Offshore drilling pressure control device and control method

Abstract

The invention provides a marine drilling pressure control device and method.The marine drilling pressure control device comprises a pressure control system and a return pressure self-control compensation system.The pressure control system is used for conducting pressure control operation on a drilled well when it is monitored that underground abnormity exists or wellhead pressure control is conducted; the return pressure self-control compensation system is used for performing automatic pressure injection on the wellhead when the actually measured pressure of the wellhead is lower than the target pressure; and when the measured pressure of the wellhead is higher than the target pressure, the inlet pressure is automatically released. According to the technical scheme, by arranging the pressure control system and the return pressure self-control compensation system, rapid pressure compensation can be automatically carried out on a wellhead after the pump is stopped, and therefore the defects that in the pump stopping pressure compensation process of traditional fine pressure control equipment, the technology is tedious, the error rate is high, and the pressure control precision is low are thoroughly overcome; and the pressure control precision of the fine pressure control equipment is greatly improved, and the time efficiency of the control process is shortened.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas drilling engineering, in particular to a marine drilling pressure control device and control method. BACKGROUND

[0002] With the continuous deepening of the exploration and development of China's marine oil and gas resources, the formation that may be drilled in the marine drilling process is becoming more and more complex, and drilling problems such as complex formation pressure system, narrow safety pressure window, high formation temperature, etc. are often encountered, which makes it easy to occur accidents such as lost circulation, well kick, blowout, etc. in the marine drilling process, accounting for more than 70% of the total drilling accidents. In order to ensure the accurate control of the wellbore pressure and the safety of well control in marine drilling, fine pressure control drilling technology and equipment have been introduced in marine drilling in recent years. The application of this technology and equipment realizes the timely and accurate control of wellbore pressure, effectively ensures the safety of drilling well control, protects and discovers oil and gas reservoirs, and improves the drilling efficiency.

[0003] The existing marine fine pressure control drilling technology and equipment are developed on the basis of mature pressure control drilling equipment on land and in view of the characteristics of the sea. The fine pressure control drilling technology and equipment can basically meet the needs of marine drilling in actual use, but there are still many deficiencies. Due to the limited space of the drilling platform and the large difference in the layout of the drilling equipment, for a long time, the cementing pump fixed on the platform has been used to replace the back pressure compensation pump set in the process of using the marine fine pressure control equipment. It is found in practice that in the process of marine drilling pump stop and single rod back pressure compensation, the cooperation of fine pressure control party, cementing party and well team is needed to complete the process. The preparation time is usually long, and it is easy to cause coordination failure, thereby greatly delaying the drilling efficiency.

[0004] At present, the method of stopping pump and holding pressure is usually used to solve this problem when stopping pump and connecting single rod at sea. Although this method can solve the problems caused by the replacement of back pressure pump by cementing pump set, the operation of the engineer is very skilled in the actual operation process, and the holding pressure accuracy is not high. Therefore, in order to improve the accuracy of marine wellbore pressure control, the fine pressure control drilling process scheme and equipment need to be upgraded and researched and developed. SUMMARY

[0005] The present application provides a marine drilling pressure control device and control method to realize the accurate control of wellhead pressure under all working conditions of marine drilling operation, accurately judge and control the overflow and loss that may occur in the process of marine drilling, and greatly improve the safety and reliability of the fine pressure control drilling equipment on the marine platform, and completely solve the impact and harm caused by well control problems on the platform.

[0006] In a first aspect, a marine drilling pressure control device is provided, comprising: a pressure control system and a back pressure self-control compensation system, wherein,

[0007] The pressure control system is used to perform pressure control operations on the drilling when downhole anomalies are detected or wellhead pressure control is performed.

[0008] The back pressure self-control compensation system is used to automatically inject pressure into the wellhead when the actual measured pressure at the wellhead is lower than the target pressure, and to automatically release the inlet pressure when the actual measured pressure at the wellhead is higher than the target pressure.

