A method and apparatus for multilayer directional perforation by cable

Abstract

The application provides a cable transmission multilayer azimuthal perforation method and device, which comprises a ground system and an underground system. The ground system comprises a logging truck, a pulley, a blowout preventer and a test cable. The blowout preventer is installed at a wellhead to prevent blowout accidents during operation. The pulley is rotatably installed above the blowout preventer. The logging truck is connected with the underground system in the casing through the test cable, the pulley and the blowout preventer. The logging truck is provided with a control system. The control system sends instructions to control the action of the underground system through the test cable. The multilayer azimuthal perforation in the well is realized through one trip, the workload of the multilayer azimuthal perforation is reduced, and the work efficiency is improved. The cable transmission multilayer azimuthal perforation system is composed of the ground system and the underground system. It belongs to the technical field of perforation completion in oil and gas field exploitation.

Description

Technical Field

[0001] This invention relates to a method and apparatus for multi-layer azimuth perforation via cable transmission, belonging to the field of perforation and well completion technology in oil and gas field development. Background Technology

[0002] Well completion perforation is a crucial method in current oil and gas extraction. Its purpose is to penetrate the casing and cement layer to reach a certain depth in the formation, increasing reservoir porosity and establishing a fluid channel between the wellbore and the target layer, thus enabling oil and gas extraction. The purpose of perforation azimuth is to improve the efficiency of perforation holes, resolve the difficulty in controlling fracture direction during fracturing, reduce sand production, and decrease fracturing initiation pressure, thereby reducing operating costs and increasing the recovery rate of low-permeability reservoirs. If directional perforation involves significant errors and uncertainties, an effective perforation hole distribution cannot be formed, failing to effectively guide downhole operations and significantly increasing the difficulty of oilfield development. The explosive impact force of the bullets used in downhole perforation operations can reach over 15,000g. The impact resistance of traditional depth calibration and orientation instruments cannot meet the requirements. Therefore, the current perforation process involves first lowering the depth calibration instrument to the target layer to find the section of the well that needs to be perforated, then taking out the depth calibration instrument and lowering the orientation tool to determine the orientation of the perforation by manually rotating the wellhead, and finally taking out the orientation tool and lowering the perforation gun to perform perforation.

[0003] The main problems with this method are:

[0004] 1) The need to repeatedly lower and lower the instrument into and out of the oil and gas well leads to low efficiency. The depth of the well section for instrument calibration is significantly different from the required depth due to factors such as different instrument weights and cable depth counting errors.

[0005] 2) The orientation of the perforation gun is determined by the keyway of the key to determine whether the orientation is specified by the positioning tool. On the one hand, the keyway must have a large clearance to facilitate key placement. On the other hand, there is currently no better way to determine whether the perforation gun has successfully placed the key. This means that the current orientation perforation cannot meet the requirements of high-precision orientation perforation. Even if the current process can successfully place the key, the error is difficult to reach about 10°. Failure to place the key will cause the current perforation section to fail.

[0006] 3) Manually moving the tubing string of the entire well to correct its orientation is feasible for wells with low deflection, but it is very difficult or even impossible to rotate it for wells with high deflection. Summary of the Invention

[0007] This invention provides a method and apparatus for cable-driven multi-layer azimuth perforation, enabling multi-layer azimuth perforation in a single downhole operation, reducing the workload of multi-layer azimuth perforation and improving work efficiency. The cable-driven multi-layer azimuth perforation system consists of a surface system and a downhole system.

[0008] To address the aforementioned issues, a cable-driven multi-layer azimuth perforation device is proposed, comprising a surface system and an underground system. The surface system includes a logging vehicle, pulleys, a blowout preventer (BOP), and a test cable. The BOP is installed at the wellhead to prevent blowout accidents during operations. The pulleys are rotated and mounted above the BOPs. The logging vehicle connects to the underground system within the casing via the test cable, passing through the pulleys and the BOP. A control system is installed inside the logging vehicle, which issues commands via the test cable to control the actions of the downhole system.

