Well bottom alternating flow field generating tool structure optimization laboratory experiment device and experiment method

Abstract

This invention relates to an indoor experimental apparatus and method for optimizing the structure of a bottom-hole alternating flow field generator. A lifting device is fixed at the center of the top of the test frame, and a top drive device is suspended at the lower end of the lifting device. A drill pipe is connected to the lower end of the top drive device, and a pulse generator and a PDC drill bit are screwed onto the lower end of the drill pipe. A transparent return channel is located below the PDC drill bit. The drain outlet of the transparent return channel is connected to a vibrating screen via a drain pipe and a drain valve. The vibrating screen is fixed above the mud tank. The inlet pipe of the mud pump is inserted into the lower part of the mud tank, and the outlet of the mud pump is connected to a high-pressure manifold. The outlet of the high-pressure manifold is connected to the inlet of the top drive device. A rock sample is placed below the PDC drill bit and fixed in the transparent return channel. Drilling mode experiments are conducted first, followed by bottom-hole flow field characteristic testing mode experiments to evaluate the performance of the pulse generator. This invention obtains the pulse jet-assisted rock-breaking effect under different parameters through experiments, which is beneficial for structural optimization and improving drilling speed.

Description

Technical Field

[0001] This invention relates to an experimental device for the petroleum industry, and more particularly to an indoor experimental device for optimizing the structure of a bottom-hole alternating flow field generator tool; this invention also relates to an indoor experimental method for optimizing the structure of a bottom-hole alternating flow field generator tool, belonging to the technical field of petroleum drilling experimental equipment. Background Technology

[0002] Pulsed jet drilling technology can effectively utilize bottom hole hydraulic energy to improve the efficiency of bottom hole fluid in clearing and assisting in rock breaking, thereby increasing the mechanical drilling rate. Its cost-reduction and efficiency-enhancing effects are even more prominent and significant in complex formations such as deep and ultra-deep wells.

[0003] The pulse jet generator is the core of this technology. Chinese invention patent CN105370213B discloses a downhole pulse jet drill bit device. This tool converts the hydraulic energy of the drilling fluid into the mechanical energy of the rotating valve disc via an impeller. Then, by aligning or offsetting the water holes on the moving valve disc and the stationary valve disc, the continuous drilling fluid flow is modulated into a discontinuous pulse jet that acts on the bottom of the well. Because the structure of the pulse jet generator is directly designed into the drill bit, the pulse jet acts directly on the bottom of the well through the water holes. This tool can greatly reduce pulse energy loss along the drilling path, enhance the pulse intensity at the bottom of the well, improve rock breaking effect, increase drilling speed, shorten the well construction cycle, and significantly reduce well construction costs.

[0004] Currently, there is no accurate evaluation of the applicability and effectiveness of different structures of this type of pulse jet generator. During field work, a lot of time is wasted in selecting tool structures, and unreasonable structure selection can easily lead to problems that affect drilling efficiency. Summary of the Invention

[0005] The primary objective of this invention is to overcome the problems existing in the prior art and provide an indoor experimental device for optimizing the structure of a bottom-hole alternating flow field generator. This device can simulate on-site working conditions, obtain the effect of pulse jet-assisted rock breaking under different impact parameters through drilling experiments, and then optimize the structural parameters to find the optimal solution suitable for on-site operations and improve drilling speed.

[0006] To address the above technical problems, this invention provides an indoor experimental device for optimizing the structure of a bottom-hole alternating flow field generator. The device includes a test frame, with a lifting device fixed at the top center of the test frame. A top drive device is suspended at the lower end of the lifting device, and a drill pipe is connected to the lower end of the top drive device. A pulse generator is screwed to the lower end of the drill pipe, and a PDC drill bit is screwed to the lower end of the pulse generator. A transparent reflux trough is located below the PDC drill bit. The drain outlet of the transparent reflux trough is connected to a vibrating screen via a drain pipe and a drain valve. The vibrating screen is fixed above the mud tank. The inlet pipe of the mud pump is inserted into the lower part of the mud tank, and the outlet of the mud pump is connected to a high-pressure manifold. The outlet of the high-pressure manifold is connected to the inlet of the top drive device.

[0007] Compared with existing technologies, this invention achieves the following beneficial effects: 1. The lifting device bears the weight of the entire drilling tool and can move the drilling tool up and down, allowing it to switch between drilling and testing states. In drilling state, the PDC drill bit rests against the rock sample for drilling; during bottom hole flow field characteristic testing, the PDC drill bit is close to the bottom of the transparent return channel. This provides a realistic simulation of the drilling tool's working state downhole from multiple angles indoors. 2. During the experiment, the mud pump is turned on first, then the top drive device is started. The drilling fluid in the mud tank is pumped out by the mud pump and enters the inlet of the top drive device through the high-pressure manifold, providing drilling fluid for the structural optimization experiment of the alternating flow field generator tool. The drilling fluid enters the pulse generator tool along the central channel of the drill pipe. The pulse generator tool generates a pulse jet that is ejected from the water eye of the PDC drill bit. The top drive device drives the drill pipe, pulse generator tool, and PDC drill bit to rotate, simulating the downhole drilling process. The return fluid system is responsible for recovering the drilling fluid after the circulation experiment. The drilling fluid falling into the transparent return tank enters the vibrating screen for screening through the drain pipe and drain valve. The clean drilling fluid flows back into the mud tank, thus realizing the circulation of drilling fluid. 3. The state of the PDC drill bit and pulse jet can be directly observed through the transparent return tank. In the laboratory, it is easy to disassemble the pulse generating tool, change its internal structure or parameters, and thus obtain the effect of pulse jet-assisted rock breaking under different impact parameters through drilling experiments. This allows for the determination of the optimal structure and optimal parameters of the pulse generating tool, thereby improving the drilling speed.

