Back pressure control device

Abstract

The present application relates to a kind of back pressure control device, including nitrogen supply device and back pressure control manifold, nitrogen supply device is used to deliver gas required by back pressure to back pressure control manifold;Back pressure control manifold includes back pressure compensation pipeline, one end of back pressure compensation pipeline is connected with nitrogen supply device, the other end of back pressure compensation pipeline is connected with the one end of first manifold, the other end of first manifold is connected with the one end of back pressure release pipeline, at least one wellhead back pressure compensation interface is provided on first manifold, and it is connected with wellhead casing valve or blowout preventer, the other end of back pressure release pipeline is connected to mud pit;Back pressure compensation pipeline is used to send gas delivered by nitrogen supply device into wellhead casing valve or blowout preventer to compensate back pressure, back pressure release pipeline is used to release gas to reduce back pressure when back pressure exceeds target value.The back pressure control device of the present application has fast pressure control reaction, accurate pressure control, and has good application prospect.

Description

Technical Field

[0001] This invention belongs to the technical field of surface well control equipment for cementing oil and gas wells, and specifically relates to a back pressure control device. Background Technology

[0002] As the scope of oil and gas development expands and deepens, the geological conditions of oil and gas reservoirs are becoming increasingly complex. Narrow density window formations place higher demands on the precision of pressure control throughout the cementing process in order to avoid uncontrolled well leakage, well kick accidents, or cementing quality accidents.

[0003] Currently, precision pressure-controlled cementing employs pressure balance cementing technology. Because the cementing process involves stopping drilling fluid circulation to install the cement head and switching between different densities of pre-flush fluid, cement, post-flush fluid, displacement fluid, and drilling fluid, if the drilling fluid slows down or stops circulating, the reduced or absent dynamic pressure in the well can easily lead to a well kick or blowout. Therefore, it is necessary to apply appropriate back pressure at the wellhead in a timely and precise manner to maintain the bottom hole pressure within a narrow density window. Although back pressure compensation devices using mud circulation throttling exist, they are unreliable in several ways. First, their response is slow, the compensation pressure range is limited, and flow fluctuations occur at low flow rates, causing back pressure fluctuations. Second, the continuously running back pressure pump during wellhead equipment replacement and waiting periods for curing results in energy waste. Finally, if the back pressure skid malfunctions, it can cause pressure imbalance, leading to cementing accidents.

[0004] Given the functional defects, large size, and high energy consumption of the aforementioned back pressure control devices for precision pressure controlled cementing, and considering the requirements of precision pressure controlled cementing construction on offshore platforms, there is an urgent need for a back pressure control device that is smaller, can adjust back pressure more quickly, and has a wider adjustment range. Summary of the Invention

[0005] To address all or some of the aforementioned problems, the present invention aims to provide a back pressure control device. This back pressure control device offers fast pressure response and precise pressure control; it eliminates the need for long-distance back pressure slurry circulation pipelines and continuous operation of circulation pumps, thereby reducing energy consumption; it is applicable in both onshore and offshore cementing operations and has excellent application prospects.

[0006] According to one aspect of the present invention, a back pressure control device is provided, 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 supply gas required for back pressure to the back pressure control manifold;

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

[0008] Furthermore, the nitrogen supply device includes several first gas cylinders, each of which is used to store gas. Each first gas cylinder 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 pressure transmitter and a first valve are installed 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 second gas cylinder is connected to a third manifold, the outlet of which is connected to the gas supply connector. The third manifold is equipped with a second pressure transmitter and a second valve. The second manifold and the third manifold are connected by a bypass pipe, and a gas booster pump is installed on the bypass pipe.

[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. A first switch ball valve is provided on the manual adjustment pipeline, and a second switch ball valve, a pressure reducing valve, and a first proportional regulating valve are provided on the automatic control pipeline.

[0011] Furthermore, the automatic control pipeline has two paths, and the manual adjustment pipeline has one path; the outlet pipeline is equipped with a check valve and a pressure transmitter.

[0012] Furthermore, the backpressure relief pipeline includes a proportional pressure relief pipeline and a safety overflow pipeline. The other end of the backpressure compensation pipeline is connected to a vertical pipe. The upper end of the vertical pipe is connected to one end of the first manifold, and 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 ends of the proportional pressure relief pipeline and the other ends of the safety overflow pipeline are both connected to the mud tank. 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 port is provided at the lower end of the vertical pipe, and the first back pressure relief port is connected to one end of the safety overflow pipeline.