[0009] In the above technical solution, by setting up a pressure control system and a back pressure self-control compensation system, it is possible to automatically and quickly compensate the pressure at the wellhead after the pump stops. This completely solves the shortcomings of traditional precision pressure control equipment in the process of pump stop pressure compensation, such as cumbersome process, high error rate and low pressure control accuracy. It greatly improves the pressure control accuracy of precision pressure control equipment, reduces the time of control process, and improves the timeliness of offshore drilling operations.

[0010] In one specific implementation scheme, the pressure control system includes a flow monitoring path and a pressure control path, wherein,

[0011] The flow monitoring channel is used to monitor the flow rate of the well when there are no abnormalities downhole.

[0012] The pressure control pathway is used to perform pressure control operations on the drilling when downhole anomalies are detected or wellhead pressure control is performed.

[0013] In one specific implementation scheme, the flow monitoring path includes a first control valve, a first pressure gauge, a seventh control valve, and a second pressure gauge connected in sequence via pipelines, used to monitor the flow rate of the well when there are no abnormalities downhole.

[0014] In one specific implementation scheme, the pressure control path includes a first control valve, a first pressure gauge, a second control valve, a sixth control valve, a throttle valve, and a second pressure gauge connected in sequence via pipelines, used to perform drilling pressure control operations when downhole anomalies are detected or wellhead pressure control is performed.

[0015] In one possible implementation, the system further includes a flow monitoring system comprising a mass flow meter path and an electromagnetic flow meter path, wherein...

[0016] The mass flow meter passage is used to monitor and measure the outlet overflow of the well when the pump is stopped;

[0017] The electromagnetic flowmeter path is used to monitor the flow rate during normal drilling.

[0018] In one specific implementation, the mass flow meter passage includes a third control valve and a mass flow meter connected in sequence via a pipeline, used to monitor and measure the outlet overflow of the well in the case of pump shutdown.

[0019] In one specific implementation, the electromagnetic flowmeter passage includes a fourth control valve and an electromagnetic flowmeter connected in sequence via a pipeline, used to monitor and measure the outlet overflow of the well when the pump is stopped.

[0020] In the above technical solution, the volume and weight of the skid are greatly reduced by simplifying the design of the flow monitoring system and the pressure control system, which improves the convenience of offshore platform operation. While simplifying the skid, a dual flow monitoring link of mass flow meter and electromagnetic flow meter is added, which not only realizes accurate flow monitoring during drilling, but also provides stronger support for monitoring the low pressure at the bottom of the well after the pump is stopped.

[0021] In one specific implementation scheme, the backpressure self-control compensation system includes an automatic pressure injection subsystem and an automatic pressure release subsystem connected to the drilling site, wherein...

[0022] The automatic pressure injection subsystem is used to automatically inject pressure into the wellhead when the measured pressure at the wellhead is lower than the target pressure.

[0023] The automatic pressure release subsystem is used to automatically release the inlet pressure when the measured pressure at the wellhead is higher than the target pressure.

[0024] In one specific implementation scheme, the automatic injection subsystem includes a fifth control valve, a pressure check valve, a plug valve, an automatic injection pump, and a water supply auxiliary pump connected in sequence via pipelines.

[0025] Secondly, a method for controlling pressure in offshore drilling is provided, including the following steps:

[0026] During normal drilling and under normal downhole conditions, the drilling fluid flow rate at the wellhead and inlet is monitored in real time using the flow monitoring mode.

[0027] When downhole anomalies are detected or wellhead pressure is controlled, the wellhead back pressure is automatically controlled through the pressure control mode.

[0028] In the case of pump shutdown or dry well, the underpressure situation at the bottom of the well is judged by real-time monitoring and accurate measurement of drilling fluid overflow.

[0029] When the wellhead provides back pressure after the pump stops, the wellhead injection mode automatically injects pressure when the measured pressure at the wellhead is lower than the target pressure, and automatically releases the inlet pressure when the measured pressure at the wellhead is higher than the target pressure.

[0030] During controlled tripping, the wellhead pressure is automatically controlled through a combination of flow monitoring and pressure control.

