A physical model for continuously adjustable slot leakage and a circulating plugging test device

Abstract

The present invention relates to a continuously adjustable slit leakage physical model and a cyclic plugging test device. The leakage physical model includes a cylinder body, on which a liquid outlet hole and a pull rod hole are provided, and a pressing plate groove is arranged at one end of the liquid outlet hole close to the pull rod hole; in the present invention, at least one connecting rod is used to connect the pull rod and the pressing plate, and by moving the pull rod, the distance of the clearance fit between the pressing plate and the inner wall of the liquid outlet hole can be adjusted, thereby adjusting the size of the simulated slit. Therefore, the size of the slit is continuously adjustable; and the cyclic plugging test device includes a leakage formation model, a first piston container, a second piston container and a high-pressure injection pump. The leakage formation model is connected to the first end of the first piston container and the first end of the second piston container through four valves, and then the high-pressure injection pump is connected to the second end of the first piston container and the second end of the second piston container through four valves; it can make the circulating liquid continuously circulate in one direction, more truly simulating the flow process of the plugging slurry in the wellbore.

Description

Technical Field

[0001] The present invention relates to the technical field of oil drilling measurement instruments, and particularly relates to a physical model for continuously adjusting the slot leakage and a cyclic plugging test device. Background Art

[0002] In the field of petroleum engineering, the problem of well leakage has always been a world-class problem, which has troubled the exploration and development of oil at home and abroad and has not been completely solved yet. Most drilling processes have different degrees of leakage. Severe well leakage will lead to a decrease in wellbore pressure, affect normal drilling, cause wellbore instability, induce formation fluids to flow into the wellbore, and cause blowouts. Well leakage can occur in shallow, medium, and deep layers, and can also occur in different geological ages, such as from the Quaternary to the Paleozoic. With the increasing proportion of deep wells and ultra-deep wells, the demand for evaluating well leakage materials in high-temperature and high-pressure formations is also increasing.

[0003] At present, a large number of researchers have studied different types of leakage problems, proposed plugging agents of various materials, and evaluated the plugging effects of these plugging agents.

[0004] The patent with the application number CN110857944A proposes a drilling fluid plugging simulation evaluation device for fixing cracks, including an air pump, a third round pipe, a slot box, and a second round pipe. The leak repair fluid circulates in the second round pipe. The slot box is connected to the third round pipe and the second round pipe, and the air pump is connected to the third round pipe. During the test, the air pump pressurizes the pressure of the third round pipe to be 0.1 MPa less than the pressure inside the second round pipe. After a period of time, the leakage volume entering the third round pipe through the slot box is recorded, and then the slot box with different slot widths is replaced, and the above steps are repeated. The above patent adjusts the slot size by changing the thickness of different slot plates. The operation of adjusting the slot size is relatively complex, and the adjustment of the slot size is not continuous. Summary of the Invention

[0005] Based on the above description, the present invention provides a physical model for continuously adjusting the slot leakage and a cyclic plugging test device. By driving a pressing plate to slide in a pressing plate groove with a pull rod, the distance between the pressing plate and the inner wall of the liquid outlet hole is adjusted, thereby adjusting the slot size. The slot size is continuously adjustable, and the method for adjusting the slot size is simple in program and convenient and fast to operate.

[0006] The technical solution of the present invention to solve the above technical problems is as follows: A continuously adjustable seam leakage physical model, comprising a cylinder body, a pull rod and a pressing plate; one end of the cylinder body is a liquid inlet end, and the other end is a liquid outlet end; the liquid outlet end is provided with a liquid outlet hole and a pull rod hole, and the liquid outlet hole communicates with the liquid inlet end; a pressing plate groove is arranged at one end of the liquid outlet hole close to the pull rod hole; the pull rod is slidably inserted into the pull rod hole; the pressing plate is slidably and sealingly matched with the inner wall of the pressing plate groove, and one side of the pressing plate is in clearance fit with the inner wall of the liquid outlet hole; at least one connecting rod is arranged between the pull rod and the pressing plate, one end of the connecting rod is hinged to the pull rod, and the other end is hinged to the pressing plate.