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

[0015] Furthermore, a second backpressure relief port is provided at the other end of the first manifold, and the second backpressure relief port is connected to one end of the proportional pressure relief pipeline; a gas supply port is provided on the vertical pipe, and the other end of the backpressure compensation pipeline is connected to the gas supply port; a pressure transmitter port 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 which is equipped 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 tank. The pressure relief main line is equipped 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 equipped with a third manual switch valve and a third proportional regulating valve.

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

[0018] Furthermore, it also includes a skid and a control unit, the control unit being used to control the nitrogen supply device and the back pressure control manifold, the control unit, the nitrogen supply device and the back pressure control manifold being all housed within the skid.

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

[0020] The backpressure control device of this invention can replace the traditional slurry backpressure compensation skid in the process of fine pressure control cementing. That is, it can be used to replace the traditional slurry backpressure compensation skid during the period when the fluid circulation in the well is about to stop. The backpressure control device of this invention has a fast pressure response and precise pressure control. Compared with the prior art, the backpressure control device of this invention does not require long-distance deployment of backpressure slurry circulation pipelines and continuous operation of circulation pumps, resulting in energy saving and consumption reduction. The backpressure control device of this invention is practical in both onshore and offshore cementing and has excellent application prospects. Attached Figure Description

[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 This is a schematic diagram of the back pressure control manifold according to an embodiment of the present invention;

[0023] Figure 3 yes Figure 2 View AA of the back pressure compensation pipeline section;

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

[0025] Figure 5 This is a schematic diagram of the planar layout of the skid in an embodiment of the present invention. Detailed Implementation

[0026] To better understand the purpose, structure, and function of this invention, a back pressure control device of this invention will be described in further detail below with reference to the accompanying drawings.

[0027] like Figure 1 , Figure 2The diagram illustrates a backpressure control device according to an embodiment of the present invention, comprising a nitrogen supply device 1 and a backpressure control manifold 2 connected to the nitrogen supply device 1. The nitrogen supply device 1 is used to supply the gas required for backpressure control to the backpressure control manifold 2. The backpressure control manifold 2 includes a backpressure compensation pipeline 202, one end of which is connected to the nitrogen supply device 1, and the other end of which is connected to one end of a first manifold 201. The other end of the first manifold 201 is connected to one end of a backpressure relief pipeline 203. The first manifold 201 is provided with at least one wellhead backpressure compensation interface 2012 connected to a wellhead casing valve or blowout preventer. The other end of the backpressure relief pipeline 203 is connected to a mud pit. The backpressure compensation pipeline 202 is used to send the gas supplied by the nitrogen supply device 1 into the wellhead casing valve or blowout preventer to compensate for backpressure, and the backpressure relief pipeline 203 is used to release gas to reduce backpressure when the backpressure 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 line 202, a first manifold 201, and a back pressure relief line 203. The back pressure compensation line 202 is used to send the gas delivered by the nitrogen supply device 1 into 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 a field pipeline. Thus, the back pressure compensation line 202 sends the gas delivered by the nitrogen supply device 1 through the wellhead back pressure compensation interface 2012 into the wellhead casing valve or blowout preventer to compensate the back pressure to the target value and achieve the purpose of pressure control. The back pressure relief line 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 this invention can replace the traditional slurry backpressure compensation skid during fine-controlled cementing processes. Specifically, it can be used when the well fluid circulation is about to stop. This backpressure control device offers fast response and precise pressure control. Compared to existing technologies, it eliminates the need for long-distance backpressure slurry circulation pipelines and continuous operation of circulation pumps, resulting in energy savings and reduced consumption. This backpressure control device is applicable to both onshore and offshore cementing and has excellent application prospects.

[0030] Among them, such as Figure 1 As shown, the nitrogen supply device 1 includes several first gas cylinders 101, each of which is used to store gas. Each first gas cylinder 101 is connected to a second manifold 102. The outlet of the second manifold 102 is connected to a gas supply connector 108, which is connected to one end of a back pressure compensation pipeline 202. A first 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 storage pressure of 14 MPa, so as to use nitrogen for pressure control. Nitrogen has the advantages of being readily available and inexpensive, 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 gas pressure transmitter 106 is used to detect the gas pressure in the manifold where it is located, and the first valve 105 is used to control the gas flow.