[0009] In the aforementioned perforation device, the underground system includes, from top to bottom, a bridle, a rotating sub-section, an upper stabilizer, a telemetry sub-section, a magnetic positioning gamma meter, a lower stabilizer, a fixed sub-section, an adjusting sub-section, a gyro sub-section, a flexible sub-section, and a perforator assembly.

[0010] In the aforementioned perforation device, the bridle serves as a connecting component, linking the test cable to the underground system; the telemetry sub acts as a data relay station, transmitting surface command signals downwards and downhole test data signals upwards; the magnetic positioning gamma ray meter determines the downhole system's insertion depth via the test casing coupling, ensuring the system is in the correct position; the fixed sub employs an electrically operated retractable claw structure to secure the downhole system to the casing, facilitating gyro sub testing and preventing other downhole instruments from rotating when adjusting the perforator assembly's azimuth; the gyro sub is based on strapdown inertial navigation. The technology includes orientation instruments used to test the azimuth of the downhole perforator group; a high-torque adjustment motor is installed inside the adjustment sub; after the gyro sub determines the azimuth of the perforator group, the adjustment motor drives the perforator group to rotate, ensuring the correct perforation direction; a flexible sub connects the perforator group to other downhole instruments, buffering the vibration generated by the explosion of the perforating projectile during perforation, protecting other downhole instruments above it; the perforator group includes multiple perforators to achieve multi-level perforation in a single downhole operation.

[0011] This invention also provides a cable-driven multi-layer azimuth perforation method, specifically as follows: First, remove the wellhead, install the blowout preventer and pulleys, adjust the parking position of the logging truck, connect the downhole system according to the design scheme, connect the breechblock and test cable, lower the downhole system to the design position, use a magnetic positioning gamma ray meter to perform depth testing, adjust the downhole system position to the optimal level based on the test results, control the electric claw of the fixed sub, fix the downhole system inside the casing, start the gyro sub test, determine the initial azimuth of the perforator group, and compare with the oil and gas well parameters according to the design scheme. The perforator assembly's azimuth deviation angle is calculated, the adjusting sub is activated, and commands are sent to accurately control the motor's rotation angle based on the calculation results. The perforator assembly is then accurately rotated to the designed azimuth, and the perforator is started to perform perforation. After perforation at the lower level is completed, the fixing sub is activated, and the electric retraction claw is activated. According to the design plan, the downhole system is lifted to the upper level. The above working steps are repeated to perform perforation again until perforation at multiple downhole levels is completed. The electric retraction claw of the fixing sub is then controlled to lift the downhole system out, the blowout preventer and pulley at the wellhead are removed, the wellhead is sealed, and the well is completed.

[0012] Compared with existing technologies, this invention integrates functions such as depth calibration, gyro-based azimuth determination, automatic control of the perforation gun's azimuth downhole via a power unit, and layered control of the perforation projectiles via ground commands. Utilizing the special vibration-damping design of the instrument sections, it enables multi-layer azimuth perforation in a single well setup, shortening the construction cycle, reducing operating costs, and increasing the automation level of the equipment. It eliminates the need for keyway positioning to determine azimuth. The integrated design of the azimuth instrument, depth calibration instrument, and perforation instrument removes the errors and uncertainties present in existing processes, facilitating accurate construction by operators according to the established procedures. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of a multi-layer azimuth perforation system for cable transmission;

[0014] Figure 2 This is a schematic diagram of the working process of a multi-layer azimuth perforation system for cable transmission;

[0015] Figure 3 This is a schematic diagram of the fixed short section structure;

[0016] Figure 4 This is a schematic diagram of the flexible short section;

[0017] Figure 5 This is a flowchart for controlling the angle of the short section. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention. Example