[0007] On the basis of the above technical solution, the present invention can be further improved as follows.

[0008] Further, the cylinder body comprises an outer cylinder body and an inner cylinder body; one end of the outer cylinder body is provided with a liquid inlet hole, forming the liquid inlet end of the cylinder body, and the other end is provided with a mounting hole; the inner cylinder body is detachably inserted into the mounting hole, and one end of the inner cylinder body far from the liquid inlet hole is the liquid outlet end of the cylinder body, and the liquid outlet hole communicates with the liquid inlet hole; a cylinder cover is arranged on one side of the inner cylinder body, and the liquid inlet hole is located between the inner cylinder body and the cylinder cover.

[0009] Further, a plug is arranged at one end of the inner cylinder body far from the liquid inlet hole; a first through hole communicating with the pull rod hole and a second through hole communicating with the liquid outlet hole are opened on the plug; the pull rod passes through the first through hole, and a limiting boss adapted to the inner end face of the plug is arranged on the pull rod.

[0010] Further, an adjusting nut is threadedly connected to the pull rod, and the adjusting nut is located at one end of the plug far from the inner cylinder body; and a sealing compression cap is arranged on the plug, the sealing compression cap is sleeved on the pull rod, and the adjusting nut abuts against the sealing compression cap.

[0011] Further, the pressing plate comprises an upper pressing plate and a lower pressing plate, and the upper pressing plate is connected to one side of the lower pressing plate close to the cylinder cover; piston blocks corresponding to the connecting rods one by one are fixed on one side of the lower pressing plate far from the cylinder cover, and the piston blocks are hinged to the connecting rods.

[0012] The present invention also proposes a circulating plugging test device, comprising a lost circulation formation model, a first piston container, a second piston container and a high-pressure injection pump; the lost circulation formation model comprises a simulation kettle and the above-mentioned leakage physical model; a leakage pipe is arranged at the liquid outlet end of the leakage physical model, and a leakage valve is arranged on the leakage pipe.

[0013] The simulation kettle is respectively connected to the first end of the first piston container and the first end of the second piston container through a first valve and a second valve; the liquid inlet end of the leakage physical model is connected to the simulation kettle, and the liquid outlet end is respectively connected to the first end of the first piston container and the first end of the second piston container through a third valve and a fourth valve;

[0014] The liquid outlet of the high-pressure injection pump is respectively connected to the second end of the first piston container and the second end of the second piston container through a fifth valve and a sixth valve; the liquid inlet of the high-pressure injection pump is respectively connected to the second end of the first piston container and the second end of the second piston container through a seventh valve and an eighth valve.

[0015] Further, electromagnetic induction switches are arranged at both ends of the first piston container and the second piston container, and the electromagnetic induction switches are respectively adapted to the pistons in the first piston container or the second piston container, and are used to automatically control the opening and closing of the first valve, the second valve, the third valve, the fourth valve, the fifth valve, the sixth valve, the seventh valve and the eighth valve.

[0016] Further, the liquid outlet end of the high-pressure injection pump is connected to the leakage formation model through a cleaning valve.

[0017] Further, the testing device further includes a buffer container, and a piston plate that is hermetically and slidably matched with the inner wall of the buffer container is arranged in the buffer container. The piston plate divides the buffer container into two sections, one of which is filled with gas and the other is connected to the liquid outlet end of the high-pressure injection pump.

[0018] Further, the testing device further includes a liquid storage tank, and the liquid storage tank is connected to the liquid inlet of the high-pressure injection pump through a liquid replenishing valve.