[0032] In one embodiment, such as Figure 1 As shown, the nitrogen supply device also includes several second gas cylinders 107, each second gas cylinder 107 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 pressure transmitter 1061 and a second valve 1051 are installed 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 installed on the bypass pipe.

[0033] In this embodiment, each second gas cylinder is, for example, a nitrogen cylinder with a storage pressure of 14 MPa, so as to use nitrogen 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 cylinder can enter the back pressure compensation pipeline 202 through the third manifold 104 and the gas supply connector; the second pressure transmitter 106 is used to detect the gas pressure in its manifold, and the second valve 105 is used to control the gas flow.

[0034] Furthermore, in embodiments where a first gas cylinder and a 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] During the specific gas supply process, firstly, open the first valve 105 connected to the second manifold 102 to supply gas to the conventional cylinder group. When the pressure of this cylinder group is lower than the maximum pressure requirement for pressure control, switch to supply gas to the high-pressure cylinder group. When the pressure of both cylinder groups is lower than the maximum pressure requirement for pressure control, start the gas booster pump 103 to boost the pressure and then supply gas.

[0036] For 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, whose boosted pressure should reach at least 10 MPa, and whose maximum compression flow rate should be no less than 30 liters / minute (when the input is 1 MPa). The gas booster pump 103 can utilize compressed air from the on-site air compressor to boost the gas in the conventional cylinder group and store it in the high-pressure cylinder group for use. Obviously, it can also compress the residual gas in the conventional cylinder group into one or more second gas cylinders in the high-pressure cylinder group before the nitrogen supply device 1 is filled, thus conserving gas resources.

[0037] In practice, 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 gas line connection and gas cylinder replacement.

[0038] In one embodiment, such as 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 automatic control pipelines 2022 and one end of all 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 automatic control pipelines 2022 and the other end of all 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. A first switch ball valve 2024 is provided on the manual adjustment pipeline 2028. A second switch ball valve 20241, a pressure reducing valve 2025, and a first proportional regulating valve 2026 are provided on the automatic control pipeline 2022.

[0039] In this embodiment, the backpressure 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. The overall structure after parallel connection is connected at one end to the gas inlet pipeline 2021 and at 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 regulating valve 2026. These valves are arranged sequentially along the gas flow direction, making it a pipeline with throttling and pressure reduction functions. The manual adjustment pipeline 2028 is only equipped with the first on / off ball valve 2024 to allow for manual emergency adjustment in case of electrical or pneumatic power failure, achieving full manual pressure control.

[0040] As a simplified implementation scheme, for example, the automatic control pipe 2022 can be configured as one channel, and the manual adjustment pipe 2028 can be configured as one channel, such as... Figure 4 As shown. Alternatively, the automatic control pipe 2022 can be configured as two-way, and the manual adjustment pipe 2028 as one-way, as shown. Figure 2 As shown.

[0041] In this embodiment, a check valve 2027 and a pressure transmitter are installed on the outlet pipe 2023. The check valve 2027 is used to ensure that the gas can only flow 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, such as Figure 2 As shown, the backpressure relief pipeline 203 includes a proportional pressure relief pipeline 205 and a safety overflow pipeline 204. The other end of the backpressure 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, and 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 ends of the proportional pressure relief pipeline 205 and the other ends of the safety overflow pipeline 204 are both connected to the mud tank. 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 line 203 includes a proportional pressure relief line 205 and a safety overflow line 204. The proportional pressure relief line 205 is used to relieve pressure when the back pressure exceeds the target value, and the safety overflow line 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. In this embodiment, the vertical pipe 2017 plays a role in gas-liquid separation. The gas moves upward 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 a role in compensating for back pressure. The separated liquid enters the mud pit through the safety overflow pipeline 204 at the lower end of the vertical pipe 2017.

[0045] The safety overflow pipeline 204 is equipped with a safety overflow valve 2034 and a pneumatic switch valve 2035. The air source of the pneumatic switch valve 2035 comes from the on-site air compressor. The pneumatic switch valve 2035 controls the on / off of air supply. It mainly takes advantage of the speed of pneumatic valves compared to electric valves, which facilitates overpressure overflow and emergency pressure relief during grouting.

[0046] The lower end of the vertical pipe 2017 is provided with a first back pressure relief port 2016, which is connected to one end of the safety overflow pipe 204.

