Simulation equipment and method for forming mud cake through circulation of underground drilling fluid

Abstract

The invention discloses a simulation device and method for forming a mud cake through circulation of underground drilling fluid, and belongs to the technical field of oil and gas well drilling. In order to solve the problems that manual taking and weighing efficiency is low, measured data are inaccurate, and mud cake performance evaluation accuracy is affected, the simulation equipment for forming the mud cake through circulation of the underground drilling fluid comprises a base, a simulation platform and a control console are fixed to the top of the base, a simulation bin is fixed to the simulation platform, and the control console is connected with the simulation bin. A drilling fluid outlet is formed in the bottom of the simulation bin, a supporting column is fixed to the inner surface of the simulation bin, a sliding column is slidably connected into the supporting column, a water collecting base is fixed to the top surface of the sliding column, a placing base is fixed to the water collecting base, a rock core is placed on the placing base, and a spraying assembly and a circulating assembly are installed on the simulation bin. According to the invention, data deviation can be reduced, so that test data can more accurately reflect performance parameters of the mud cake under a real working condition, and the credibility of a test result is improved.

Description

Technical Field

[0001] This invention relates to the field of oil and gas well drilling technology, specifically to a simulation device and method for forming mud cake through downhole drilling fluid circulation. Background Technology

[0002] Mud cake is formed by the filtration of drilling fluid in the formation. As the drilling depth increases, the pressure and temperature of the formation continue to increase. Under the action of pressure difference, the solid phase in the drilling fluid is filtered and deposited on the well wall during the circulation process in the well to form mud cake. Mud cake is an important factor affecting the stability of the well wall.

[0003] Chinese patent CN109541175B discloses an apparatus and method for simulating the circulation of drilling fluid in a well to form mud cake. This apparatus and method overcome the problem that in previous devices, the drilling fluid was only stirred in a closed cavity rather than in the actual flow and circulation state in the well. At the same time, it can realistically simulate the pressure in the actual wellbore and formation, and simulate the mud cake formation process under the temperature and pressure conditions in the well, maximizing the realism of simulating the formation and flushing process of mud cake.

[0004] The patent mentioned above determines whether a core sample is saturated with drilling fluid by manually removing and weighing it. However, the core weighing process relies on manually opening the simulation chamber to remove and place the core, which not only increases the labor intensity of the staff but also takes a long time, seriously affecting the efficiency of the test. Secondly, the manual removal and weighing of the core sample can easily cause drilling fluid loss, which will lead to inaccurate measurement of the amount of drilling fluid absorbed by the core sample. This will cause deviations in the simulated data of mud cake formation, resulting in deviations in the test results and affecting the accuracy of mud cake performance evaluation.

[0005] To address the above issues, a simulation device and method for forming mud cake through downhole drilling fluid circulation is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a simulation device and method for forming mud cake through downhole drilling fluid circulation. By using this invention, the problems of slow efficiency, inaccurate measurement data, and impaired accuracy of mud cake performance evaluation caused by manual weighing are solved.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a simulation device for forming mud cake by circulating drilling fluid in a downhole well, comprising a base, a simulation platform and a control console fixed on the top of the base, a simulation chamber fixed on the simulation platform, a drilling fluid outlet at the bottom of the simulation chamber, a support column fixed on the inner surface of the simulation chamber, a sliding column slidably connected inside the support column, a water collection seat fixed on the top surface of the sliding column, a placement seat fixed on the water collection seat, a core placed on the placement seat, and a spray assembly and a circulation assembly installed on the simulation chamber;

[0008] The simulation chamber is equipped with a drainage weighing assembly, which includes an electric actuator fixedly connected to the bottom of the simulation chamber. A lifting plate is fixedly connected to the top of the electric actuator, and an arc-shaped plate is fixedly connected to the lifting plate. A water collection pipe is connected to the bottom of the water collection base, and a drain pipe is connected to the end of the water collection pipe. A piston is slidably connected inside the water collection pipe. A sliding rod is fixedly connected to the end of the piston, and a protruding rod is fixedly connected to the end of the sliding rod. A slidable groove plate is slidably sleeved on the outside of the protruding rod. An electromagnet is fixedly connected to the top surface of the slidable groove plate. A second spring is fixedly connected to the top of the electromagnet, and an electromagnet is fixedly connected to the other end of the second spring. A support column is slidably connected to the side wall of the slidable groove plate. An extension column is slidably connected inside the support column. An electromagnet is fixedly fixed to the bottom surface of the extension column, and an electromagnet is fixedly fixed to the inner surface of the simulation chamber.

[0009] Furthermore, a U-shaped pipe is connected to the bottom of the drilling fluid outlet, a delivery pipe is connected to one end of the U-shaped pipe, an output pipe is connected to one end of the delivery pipe, a delivery pump is installed on the output pipe, and a drilling fluid storage tank is fixed on the base, the drilling fluid storage tank being connected to the delivery pipe.

[0010] Furthermore, a frustum is fixedly connected to the bottom surface of the sliding column, a cavity is opened inside the support column, the frustum is slidably connected to the cavity, and a first spring is sleeved on the outer ring of the sliding column, with the two ends of the first spring being fixedly connected to the top surface of the frustum and the inner top surface of the support column, respectively.

[0011] Furthermore, a pressure sensor is installed on the bottom surface of the truncated cone, and the pressure sensor is electrically connected to the control console.

[0012] Furthermore, a groove is provided inside the support column, the extension column is slidably connected to the groove, and a compression spring is fixedly connected between the extension column and the groove. The two ends of the compression spring are fixedly connected to the inner wall of the groove and the top surface of the extension column, respectively.