[0031] In the above technical solution, by optimizing the precision pressure controlled drilling equipment and control system, the pressure control method of the traditional precision pressure controlled drilling system is improved. It can quickly judge the discovery of overflow and leakage during marine drilling and provide precise back pressure control, thereby improving drilling efficiency and well control safety. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of the pressure control system and flow monitoring system provided in the embodiments of this application;

[0033] Figure 2 This is a schematic diagram of the structure of the marine drilling pressure control device provided in the embodiments of this application;

[0034] Figure 3 This is a schematic diagram of the structure of the remote control device provided in the embodiments of this application;

[0035] Figure 4 This is a flowchart illustrating the marine drilling pressure control method provided in an embodiment of this application.

[0036] Among them, 100-flow monitoring and pressure control system, 200-backpressure self-control compensation system, 300-signal acquisition and control system, 400-central control system, 101-first manual flat plate valve, 102-first pressure gauge, 103-second manual flat plate valve, 104-first hydraulic flat plate valve, 105-throttle valve, 106-pipeline purging interface, 107-second hydraulic flat plate valve, 108-second pressure gauge, 109-third manual flat plate valve, 110-mass flow meter, 111-electromagnetic flow meter, 112-fourth manual flat plate valve, fifth manual flat plate valve, 201, 202- Pressure check valve, 203-plug valve, 204-automatic injection pump, 205-automatic pressure relief valve, 206-flow interruption check valve, 207-water supply auxiliary pump, 301-hydraulic control system, 302-PLC control system, 303-injection pump control system, 304-local pressure control system, 305-control value display device, 306-integrated control pipeline harness, 401-hydraulic comprehensive calculation system and database, 402-remote automatic pressure control system, 403-drilling parameter analysis and downhole anomaly early warning system, 404-remote video monitoring system, 405-platform supervision center decision-making system. Detailed Implementation

[0037] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. Through these descriptions, the features and advantages of the present application will become clearer and more apparent.

[0038] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0039] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0040] To facilitate understanding of the marine drilling pressure control device and method provided in this application embodiment, its application scenario will be explained first. The marine drilling pressure control device provided in this application embodiment is used to achieve precise control of wellhead pressure under all working conditions of marine drilling operations. It can accurately judge and control possible overflows and leaks during marine drilling, while greatly improving the safety and reliability of precision pressure-controlled drilling equipment on offshore platforms, completely solving the impact and hazards caused to the platform by well control problems. It is applied in the field of marine drilling. Currently, the common method for solving this problem at sea is to stop the pump and pressurize it when connecting a single joint after pump shutdown. Although this method can solve the drawbacks of replacing the back pressure pump with a cementing pump set, the actual operation requires highly skilled engineers, and the pressurization accuracy is not high. Therefore, in order to improve the accuracy of marine pressure-controlled wellbore pressure control, the pressure-controlled drilling process and equipment urgently need to be upgraded and researched and developed. Therefore, this application provides a marine drilling pressure control device and method to achieve precise control of wellhead pressure under all operating conditions of marine drilling. It can accurately judge and control potential overflows and leaks during marine drilling, while greatly improving the safety and reliability of precision pressure control drilling equipment for offshore platforms, and completely solving the impact and hazards to the platform caused by well control problems. The following detailed description, in conjunction with specific accompanying drawings, illustrates the embodiments.

[0041] refer to Figures 1 to 3 , Figure 1 This is a schematic diagram of the structure of the pressure control system and flow monitoring system provided in the embodiments of this application; Figure 2 This is a schematic diagram of the structure of the marine drilling pressure control device provided in the embodiments of this application; Figure 3 This is a schematic diagram of the structure of the remote control device provided in an embodiment of this application. Figure 1This application provides a marine drilling pressure control device, including: a pressure control system and a back pressure self-control compensation system, wherein...

[0042] The pressure control system is used to perform pressure control operations on the drilling when downhole anomalies are detected or wellhead pressure control is performed.

[0043] The back pressure self-control compensation system is used to automatically inject pressure into the wellhead when the actual measured pressure at the wellhead is lower than the target pressure, and to automatically release the inlet pressure when the actual measured pressure at the wellhead is higher than the target pressure.