[0008] As an improvement to the present invention, a rock sample is provided below the PDC drill bit, and the sidewall of the rock sample is fixed in the transparent reflux groove by a clamping device. This allows for direct simulation and evaluation of the working state of the PDC drill bit during bottom hole drilling.

[0009] As a further improvement of the present invention, top drive support arms are symmetrically connected to both sides of the top drive device. The outer ends of the top drive support arms are fitted onto the columns of the test frame and can slide up and down. The upper and lower ends of the drill rod are respectively provided with straightening clamps, which are fixed to the columns of the test frame via the drill rod support arms. The top drive support arms can prevent the top drive device from rotating. When the lifting device performs lifting or lowering actions, the outer ends of the top drive support arms float up and down on the columns of the test frame, allowing the top drive device and drill bit to change height. The straightening clamps are fitted onto the upper and lower ends of the drill rod, keeping the drill rod in a vertical position without hindering its rotation.

[0010] As a further improvement of the present invention, a water inlet valve is installed on the inlet pipe of the mud pump; a diverter pipe is connected to the high-pressure manifold, a diverter valve is installed on the diverter pipe, and the outlet of the diverter pipe is connected to the mud tank; a flow meter is installed between the diverter pipe and the inlet of the top drive device. The water inlet valve can control the inlet flow rate of the mud pump. When the diverter valve is opened, the high-pressure drilling fluid at the outlet of the mud pump returns to the mud tank through the diverter pipe and the diverter valve, so as to reduce the starting load of the mud pump. The diverter valve is gradually closed, and the readings of the flow meter and the pressure gauge on the high-pressure manifold are observed to gradually rise to the set value. By adjusting the opening degree of the diverter valve, the drilling pressure and discharge rate can be easily adjusted.

[0011] As a further improvement of the present invention, a force gauge is provided between the lifting device and the top drive device, a displacement sensor is installed between the top of the top drive device and the top of the test frame, a high-speed camera is fixed at the bottom center of the transparent return trough, and the bottom support of the transparent return trough is supported on the ground by a gravity sensor. The signal lines of the force gauge, displacement sensor, gravity sensor, and high-speed camera are connected to a data acquisition terminal. The force gauge can test the impact force on the drill string, and obtain parameters such as jet impact intensity and impact frequency through the impact force test. The high-speed camera can capture the morphology of the sand pre-laid in the transparent return trough under jet impact, and evaluate the flow field characteristics at the bottom of the well.

[0012] As a further improvement of the present invention, the pulse generating tool includes a cylinder, the upper end of which is provided with a cylinder inlet, the lower end of which is provided with a cylinder outlet, the middle section of the inner cavity of the cylinder is provided with an upper shaft coaxial with the cylinder, the middle part of the upper shaft is supported in a bearing seat by a bearing, the outer periphery of the bearing seat is supported on the upper step of the cylinder by a bearing seat flange, a plurality of water-permeable holes are evenly distributed on the bearing seat flange, the lower end of the upper shaft is screwed to the upper part of the central hole of the impeller, the lower part of the central hole of the impeller is screwed to the lower part of the lower shaft, the lower end of the lower shaft is fixed in the central hole of the moving valve disc, the moving valve disc covers the stationary valve disc, the outer periphery of the lower end face of the stationary valve disc is supported on the lower step of the cylinder, and the moving valve disc and the stationary valve disc are respectively provided with flow holes. High-pressure drilling fluid flows through the permeable holes on the bearing housing flange at high speed to the impeller, causing the impeller to rotate around the upper shaft. Simultaneously, the lower shaft drives the moving valve disc to rotate above the stationary valve disc. The flow holes of the moving and stationary valve discs alternately connect or deviate, modulating the continuous drilling fluid flow into a discontinuous pulse jet, thus creating an alternating flow field at the bottom of the well. By replacing the impeller, moving valve disc, or stationary valve disc in the pulse generating tool, and testing impellers with different numbers of blades, different inner diameters, or different blade pitches, as well as moving or stationary valve discs with different orifice shapes or numbers, the drilling effect is evaluated, and the structural parameters of the pulse generating tool are optimized to find the optimal solution for field operations.

[0013] As a further improvement of the present invention, the bottom of the bearing housing is closed, a lower bearing assembly is installed in the inner cavity of the bearing housing, an upper bearing assembly is provided at the upper end of the bearing housing, an upper pressure plate is provided above the upper bearing assembly, a locking nut is provided above the upper pressure plate, and the locking nut is screwed onto the upper shaft. The lower bearing assembly is a radial ball bearing, and the upper bearing assembly is a thrust bearing. The radial ball bearing allows the upper shaft to rotate flexibly while ensuring that the upper shaft is coaxial with the cylinder and does not produce large sway; the thrust bearing can transfer the weight suspended by the upper shaft to the bearing housing and reduce rotational resistance; the upper pressure plate and the locking nut serve as axial positioning.

[0014] As a further improvement of the present invention, an inlet pressure sensor is installed on the outer wall of the cylinder inlet, and an outlet pressure sensor is installed on the outer wall of the cylinder outlet. A magnet is installed on the impeller, and a counter capable of sensing the magnet is installed on the outer wall of the cylinder. The signal lines of the inlet pressure sensor, outlet pressure sensor, and counter are connected to a data acquisition terminal. The inlet and outlet pressure sensors can measure the pressure values ​​of the drilling fluid at the inlet and outlet of the pulse generating tool, as well as the pressure drop generated by the pulse generating tool. The pulse intensity is jointly determined by the drilling fluid pressure measured by the outlet pressure sensor and the pulse jet impact force measured by the gravity sensor at the bottom of the return tank. The impeller rotation speed is obtained by measuring the number of revolutions of the impeller within a certain time through the counter and sensing the magnet.