[0013] Furthermore, the top of the output pipe is connected to a drilling fluid injection pipe, and the spray assembly includes a mounting bracket fixedly connected to the side wall of the simulation chamber. A motor is fixedly connected to the top of the mounting bracket, and a drive shaft is fixedly connected to the output end of the motor. A drive gear is fixedly sleeved on the outside of the drive shaft. A support shaft is fixedly connected to the top surface of the simulation chamber, and a driven gear is rotatably connected to the support shaft. A nozzle is fixedly connected in the middle of the driven gear, and the nozzle is rotatably connected to the support shaft and rotatably sleeved with the drilling fluid injection pipe.

[0014] Furthermore, the circulation assembly includes a connecting rod fixedly connected to the bottom surface of the transmission shaft, a turntable fixedly connected to the bottom of the connecting rod, an embedded rod fixedly connected to the bottom surface of the turntable, a pressure tank fixedly connected to the top surface of the simulation platform, a pressure relief valve installed on the top of the pressure tank, a sleeve fixedly connected to the inner wall of the pressure tank, a piston 2 slidably connected inside the sleeve, a loop plate fixedly connected to the end side of the piston 2, and the loop plate slidingly sleeved with the protruding rod.

[0015] Furthermore, the side wall of the pressure tank is connected to a gas transmission pipe, a control valve is installed on the gas transmission pipe, and the other end of the gas transmission pipe is connected to a drilling fluid storage tank.

[0016] Furthermore, the side wall of the U-shaped tube is connected to a drain water pipe, the bottom of the drain water pipe is connected to a second drilling fluid storage tank, the end of the second drilling fluid storage tank is connected to a delivery pipe, and the delivery pipe is connected to the simulation chamber.

[0017] The present invention also proposes another technical solution: a simulation method for a simulation device for forming mud cake through downhole drilling fluid circulation, comprising the following steps:

[0018] S1: Open the simulation chamber, place the core on the placement seat, and the weight of the core is transmitted to the sliding column through the placement seat, causing the sliding column to move downward against the elastic force of the first spring. The pressure sensor on the bottom of the sliding column converts the sensed pressure signal into an electrical signal, and displays and records the weight of the core through the control console.

[0019] S2: Start the electric actuator to extend upward, driving the lifting plate and arc plate to rise. The lifting plate pushes the water collection seat and core to rise, and the pressure sensor pressure value is cleared to zero. At the same time, the arc plate pushes the inclined plate to slide up along the support column. The vertical movement of the inclined plate is converted into the horizontal movement of the convex rod through the annular inclined groove, which drives the piston to slide outward in the water collection pipe, so that a negative pressure environment is formed in the water collection seat and water collection pipe, completing the preparation before drilling fluid injection.

[0020] S3: Close the output pipe solenoid valve to block the delivery pipe and the U-shaped pipe channel, turn on the delivery pump to send the drilling fluid in the drilling fluid storage tank one into the drilling fluid injection pipe, and start the motor at the same time to drive the nozzle to rotate on the top of the simulation chamber through gear transmission to rotate and spray the core. The drilling fluid that is not adsorbed flows into the drilling fluid storage tank two.

[0021] S4: When the motor drives the transmission shaft to rotate, it synchronously drives the turntable and the inner rod to rotate. The inner rod pushes the return plate to make the piston two slide back and forth in the pressure tank sleeve to pressurize. After the control valve is opened, the drilling fluid in the drilling fluid storage tank two is sent back to the simulation chamber through the delivery pipe to spray again.

[0022] S5: Turn off the delivery pump to stop the drilling fluid delivery, let it stand to allow the surface drilling fluid to leak into the water collection seat, de-energize electromagnet one and electromagnet two, and energize electromagnet three and electromagnet four, fix the support column, start the electric push rod to retract, the arc plate disengages from the inclined plate, the inclined plate moves down and drives piston one to slide back, squeezing out the drilling fluid in the water collection pipe and discharging it through the drain pipe.

[0023] S6: After the core absorbs drilling fluid, its gravity increases, causing the slide column to move down again. The pressure sensor detects the pressure signal and transmits it to the control console. The weight of the core is obtained through data analysis, and it is determined whether the core has reached a saturated state. If it is saturated, the subsequent mud cake forming step is carried out. If it is not saturated, the steps S3-S6 are repeated until it is saturated.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] By incorporating a drainage weighing component, this equipment eliminates the need for manual opening of the simulation chamber to weigh cores during simulation tests. Pressure sensors automatically convert pressure signals into electrical signals, and the control panel directly displays the core weight, reducing manual operation, lowering the workload of staff, and avoiding time-consuming manual processes, thus improving test efficiency. It also prevents drilling fluid loss during manual core handling, ensuring accurate measurement of the amount of drilling fluid absorbed by the core and preventing deviations in the mud cake formation simulation data due to drilling fluid loss, making the test results more reliable. Furthermore, it enables real-time monitoring of the drilling fluid state absorbed by the core, allowing for flexible adjustments to the test procedures based on the monitoring results, optimizing the test process, and enhancing the scientific rigor of the mud cake formation simulation test. Effectiveness: The spraying assembly sprays drilling fluid onto the core surface in a circular motion, avoiding the problems of excessively thick or thin localized areas caused by traditional fixed spraying. This ensures uniform adsorption of drilling fluid in all areas of the core, forming a mud cake of consistent thickness. This more realistically simulates the uniformity of downhole mud cakes and improves the accuracy of mud cake performance evaluation. After being pressurized by the circulation assembly, the fluid is re-transported to the simulation chamber for spraying through the delivery pipe, enabling the reuse of drilling fluid, reducing resource waste, and lowering test costs. The rotating spraying and recycling mechanism more closely resembles the dynamic scouring and penetration effects of drilling fluid during actual drilling, making the mud cake formation process more consistent with downhole physical laws. The test data can more accurately reflect the performance parameters of the mud cake under real working conditions, improving the credibility of the test results. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0027] Figure 2 This is a schematic diagram of the overall structure of the invention;