[0044] In the above technical solution, by setting up a pressure control system and a back pressure self-control compensation system, it is possible to automatically and quickly compensate the pressure at the wellhead after the pump stops. This completely solves the shortcomings of traditional precision pressure control equipment in the process of pump stop pressure compensation, such as cumbersome process, high error rate and low pressure control accuracy. It greatly improves the pressure control accuracy of precision pressure control equipment, reduces the time of control process, and improves the timeliness of offshore drilling operations.

[0045] In one specific implementation scheme, the pressure control system includes a flow monitoring path and a pressure control path, wherein,

[0046] The flow monitoring channel is used to connect to the flow monitoring system for flow monitoring when there are no abnormalities downhole;

[0047] The flow monitoring system is used to monitor and measure the outlet overflow during pump shutdown and to monitor the flow during normal drilling, using a dual flow monitoring mode.

[0048] The pressure control pathway is used to perform pressure control operations on the drilling when downhole anomalies are detected or wellhead pressure control is performed.

[0049] In one specific implementation scheme, the flow monitoring path includes a first control valve, a first pressure gauge, a seventh control valve, and a second pressure gauge connected in sequence via pipelines, used to monitor the flow rate of the well when there are no abnormalities downhole.

[0050] Specifically, the first control valve is a first manual control valve 101; the seventh control valve is a second hydraulic plate valve 107. The flow monitoring path includes a first manual plate valve 101, a first pressure gauge 102, a pipeline purging interface 106, a second hydraulic plate valve 107, and a second pressure gauge 108 connected in sequence through pipelines, used to perform drilling pressure control operations when downhole anomalies are detected or wellhead pressure control is performed.

[0051] In a specific implementation, the flow monitoring path also includes a pipeline purging interface 106, which is connected between the first pressure gauge 102 and the second hydraulic flat valve 107 via a pipeline.

[0052] In one specific implementation scheme, the pressure control path includes a first control valve, a first pressure gauge, a second control valve, a sixth control valve, a throttle valve, and a second pressure gauge connected in sequence via pipelines.

[0053] Specifically, the first control valve is a first manual control valve 101; the second control valve is a second manual flat plate valve 103; and the sixth control valve is a first hydraulic flat plate valve 104. The pressure control path includes a first manual flat plate valve 101, a first pressure gauge 102, a second manual flat plate valve 103, a first hydraulic flat plate valve 104, a throttle valve 105, and a second pressure gauge 108 connected in sequence via pipelines.

[0054] In one possible implementation, the flow monitoring system includes a mass flow meter path and an electromagnetic flow meter path, wherein,

[0055] The mass flow meter passage is used to monitor and measure the outlet overflow of the well when the pump is stopped;

[0056] The electromagnetic flowmeter path is used to monitor the flow rate during normal drilling.

[0057] In one specific implementation, the mass flow meter passage includes a third control valve and a mass flow meter 110 connected in sequence via a pipeline, used to monitor and measure the outlet overflow of the well when the pump is stopped.

[0058] Specifically, the third control valve is a third manual flat valve 109. The mass flow meter passage includes the third manual flat valve 109 and the mass flow meter 110 connected in sequence by pipelines, used to monitor and measure the outlet overflow of the well in the pump-stopped state.

[0059] In one possible implementation, the electromagnetic flowmeter passage includes a fourth control valve and an electromagnetic flowmeter connected in sequence via a pipeline.

[0060] Specifically, the fourth control valve is a fourth manual flat plate valve 112. The electromagnetic flowmeter passage includes the fourth manual flat plate valve 112 and the electromagnetic flowmeter 111 connected in sequence via pipelines.

[0061] In one specific implementation scheme, specifically, the flow monitoring and pressure control system 100 includes the pressure control system and the flow monitoring system, wherein,

[0062] The pressure control system is divided into two channels. One is the flow monitoring channel, which mainly provides a larger flow path for flow monitoring when there are no abnormalities downhole. This can not only effectively prevent pipeline blockage, but also reduce pressure loss in surface pipelines. It includes: a first manual flat plate valve 101, a first pressure gauge 102, a pipeline purging interface 106, a second hydraulic flat plate valve 107, and a second pressure gauge 108.