[0015] Another objective of this invention is to overcome the problems existing in the prior art and provide an indoor experimental method for optimizing the structure of a bottom-hole alternating flow field generator tool. This method can simulate on-site working conditions, obtain the effect of pulse jet-assisted rock breaking under different impact parameters through drilling experiments, and then optimize the structural parameters to find the optimal solution suitable for on-site operations and improve drilling speed.

[0016] To address the above technical problems, the present invention provides an indoor experimental method for optimizing the structure of a bottom-hole alternating flow field generator tool, comprising the following steps in sequence: S1, fixing the pulse generator tool on the test frame; S2, connecting the mud pump and its circulation manifold; S3, conducting a drilling mode experiment to evaluate the performance of the pulse generator tool; S4, conducting a bottom-hole flow field characteristic test mode experiment to further evaluate the performance of the pulse generator tool; S5, after the experiment, first turning off the data acquisition terminal, and then turning off the mud pump.

[0017] As an improvement to the present invention, step S1 includes the following sub-steps:

[0018] S1.1 Fix the lifting device at the top center of the test frame, suspend the tension gauge below the lifting device, suspend the top drive device at the lower end of the tension gauge, and symmetrically install the top drive support arms on both sides of the top drive device. The outer end of the top drive support arm is fitted onto the column of the test frame and can slide up and down.

[0019] S1.2. Screw the PDC drill bit onto the lower end of the pulse generator tool, and screw the pulse generator tool onto the bottom of the drill pipe;

[0020] S1.3 Connect the drill rod to the lower end of the top drive device, and install straightening clamps at the upper and lower ends of the drill rod respectively. The straightening clamps are fixed to the column of the test frame by the drill rod support arm.

[0021] S1.4 Install a transparent reflux trough below the PDC drill bit. The bottom support of the transparent reflux trough is supported on the ground by a gravity sensor.

[0022] As a further improvement of the present invention, step S2 includes the following sub-steps:

[0023] S2.1 Install a vibrating screen above the mud tank;

[0024] S2.2 Connect the drain outlet of the transparent return trough to the vibrating screen via a drain pipe and a drain valve.

[0025] S2.3 Install a mud pump and a water inlet valve at the inlet of the mud pump. Insert the inlet pipe of the water inlet valve into the lower part of the mud tank. Connect a high-pressure manifold to the outlet of the mud pump. Install a flow meter in the high-pressure manifold and connect the outlet of the high-pressure manifold to the inlet of the top drive device.

[0026] S2.4 Connect a diverter pipe upstream of the flow meter, install a diverter valve on the diverter pipe, and connect the outlet of the diverter pipe to the mud tank.

[0027] As a further improvement of the present invention, step S3 includes the following sub-steps:

[0028] S3.1 Place a rock sample below the PDC drill bit, and fix the sidewall of the rock sample in the transparent reflux groove by a clamping device;

[0029] S3.2 Install a displacement sensor between the top of the top drive device and the top of the test frame, and connect the signal line of the displacement sensor to the data acquisition terminal.

[0030] S3.3 First, turn on the mud pump, then turn on the top drive device to simulate the field conditions and make the PDC drill bit drill into the rock sample;

[0031] S3.4 Adjust the drilling pressure and displacement, and record the change of drilling displacement over time using a displacement sensor;

[0032] S3.5 Replace the impeller, moving valve disc, or stationary valve disc in the pulse generator tool, and conduct tests on impellers with different numbers of blades, different inner diameters, or different blade pitches. Conduct tests on moving valve discs or stationary valve discs with different opening shapes or numbers of openings, evaluate the drilling effect, and optimize the structural parameters of the pulse generator tool.

[0033] As a further improvement of the present invention, step S4 includes the following sub-steps:

[0034] S4.1 Remove the rock sample and lay a layer of sand at the bottom of the transparent reflux trough to simulate the rock cuttings at the bottom of the well.

[0035] S4.2 Install an inlet pressure sensor at the inlet end of the pulse generator and an outlet pressure sensor at the outlet end of the pulse generator. Install a counter that can sense the magnetic block on the outer wall of the pulse generator, with the magnetic block mounted on the impeller of the pulse generator. Fix a high-speed camera at the bottom center of the transparent reflux trough. Connect the signal lines of the pressure sensor, the counter, and the high-speed camera to the data acquisition terminal.

[0036] S4.3. Lower the height of the top drive device and drill pipe so that the bottom of the PDC drill bit contacts the upper surface of the sand layer;

[0037] S4.4. Turn on the mud pump to simulate the disturbance effect of pulse jet on the cuttings bed at the bottom of the well;

[0038] S4.5 Adjust drilling pressure and displacement, monitor the pressure changes at the inlet and outlet of the pulse generator tool, as well as the overall gravity of the transparent return channel, and record the sand layer morphology at the bottom of the transparent return channel with a high-speed camera;

[0039] S4.6 Replace the impeller, moving valve disc, or stationary valve disc in the pulse generator tool, and test impellers with different numbers of blades, different inner diameters, or different blade pitches. Test moving valve discs or stationary valve discs with different opening shapes or numbers of openings, evaluate the test results, and optimize the structural parameters of the pulse generator tool.

[0040] Compared to existing technologies, this invention achieves the following beneficial effects: This invention can realistically simulate the use of pulse generators in the field at full scale; the drilling mode reflects the on-site drilling effect; and the drilling situation of the PDC drill bit on rock samples can be intuitively observed. The bottom-hole flow field characteristic testing mode can evaluate the impeller speed, drilling fluid pulsation characteristics, and bottom-hole flow field, obtaining various characteristic parameters. The pulse intensity is jointly achieved by the drilling fluid pressure measured by the outflow pressure sensor and the pulse jet impact force measured by the gravity sensor at the bottom of the return channel.