[0019] like Figures 1 to 5 As shown, the present invention discloses a cable-transmitted multi-layer azimuth perforation device, comprising a surface system 1 and an underground system 2. The surface system 1 includes a logging vehicle 11, a pulley 12, a blowout preventer 13, and a test cable 14. The blowout preventer 13 is installed at the wellhead to prevent blowout accidents during operation. The pulley 12 is rotatably mounted above the blowout preventer 13. The logging vehicle 11 is connected to the underground system 2 inside the casing via the test cable 14, through the pulley 12, and through the blowout preventer 13. A control system is installed inside the logging vehicle 11, and commands are issued by the control system via the test cable 14 to control the operation of the downhole system 2.

[0020] The underground system 2 includes, from top to bottom, the following components assembled in sequence: bridle 21, rotating sub-section 22, upper centralizer 23, telemetry sub-section 24, magnetic positioning gamma meter 25, lower centralizer 26, fixed sub-section 27, adjusting sub-section 28, gyro sub-section 29, flexible sub-section 210, and perforator assembly 211.

[0021] The bridle 21 serves as a connecting component, linking the test cable 14 to the underground system 2; the telemetry sub 24 acts as a data relay station, transmitting ground command signals downwards and downhole test data signals upwards; the magnetic positioning gamma meter 25 determines the downhole system's insertion depth via the test casing coupling, ensuring the system is in the correct position; the fixing sub 27 employs an electrically operated claw structure to fix the downhole system to the casing, facilitating gyro sub testing and preventing other downhole instruments from rotating during perforator group azimuth adjustments; the gyro sub 29 is a directional instrument based on strapdown inertial technology. Used for testing the orientation of the downhole perforator group; a high-torque adjusting motor is installed inside the adjusting section 28. After the gyro section 29 determines the orientation of the perforator group 211, the adjusting motor drives the perforator group 211 to rotate, ensuring the correct perforation direction of the perforator group 211; the flexible section 210 connects the perforator group 211 and other downhole instruments, buffering the vibration generated by the explosion of the perforating projectile during perforation, and protecting other downhole instruments above it; the perforator group 211 includes multiple perforators to achieve multi-level perforation in a single downhole operation.

[0022] The underground system 2 is fixed to the casing wall inside the casing by an electrically operated retractable claw structure. The fixing sub 27 is used to prevent other downhole instruments from rotating when adjusting the azimuth of the perforator assembly 211. The fixing sub 27, as shown... Figure 3As shown, the fixed short section 27 mainly consists of a plug assembly 271, a circuit assembly 272, a power supply assembly 273, a motor assembly 274, an outer tube 275, a dynamic sealing assembly 276, a transmission assembly 277, a telescopic arm assembly 278, a lower connector assembly 279, and a socket assembly 2710. The motor assembly 274 uses a custom-designed high-temperature shock-absorbing motor with a self-made gearbox, which can self-lock when the telescopic arm is fully extended. The dynamic sealing assembly 276 uses three sets of high-temperature, high-pressure Chevron seals with rolling bearings to meet the sealing and positioning requirements of the transmission assembly 277 during rotation. The transmission assembly 277 mainly consists of two drive shafts connected by a safety pin. If the telescopic arm is damaged by the explosive impact and vibration of the perforator assembly 211 after extension and cannot be retracted, the instrument string can be lifted to cut the safety pin, disengaging the two drive shafts and reducing the resistance to retracting the telescopic arm, thus releasing the fixation. The telescopic boom assembly 278 mainly consists of a fixed block, a telescopic boom, and a transmission nut. The motor assembly outputs torque to drive the transmission component to rotate, and the displacement of the transmission nut causes the telescopic boom to open or retract. The fixed block is designed with vertical friction stripes to enhance its anti-rotation capability. Because part of the telescopic boom assembly 278 cannot be sealed, the internal wiring of the short section uses a custom high-temperature and high-pressure rubber tail seal method, and is then resealed and connected to the socket assembly 2710 through the lower connector assembly.