[0028] Figure 3 This is a schematic diagram of the overall cross-sectional structure of the present invention;

[0029] Figure 4This is a schematic diagram of the support and sliding column structure of the present invention;

[0030] Figure 5 This is a schematic diagram of the drainage weighing component structure of the present invention;

[0031] Figure 6 for Figure 5 A schematic diagram of the cross-sectional structure;

[0032] Figure 7 This is a schematic diagram of some components of the drainage weighing assembly of the present invention;

[0033] Figure 8 This is a schematic diagram of the structure of some components of the circulation component of the present invention;

[0034] Figure 9 This is a schematic diagram of the loop component structure of the present invention;

[0035] Figure 10 This is a front view of the spray assembly of the present invention;

[0036] Figure 11 This is a bottom view of the spray assembly structure of the present invention;

[0037] Figure 12 This is a schematic diagram of the axial view of the spray assembly of the present invention.

[0038] In the diagram: 1. Base; 2. Simulation platform; 21. Drilling fluid outlet; 22. U-shaped pipe; 23. Output pipe; 24. Transfer pump; 25. Drilling fluid storage tank one; 3. Control console; 4. Simulation chamber; 5. Support column; 6. Sliding column; 61. Cavity; 62. Frustum; 63. Pressure sensor; 64. First spring; 7. Water collection seat; 71. Water collection pipe; 72. Drainage pipe; 8. Placement seat; 9. Core; 10. Drainage and weighing assembly; 101. Electric actuator; 102. Lifting plate; 103. Arc plate; 104. Piston one; 105. Sliding rod; 106. Protruding rod; 107. Inclined groove plate; 108. Electromagnet one; 109. Second spring; 110. Electromagnet two; 111 11. Support column; 112. Groove; 113. Compression spring; 114. Extension column; 115. Electromagnet three; 116. Electromagnet four; 11. Drilling fluid injection pipe; 12. Spray assembly; 121. Mounting bracket; 122. Motor; 123. Drive shaft; 124. Drive gear; 125. Driven gear; 126. Nozzle; 127. Support shaft; 13. Circulation assembly; 131. Connecting rod; 132. Turntable; 133. Embedded rod; 134. Reverse plate; 135. Piston two; 136. Pressure tank; 137. Sleeve; 138. Pressure relief valve; 139. Gas supply pipe; 140. Control valve; 141. Drainage water pipe; 142. Drilling fluid storage tank two; 143. Infusion pipe. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] To address the technical problem that the equipment needs to repeatedly weigh and remove core 9 when simulating drilling fluid saturation, resulting in a slow process and potential drilling fluid loss during the weighing and removal process, which can lead to deviations in the simulation data during subsequent mud cake formation, the following measures are proposed. Figure 1 - Figure 9 As shown, the following preferred technical solutions are provided:

[0041] A simulation device for forming mud cake by circulating drilling fluid in a downhole well includes a base 1, a simulation platform 2 and a control console 3 fixed on the top of the base 1, a simulation chamber 4 fixed on the simulation platform 2, a drilling fluid outlet 21 opened at the bottom of the simulation chamber 4, a support column 5 fixed on the inner surface of the simulation chamber 4, a sliding column 6 slidably connected inside the support column 5, a water collection seat 7 fixed on the top surface of the sliding column 6, a placement seat 8 fixed on the water collection seat 7, and a core 9 placed on the placement seat 8.

[0042] The simulation chamber 4 is equipped with a drainage weighing assembly 10. The drainage weighing assembly 10 includes an electric push rod 101 fixedly connected to the bottom of the simulation chamber 4, a lifting plate 102 fixedly connected to the top of the electric push rod 101, an arc plate 103 fixedly connected to the lifting plate 102, a water collection pipe 71 connected to the bottom of the water collection base 7, a drain pipe 72 connected to the end of the water collection pipe 71, a piston 104 slidably connected inside the water collection pipe 71, a slide rod 105 fixedly connected to the end of the piston 104, and a protrusion fixedly connected to the end of the slide rod 105. Rod 106, with a slidable groove plate 107 externally slidably connected to the outside of the protruding rod 106. Electromagnet 108 is fixedly connected to the top surface of the slidable groove plate 107. A second spring 109 is fixedly connected to the top of the first electromagnet 108. Electromagnet 2 110 is fixedly connected to the other end of the second spring 109. A support column 111 is slidably connected to the side wall of the slidable groove plate 107. An extension column 114 is slidably connected inside the support column 111. Electromagnet 3 115 is fixed to the bottom surface of the extension column 114. Electromagnet 4 116 is fixed to the inner surface of the simulation chamber 4.

[0043] A frustum 62 is fixedly connected to the bottom surface of the sliding column 6. A cavity 61 is opened inside the support column 5. The frustum 62 and the cavity 61 are slidably connected. A first spring 64 is sleeved on the outer ring of the sliding column 6. The two ends of the first spring 64 are fixedly connected to the top surface of the frustum 62 and the inner top surface of the support column 5, respectively. A pressure sensor 63 is installed on the bottom surface of the frustum 62. The pressure sensor 63 is electrically connected to the control console 3.

[0044] The support column 111 has a groove 112 inside, the extension column 114 is slidably connected to the groove 112, and a compression spring 113 is fixedly connected between the extension column 114 and the groove 112. The two ends of the compression spring 113 are fixedly connected to the inner wall of the groove 112 and the top surface of the extension column 114, respectively.