[0063] Another pathway is the pressure control pathway, whose main function is to switch to the pressure control pathway in a timely manner when downhole anomalies are detected or wellhead pressure control is performed, so as to perform pressure control operations on the drilling in a timely manner. It includes: first manual plate valve 101, first pressure gauge 102, second manual plate valve 103, first hydraulic plate valve 104, throttle valve 105, and second pressure gauge 108.

[0064] The flow monitoring system is also divided into two channels. One is the mass flow meter channel, which is mainly used because the mass flow meter has a small diameter and high measurement accuracy. It can effectively monitor and measure the outlet overflow when the pump is stopped. It includes: the third manual flat valve 109 and the mass flow meter 110.

[0065] The other path is the electromagnetic flowmeter passage. Its main function is that the electromagnetic flowmeter has a larger diameter, which can not only reduce the pressure loss of the ground pipeline during normal drilling, but also prevent the flowmeter from being blocked, greatly improving the safety and reliability of the equipment. It includes: the fourth manual flat valve 112 and the electromagnetic flowmeter 111.

[0066] In the above technical solution, the volume and weight of the skid are greatly reduced by simplifying the design of the flow monitoring system and the pressure control system, which improves the convenience of offshore platform operation. While simplifying the skid, a dual flow monitoring link of mass flow meter and electromagnetic flow meter is added, which not only realizes accurate flow monitoring during drilling, but also provides stronger support for monitoring the low pressure at the bottom of the well after the pump is stopped.

[0067] In one specific implementation scheme, the backpressure self-control compensation system includes an automatic pressure injection subsystem and an automatic pressure release subsystem connected to the drilling site, wherein...

[0068] The automatic pressure injection subsystem is used to automatically inject pressure into the wellhead when the measured pressure at the wellhead is lower than the target pressure.

[0069] The automatic pressure release subsystem is used to automatically release the inlet pressure when the measured pressure at the wellhead is higher than the target pressure.

[0070] In one specific implementation scheme, the automatic pressure injection subsystem and the automatic pressure release subsystem are connected in parallel via pipelines, wherein...

[0071] The automatic pressure injection subsystem includes a fifth control valve 201, a pressure check valve 202, a plug valve 203, an automatic pressure injection pump 204, and a water supply auxiliary pump 207, which are connected in sequence through pipelines.

[0072] The automatic pressure relief subsystem includes an automatic pressure relief valve 205 and a flow-stopping check valve 206 connected in sequence via pipelines.

[0073] Specifically, the fifth control valve is the fifth manual flat valve 201.

[0074] refer to Figure 2 In one specific implementation scheme, it also includes a signal acquisition and control system 300, which includes a hydraulic control system 301, a PLC control system 302, a pressure injection pump control system 303, a local pressure control system 304, a control value display device 305, and an integrated control wiring harness 306.

[0075] The hydraulic control system 301 includes an electric / pneumatic / manual hydraulic pressurization device, an energy accumulator, and a hydraulic control system. Its main function is to provide hydraulic power to various hydraulic control components of the system and to control the opening and closing actions of the throttle valve, hydraulic actuator, and hydraulic flat valve through the hydraulic pipeline in the integrated control tube bundle 306.

[0076] The PLC control system 302 acquires signals and display values ​​from various instrument actuators through the signal transmission lines in the integrated control tube bundle 306, and analyzes and calculates feedback to control the switching state of each actuator, thereby achieving the expected target pressure control value.

[0077] The injection pump control system 303 includes a remote control mode and a local control mode. In the remote mode, the back pressure self-control compensation system 200 can be automatically controlled through the central control system 400. In the local mode, the target pressure can be controlled by manually adjusting the buttons and handles of the local injection pump control system.

[0078] The local pressure control system 304 includes a remote control mode and a local control mode. In the remote control mode, the flow monitoring and pressure control system 100 can be automatically controlled through the central control system 400. In the local mode, the target pressure can be controlled by manually adjusting the buttons and handles of the local pressure system.

[0079] The control numerical display device 305 mainly provides the display of the on / off status and numerical status of each valve, instrument, and pump group in local mode.