[0019] Compared with the prior art, the technical solution of the present application has the following beneficial technical effects:

[0020] 1. In the present invention, through the hinge connection of the connecting rod with the pull rod and the pressing plate, the movement of the pull rod in the pull rod hole can drive the pressing plate to move in the pressing plate groove, so as to adjust the distance between the pressing plate and the inner wall of the liquid outlet hole, and further adjust the size of the gap. The size of the gap in the present invention is continuously adjustable, and the method for adjusting the size of the gap has a simple program and is convenient and fast to operate;

[0021] 2. In the present invention, by providing the first piston container and the second piston container, and controlling the on-off of both ends of the first piston container and the second piston container through the first valve, the second valve, the third valve, the fourth valve, the fifth valve, the sixth valve, the seventh valve and the eighth valve respectively, it can make the circulating liquid continuously circulate in one direction, and more realistically simulate the flow process of the plugging slurry underground. Description of the Drawings

[0022] Figure 1 An exploded view of a physical model of continuous slit leakage provided by an embodiment of the present invention;

[0023] Figure 2 A sectional view of the cylinder body in an embodiment of the present invention;

[0024] Figure 3 A sectional view of a physical model of continuous slit leakage provided by an embodiment of the present invention;

[0025] Figure 4 An exploded view of a cyclic plugging test device provided by an embodiment of the present invention.

[0026] In the attached drawings, the list of components represented by each reference numeral is as follows:

[0027] 1. Cylinder body; 11. Outer cylinder body; 111. Liquid inlet hole; 112. Installation hole; 113. External thread; 12. Inner cylinder body; 121. Liquid outlet hole; 122. Pull rod hole; 123. Pressure relief hole; 124. Pressing plate groove; 125. Communication hole; 13. Cylinder cover; 14. Plug; 141. Clamping convex; 142. First through hole; 143. Second through hole; 144. Internal thread; 15. Plug pressing cap; 16. Sealing plug block; 17. Sealing pressing cap; 18. Adjusting nut; 2. Pull rod; 21. Limit convex; 3. Pressing plate; 31. Upper pressing plate; 32. Lower pressing plate; 33. Piston block; 4. Connecting rod;

[0028] 101. Leakage physical model; 102. Simulation kettle; 103. First piston container; 104. Second piston container; 105. High-pressure injection pump; 106. Liquid storage tank; 107. Buffer container; 201. First valve; 202. Second valve; 203. Third valve; 204. Fourth valve; 205. Fifth valve; 206. Sixth valve; 207. Seventh valve; 208. Eighth valve; 301. Liquid replenishing valve; 302. Air vent valve; 303. Cleaning valve; 304. Exhaust valve; 305. Leakage liquid valve; 306. Pre-inflation valve; 401. First pressure sensor; 402. Second pressure sensor; 403. Third pressure sensor; 501. Liquid discharge valve. Detailed implementation manners

[0029] To facilitate the understanding of the present application, the present application will be described more comprehensively below with reference to the relevant attached drawings. Embodiments of the present application are shown in the attached drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used in the description of this application herein are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0031] Embodiment 1

[0032] A physical model of continuous seam leakage, as Figure 1 shown, includes a cylinder body 1, a pull rod 2 and a pressing plate 3. And as Figure 2 shown, the cylinder body 1 includes an outer cylinder body 11, an inner cylinder body 12, a cylinder cover 13, a plug 14 and a plug pressing cap 15.

[0033] One end of the outer cylinder body 11 is provided with a liquid inlet hole 111 as the liquid inlet end of the cylinder body 1, and the other end is provided with an installation hole 112. The cylinder cover 13 is arranged on one side of the inner cylinder body 12, and the inner cylinder body 12 and the cylinder cover 13 are detachably connected to form a complete cylinder, which are jointly inserted into the installation hole 112. The plug 14 is arranged at one end of the inner cylinder body 12 far from the liquid inlet hole 111, and a ring-shaped clamping convex 141 is arranged on the outer wall of one end of the plug 14 close to the inner cylinder body 12. The plug pressing cap 15 is sleeved on one end of the plug 14 far from the inner cylinder body 12, and the outer wall of the plug pressing cap 15 is detachably connected to the inner wall of the outer cylinder body 11 through threads. The end face of the plug pressing cap 15 abuts against the clamping convex 141 to press the plug 14 tightly on the inner cylinder body 12, so as to press the inner cylinder body 12 tightly in the installation hole 112.