[0023] A special flexible short section 210 is used to achieve shock absorption between the short section and the perforating gun during depth adjustment, orientation setting, and adjustment, reducing impact vibrations exceeding 20,000g to less than 100g. The flexible short section 210 utilizes its internal shock-absorbing elements to absorb or reduce longitudinal and lateral impact vibrations from the perforator assembly, thereby protecting the system. Its components are as follows... Figure 4As shown. The flexible sub-section 210 mainly consists of a socket assembly 2101, an upper connector assembly 2102, a radial damping assembly 2103, a connecting rod 2104, an axial damping assembly 2105, a lower connector assembly 2106, and a socket assembly 2107. The socket assembly 2101 uses a Swiss-made LEMO 10-pin socket that is compatible with the gyroscope sub-section 29. The upper connector assembly 2102 and the gyroscope sub-section 29 are connected by a flexible joint. The radial damping assembly 2103 mainly consists of damping springs and rubber damping blocks, used to reduce the impact of radial vibration on the instrument string at the moment of perforator assembly 211 detonation. The axial damping assembly 2105 mainly consists of anti-rotation sliders, connecting rods, damping springs, and damping rubber rings. The connecting rod has an anti-rotation guide groove, and the anti-rotation slider works in conjunction with the guide groove. The lower connector assembly 2106 can slide up and down when impacted by the detonation of perforator assembly 211. The vibration frequency is reduced by the alternating series of damping springs and rubber rings, thereby reducing the impact of axial vibration on the instrument string. The socket assembly 2107 uses a single-core socket and a sealing interface compatible with perforator assembly 211. When connecting the instrument string in the field, first connect the flexible short section 210 to the perforator assembly 211, and then connect the connected instrument string to the gyroscope short section 29. This connection is designed as a flexible joint, eliminating the need to rotate the instrument string and reducing the difficulty of instrument connection. Protection Point: The flexible short-section axial damping system uses three-stage high-temperature fluororubber and two-stage alloy silicon-manganese springs to achieve alternating damping. The rubber at both ends is harder, the middle stage rubber has half the hardness of the rubber at both ends, and the spring hardness is 2 / 3 of the hardest rubber. The spring has a force cycle count of no less than 10. 6 .

[0024] The orientation section utilizes a miniaturized design employing a three-axis all-solid-state gyroscope and a three-axis MEMS accelerometer. The inertial systems of the gyroscope and accelerometer are mounted using a special vibration-damping structure, reducing vibration and impact by more than five times. The gyroscope and accelerometer are soldered onto a PCB board with a low coefficient of thermal expansion. The PCB board is then bonded to a metal base using high-temperature (200℃) sulfur-resistant silicone rubber, with the rubber thickness controlled between 3mm and 5mm. The metal base is further bonded to the structural support of the orientation section using high-temperature epoxy resin via springs.

[0025] To meet the testing requirements of vertical wells, highly deviated wells, and horizontal wells, a 9-axis sensitive inertial element is used for positioning measurement. It directly measures and calculates the azimuth and automatically adjusts the azimuth of the perforating gun. A high-speed DSP and FPGA are used to calculate the azimuth angle and control the rotation angle of the adjustment section 28. The 9-axis sensitive inertial element includes a 3-axis gyroscope and two 3-axis accelerometers with a 45° difference in their X and Z mounting angles. One accelerometer is horizontally mounted with the gyroscope along the X-axis, and the other accelerometer is mounted at a 45° angle to the gyroscope along the X-axis.