[0041] The ultimate goal of using alternating flow field tools is to increase drilling speed. This invention, through drilling experiments, provides a clear and intuitive understanding of the structural characteristics of different pulse-generating tools, the speed-increasing effects of different drilling fluid parameters, and different drilling parameters. Furthermore, by installing a high-speed camera at the bottom of the transparent return channel, this invention allows direct observation of the flow field morphology under the action of the pulse jet, which is of great significance for guiding drill bit design and optimizing pulse parameters. The structure to be optimized in this invention uses the same connections as other structures. This means that when replacing the component to be optimized, other parts can be reused without adjustment or replacement, making adjustments convenient, easy to implement, and cost-effective. Attached Figure Description

[0042] Figure 1 This is a structural diagram of the indoor experimental device for optimizing the well bottom alternating flow field generator structure in this invention.

[0043] Figure 2 This is a cross-sectional view of the pulse generating tool in this invention.

[0044] Figure 3 This is a schematic diagram of the impeller in embodiment one of the pulse generator tools.

[0045] Figure 4 This is a top view of Embodiment 1 of the moving valve disc in the pulse generator tool.

[0046] Figure 5 This is a top view of Embodiment 2 of the moving valve disc in the pulse generator tool.

[0047] In the diagram: 1. Mud pump, 2. High-pressure manifold, 3. Diverter valve, 4. Flow meter, 5. Test frame, 6. Drain valve, 7. Vibrating screen, 8. Mud tank, 9. Water inlet valve, 10. Data acquisition terminal, 11. Lifting device, 12. Force gauge, 13. Top drive device, 14. Top drive support arm, 15. Drill rod support arm, 16. Drill rod, 17a. Inlet pressure sensor, 17b. Outlet pressure sensor; 18. Counter, 19. Pulse generator, 19a. Cylinder. 19b. Impeller, 19b1. Blade, 19c. Moving valve disc, 19c1. Moving valve disc flow hole, 19d. Locking nut, 19e. Upper pressure plate, 19f. Upper bearing pair, 19g. Bearing housing, 19h. Lower bearing pair, 19j. Upper shaft, 19k. Lower shaft, 19m. Static valve disc; 19m1. Static valve disc flow hole, 20. PDC drill bit, 21. Rock sample, 22. Displacement sensor, 23. Gravity sensor, 24. Transparent reflux trough, 25. High-speed camera. Detailed Implementation

[0048] like Figure 1 As shown, the indoor experimental device for optimizing the structure of the bottom-hole alternating flow field generator of the present invention includes a test frame 5. A lifting device 11 is fixed at the top center of the test frame 5. A top drive device 13 is suspended at the lower end of the lifting device 11. A drill rod 16 is connected to the lower end of the top drive device 13. A pulse generator 19 is screwed to the lower end of the drill rod 16. A PDC drill bit 20 is screwed to the lower end of the pulse generator 19. A transparent return channel 24 is provided below the PDC drill bit 20. The drain outlet of the transparent return channel 24 is connected to a vibrating screen 7 through a drain pipe and a drain valve 6. The vibrating screen 7 is fixed above the mud tank 8. The inlet pipe of the mud pump 1 is inserted into the lower part of the mud tank 8. The outlet of the mud pump 1 is connected to a high-pressure manifold 2. The outlet of the high-pressure manifold 2 is connected to the inlet of the top drive device 13.

[0049] The lifting device 11 bears the weight of the entire drill string and can move the drill string up and down, allowing it to switch between drilling and testing states. In drilling mode, the PDC drill bit 20 rests against the rock sample 21; during bottom hole flow field characteristic testing, the PDC drill bit 20 is close to the bottom of the transparent return channel 24. This provides a multi-directional, realistic simulation of the drill string's working state downhole.

[0050] During the experiment, mud pump 1 was turned on first, followed by the top drive unit 13. Drilling fluid in mud tank 8 was pumped out by mud pump 1 and entered the inlet of top drive unit 13 through high-pressure manifold 2, providing drilling fluid for the structural optimization experiment of the alternating flow field generating tool. The drilling fluid entered the pulse generating tool 19 along the central channel of drill pipe 16. The pulse generating tool 19 generated a pulse jet that was ejected from the water hole of PDC drill bit 20. Top drive unit 13 drove drill pipe 16, pulse generating tool 19, and PDC drill bit 20 to rotate, simulating the downhole drilling process. The return fluid system is responsible for recovering the drilling fluid after the circulation experiment. The drilling fluid that fell into the transparent return tank 24 entered the vibrating screen 7 for screening through the drain pipe and drain valve 6. The clean drilling fluid flowed back into mud tank 8, thus realizing the circulation of drilling fluid.

[0051] The PDC drill bit 20 and the state of the pulse jet can be directly observed through the transparent return channel 24. In the laboratory, the pulse generator tool 19 can be easily disassembled to change its internal structure or parameters, thereby obtaining the pulse jet-assisted rock-breaking effect under different impact parameters through drilling experiments. This allows for the determination of the optimal structure and parameters of the pulse generator tool 19, thereby improving drilling speed.

[0052] A rock sample 21 is placed below the PDC drill bit 20, and the sidewall of the rock sample 21 is fixed in the transparent return groove 24 by a clamping device. The working state of the PDC drill bit 20 during bottom hole drilling can be directly simulated and evaluated.

[0053] Top drive support arms 14 are symmetrically connected to both sides of the top drive device 13. The outer ends of the top drive support arms 14 are fitted onto the columns of the test frame 5 and can slide up and down. The upper and lower ends of the drill rod 16 are respectively equipped with straightening clamps, which are fixed to the columns of the test frame 5 via drill rod support arms 15. The top drive support arms 14 can prevent the top drive device 13 from rotating. When the lifting device 11 performs lifting or lowering actions, the outer ends of the top drive support arms 14 float up and down on the test frame columns, allowing the top drive device 13 and the drill string to change height. The straightening clamps are fitted onto the upper and lower ends of the drill rod 16, keeping the drill rod 16 in a vertical position without hindering its rotation.