[0034] A liquid outlet hole 121 is arranged between the inner cylinder body 12 and the cylinder cover 13. By removing the plug pressing cap 15, the plug 14, the outer cylinder body 11 and the cylinder cover 13 can be easily taken out, and then the cylinder cover 13 is removed from the outer cylinder body 11, so that the liquid outlet hole 121 can be exposed, which is convenient for observing the plugging situation. One end of the liquid outlet hole 121 is communicated with the liquid inlet hole 111, and the end far from the liquid inlet hole 111 bends inward, so that the end of the liquid outlet hole 121 is located on the inner cylinder body 12, and the end of the inner cylinder body 12 far from the liquid inlet hole 111 is used as the liquid outlet end of the cylinder body 1. A pull rod hole 122 is also arranged at one end of the inner cylinder body 12 far from the liquid inlet hole 111 for inserting the pull rod 2. In this embodiment, a pressure relief hole 123 communicating with the liquid inlet hole 111 is also arranged at the bottom of the pull rod hole 122 for maintaining the pressure stability at the bottom of the liquid inlet hole 111 when the pull rod 2 slides in the pull rod hole 122. A first through hole 142 and a second through hole 143 penetrating the plug 14 are arranged on the plug 14. The first through hole 142 is communicated with the pull rod hole 122, and the second through hole 143 is communicated with the liquid outlet hole 121. And in this embodiment, sealing plug blocks 16 are arranged at the connection of the first through hole 142 and the pull rod hole 122 and at the connection of the second through hole 143 and the liquid outlet hole 121 to ensure that the plugging slurry will not leak from the gap between the inner cylinder body 12 and the plug 14.

[0035] The pull rod 2 is inserted into the pull rod hole 122, and the end of the pull rod 2 extends out from the first through hole 142. A limiting boss 21 is provided on the pull rod 2, and the limiting boss 21 is adapted to the end of the plug 14 close to the inner cylinder 12. By using the plug 14 to resist the limiting boss 21, the farthest position where the pull rod 2 can be pulled outwards can be limited.

[0036] On one side of the liquid outlet hole 121 close to the pull rod hole 122, a pressing plate groove 124 is provided, and the pressing plate 3 is arranged in the pressing plate groove 124. In this embodiment, the pressing plate 3 includes an upper pressing plate 31, a lower pressing plate 32 and at least one piston block 33. The lower pressing plate 32 is in sliding and sealing fit with the inner wall of the pressing plate groove 124. The upper pressing plate 31 is installed on the side of the lower pressing plate 32 close to the cylinder cover 13 through the cooperation of a T-shaped groove and a T-shaped key, and the upper pressing plate 31 has a clearance fit with the inner wall on the side of the liquid outlet hole 121 away from the pressing plate groove 124, so that the plugging slurry can flow through, thereby simulating a gap. By changing the distance of the clearance fit, the size of the gap can be adjusted. The piston blocks 33 are all fixed on the side of the lower pressing plate 32 close to the bottom of the pressing plate groove 124.

[0037] At least one communication hole 125 is further provided between the pull rod hole 122 and the pressing plate groove 124. A connecting rod 4 is arranged in each communication hole 125, and the connecting rods 4 correspond to the piston blocks 33 one by one. One end of the connecting rod 4 is hinged to the pull rod 2, and the other end is hinged to the corresponding piston block 33, so as to connect the pull rod 2 and the pressing plate 3. By moving the pull rod 2 in the pull rod hole 122, the pressing plate 3 can be moved in the pressing plate groove 124, thereby adjusting the size of the gap.

[0038] At the opening of the first through hole 142, a sealing compression cap 17 and an adjusting nut 18 sleeved on the pull rod 2 are provided. The sealing compression cap 17 is threadedly connected to the plug 14. The adjusting nut 18 abuts against the end of the sealing compression cap 17 away from the plug 14 through a sealing washer, and the adjusting nut 18 is threadedly connected to the pull rod 2. By rotating the adjusting nut 18, the sliding of the pull rod 2 in the pull rod hole 122 can be controlled, so as to control the sliding of the pressing plate 3 in the pressing plate groove 124, and further adjust the size of the gap. And by adjusting the position of the adjusting nut 18 on the pull rod 2, the current size of the gap can be indicated.