[0026] The motor of adjustment section 28 cannot use ordinary brushed DC motors and photoelectric encoders because their impact resistance is insufficient and they are easily damaged. This embodiment uses a high-vibration-resistant oil-immersed pressure-resistant high-temperature brushless motor with a planetary drive adjustment mechanism and reducer. The motor is required to withstand a pressure of not less than 200MPa, a temperature of not less than 200℃, an impact resistance of not less than 30000g, and a vibration resistance of not less than 280g. A rotary transformer is used to read the motor's rotation angle and control its speed. The rotor of the rotary transformer is coaxial with the motor. The output signal of the rotary transformer is decoded by the ADU6802 decoding circuit and sent to the FPGA for processing. The calculated value is used to control the motor's running speed. Current detection uses a magnetic balance Hall element to implement motor overload protection. The FPGA sends the angle position data to the DSP2812 circuit, which processes the data in conjunction with the gyroscope's azimuth acquisition data and uploads it to the telemetry section 24. The angle control process of adjustment section 28 is as follows: Figure 5 As shown.

[0027] Each perforator is connected by a cascaded switch, which opens upon command to control the detonation voltage of each layer. The cascaded switch uses electronic switches instead of ordinary relays to improve shock resistance. It consists of a low-impedance PMOS transistor with a voltage of at least 450V, an NMOS transistor with a current of at least 2A, a fast Schottky diode, a bidirectional transient suppression diode with a voltage of at least 450V and a current greater than 2A, and a 5W level adjustment resistor.

[0028] The magnetic positioning gamma uses high-temperature sponge, springs, and non-magnetic titanium alloy mounting cylinders for shock absorption. Externally, high-permeability magnetic shielding material is used to protect the crystal and phototube from the magnetic field after the metal tubes such as sleeves are magnetized, thus improving counting stability.

[0029] The specific method for multi-layer azimuth perforation in cable transmission is as follows:

[0030] First, remove the wellhead, install the blowout preventer 13 and pulley 12, adjust the parking position of the logging truck 11, connect the downhole system 2 according to the design plan, connect the bridle 21 and test cable 14, lower the downhole system 2 to the design position, use the magnetic positioning gamma meter 25 to perform depth testing, adjust the position of the downhole system 2 to the optimal position based on the test results, control the electric claw of the fixed sub 27 to fix the downhole system 2 inside the casing, start the gyro sub 29 test to determine the initial orientation of the perforator assembly 211, and calculate the orientation of the perforator assembly 211 according to the oil and gas well parameters and the design plan. If the angle deviates, start the adjusting section 28, send a command according to the calculation results to accurately control the rotation angle of the motor, adjust the azimuth of the perforator group 211, and accurately rotate the perforator group 211 to the designed azimuth. Then start the perforator to perform perforation. After the perforation of the lower layer is completed, start the fixed section 27, and the electric claw retracts. According to the design plan, the downhole system 2 is lifted to the upper layer. Perforation is performed again according to the above working steps until the perforation of multiple layers of the downhole is completed. Control the electric claw retracting of the fixed section 27 to lift the downhole system 2 out, remove the blowout preventer 13 and pulley 12 at the wellhead, seal the wellhead, and complete the well.