[0045] Specifically, in the initial state, the electric actuator 101 is in a retracted state, and the lifting plate 102 fixed thereto is not in contact with the water collection seat 7. Electromagnet 108 and electromagnet 315 are energized, causing the inclined slot plate 107 to attract the support column 111, so that the support column 111 and the inclined slot plate 107 form a whole. Electromagnet 315 and electromagnet 416 at the bottom of the extension column 114 are also not energized, and there is no contact between electromagnet 315 and electromagnet 416. When the compression spring 113 releases the relative restriction, it will use its own performance to drive the extension column 114 to slide quickly into the groove 112, so that the extension column 114 and electromagnet 315 enter the groove 112 and are suspended.

[0046] When conducting a simulated downhole mud cake formation test on core 9, the simulation chamber 4 is first opened, and the core 9 to be tested is placed in the placement seat 8. Core 9 has its own gravity. When core 9 enters the placement seat 8, as... Figure 4 As shown, the weight of the core 9 is transmitted to the slide column 6 through the placement seat 8, causing the slide column 6 to move downward a certain distance against the elastic force of the first spring 64. As the slide column 6 moves downward, the pressure sensor 63 on the bottom surface of the slide column 6 is subjected to the pressure of the slide column 6 and the core 9. According to Hooke's Law, the elastic force of the first spring 64 is proportional to the deformation. Within the elastic limit, the elastic force of the first spring 64 is equal to the weight of the object. The pressure measured by the pressure sensor 63 is equal to the sum of the weight of the object and the weight of the slide column 6 (before measurement, the weight line of the connected parts is measured, and then subtracted from the measurement result to obtain the weight of the core 9). When the pressure sensor 63 senses the pressure, it converts the sensed pressure signal into an electrical signal, which is then displayed in digital form by the control console 3 connected to the pressure sensor 63, so that the staff conducting the experiment can view and record it.

[0047] like Figures 1-7As shown, after the weight of the core 9 is weighed, drilling fluid needs to be injected. Before injecting the drilling fluid, the water collection seat 7, the placement platform, and the core 9 need to be supported. When supporting, the electric actuator 101 is activated and extends upward. Since the electric actuator 101 is fixedly connected to the lifting plate 102, the lifting plate 102 at its top will rise synchronously as the electric actuator 101 extends. When the lifting plate 102 rises to contact the water collection seat 7, it will drive the water collection seat 7 to rise, and the core 9 in the placement seat 8 above it will also rise. Since the water collection seat 7 is fixedly connected to the sliding column 6, the sliding column 6 connected to the water collection seat 7 will also slide upward in the cavity 61 of the sliding column 6 and squeeze the first spring 64, so that the pressure is released. At this time, the pressure value detected by the pressure sensor 63 is cleared to zero.

[0048] like Figure 3 , Figure 5-7 As shown, as the electric actuator 101 drives the lifting plate 102 to rise vertically, the arc-shaped plate 103 fixed to it moves upward synchronously. When the arc-shaped plate 103 contacts the inclined slot plate 107, based on the sliding connection structure between the inclined slot plate 107 and the support column 111, the inclined slot plate 107 slides upward along the axis of the support column 111 under the thrust. Figure 8 As shown, during the upward movement of the inclined plate 107, the annular inclined groove converts the vertical displacement into the horizontal movement of the protruding rod 106, pushing the protruding rod 106 to slide outward radially.

[0049] Because the convex rod 106, the sliding rod 105, and the piston 104 adopt a rigid connection design, and the piston 104 is tightly fitted to the inner wall of the water collection pipe 71, the horizontal displacement of the convex rod 106 is directly transmitted to the piston 104 through the sliding rod 105, causing the piston 104 to slide outward in the water collection pipe 71. During this process, the water collection seat 7 and the cavity of the water collection pipe 71 form a volume increase trend. Utilizing the principle of negative pressure in fluid mechanics, the internal space is quickly evacuated. Thus, a negative pressure environment is formed in the simulation chamber 4, completing the fully automated preparation process before drilling fluid injection and providing standardized initial conditions for subsequent tests.

[0050] like Figure 3 and Figure 5 As shown, when drilling fluid is injected, some drilling fluid will remain on the water collection seat 7 and the placement seat 8. During weighing, the residual drilling fluid will affect the weighing result, which in turn will affect the judgment of the saturation state of the core 9. Therefore, multiple through holes are opened on the top of the water collection seat 7, and the top is set in an inclined shape. When the drilling fluid is sprayed, the drilling fluid remaining on the water collection seat 7 will fall into the water collection seat 7 and enter the water collection pipe 71.

[0051] After the drilling fluid has been injected for a period of time, it is necessary to determine whether the core 9 has absorbed the drilling fluid to the point of saturation. In the existing technology, when judging the saturation state of the core 9, the delivery of drilling fluid is stopped first, then the simulation chamber 4 is opened, and then the core 9 is manually taken out for weighing. However, in this process, some of the drilling fluid in the core 9 is easily lost.

[0052] like Figure 3 As shown, compared with the prior art, when this equipment makes a judgment, it first shuts off the delivery pump 24 to stop the delivery of drilling fluid, and then lets it stand for a while. After the drilling fluid floating on the surface leaks into the water collection seat 7, the core 9 needs to be weighed for judgment. Before judgment, the drilling fluid stored in the water collection seat 7 needs to be drained. During drainage, the support column 111 needs to be fixed to the inner surface of the simulation chamber 4, and then the inclined plate 107 is supported. At this time, electromagnet one 108 and electromagnet two... When power is cut off between 110 and 116, the second spring 109 is released from its restriction and regains its elasticity, activating electromagnets 115 and 116. Electromagnets 115 and 116 are energized and generate an attractive force, causing the extension column 114 to slide within the groove 112 under the action of the attractive force and stretching the compression spring 113. This causes electromagnets 115 and 116 to adhere to each other, so that the support column 111 is firmly adhered to the inner surface of the simulation chamber 4. At this time, the support column 111 is in a fixed and static state.