[0080] The integrated control wiring harness 306 includes hydraulic lines, signal lines, power lines, and outer protective sleeves for the lines.

[0081] refer toFigure 3 In one specific implementation scheme, it also includes a central control system 400, which centrally controls the precision pressure control drilling system through a data processing server, a data acquisition and transmission local operation console, a hydraulic control system, and a PLC control system; it includes a hydraulic comprehensive calculation system and database 401, a remote automatic pressure control system 402, a drilling parameter analysis and downhole anomaly early warning system 403, a remote video monitoring system 404, and a platform supervision center decision-making system 405.

[0082] Among them, the hydraulic integrated calculation system and database 401 can transmit and receive integrated logging data through the well site data WITS (Wellsite Information Transfer Specification). Based on the actual parameters of the working well, it calculates the bottom hole ECD in real time and provides pressure control data for the remote pressure automatic control device 402. At the same time, it has a database acquisition function, which can collect data and atlases generated during the pressure controlled drilling process, providing technical support for subsequent operation analysis.

[0083] The remote pressure automatic control system 402 can automatically control the flow monitoring and pressure control system 100 and the back pressure automatic control compensation system 200 remotely.

[0084] The Drilling Parameter Analysis and Downhole Anomaly Early Warning System 403 provides timely early warnings for abnormal changes in drilling parameters such as drilling time, suspended weight, pump pressure, flow rate, gas measurement values, tripping and grouting and return volume measurement, and chloride content. This alerts pressure-controlled drilling engineers to make proactive judgments on downhole anomalies and to prepare relevant emergency response plans.

[0085] The remote video monitoring system 404 performs remote video monitoring of the wellhead RCD (Rotating Control Device) of the controlled pressure drilling equipment, the rotating blowout preventer, and the entire controlled pressure drilling equipment, and tracks the equipment's operating status in real time.

[0086] The platform monitoring center decision system 405 transmits key data and equipment monitoring videos of the precision pressure control equipment to the drilling platform monitoring decision center via network cable. The platform monitor can then issue accurate pressure control drilling operation instructions to the pressure control engineer based on the actual situation.

[0087] It should be noted that during the installation of the marine drilling pressure control device, the following precautions should be taken: When conducting precision pressure control drilling operations on marine drilling platforms, some platforms cannot provide the precision pressure control contractor for pressure control tripping operations because the reverse circulation pipeline is a well control device. In such cases, it is advisable to use a cementing pump instead of a drilling pump, and achieve wellhead pressure control through a grouting pipeline, a rotary blowout preventer, a pressure control passage, and an electromagnetic flowmeter passage. The water supply to the injection pump is connected to the freshwater supply port of the drilling platform. Each platform has a different interface. During the precision pressure control reconnaissance, it is important to record the type and size of the interface to facilitate onshore procurement.

[0088] During the use of the aforementioned marine drilling pressure control device, the following precautions should be taken: If the remote control of the injection pump fails, back pressure can be manually provided to the wellhead through local control mode. If the injection pump fails completely, the pump can be slowly stopped by closing the fifth manual flat valve 201 and communicating with the driller by adjusting the opening of the throttle valve 105. At the same time, the throttle valve should be slowly closed to ensure that the wellhead back pressure is equal to the target back pressure after the pump is stopped and the throttle valve is closed.

[0089] refer to Figure 4 , Figure 4 This is a flowchart illustrating a marine drilling pressure control method provided in an embodiment of this application. Figure 4 This application provides a method for controlling pressure in offshore drilling, comprising the following steps:

[0090] During normal drilling and under normal downhole conditions, the drilling fluid flow rate at the wellhead and inlet is monitored in real time using the flow monitoring mode.

[0091] When downhole anomalies are detected or wellhead pressure is controlled, the wellhead back pressure is automatically controlled through the pressure control mode.

[0092] In the case of pump shutdown or dry well, the underpressure situation at the bottom of the well is judged by real-time monitoring and accurate measurement of drilling fluid overflow.

