which is connected to a third manifold (104). The outlet of the third manifold (104) is connected to the gas supply connector (108). The third manifold (104) is provided with a second air pressure transmitter (1061) and a second valve (1051). The second manifold (102) and the third manifold (104) are connected via a bypass pipe, and a gas booster pump (103) is provided on the bypass pipe.

4. The back pressure control device according to claim 1, characterized in that: The back pressure compensation pipeline (202) comprises at least one automatic control pipeline (2022) and at least one manual adjustment pipeline (2028), one end of all the automatic control pipelines (2022) and one end of all the manual adjustment pipelines (2028) are connected to one end of the gas inlet pipeline (2021), the other end of the gas inlet pipeline (2021) is connected to the nitrogen supply device (1), the other end of all the automatic control pipelines (2022) and the other end of all the manual adjustment pipelines (2028) are connected to one end of the outlet pipeline (2023), the other end of the outlet pipeline (2023) is connected to one end of the first manifold (201), the manual adjustment pipeline (2028) is provided with a first switch ball valve (2024), and the automatic control pipeline (2022) is provided with a second switch ball valve (20241), a pressure reducing valve (2025) and a first proportional control valve (2026).

5. The back pressure control device according to claim 4, characterized in that: The automatic control pipeline (2022) is divided into two lines, and the manual adjustment pipeline (2028) is divided into one line; a one-way valve (2027) and a pressure transmitter are provided on the outlet pipeline (2023).

6. The back pressure control device according to claim 1, characterized in that: The back pressure relief pipeline (203) comprises a proportional pressure relief pipeline (205) and a safety overflow pipeline (204); the other end of the back pressure compensation pipeline (202) is connected to a vertical pipe (2017); the upper end of the vertical pipe (2017) is connected to one end of the first manifold (201); the other end of the first manifold (201) is connected to one end of the proportional pressure relief pipeline (205); the lower end of the vertical pipe (2017) is connected to one end of the safety overflow pipeline (204); the other end of the proportional pressure relief pipeline (205) and the other end of the safety overflow pipeline (204) are both connected to the mud pool; the safety overflow pipeline (204) is used for overpressure overflow and emergency pressure relief, and the proportional pressure relief pipeline (205) is used for pressure relief.

7. The back pressure control device according to claim 6, characterized in that: The safety overflow pipeline (204) is provided with a safety overflow valve (2034) and a pneumatic switch valve (2035); the lower end of the vertical pipe (2017) is provided with a first back pressure relief interface (2016), and the first back pressure relief interface (2016) is connected to one end of the safety overflow pipeline (204).

8. The back pressure control device according to claim 1, characterized in that: The back pressure relief pipeline (203) comprises a proportional pressure relief pipeline (205) and a manual back pressure relief branch. The other end of the back pressure compensation pipeline (202) is connected to a vertical pipe (2017). The upper end of the vertical pipe (2017) is connected to one end of the first manifold (201). The other end of the first manifold (201) is connected to one end of the proportional pressure relief pipeline (205). The lower end of the vertical pipe (2017) is connected to one end of the manual back pressure relief branch. The other end of the proportional pressure relief pipeline (205) and the other end of the manual back pressure relief branch are both connected to the mud pool. A first manual switch valve (20321) is provided on the manual back pressure relief branch. The proportional pressure relief pipeline (205) is used for pressure relief.

9. The back pressure control device according to claim 6 or 8, characterized in that: The other end of the first manifold (201) is provided with a second back-pressure relief interface (2015), and the second back-pressure relief interface (2015) is connected to one end of the proportional pressure relief pipeline (205); the vertical pipe (2017) is provided with a gas supply interface (2011), and the other end of the back-pressure compensation pipeline (202) is connected to the gas supply interface (2011); the first manifold (201) or the vertical pipe (2017) is provided with a pressure transmitter interface (2014).

10. The back pressure control device according to claim 6 or 8, characterized in that: The proportional pressure relief pipeline (205) comprises at least one pressure relief branch, each of which is provided with a second manual switch valve (2032) and a second proportional regulating valve (2033), one end of all the pressure relief branches is connected to one end of the pressure relief main line, and the other end of all the pressure relief branches is connected to the mud pool, an electric switch valve (2031) is provided on the pressure relief main line, and the other end of the pressure relief main line is connected to the other end of the first manifold (201); alternatively, a third manual switch valve (20321) and a third proportional regulating valve (20331) are provided on the proportional pressure relief pipeline (205).

11. The back pressure control device according to claim 1, characterized in that: There are three wellhead back pressure compensation interfaces (2012), and each wellhead back pressure compensation interface (2012) is provided with a switch valve (2013).

12. The back pressure control device according to claim 1, characterized in that: It also includes a skid body and a control host, wherein the control host is used to control the nitrogen supply device (1) and the back pressure control manifold (2), and the control host, the nitrogen supply device (1) and the back pressure control manifold (2) are all arranged in the skid body.

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