[0053] Then, the electric actuator 101 is activated for retraction. The lifting plate 102 at the top of the electric actuator 101 then slides down. As the lifting plate 102 slides down, the arc-shaped plate 103, which is fixed to the lifting plate 102, moves down synchronously, causing the arc-shaped plate 103 to disengage from the inclined slot plate 107, thereby releasing the resistance to the inclined slot plate 107. At the moment the arc-shaped plate 103 disengages, the second spring 109 releases its relative restriction and drives the inclined slot plate 107 to move down, causing the inclined slot plate 107 to move along the support... The column 111 slides vertically downward, and because the protruding rod 106 is slidably connected to the inclined groove plate 107, the vertical downward movement of the inclined groove plate 107 will be converted into the horizontal movement of the protruding rod 106. This causes the sliding rod 105 on the end of the protruding rod 106 to drive the piston 104 to slide back in the water collection pipe 71. As the piston 104 slides in contact with the water collection pipe 71, it will squeeze out the drilling fluid in the water collection pipe 71 and let it leak out through the drain pipe 72, so that the excess drilling fluid is discharged.

[0054] like Figure 3-5As shown, with the discharge of drilling fluid, the weight of the core 9 increases after absorbing the drilling fluid. This increased weight is transmitted to the sliding column 6 via the placement seat 8, causing the sliding column 6 to move downwards a certain distance against the elastic force of the first spring 64. As the sliding column 6 moves downwards, the pressure sensor 63 on the bottom surface of the sliding column 6 is subjected to the pressure of the sliding column 6 and the core 9, thus detecting the tension of the first spring 64. Since the tension of the first spring 64 is adapted to gravity, the pressure sensor 63 detects that the weight of the core 9 and the connecting components is transmitted to the control console 3. The pressure sensor 63 converts the sensed pressure signal into an electrical signal, which the control console 3 then analyzes. By subtracting the weight of the connecting components themselves, the weight of core 9 can be obtained. The weight is displayed in numerical form on console 3 so that the personnel conducting the experiment can check the weight of core 9 and determine whether core 9 is saturated. If it is saturated, the subsequent mud cake forming step continues. The mud cake forming step is already described in the prior art document (publication number CN109541175B), so it will not be described in detail. If it is determined that core 9 is unsaturated, drilling fluid is injected. After a period of time, the above steps are repeated for weighing and judgment until core 9 is saturated and then the subsequent operation continues.

[0055] This setup enables fully automated control of the entire process, allowing for the removal of drilling fluid residue, dynamic weighing of core 9, and determination of saturation status without manual intervention. This not only reduces the labor intensity of operators but also eliminates drilling fluid loss by avoiding manual contact with core 9, ensuring that the weighing data accurately reflects the adsorption amount of core 9. This provides a reliable basis for mud cake formation simulation and effectively improves the accuracy of experimental data and process stability.

[0056] To address the technical problem of uneven drilling fluid spraying during the drilling fluid spraying process, resulting in uneven mud cake formation, affecting the test results of simulation data, and hindering the effective utilization of drilling fluid, such as... Figure 1 - Figure 3 , Figures 9-12 As shown, the following preferred technical solutions are provided:

[0057] A U-shaped pipe 22 is connected to the bottom of the drilling fluid outlet 21. A delivery pipe is connected to one end of the U-shaped pipe 22, and an output pipe 23 is connected to the other end of the delivery pipe. A delivery pump 24 is installed on the output pipe 23. A drilling fluid storage tank 25 is fixed on the base 1 and is connected to the delivery pipe. A drilling fluid injection pipe 11 is connected to the top of the output pipe 23. The drilling fluid storage tank 25 serves as the initial fluid source and is connected to the output pipe 23 via the delivery pipe. After the delivery pump 24 starts, the drilling fluid in the storage tank 25 is pumped into the drilling fluid injection pipe 11 through the output pipe 23, providing power for the spraying process.

[0058] A spray assembly 12 is installed on the simulation chamber 4. The spray assembly 12 includes a mounting frame 121 fixedly connected to the side wall of the simulation chamber 4. A motor 122 is fixedly connected to the top of the mounting frame 121. A drive shaft 123 is fixedly connected to the output end of the motor 122. A drive gear 124 is fixedly sleeved on the outside of the drive shaft 123. A support shaft 127 is fixedly connected to the top surface of the simulation chamber 4. A driven gear 125 is rotatably connected to the support shaft 127. A nozzle 126 is fixedly connected in the middle of the driven gear 125. The nozzle 126 is rotatably connected to the support shaft 127 and rotatably sleeved with the drilling fluid injection pipe 11. Traditional nozzles 126 have a fixed spray angle, which can easily create spray blind spots. Rotating nozzles 126 use centrifugal force to diffuse the drilling fluid into a mist. Combined with the airflow disturbance in the simulation chamber 4, this can eliminate the spray dead angle on the leeward side of the core 9. The tangential velocity generated by the rotation of nozzles 126 causes relative motion between the drilling fluid and the surface of the core 9, simulating the scouring effect of downhole drilling fluid and more realistically reflecting the adsorption characteristics of the core 9 in a dynamic fluid environment.