[0054] A water inlet valve 9 is installed on the inlet pipe of mud pump 1; a diverter pipe is connected to high-pressure manifold 2, and a diverter valve 3 is installed on the diverter pipe. The outlet of the diverter pipe is connected to mud tank 8; a flow meter 4 is installed between the diverter pipe and the inlet of top drive device 13. The water inlet valve 9 can control the inlet flow of mud pump 1. When the diverter valve 3 is opened, the high-pressure drilling fluid at the outlet of mud pump 1 returns to mud tank 8 through the diverter pipe and diverter valve 3 to reduce the starting load of mud pump 1. The diverter valve 3 is gradually closed, and the reading of flow meter 4 and pressure gauge on high-pressure manifold 2 are observed to gradually rise to the set value. By adjusting the opening of diverter valve 3, drilling pressure and discharge rate can be easily adjusted.

[0055] A force gauge 12 is installed between the lifting device 11 and the top drive device 13. A displacement sensor 22 is installed between the top of the top drive device 13 and the top of the test frame 5. A high-speed camera 25 is fixed at the bottom center of the transparent return trough 24. The bottom support of the transparent return trough 24 is supported on the ground by a gravity sensor 23. The signal lines of the force gauge 12, displacement sensor 22, gravity sensor 23, and high-speed camera 25 are connected to the data acquisition terminal 10. The force gauge 12 can test the impact force on the drill string, and obtain parameters such as jet impact intensity and impact frequency through the impact force test. The high-speed camera 25 can capture the morphology of the sand pre-laid in the transparent return trough 24 under jet impact, and evaluate the flow field characteristics at the bottom of the well.

[0056] like Figure 2 As shown, the pulse generating tool 19 includes a cylindrical body 19a. The upper end of the cylindrical body 19a has a water inlet, and the lower end has a water outlet. An upper shaft 19j, coaxial with the cylindrical body, is located in the middle section of the inner cavity of the cylindrical body 19a. The middle part of the upper shaft 19j is supported in a bearing seat 19g by a bearing. The outer periphery of the bearing seat 19g is supported on the upper step of the cylindrical body 19a by a bearing seat flange. Multiple water-permeable holes are evenly distributed on the bearing seat flange. The lower end of shaft 19j is screwed onto the upper part of the central hole of impeller 19b. Multiple blades 19b1 are provided on the outer periphery of impeller 19b. A lower shaft 19k is screwed onto the lower part of the central hole of impeller 19b. The lower end of lower shaft 19k is fixed in the central hole of moving valve disc 19c. Moving valve disc 19c covers stationary valve disc 19m. The lower end face of stationary valve disc 19m is supported on the lower step of cylinder 19a. Flow holes are provided on moving valve disc 19c and stationary valve disc 19m respectively.

[0057] High-pressure drilling fluid passes through the permeable holes on the bearing housing flange and flows at high speed to the impeller 19b, causing the impeller 19b to rotate around the upper shaft 19j. Simultaneously, the lower shaft 19k drives the moving valve disc 19c to rotate above the stationary valve disc 19m. The flow holes 19c1 and 19m1 of the moving valve disc alternately connect or deviate, modulating the continuous drilling fluid flow into a discontinuous pulse jet, thereby generating an alternating flow field at the bottom of the well. By replacing the impeller 19b, moving valve disc 19c, or stationary valve disc 19m in the pulse generating tool 19, tests are conducted on impellers 19b with different numbers of blades, different inner diameters, or different blade pitches. Tests are also conducted on moving valve discs 19c or stationary valve discs 19m with different opening shapes or numbers of openings. The drilling effect is evaluated, and the structural parameters of the pulse generating tool 19 are optimized to find the optimal solution suitable for field operations.

[0058] The bottom of the bearing housing 19g is closed. A lower bearing assembly 19h is installed inside the bearing housing 19g. An upper bearing assembly 19f is located at the upper end of the bearing housing 19g. An upper pressure plate 19e is located above the upper bearing assembly 19f. A locking nut 19d is located above the upper pressure plate 19e and screwed onto the upper shaft 19j. The lower bearing assembly 19h is a radial ball bearing, and the upper bearing assembly 19f is a thrust bearing. The radial ball bearing allows the upper shaft 19j to rotate flexibly while ensuring that the upper shaft 19j is coaxial with the cylinder 19a and does not produce large swaying. The thrust bearing transfers the weight suspended by the upper shaft 19j to the bearing housing 19g and reduces rotational resistance. The upper pressure plate 19e and the locking nut 19d serve as axial positioning elements.

[0059] An inlet pressure sensor 17a is installed on the outer side of the cylinder wall at the inlet, and an outlet pressure sensor 17b is installed on the outer side of the cylinder wall at the outlet. The signal lines of the inlet and outlet pressure sensors 17a and 17b are connected to the data acquisition terminal 10. The inlet and outlet pressure sensors 17a and 17b can measure the pressure values ​​of the drilling fluid at the inlet and outlet of the pulse generating tool 19, as well as the pressure drop generated after passing through the pulse generating tool 19. The pulse intensity is determined by the drilling fluid pressure measured by the outlet pressure sensor 17b and the pulse jet impact force measured by the gravity sensor 23 at the bottom of the return channel.

[0060] A magnet is installed on the impeller 19b, and a counter 18 that can sense the magnet is installed on the outer wall of the cylinder 19a. The signal line of the counter 18 is connected to the data acquisition terminal 10. The number of revolutions of the impeller 19b within a certain period of time is measured by the counter 18 through the sensing magnet, and the rotational speed of the impeller 19b is obtained.