[0039] In addition, in this embodiment, an external thread 113 is provided on the outer wall of the end of the outer cylinder 11 where the liquid inlet hole 111 is provided, for directly installing on the simulation kettle 02 to connect the liquid inlet hole 111 to the simulation kettle 02. The plugging slurry enters the liquid inlet hole 111 from the simulation kettle 02, and the plugging slurry flows through the liquid outlet hole 121 and then flows out from the second through hole 143. An internal thread 144 is provided at the outlet of the second through hole 143 for connecting with a conduit.

[0040] The gap size simulated by the continuously adjustable gap leakage physical model of this embodiment is continuously adjustable, and only by pulling or pushing the pull rod 2 can the gap size be adjusted. The adjustment method has a simple program and is convenient and fast to operate.

[0041] The continuously adjustable gap leakage physical model of the present invention can not only be used for specific slit width simulation, that is, only one specific slit width can be tested in each experiment, but also for dynamic slit width simulation, that is, the simulated slit width can be dynamically adjusted during the test. In addition, the continuously adjustable gap leakage physical model of the present invention can not only be used for cyclic plugging leakage tests, but also for other occasions that require simulating slit width, which are not limited here.

[0042] Embodiment 2

[0043] A cyclic plugging leakage test device includes a leakage formation model, a first piston container 103, a second piston container 104, a high-pressure injection pump 105, a liquid storage tank 106 and a buffer container 107. Among them, the leakage formation model includes a leakage physical model 101 and a simulation kettle 102, and the leakage physical model 101 is the continuously adjustable gap leakage physical model of Embodiment 1.

[0044] Pistons that are slidably and sealingly fitted with the inner walls are provided in both the first piston container 103 and the second piston container 104. The pistons separate the first end and the second end. After plugging slurry is injected into one end, the plugging slurry pushes the piston to move towards the other end, thereby discharging the plugging slurry at the other end. In this embodiment, the first ends of the first piston container 103 and the second piston container 104 are located at the upper end, and the second ends of the first piston container 103 and the second piston container 104 are located at the lower end.

[0045] The liquid outlet of the high-pressure injection pump 105 is respectively connected to the second end of the first piston container and the second end of the second piston container 104 through a fifth valve 205 and a sixth valve 206. The liquid inlet of the high-pressure injection pump 105 is respectively connected to the second end of the first piston container 103 and the second end of the second piston container 104 through a seventh valve 207 and an eighth valve 208. By controlling the opening and closing of the fifth valve 205, the sixth valve 206, the seventh valve 207 and the eighth valve 208, the high-pressure injection pump 105 can sequentially and cyclically push the pistons in the first piston container 103 and the second piston container 104 to move upward, so that the first piston container 103 and the second piston container 104 sequentially and cyclically discharge the plugging slurry from the first end, and when the piston in one of the piston containers moves upward to discharge the plugging slurry from the first end, the piston in the other piston container moves downward to only suck the plugging slurry into the first end.

[0046] In addition, the liquid storage tank 106 is connected to the liquid inlet end of the high-pressure injection pump 105 through a liquid replenishing valve 301, and is used to supplement plugging slurry into the device when it is necessary to discharge the gas in the device, or to inject clean water into the device when it is necessary to clean.

[0047] A piston is provided inside the buffer container 107. The piston separates the two ends of the buffer container 107. One end of the buffer container 107 is provided with a pre-charging valve 306 for pre-charging gas, generally nitrogen, into one end of the buffer container. The other end of the buffer container 107 is connected to the liquid outlet end of the high-pressure injection pump 105. Since the high-pressure injection pump 105 is a piston pump, there will be certain pulses, which will cause the pressure value to fluctuate up and down. When there is a pressure fluctuation, the piston inside the buffer container 107 will move up and down. Since the gas is relatively easy to be compressed, the purpose of eliminating the pressure fluctuation can be achieved.