[0059] The simulation chamber 4 is equipped with a circulation assembly 13, which includes a connecting rod 131 fixedly connected to the bottom of the drive shaft 123. A turntable 132 is fixedly connected to the bottom of the connecting rod 131, and an embedded rod 133 is fixedly fixed to the bottom of the turntable 132. A pressure tank 136 is fixedly connected to the top of the simulation platform 2. A pressure relief valve 138 is installed on the top of the pressure tank 136. A sleeve 137 is fixedly connected to the inner wall of the pressure tank 136. A piston 135 is slidably connected inside the sleeve 137. The piston 135 is fixed at one end. A U-shaped plate 134 is fixedly connected to the pressure tank 136, and the U-shaped plate 134 slides in a sleeve with the protruding rod 106. A gas supply pipe 139 is connected to the side wall of the pressure tank 136, and a control valve 140 is installed on the gas supply pipe 139. The other end of the gas supply pipe 139 is connected to the second drilling fluid storage tank 142. A drain water pipe 141 is connected to the side wall of the U-shaped pipe 22, and the bottom of the drain water pipe 141 is connected to the second drilling fluid storage tank 142. A delivery pipe 143 is connected to the end of the second drilling fluid storage tank 142, and the delivery pipe 143 is connected to the simulation chamber 4. The reciprocating motion of the second piston 135 compresses the gas in the pressure tank 136, and the gas pressure is transmitted to the second drilling fluid storage tank 142 through the gas supply pipe 139. When the pressure inside the tank exceeds the adsorption resistance of the core 9, the drilling fluid flows back to the simulation chamber 4 through the delivery pipe 143, forming a circulating spray.

[0060] Specifically, when injecting drilling fluid, a solenoid valve is installed in the output pipe 23. The solenoid valve controls the closure of the connection between the delivery pipe and the U-shaped pipe 22, then the delivery pump 24 is turned on. The delivery pump 24 draws the drilling fluid from the drilling fluid storage tank 25 into the output pipe 23 and delivers it into the drilling fluid injection pipe 11. As the drilling fluid is delivered, it enters the nozzle 126. Simultaneously, the motor 122 is started. When the motor 122 starts, it drives the drive shaft 123 at its output end to rotate. Since the drive shaft 123 is fixedly connected to the driving gear 124, and the driven gear 125 is rotatably connected to the support shaft 127, which is fixedly connected to the simulation chamber 4, as shown... Figures 1-3 , Figures 10-12 As shown, when the drive shaft 123 rotates, the drive gear 124 will rotate synchronously, and under the action of gear meshing, it will drive the driven gear 125 to rotate. As the driven gear 125 rotates, the nozzle 126 fixed thereto will rotate synchronously on the top of the simulation chamber 4, so that the drilling fluid will be sprayed. The sprayed drilling fluid will come into contact with the surface of the core 9, so that the core 9 will absorb the drilling fluid. As the nozzle 126 continues to spray, the drilling fluid that is not absorbed by the core 9 will flow into the drilling fluid storage tank 142 through the drilling fluid outlet 21, so that the used drilling fluid can be collected.

[0061] And during the process of motor 122 driving transmission shaft 123 to rotate, such as Figures 10-12 As shown, since the connecting rod 131 is fixedly connected to the drive shaft 123, when the drive shaft 123 rotates, the connecting rod 131 will synchronously drive the bottom turntable 132 to rotate. As the turntable 132 rotates, the embedded rod 133 fixed on the bottom surface of the turntable 132 will rotate synchronously and thus shift, and as... Figure 9As shown, the inner wall of the pressure tank 136 is fixedly connected to the sleeve 137, the piston 135 is slidably connected to the sleeve 137, and the piston 135 is fixedly connected to the spiral plate 134. The spiral plate 134 is slidably sleeved with the inner rod 133. Therefore, when the inner rod 133 rotates, it will move in the spiral groove of the spiral plate 134, thereby pushing the spiral plate 134 to move horizontally. As the spiral plate 134 moves horizontally, the piston 135 fixed to it slides in the sleeve 137. As the turntable 132 continues to rotate, the inner rod 133 will rotate continuously around the circumference, thereby transmitting force to the spiral plate 134, causing the spiral plate 134 to drive the piston 135 to slide back and forth in the sleeve 137. As piston 135 continues its reciprocating motion, it continuously pressurizes the pressure tank 136, then opens the control valve 140. As the pressure increases, the drilling fluid flowing into the drilling fluid storage tank 142 is transported back to the simulation chamber 4 through the delivery pipe 143, allowing the core 9 in the simulation chamber 4 to be sprayed again. This enables the drilling fluid to be reused, reducing drilling fluid loss and ensuring uniform spraying on the surface of the core 9, resulting in a more uniform mud cake formation. This avoids the phenomenon of mud cake being too thick in some areas and too thin in others, thus more realistically reflecting the uniformity of the downhole mud cake and further improving the accuracy of mud cake performance evaluation.

[0062] To better explain the above embodiments, another implementation method is proposed: a simulation method for a downhole drilling fluid circulation simulation device to form mud cake, comprising the following steps:

[0063] Step 1: Open the simulation chamber 4 and place the core 9 on the placement seat 8. The weight of the core 9 is transmitted to the sliding column 6 through the placement seat 8, causing the sliding column 6 to move downward against the elastic force of the first spring 64. The pressure sensor 63 on the bottom surface of the sliding column 6 converts the sensed pressure signal into an electrical signal, and displays and records the weight of the core 9 through the control console 3.

[0064] Step 2: Start the electric actuator 101 to extend upward, driving the lifting plate 102 and the arc plate 103 to rise. The lifting plate 102 pushes the water collection seat 7 and the core 9 to rise, and the pressure sensor 63 resets the pressure value to zero. At the same time, the arc plate 103 pushes the inclined plate 107 to slide upward along the support column 111. The vertical movement of the inclined plate 107 is converted into the horizontal movement of the protruding rod 106 through the annular inclined groove, which drives the piston 104 to slide outward in the water collection pipe 71, so that a negative pressure environment is formed in the water collection seat 7 and the water collection pipe 71, completing the preparation before drilling fluid injection.