[0093] When the wellhead provides back pressure after the pump stops, the wellhead injection mode automatically injects pressure when the measured pressure at the wellhead is lower than the target pressure, and automatically releases the inlet pressure when the measured pressure at the wellhead is higher than the target pressure.

[0094] During controlled tripping, the wellhead pressure is automatically controlled through a combination of flow monitoring and pressure control.

[0095] Specifically, S1: Under normal drilling conditions with no downhole abnormalities, the flow monitoring mode can be switched to. After the drilling fluid returns from the wellhead rotating blowout preventer, it passes through the flow monitoring path and the electromagnetic flowmeter path for real-time monitoring of the inlet and outlet flow rates. Because the electromagnetic flowmeter and the straight-through pipeline have a large diameter, it can not only significantly reduce pressure loss in the surface pipeline, but also effectively prevent blockage of the throttle valve by downhole debris or other impurities in the drilling fluid, which could lead to increased wellhead pressure and well leakage.

[0096] S2: When the drilling parameter analysis and downhole anomaly early warning system 403 issues a downhole anomaly early warning or the pressure control drilling engineer receives a wellhead back pressure control command, it switches to pressure control mode, quickly opens the first hydraulic plate valve 104, and simultaneously closes the second hydraulic plate valve 107. After the drilling fluid returns from the wellhead rotating blowout preventer, it passes through the pressure control passage and the electromagnetic flowmeter passage. At the same time, the wellhead back pressure target value is set according to the hydraulic integrated calculation system and database 401 calculated data or monitoring commands, thereby realizing automatic control of the wellhead back pressure.

[0097] S3: In the case of pump shutdown or dry well conditions, drilling fluid overflow can be monitored and accurately measured in real time through the pressure control channel and the mass flow meter channel, so as to determine the underpressure situation at the bottom of the well.

[0098] S4: When back pressure is provided at the wellhead after pump shutdown, quickly switch to wellhead injection mode. At this time, the system will automatically close the throttle valve 105 and the second hydraulic plate valve 107, and simultaneously open the water supply auxiliary pump 207 and the automatic injection pump 206 to inject pressure at the wellhead. When the measured pressure at the wellhead equals the target set pressure, the injection pump 206 and the water supply auxiliary pump 207 will automatically shut down. When the wellhead pressure changes due to the up-and-down movement of the drill string caused by pressure decay, if the measured pressure at the wellhead is lower than the target pressure by 0.2 MPa, the injection pump will automatically start. If the measured pressure at the wellhead is higher than the target pressure by 0.2 MPa, the automatic pressure relief valve will open to automatically relieve pressure, thereby ensuring that the measured pressure at the wellhead is within ±0.2 MPa of the target pressure.

[0099] S5: During controlled-pressure tripping, after stopping the pump, the system first quickly switches to the wellhead injection mode to provide back pressure to the wellhead. Then, the controlled-pressure drilling engineer notifies the drilling rig to switch the drilling pump to the reverse circulation line. Before the driller starts the pump, the controlled-pressure drilling engineer switches the control mode from injection mode to pressure control mode. The controlled-pressure engineer sets the target back pressure at the wellhead, and the driller slowly starts the pump. The drilling fluid enters through the drilling four-way valve, returns through the rotary blowout preventer, and passes through the pressure control passage and the electromagnetic flowmeter passage to implement precise automatic control of the wellhead pressure.

[0100] In the above technical solution, by optimizing the precision pressure controlled drilling equipment and control system, the pressure control method of the traditional precision pressure controlled drilling system is improved. It can quickly judge the discovery of overflow and leakage during marine drilling and provide precise back pressure control, thereby improving drilling efficiency and well control safety.

[0101] Those skilled in the art will know that this application can be implemented as a system, method, or computer program product.

[0102] Therefore, this disclosure can be implemented in the following forms: it can be entirely hardware, entirely software (including firmware, resident software, microcode, etc.), or a combination of hardware and software, generally referred to herein as a "circuit," "module," or "system." Furthermore, in some embodiments, this application can also be implemented as a computer program product in one or more computer-readable media, which contains computer-readable program code.