[0048] A first pressure sensor 401 and a vent valve 302 are also provided at the liquid outlet of the high-pressure injection pump 105. The first pressure sensor 401 is used to measure the output pressure of the injection pump 105, and the vent valve 302 is used for venting the injection pump 105.

[0049] The top of the simulation kettle 102 is connected to the first end of the first piston container 103 and the first end of the second piston container 104 through a first valve 201 and a second valve 202 respectively. The liquid inlet hole of the leakage physical model 101 is connected to the bottom side wall of the simulation kettle 102, and the liquid outlet holes are connected to the first end of the first piston container 103 and the first end of the second piston container 104 through a third valve 203 and a fourth valve 204 respectively. By controlling the opening and closing of the first valve 201, the second valve 202, the third valve 203 and the fourth valve 204, the first piston container 103 and the second piston container 104 can inject the plugging slurry into the simulation kettle 102 in turn. And when one of the piston containers injects the plugging slurry into the simulation kettle 102, the plugging slurry flows through the simulation kettle 102 and the leakage physical model 101 and then is sucked by the other piston container, so as to realize that the plugging slurry always circulates in the same direction continuously, truly simulating the flowing process of the plugging slurry in the wellbore.

[0050] A heating device and a temperature sensor are provided outside the simulation kettle 102 to regulate the temperature inside the simulation kettle 102 to reach the required temperature for the experiment, so as to simulate the temperature of the leakage formation and the formation pressure. A stirrer is provided at the bottom of the simulation kettle 102 to suspend the plugging particles in the plugging slurry, so as to simulate the process of drilling circulation. A drain valve 501 is also provided on the bottom side wall of the simulation kettle 102. The drain valve 501 is used for draining the liquid and relieving the pressure of the simulation kettle 102. A second pressure sensor 402 and an exhaust valve 304 are also provided on the top of the simulation kettle 102. The second pressure sensor 402 is used to measure the working pressure of the simulation kettle 102, and the exhaust valve 304 is used for exhausting and venting the simulation kettle 102.

[0051] The liquid outlet hole of the leakage physical model 101 is also connected to a liquid leakage pipe, and a liquid leakage valve 305 is arranged on the liquid leakage pipe. The leaked liquid can be collected through the liquid leakage pipe. A third pressure sensor 403 is also arranged at the liquid outlet end of the leakage physical model 101 for measuring the outlet pressure of the leakage physical model 101.

[0052] In this embodiment, the liquid outlet end of the high-pressure injection pump 105 is connected to the leakage formation model through a cleaning valve 303. When it is necessary to connect the high-pressure injection pump 105 and the leakage formation model, the cleaning valve 303 needs to be opened, for example, during exhaust and cleaning.

[0053] Electromagnetic induction switches are arranged at both ends of the first piston container 103 and the second piston container 104. The electromagnetic induction switches are respectively adapted to the pistons in the corresponding first piston container 103 or second piston container 104, and are used to automatically control the opening and closing of the first valve 201, the second valve 202, the third valve 203, the fourth valve 204, the fifth valve 205, the sixth valve 206, the seventh valve 207 and the eighth valve 208.

[0054] In addition, the first valve 201, the second valve 202, the third valve 203, the fourth valve 204, the fifth valve 205, the sixth valve 206, the seventh valve 207 and the eighth valve 208 in this embodiment are all pneumatic high-pressure ball valves, and the maximum working pressure is 50 Mpa. The liquid filling valve 301, the vent valve 302, the cleaning valve 303, the exhaust valve 304, the liquid leakage valve 305 and the pre-inflation valve 306 are all manual high-pressure stop valves, all of which are on-off valves and have no throttling effect. All the pipelines in this embodiment are high-pressure resistant pipelines. The working pressures of the first pressure sensor 401, the second pressure sensor 402 and the third pressure sensor 403 are less than or equal to 50 MPa, and the accuracy of pressure measurement is 0.25% FS.