[0065] Step 3: Close the solenoid valve of the output pipe 23 to block the passage between the delivery pipe and the U-shaped pipe 22, turn on the delivery pump 24 to send the drilling fluid in the drilling fluid storage tank 1 25 into the drilling fluid injection pipe 11, and at the same time start the motor 122 to drive the nozzle 126 to rotate at the top of the simulation chamber 4 through gear transmission to rotate and spray the core 9. The drilling fluid that is not adsorbed flows into the drilling fluid storage tank 2 142.

[0066] Step 4: When the motor 122 drives the transmission shaft 123 to rotate, it synchronously drives the turntable 132 and the inner rod 133 to rotate. The inner rod 133 pushes the guide plate 134 to make the piston 135 slide back and forth in the sleeve 137 of the pressure tank 136 to pressurize. After opening the control valve 140, the drilling fluid in the drilling fluid storage tank 142 is sent back to the simulation chamber 4 through the delivery pipe 143 for spraying again.

[0067] Step 5: Turn off the delivery pump 24 to stop the drilling fluid delivery, let it stand to allow the surface drilling fluid to leak into the water collection seat 7, de-energize electromagnet 108 and electromagnet 210, and energize electromagnet 315 and electromagnet 416, fix the support column 111, start the electric push rod 101 to retract, the arc plate 103 disengages from the inclined groove plate 107, the inclined groove plate 107 moves down and drives piston 104 to slide back, squeezing out the drilling fluid in the water collection pipe 71 and discharging it through the drain pipe 72;

[0068] Step 6: After the core 9 absorbs drilling fluid, its gravity increases, causing the slide column 6 to move down again. The pressure sensor 63 detects the pressure signal and transmits it to the control console 3. The weight of the core 9 is obtained through data analysis, and it is determined whether the core 9 has reached a saturated state. If it is saturated, the subsequent mud cake forming step is carried out. If it is not saturated, steps S3-S6 are repeated until it is saturated.

[0069] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0070] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A simulation device for the formation of a mud cake by a circulating drilling fluid downhole, comprising a base (1), characterized in that: The top of the base (1) is fixed with an analog platform (2) and a control console (3), the analog platform (2) is fixed with an analog bin (4), the bottom of the analog bin (4) is provided with a drilling fluid discharge port (21), the inner surface of the analog bin (4) is fixed with a support column (5), the support column (5) is slidably connected with a sliding column (6), the top surface of the sliding column (6) is fixed with a water collecting seat (7), the water collecting seat (7) is fixed with a placing seat (8), the placing seat (8) is placed with a core (9), the analog bin (4) is provided with a spraying assembly (12) and a circulating assembly (13); The inner surface of the analog bin (4) is provided with a drainage weighing assembly (10), the drainage weighing assembly (10) comprises an electric push rod (101) fixedly connected with the bottom surface of the analog bin (4), the top of the electric push rod (101) is fixedly connected with a jacking plate (102), the jacking plate (102) is fixedly connected with an arc plate (103), the bottom of the water collecting seat (7) is communicated with a water collecting pipe (71), the end side of the water collecting pipe (71) is communicated with a liquid discharge pipe (72), the water collecting pipe (71) is slidably connected with a piston one (104), the end side of the piston one (104) is fixedly connected with a sliding rod (105), the end side of the sliding rod (105) is fixedly connected with a convex rod (106), the outer part of the convex rod (106) is slidably sleeved with an inclined chute plate (107), the top surface of the inclined chute plate (107) is fixedly connected with an electromagnet one (108), the top of the electromagnet one (108) is fixedly connected with a second spring (109), the other end of the second spring (109) is fixedly connected with an electromagnet two (110), the side wall of the inclined chute plate (107) is slidably connected with a supporting column (111), the supporting column (111) is slidably connected with an extension column (114), the bottom surface of the extension column (114) is fixedly connected with an electromagnet three (115), the inner surface of the analog bin (4) is fixedly connected with an electromagnet four (116).

2. A simulated device for forming a mud cake from a circulating drilling fluid downhole according to claim 1, wherein: The bottom of the drilling fluid discharge port (21) is communicated with a U-shaped pipe (22), the end side of the U-shaped pipe (22) is communicated with a conveying pipe, the end side of the conveying pipe is communicated with an output pipe (23), the output pipe (23) is provided with a conveying pump (24), the base (1) is fixed with a drilling fluid storage tank one (25), the drilling fluid storage tank one (25) is communicated with the conveying pipe.

3. A simulated device for forming a mud cake from a circulating drilling fluid downhole according to claim 2, wherein: The bottom surface of the sliding column (6) is fixedly connected with a circular table (62), the support column (5) is provided with a cavity (61), the circular table (62) is slidably connected with the cavity (61), the outer circle of the sliding column (6) is sleeved with a first spring (64), the two ends of the first spring (64) are fixedly connected with the top surface of the circular table (62) and the inner top surface of the support column (5) respectively.

4. A simulated apparatus for forming a mud cake from a circulating drilling fluid downhole as claimed in claim 3, wherein: The bottom surface of the circular table (62) is provided with a pressure sensor (63), the pressure sensor (63) is electrically connected with the control console (3).

5. A simulated apparatus for forming a mud cake from a circulating drilling fluid downhole as claimed in claim 4, wherein: The support column (111) is provided with a groove (112), the extension column (114) is in sliding connection with the groove (112), and the extension column (114) and the groove (112) are fixedly connected with a compression spring (113), and the two ends of the compression spring (113) are fixedly connected with the inner wall of the groove (112) and the top surface of the extension column (114) respectively.