[0103] Any combination of one or more computer-readable media may be used. A computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. A computer-readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this document, a computer-readable storage medium can be any tangible medium that contains or stores a program that can be used by or in connection with an instruction execution system, apparatus, or device.

[0104] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application. Based on this, various substitutions and improvements can be made to this application, all of which fall within the protection scope of this application.

Claims

1. A marine drilling pressure control device, characterized in that, include: Pressure control system and back pressure self-control compensation system, among which, The pressure control system is used to perform pressure control operations on the drilling when downhole anomalies are detected or wellhead pressure control is performed. The back pressure self-control compensation system is used to automatically inject pressure into the wellhead when the actual measured pressure at the wellhead is lower than the target pressure, and to automatically release the inlet pressure when the actual measured pressure at the wellhead is higher than the target pressure.

2. The marine drilling pressure control device according to claim 1, characterized in that, The pressure control system includes a flow monitoring path and a pressure control path, wherein, The flow monitoring channel is used to monitor the flow rate of the well when there are no abnormalities downhole. The pressure control pathway is used to perform pressure control operations on the drilling when downhole anomalies are detected or wellhead pressure control is performed.

3. The marine drilling pressure control device according to claim 2, characterized in that, The flow monitoring channel includes a first control valve, a first pressure gauge, a seventh control valve, and a second pressure gauge connected in sequence through pipelines, used to monitor the flow rate of the well when there are no abnormalities downhole.

4. The marine drilling pressure control device according to claim 2, characterized in that, The pressure control pathway includes a first control valve, a first pressure gauge, a second control valve, a sixth control valve, a throttle valve, and a second pressure gauge connected in sequence via pipelines. It is used to perform drilling pressure control operations when downhole anomalies are detected or wellhead pressure control is performed.

5. The marine drilling pressure control device according to claim 1, characterized in that, It also includes the flow monitoring system, which comprises a mass flow meter path and an electromagnetic flow meter path, wherein, The mass flow meter passage is used to monitor and measure the outlet overflow of the well when the pump is stopped; The electromagnetic flowmeter path is used to monitor the flow rate during normal drilling.

6. The marine drilling pressure control device according to claim 5, characterized in that, The mass flow meter passage includes a third control valve and a mass flow meter connected in sequence through a pipeline, used to monitor and measure the outlet overflow of the well when the pump is stopped.

7. The marine drilling pressure control device according to claim 5, characterized in that, The electromagnetic flowmeter passage includes a fourth control valve and an electromagnetic flowmeter connected in sequence through a pipeline, used to monitor and measure the outlet overflow of the well when the pump is stopped.

8. The marine drilling pressure control device according to any one of claims 1-7, characterized in that, The backpressure self-control compensation system includes an automatic pressure injection subsystem and an automatic pressure release subsystem connected to the drilling site. The automatic pressure injection subsystem is used to automatically inject pressure into the wellhead when the measured pressure at the wellhead is lower than the target pressure. The automatic pressure release subsystem is used to automatically release the inlet pressure when the measured pressure at the wellhead is higher than the target pressure.

9. The marine drilling pressure control device according to claim 8, characterized in that, The automatic pressure injection subsystem includes a fifth control valve, a pressure check valve, a plug valve, an automatic pressure injection pump, and a water supply auxiliary pump, which are connected in sequence through pipelines.

10. A method for controlling pressure in offshore drilling, characterized in that, Includes the following steps: During normal drilling and under normal downhole conditions, the drilling fluid flow rate at the wellhead and inlet is monitored in real time using the flow monitoring mode. When downhole anomalies are detected or wellhead pressure is controlled, the wellhead back pressure is automatically controlled through the pressure control mode. In the case of pump shutdown or dry well, the underpressure situation at the bottom of the well is judged by real-time monitoring and accurate measurement of drilling fluid overflow. When the wellhead provides back pressure after the pump stops, the wellhead injection mode automatically injects pressure when the measured pressure at the wellhead is lower than the target pressure, and automatically releases the inlet pressure when the measured pressure at the wellhead is higher than the target pressure. During controlled tripping, the wellhead pressure is automatically controlled through a combination of flow monitoring and pressure control.

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