[0061] like Figure 2 , Figure 3 As shown, both the upper and lower sections of impeller 19b are machined with internal threads for screwing into the upper shaft 19j and lower shaft 19k. By changing the number N of blades 19b1, the inner diameter NJ of impeller 19b, and the pitch LJ of impeller 19b, the different rotational speeds, drilling fluid pulsation characteristics, and drilling effects produced by different impeller structures can be analyzed. Since the only connections between impeller 19b and other components are its outer diameter, length, and upper and lower threads, by keeping these four parameters constant, the structural parameters of impeller 19b can be optimized simply by adjusting this one component.

[0062] Figure 4 In one embodiment of the moving valve disc 19c, the moving valve disc flow holes 19c1 on the moving valve disc 19c are circular, and three, four or five are evenly distributed on the same circumference. The static valve disc flow holes 19m1 on the static valve disc 19m can also be circular, or fan-shaped or other shapes, and three, four or five can be symmetrically distributed. They can be replaced one by one in the experiment for testing.

[0063] Figure 5 In the second embodiment of the moving valve disc 19c, the moving valve disc flow holes 19c1 on the moving valve disc 19c are fan-shaped, with three evenly distributed on the same circumference. The dashed line represents the stationary valve disc flow holes 19m1 on the stationary valve disc 19m, which are circular, with four evenly distributed on the same circumference.

[0064] By changing the shape, number, diameter, and other dimensions of the flow passage 19c1 on the moving valve disc and / or the flow passage 19m1 on the stationary valve disc, the structure of the pulse generating tool 19 can be optimized, which is convenient and highly operable.

[0065] The indoor experimental method for optimizing the structure of the wellbore alternating flow field generator of the present invention includes the following steps:

[0066] S1. Fix the pulse generator 19 onto the test frame 5;

[0067] S2, connect mud pump 1 and its circulation manifold;

[0068] S3. Conduct drilling mode experiments to evaluate the performance of pulse generation tool 19;

[0069] S4. Conduct a test mode experiment on the bottom flow field characteristics to further evaluate the performance of the pulse generator tool 19;

[0070] S5. After the experiment, first turn off the data acquisition terminal 10, and then turn off the mud pump 1.

[0071] Step S1 includes the following sub-steps:

[0072] S1.1 Fix the lifting device 11 at the top center of the test frame 5, suspend the tension gauge 12 below the lifting device 11, suspend the top drive device 13 at the lower end of the tension gauge 12, and symmetrically install the top drive support arms 14 on both sides of the top drive device 13. The outer end of the top drive support arm 14 is fitted on the column of the test frame 5 and can slide up and down.

[0073] S1.2. Screw the PDC drill bit 20 onto the lower end of the pulse generating tool 19, and screw the pulse generating tool 19 onto the lower part of the drill rod 16.

[0074] S1.3 Connect the drill rod 16 to the lower end of the top drive device 13, and install straightening clamps at the upper and lower ends of the drill rod 16 respectively. The straightening clamps are fixed to the column of the test frame 5 through the drill rod support arm 15 respectively.

[0075] S1.4. A transparent return channel 24 is installed below the PDC drill bit 20. The bottom support of the transparent return channel 24 is supported on the ground by a gravity sensor 23.

[0076] Step S2 includes the following sub-steps:

[0077] S2.1 Install a vibrating screen 7 above the mud tank 8;

[0078] S2.2 Connect the drain outlet of the transparent return trough 24 to the vibrating screen 7 through a drain pipe and a drain valve 6.

[0079] S2.3 Install mud pump 1, install water valve 9 at the inlet of mud pump 1, insert the inlet pipe of water valve 9 into the lower part of mud tank 8, connect high pressure manifold 2 at the outlet of mud pump 1, install flow meter 4 in high pressure manifold 2, and connect the outlet of high pressure manifold 2 to the inlet of top drive device 13.

[0080] S2.4 Connect a diversion pipe upstream of the flow meter 4, install a diversion valve 3 on the diversion pipe, and connect the outlet of the diversion pipe to the mud tank 8.

[0081] Step S3 includes the following sub-steps:

[0082] S3.1 Place rock sample 21 below PDC drill bit 20, and fix the sidewall of rock sample 21 in transparent reflux groove 24 by clamping device;

[0083] S3.2 Install a displacement sensor 22 between the top of the top drive device 13 and the top of the test frame 5, and connect the signal line of the displacement sensor 22 to the data acquisition terminal 10.

[0084] S3.3 First, turn on the mud pump 1, then turn on the top drive device 13 to simulate the field conditions and make the PDC drill bit 20 drill on the rock sample 21.

[0085] S3.4 Adjust the drilling pressure and displacement, and record the change of drilling displacement over time using displacement sensor 22;

[0086] S3.5 Replace the impeller 19b, moving valve disc 19c, or stationary valve disc 19m in the pulse generating tool 19. Test the impeller 19b with different numbers of blades, different inner diameters, or different blade pitches. Test the moving valve disc 19c or stationary valve disc 19m with different opening shapes or numbers of openings. Evaluate the drilling effect and optimize the structural parameters of the pulse generating tool 19.

[0087] Step S4 includes the following sub-steps:

[0088] S4.1 Remove rock sample 21 and lay a layer of sand at the bottom of transparent reflux trough 24 to simulate rock cuttings at the bottom of the well.

[0089] S4.2 Install an inlet pressure sensor 17a at the inlet end of the pulse generating tool 19, and an outlet pressure sensor 17b at the outlet end of the pulse generating tool 19. Install a counter 18 that can sense the magnetic block on the outer wall of the pulse generating tool 19, with the magnetic block installed on the impeller 19b of the pulse generating tool 19. Fix a high-speed camera 25 at the bottom center of the transparent return trough 24. The signal lines of the pressure sensor, the counter 18, and the high-speed camera 25 are all connected to the data acquisition terminal 10.