[0047] As an alternative, the safety overflow pipe 204 can be replaced with a manual backpressure relief branch to achieve emergency manual control throughout the backpressure control process. Specifically, such as... Figure 4 As shown, the backpressure relief pipeline 203 includes a proportional pressure relief pipeline 205 and a manual backpressure relief branch. The other end of the backpressure 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, and 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 backpressure relief branch. The other ends of both the proportional pressure relief pipeline 205 and the manual backpressure relief branch are connected to a mud pit. A first manual switch valve 20321 is installed on the manual backpressure relief branch. The proportional pressure relief pipeline 205 is used for pressure relief. In this scheme, the first manual switch valve 20321 on the manual backpressure relief branch enables emergency manual control of the entire backpressure control process. Similarly, the lower end of the vertical pipe 2017 is provided with a first back pressure relief port 2016, which is connected to one end of the manual back pressure relief branch.

[0048] The first manifold 201 or the vertical pipe 2017 is equipped with a pressure transmitter interface 2014. The transmitter interface 2014 is used to install a pressure transmitter through the instrument valve for accurate measurement of the pressure at the sleeve port. It should be further noted that the pressure transmitter installed here should have a built-in backup battery and a pressure display panel to facilitate manual operation to control the back pressure in case of abnormal power failure.

[0049] Specifically, for the scheme of setting up a safety overflow pipeline 204 and the scheme of setting up a manual backpressure relief branch: the other end of the first manifold 201 is provided with a second backpressure relief interface 2015, which 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 backpressure compensation pipeline 202 is connected to the gas supply interface 2011, preferably the other end of the backpressure compensation pipeline 202 is detachably connected to the gas supply interface 2011.

[0050] Regarding the aforementioned proportional pressure relief pipeline 205: (e.g.) Figure 2As shown, the proportional pressure relief pipeline 205 includes at least one pressure relief branch. Each pressure relief branch is equipped with a second manual switch valve 2032 and a second proportional regulating valve 2033. One end of all pressure relief branches is connected to one end of the pressure relief main line, and the other end of all pressure relief branches is connected to the mud tank. An electric switch valve 2031 is installed 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 practical implementation, for example, the pressure relief branch is configured as two branches. Each pressure relief branch is equipped with a second manual switch valve 2032 and a second proportional regulating valve 2033. The second manual switch valve 2032 facilitates manual control of the pressure relief branch's on / off state to select the appropriate pressure relief branch. The second proportional regulating valve 2033 is used to control the pressure relief rate. One end of all pressure relief branches is connected to one end of the pressure relief main line, and the other end of all pressure relief branches is connected to the mud pit. The other end of the pressure relief main line is connected to the other end of the first manifold 201. The electric switch valve 2031 installed on the pressure relief main line is used for overall control of the proportional pressure relief pipeline 205.

[0052] As an alternative, the proportional pressure relief line 205 is configured as a single line, that is, it is connected to... Figure 2 Compared to the proportional pressure relief pipeline 205 shown, which includes a pressure relief main line and pressure relief branches, this embodiment omits one pressure relief branch and the electric switching valve 2031. Pressure relief control is directly completed by the third proportional regulating valve, that is, as shown in the figure. Figure 4 As shown, a third manual switch valve 20321 and a third proportional regulating valve 20331 are installed on the proportional pressure relief pipeline 205.

[0053] In one embodiment, there are three wellhead backpressure compensation interfaces 2012, and each wellhead backpressure compensation interface 2012 is equipped 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 in the figure) via field piping to control the casing pressure. The number of wellhead backpressure compensation interfaces 2012 can be one or more. When there is only one, it is connected to the wellhead casing valve or blowout preventer. When there are more than one, one interface is connected to the wellhead casing valve or blowout preventer, and the others are spare interfaces. When spare interfaces exist, one can be selected as the connection port for the field slurry backpressure compensation system. This connection port is connected to the wellhead casing valve or blowout preventer as a mud inlet / outlet.

[0055] In one embodiment, the system also includes a skid and a control unit. The control unit is used to control the nitrogen supply device 1 and the back pressure control manifold 2. The control unit, the nitrogen supply device 1, and the back pressure control manifold 2 are all located inside the skid.