6. A simulated apparatus for forming a mud cake from a circulating drilling fluid downhole as claimed in claim 5 wherein: The top of the output pipe (23) is communicated with a drilling fluid injection pipe (11), the spraying assembly (12) comprises a mounting frame (121) fixedly connected to the side wall of the simulation bin (4), the top of the mounting frame (121) is fixedly connected with a motor (122), the output end of the motor (122) is fixedly connected with a transmission shaft (123), the outer portion of the transmission shaft (123) is fixedly sleeved with a driving gear (124), the top surface of the simulation bin (4) is fixedly connected with a support shaft (127), the support shaft (127) is rotatably connected with a driven gear (125), the middle portion of the driven gear (125) is fixedly connected with a spray head (126), the spray head (126) is rotatably connected with the support shaft (127), and the spray head (126) is rotatably sleeved with the drilling fluid injection pipe (11).

7. A simulated device for forming a mud cake from a circulating drilling fluid downhole according to claim 6, wherein: The circulating assembly (13) comprises a connecting rod (131) fixedly connected to the bottom surface of the transmission shaft (123), the bottom of the connecting rod (131) is fixedly connected with a rotating disc (132), the bottom surface of the rotating disc (132) is fixedly connected with an embedded rod (133), the top surface of the simulation platform (2) is fixedly connected with a pressure tank (136), the top of the pressure tank (136) is provided with a pressure relief valve (138), the inner wall of the pressure tank (136) is fixedly connected with a sleeve (137), the sleeve (137) is slidably connected with a piston (135), the end side of the piston (135) is fixedly connected with a meander plate (134), and the meander plate (134) is sleeved with the protruding rod (106) in sliding mode.

8. A simulated apparatus for forming a mud cake from a circulating drilling fluid downhole according to claim 7, wherein: The side wall of the pressure tank (136) is communicated with a gas conveying pipe (139), the gas conveying pipe (139) is provided with a control valve (140), and the other end of the gas conveying pipe (139) is communicated with a drilling fluid storage tank (142).

9. A simulated apparatus for forming a mud cake from a circulating drilling fluid downhole according to claim 8, wherein: The side wall of the U-shaped pipe (22) is communicated with a drainage water pipe (141), the bottom of the drainage water pipe (141) is communicated with the drilling fluid storage tank (142), the end side of the drilling fluid storage tank (142) is communicated with a liquid conveying pipe (143), and the liquid conveying pipe (143) is communicated with the simulation bin (4).

10. A simulation method applied to a simulation device for forming a mud cake of a drilling fluid circulating downhole according to any one of claims 1 to 9, characterized in that, The method comprises the following steps: S1: open the simulation bin (4), place the core (9) on the placing seat (8), the gravity of the core (9) is transmitted to the sliding column (6) through the placing seat (8), the sliding column (6) is lowered under the action of the elastic force of the first spring (64), the pressure sensor (63) on the bottom surface of the sliding column (6) converts the sensed pressure signal into an electric signal, and the weight of the core (9) is displayed through the control console (3) and recorded. S2: Start the electric push rod (101) to stretch out upward, drive the jacking plate (102) and the arc plate (103) to rise, the jacking plate (102) pushes the water collecting seat (7) and the core (9) to rise, the pressure sensor (63) pressure value clears zero, at the same time, the arc plate (103) pushes the inclined chute plate (107) to slide along the support column (111), and the inclined chute plate (107) is converted into the horizontal movement of the convex rod (106) through the vertical movement of the annular chute, drives the piston one (104) to slide outward in the water collecting pipe (71), so that the water collecting seat (7) and the water collecting pipe (71) form a negative pressure environment, and the preparation before the drilling fluid injection is completed; S3: Close the output pipe (23) electromagnetic valve to block the channel of the conveying pipe and the U-shaped pipe (22), open the conveying pump (24) to send the drilling fluid in the drilling fluid storage tank one (25) into the drilling fluid injection pipe (11), and simultaneously start the motor (122), drive the nozzle (126) to rotate at the top of the simulation bin (4) through gear transmission, and spray the core (9); the drilling fluid not adsorbed flows into the drilling fluid storage tank two (142); S4: When the motor (122) drives the transmission shaft (123) to rotate, the turntable (132) and the embedded rod (133) are synchronously driven to rotate, the embedded rod (133) pushes the meandering plate (134) to make the piston two (135) reciprocate in the sleeve (137) of the pressure tank (136) to pressurize, after the control valve (140) is opened, the drilling fluid in the drilling fluid storage tank two (142) is sent back to the simulation bin (4) through the liquid conveying pipe (143) for spraying again; S5: Close the conveying pump (24) to stop the drilling fluid conveying, and stand still to make the surface drilling fluid leak into the water collecting seat (7), deenergize the electromagnet one (108) and the electromagnet two (110), energize the electromagnet three (115) and the electromagnet four (116), fix the support column (111), start the electric push rod (101) to recover, the arc plate (103) is separated from the inclined chute plate (107), the inclined chute plate (107) moves downward to drive the piston one (104) to slide back, and the drilling fluid in the water collecting pipe (71) is squeezed out through the liquid discharge pipe (72); S6: After the core (9) adsorbs the drilling fluid, the gravity increases, the slide column (6) moves downward again, the pressure sensor (63) detects the pressure signal and transmits it to the control console (3), the weight of the core (9) is obtained through data analysis, whether the core (9) reaches the saturation state is judged, if saturated, the subsequent mud cake forming step is carried out, if not saturated, the steps S3-S6 are repeated until saturated.

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