[0090] S4.3. Lower the height of the top drive device 13 and the drill pipe 16 so that the bottom of the PDC drill bit 20 contacts the upper surface of the sand layer.

[0091] S4.4. Turn on mud pump 1 to simulate the disturbance effect of pulse jet on the cuttings bed at the bottom of the well;

[0092] S4.5 Adjust the drilling pressure and discharge rate, monitor the pressure changes at the inlet and outlet of the pulse generating tool 19, as well as the overall gravity of the transparent return channel 24, and use the high-speed camera 25 to record the sand layer morphology at the bottom of the transparent return channel 24.

[0093] S4.6 Replace the impeller 19b, moving valve disc 19c, or stationary valve disc 19m in the pulse generating tool 19. Test the impeller 19b with different numbers of blades, different inner diameters, or different blade pitches. Test the moving valve disc 19c or stationary valve disc 19m with different opening shapes or numbers of openings. Evaluate the test results and optimize the structural parameters of the pulse generating tool 19.

[0094] This invention can fully simulate the use of the on-site pulse generator tool 19, and the drilling mode reflects the on-site drilling effect, allowing for direct observation of the drilling situation of the PDC drill bit 20 on the rock sample 21. The bottom hole flow field characteristic test mode can evaluate the rotational speed of the impeller 19b, the drilling fluid pulsation characteristics, and the flow field at the bottom hole, obtaining various characteristic parameters.

[0095] This invention allows direct observation of the flow field morphology under the action of the pulsed jet by installing a high-speed camera 25 at the bottom of the transparent return channel 24. This is of great significance for guiding drill bit design and optimizing pulse parameters. The structure to be optimized in this invention uses the same connections as other structures. This means that when replacing the component to be optimized, other parts can be reused without adjustment or replacement, making adjustments convenient, easy to implement, and cost-effective.

[0096] The above description is merely a preferred embodiment of the present invention and does not limit the scope of patent protection of the present invention. Besides the above embodiments, the present invention may have other implementations. All technical solutions formed by equivalent substitution or equivalent transformation fall within the scope of protection claimed by the present invention. Technical features of the present invention not described can be implemented by or using existing technology, and will not be elaborated here.

Claims

1. An indoor experimental method for optimizing the structure of a wellbore alternating flow field generator, comprising the following steps: S1. Fix the pulse generator on the test stand; S2, connect the mud pump and its circulation manifold; S3. Conduct drilling mode experiments to evaluate the performance of the pulse generation tool; S4. Conduct a test mode experiment on the bottom hole flow field characteristics to further evaluate the performance of the pulse generation tool; S5. After the experiment, first turn off the data acquisition terminal, and then turn off the mud pump. Step S4 includes the following sub-steps: S4.1 Remove the rock sample and lay a layer of sand at the bottom of the transparent reflux trough to simulate the rock cuttings at the bottom of the well. S4.2 Install an inlet pressure sensor at the inlet end of the pulse generator and an outlet pressure sensor at the outlet end of the pulse generator. Install a counter that can sense the magnetic block on the outer wall of the pulse generator, with the magnetic block mounted on the impeller of the pulse generator. Fix a high-speed camera at the bottom center of the transparent reflux trough. Connect the signal lines of the pressure sensor, the counter, and the high-speed camera to the data acquisition terminal. S4.

3. Lower the height of the top drive device and drill pipe so that the bottom of the PDC drill bit contacts the upper surface of the sand layer; S4.

4. Turn on the mud pump to simulate the disturbance effect of pulse jet on the cuttings bed at the bottom of the well; S4.5 Adjust drilling pressure and displacement, monitor the pressure changes at the inlet and outlet of the pulse generator tool, as well as the overall gravity of the transparent return channel, and record the sand layer morphology at the bottom of the transparent return channel with a high-speed camera; S4.6 Replace the impeller, moving valve disc, or stationary valve disc in the pulse generator tool, and test impellers with different numbers of blades, different inner diameters, or different blade pitches. Test moving valve discs or stationary valve discs with different opening shapes or numbers of openings, evaluate the test results, and optimize the structural parameters of the pulse generator tool.

2. The indoor experimental method for optimizing the structure of the wellbore alternating flow field generator according to claim 1, characterized in that, Step S1 includes the following sub-steps: S1.1 Fix the lifting device at the top center of the test frame, suspend the tension gauge below the lifting device, suspend the top drive device at the lower end of the tension gauge, and symmetrically install the top drive support arms on both sides of the top drive device. The outer end of the top drive support arm is fitted onto the column of the test frame and can slide up and down. S1.

2. Screw the PDC drill bit onto the lower end of the pulse generator tool, and screw the pulse generator tool onto the bottom of the drill pipe; S1.3 Connect the drill rod to the lower end of the top drive device, and install straightening clamps at the upper and lower ends of the drill rod respectively. The straightening clamps are fixed to the column of the test frame by the drill rod support arm. S1.4 Install a transparent reflux trough below the PDC drill bit. The bottom support of the transparent reflux trough is supported on the ground by a gravity sensor.

3. The indoor experimental method for optimizing the structure of the wellbore alternating flow field generator according to claim 1, characterized in that, Step S2 includes the following sub-steps: S2.1 Install a vibrating screen above the mud tank; S2.2 Connect the drain outlet of the transparent return trough to the vibrating screen via a drain pipe and a drain valve. S2.3 Install a mud pump and a water inlet valve at the inlet of the mud pump. Insert the inlet pipe of the water inlet valve into the lower part of the mud tank. Connect a high-pressure manifold to the outlet of the mud pump. Install a flow meter in the high-pressure manifold and connect the outlet of the high-pressure manifold to the inlet of the top drive device. S2.4 Connect a diverter pipe upstream of the flow meter, install a diverter valve on the diverter pipe, and connect the outlet of the diverter pipe to the mud tank.