[0056] The control host consists of a PLC main unit, necessary expansion modules, a matching human-machine interface, and a power supply, housed in an explosion-proof enclosure. Through specially developed PLC application software, it achieves at least the following functions:

[0057] 1) The basic host computer communication parameters, gas source working pressure, and low gas source pressure alarm value can be set or modified through the settings interface;

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

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

[0060] For the skid, a frame structure is preferred, used to carry the nitrogen supply device 1, the back pressure control manifold 2, and the control host, with a monitoring room and electrical cabinet area isolated within it. For example... Figure 5 As shown, the skid is equipped with a back pressure control manifold planning area, a nitrogen supply device planning area, a monitoring room planning area, and an electrical cabinet planning area. The nitrogen supply device and back pressure control manifold 2 are arranged in the three-dimensional space of the skid planning area, saving the skid's floor space while facilitating operation and maintenance. The skid should be equipped with appropriate supports and brackets to support and fix the aforementioned nitrogen supply device 1, back pressure control manifold 2, control host, electrical cabinet, monitor, etc. In addition, the skid is easy to hoist, transport, and install.

[0061] The backpressure control device of this invention can replace the traditional slurry backpressure compensation skid in the process of fine pressure control cementing. When the fluid in the well is about to stop circulating, it switches to the backpressure control device of this invention to automatically control gas replenishment or depressurization to achieve automatic backpressure control. The backpressure control device of this invention has a fast pressure response, precise pressure control, readily available and inexpensive nitrogen, does not increase pollution after use, and has a compact structure. It does not require long-distance backpressure slurry circulation pipelines and continuous operation of circulation pumps, saving energy and reducing consumption. It is applicable to both onshore and offshore cementing and has a promising application prospect.

[0062] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application should have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0063] Furthermore, the terms "a," "two," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly defined.

[0064] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

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

Claims

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

2. The back pressure control device according to claim 1, characterized in that, The nitrogen supply device (1) includes several 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), which is connected to one end of the back pressure compensation pipeline (202). The second manifold (102) is equipped with a first pressure transmitter (106) and a first valve (105).

3. The back pressure control device according to claim 2, characterized in that, The nitrogen supply device also includes several second gas cylinders, each of which is used to store gas. Each second gas cylinder 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 equipped with a second pressure transmitter (1061) and a second valve (1051). The second manifold (102) and the third manifold (104) are connected by a bypass pipe, and a gas booster pump (103) is installed on the bypass pipe.

4. The back pressure control device according to claim 1, characterized in that, 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). 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). A first switch ball valve (2024) is provided on the manual adjustment pipeline (2028). A second switch ball valve (20241), a pressure reducing valve (2025), and a first proportional regulating valve (2026) are provided on the automatic control pipeline (2022).

5. The back pressure control device according to claim 4, characterized in that, The automatic control pipeline (2022) has two paths, and the manual adjustment pipeline (2028) has one path; the outlet pipeline (2023) is equipped with a check valve (2027) and a pressure transmitter.

6. The back pressure control device according to claim 1, characterized in that, The backpressure relief pipeline (203) includes a proportional pressure relief pipeline (205) and a safety overflow pipeline (204). The other end of the backpressure 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), and 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 ends of the proportional pressure relief pipeline (205) and the other ends of the safety overflow pipeline (204) are both connected to the mud tank. 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 equipped with a safety overflow valve (2034) and a pneumatic switch valve (2035); the lower end of the vertical pipe (2017) is equipped with a first back pressure relief port (2016), which 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 backpressure relief pipeline (203) includes a proportional pressure relief pipeline (205) and a manual backpressure relief branch. The other end of the backpressure 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 backpressure relief branch. The other end of the proportional pressure relief pipeline (205) and the other end of the manual backpressure relief branch are both connected to the mud tank. A first manual switch valve (20321) is provided on the manual backpressure 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 port (2015), which is connected to one end of the proportional pressure relief pipeline (205); a gas supply port (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 port (2011); a pressure transmitter port (2014) is provided on the first manifold (201) or the vertical pipe (2017).

10. The back pressure control device according to claim 6 or 8, characterized in that, The proportional pressure relief pipeline (205) includes at least one pressure relief branch. Each pressure relief branch is equipped 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 tank. An electric switch valve (2031) is installed 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, the proportional pressure relief pipeline (205) is equipped with a third manual switch valve (20321) and a third proportional regulating valve (20331).

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

12. The back pressure control device according to claim 1, characterized in that, It also includes a skid and a control host, the control host being 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 located in the skid.

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