[0031] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-layer azimuth perforation device for cable transmission, characterized in that: The system includes a surface system (1) and an underground system (2). The surface system (1) includes a logging truck (11), a pulley (12), a blowout preventer (13), and a test cable (14). The blowout preventer (13) is installed at the wellhead to prevent blowout accidents during operation. The pulley (12) is rotatably mounted above the blowout preventer (13). The logging truck (11) is connected to the underground system (2) inside the casing via the test cable (14), through the pulley (12), and through the blowout preventer (13). 1) An internal control system is installed, which sends commands through the test cable (14) to control the operation of the underground system (2); the underground system (2) includes, from top to bottom, the following components assembled in sequence: bridle (21), rotating sub (22), upper stabilizer (23), telemetry sub (24), magnetic positioning gamma meter (25), lower stabilizer (26), fixed sub (27), adjusting sub (28), gyro sub (29), flexible sub (210), and perforator assembly (211); The fixed short section (27) mainly consists of a plug assembly (271), a circuit assembly (272), a power supply assembly (273), a motor assembly (274), an outer tube (275), a dynamic sealing assembly (276), a transmission assembly (277), a telescopic arm assembly (278), a lower connector assembly (279), and a socket assembly (2710). The transmission assembly (277) mainly consists of two transmission shafts, with a safety pin at the connection. When the telescopic arm extends, if it is damaged by the explosive impact and vibration of the perforator assembly (211) and cannot be retracted, the instrument string is lifted to cut the safety pin, the two transmission shafts disengage, the resistance to retracting the telescopic arm decreases, and the fixation is released. The telescopic arm assembly (278) mainly consists of a fixed block, a telescopic arm, and The transmission nut is composed of a motor assembly that outputs torque to drive the transmission component to rotate. The telescopic arm can perform opening or retraction actions by shifting the transmission nut. The fixed block is designed with vertical friction stripes to enhance its anti-rotation capability. Since the telescopic arm assembly (278) cannot be sealed, the internal wires of the short section adopt a customized high-temperature and high-pressure rubber tail sealing method, and are then sealed and connected to the socket assembly (2710) through the lower connector assembly (279). The flexible short section (210) is mainly composed of the socket assembly (2101), the upper connector assembly (2102), the radial damping assembly (2103), the connecting rod (2104), the axial damping assembly (2105), the lower connector assembly (2106), and the socket assembly (2107).

2. The cable transmission multi-layer positioning perforation device according to claim 1, characterized in that: The bridle (21) serves as a connecting component, connecting the test cable (14) to the underground system (2); the telemetry sub (24) acts as a data relay station, transmitting ground command signals downwards and downhole test data signals upwards; the magnetic positioning gamma meter (25) determines the depth of the underground system by testing the casing coupling, ensuring the underground system is in the correct position; the fixed sub (27) uses an electrically operated claw structure to fix the underground system to the casing, facilitating gyro sub testing and preventing other downhole instruments from rotating when adjusting the perforator group's orientation; the gyro sub (29) is a directional instrument based on strapdown inertial technology, using... The perforator group is tested for its orientation. A high-torque adjustment motor is installed in the adjustment section (28). After the gyro section (29) determines the orientation of the perforator group (211), the adjustment motor drives the perforator group (211) to rotate, ensuring the correct perforation direction of the perforator group (211). The flexible section (210) is connected between the perforator group (211) and other downhole instruments. When the perforator is perforating, it buffers the vibration generated by the explosion of the perforating bullet and protects other downhole instruments above it. The perforator group (211) includes multiple perforators to achieve multi-level perforation in a single downhole operation.

3. A method for multi-layer azimuth perforation using a perforation device as described in claim 1 or 2, characterized in that: First, remove the wellhead, install the blowout preventer (13) and pulley (12), adjust the parking position of the logging truck (11), connect the underground system (2) according to the design plan, connect the bridle (21) and test cable (14), lower the underground system (2) to the design position, use the magnetic positioning gamma meter (25) to perform depth testing, adjust the position of the underground system (2) to the optimal position according to the test results, control the electric claw of the fixed sub (27) to fix the underground system (2) inside the casing, start the gyro sub (29) test, determine the initial orientation of the perforator group (211), compare with the oil and gas well parameters, and calculate the perforator group (211) according to the design plan. 11) When the azimuth deviates from the angle, start the adjustment section (28), send the command according to the calculation result to accurately control the rotation angle of the motor, adjust the azimuth of the perforator group (211), accurately turn the perforator group (211) to the design azimuth, and then start the perforator to perforate. After the perforation of the lower layer is completed, start the fixed section (27), retract the claw electrically, and lift the underground system (2) to the upper layer according to the design plan. Refer to the above working process to perforate again until the perforation of multiple layers in the well is completed. Control the fixed section (27) to retract the claw electrically, lift the underground system (2), remove the blowout preventer (13) and pulley (12) at the wellhead, seal the wellhead, and complete the well.

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