4. The indoor experimental method for optimizing the structure of the wellbore alternating flow field generator according to claim 1, characterized in that, Step S3 includes the following sub-steps: S3.1 Place a rock sample below the PDC drill bit, and fix the sidewall of the rock sample in the transparent reflux groove by a clamping device; S3.2 Install a displacement sensor between the top of the top drive device and the top of the test frame, and connect the signal line of the displacement sensor to the data acquisition terminal. S3.3 First, turn on the mud pump, then turn on the top drive device to simulate the field conditions and make the PDC drill bit drill into the rock sample; S3.4 Adjust the drilling pressure and displacement, and record the change of drilling displacement over time using a displacement sensor; S3.5 Replace the impeller, moving valve disc, or stationary valve disc in the pulse generator tool, and conduct tests on impellers with different numbers of blades, different inner diameters, or different blade pitches. Conduct tests on moving valve discs or stationary valve discs with different opening shapes or numbers of openings, evaluate the drilling effect, and optimize the structural parameters of the pulse generator tool.

5. An indoor experimental apparatus for optimizing the structure of a bottom-hole alternating flow field generator tool, used for the indoor experimental method for optimizing the structure of a bottom-hole alternating flow field generator tool as described in claim 1, comprising an experimental frame, characterized in that: A lifting device is fixed at the top center of the test frame. A top drive device is suspended at the lower end of the lifting device. A drill rod is connected to the lower end of the top drive device. A pulse generator is screwed to the lower end of the drill rod. A PDC drill bit is screwed to the lower end of the pulse generator. A transparent reflux trough is provided below the PDC drill bit. The drain outlet of the transparent reflux trough is connected to a vibrating screen through a drain pipe and a drain valve. The vibrating screen is fixed above the mud tank. The inlet pipe of the mud pump is inserted into the lower part of the mud tank. The outlet of the mud pump is connected to a high-pressure manifold. The outlet of the high-pressure manifold is connected to the inlet of the top drive device.

6. The indoor experimental device for optimizing the structure of the wellbore alternating flow field generator according to claim 5, characterized in that: A rock sample is placed below the PDC drill bit, and the sidewall of the rock sample is fixed in the transparent reflux groove by a clamping device.

7. The indoor experimental device for optimizing the structure of the well bottom alternating flow field generator according to claim 5, characterized in that: The top drive device is symmetrically connected to both sides of the top drive support arm. The outer end of the top drive support arm is fitted onto the column of the test frame and can slide up and down. The upper and lower ends of the drill rod are respectively provided with straightening clamps, which are fixed to the column of the test frame by the drill rod support arm.

8. The indoor experimental device for optimizing the structure of the well bottom alternating flow field generator according to claim 5, characterized in that: A water inlet valve is installed on the inlet pipe of the mud pump; a diversion pipe is connected to the high-pressure manifold, a diversion valve is installed on the diversion pipe, and the outlet of the diversion pipe is connected to the mud tank; a flow meter is installed between the diversion pipe and the inlet of the top drive device.

9. The indoor experimental device for optimizing the structure of the well bottom alternating flow field generator according to claim 5, characterized in that: A tension gauge is provided between the lifting device and the top drive device. A displacement sensor is installed between the top of the top drive device and the top of the test frame. A high-speed camera is fixed at the bottom center of the transparent reflux trough. The bottom support of the transparent reflux trough is supported on the ground by a gravity sensor. The signal lines of the tension gauge, displacement sensor, gravity sensor and high-speed camera are connected to the data acquisition terminal.

10. The indoor experimental device for optimizing the structure of the well bottom alternating flow field generator according to claim 5, characterized in that: The pulse generating tool includes a cylinder with a water inlet at the upper end and a water outlet at the lower end. An upper shaft, coaxial with the cylinder, is located in the middle section of the cylinder's inner cavity. The middle part of the upper shaft is supported in a bearing seat by a bearing. The outer periphery of the bearing seat is supported on the upper step of the cylinder by a bearing seat flange. Multiple water-permeable holes are evenly distributed on the bearing seat flange. The lower end of the upper shaft is screwed onto the upper part of the impeller's central hole. A lower shaft is screwed onto the lower part of the impeller's central hole. The lower end of the lower shaft is fixed in the central hole of a moving valve disc. The moving valve disc covers a stationary valve disc, and the outer periphery of the lower end face of the stationary valve disc is supported on the lower step of the cylinder. Flow holes are provided on both the moving and stationary valve discs.

11. The indoor experimental device for optimizing the structure of the well bottom alternating flow field generator according to claim 10, characterized in that: The bottom of the bearing housing is closed, a lower bearing assembly is installed in the inner cavity of the bearing housing, an upper bearing assembly is provided at the upper end of the bearing housing, an upper pressure plate is provided above the upper bearing assembly, a locking nut is provided above the upper pressure plate, and the locking nut is screwed onto the upper shaft. The lower bearing assembly is a radial ball bearing, and the upper bearing assembly is a thrust bearing.

12. The indoor experimental device for optimizing the structure of the wellbore alternating flow field generator according to claim 10, characterized in that: An inlet pressure sensor is installed on the outer side of the cylinder wall at the inlet of the cylinder, and an outlet pressure sensor is installed on the outer side of the cylinder wall at the outlet of the cylinder. A magnet is installed on the impeller, and a counter that can sense the magnet is installed on the outer wall of the cylinder. The signal lines of the inlet pressure sensor, the outlet pressure sensor, and the counter are connected to a data acquisition terminal.

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