[0055] The plugging test method of this embodiment is as follows:

[0056] (a) Adjust the pistons in the first piston container 103 and the second piston container 104 so that one piston moves to the first end and the other piston moves to the second end.

[0057] The specific method is preferably as follows: Before the experiment, close all pneumatic high-pressure ball valves and manual high-pressure globe valves. After opening the liquid filling valve 301 and the cleaning valve 303, turn on the high-pressure injection pump 105. Open the third valve 203 and the seventh valve 207 through the manual control of the computer software, so that the piston in the first piston container 103 moves to the lowest end of the container, then close the third valve 203 and the seventh valve 207, and close the cleaning valve 303. Open the exhaust valve 304, and open the second valve 202 and the sixth valve 206 through computer control, so that the piston in the liquid storage piston container 8 runs to the uppermost end of the piston container 8, then close the exhaust valve 304, and close the second valve 202 and the sixth valve 206.

[0058] (b) Fill the lost circulation formation model with the lost circulation plugging slurry and discharge the air in the test device.

[0059] The specific method is preferably as follows: Open the upper cover of the simulation kettle 102 and fill the simulation kettle 102 with the lost circulation plugging slurry to be tested, and then close the upper cover of the simulation kettle 102. Open the liquid filling valve 301 and the vent valve 302, turn on the high-pressure injection pump 105 in the software, and exhaust the air in the buffer container 107 and the surrounding pipelines, then close the vent valve 302. Open the cleaning valve 303 and the exhaust valve 304, and open the first valve 201, the second valve 202, the third valve 203 and the fourth valve 204 through computer control. Turn on the high-pressure injection pump 105 to make the liquid in the liquid storage tank 106 enter the simulation kettle 102 to discharge the air in the lost circulation formation model and the surrounding pipelines. After a continuous large amount of liquid flows out from behind the exhaust valve 304, turn off the high-pressure injection pump 105, the liquid filling valve 301, the cleaning valve 303, the exhaust valve 304, the first valve 201, the second valve 202, the third valve 203 and the fourth valve 204 in sequence. Then turn on the stirrer in the simulation kettle 102 to suspend the lost circulation particles in the lost circulation plugging slurry. The rotation speed of the lost circulation liquid stirring is: 0 - 600 r / min (stepless speed regulation).

[0060] (c) Heat the lost circulation plugging slurry in the simulation kettle 102 to make the lost circulation plugging slurry in the simulation kettle 102 reach the test required temperature. Since the whole set of equipment can reach a fully sealed state, so while heating, the pressure in the simulation kettle 102 can continuously rise to increase the boiling point of the solution, simulating the downhole working conditions to the greatest extent. The working temperature range of this embodiment is room temperature to 180 °C, and the temperature control accuracy is ±1 °C.

[0061] (d) Adjust the gap of the lost circulation physical model 101 to the size required for the test. Test the lost circulation formation model.

[0062] (e) Turn on the control software on the computer, click on automatic operation, and control the opening and closing of the first valve 201, the second valve 202, the third valve 203, the fourth valve 204, the fifth valve 205, the sixth valve 206, the seventh valve 207, and the eighth valve 208 through the PLC, so as to ensure that the plugging slurry always flows unidirectionally along the simulation kettle 102 towards the lost physical model 101. The inner diameter of the lost fluid circulation pipeline needs to be able to allow the smooth passage of single-particle plugging materials with a diameter of Φ8mm, and the pipeline bend angle is greater than or equal to 120 degrees.

[0063] Specifically, when the piston in the first piston container 103 moves to the first end, or the piston in the second piston container 104 moves to the second end, close the first valve 201, the fourth valve 204, the fifth valve 205, and the eighth valve 208, and open the second valve 202, the third valve 203, the sixth valve 206, and the seventh valve 207.

[0064] When the piston in the first piston container 103 moves to the second end, or the piston in the second piston container 104 moves to the first end, close the second valve 202, the third valve 203, the sixth valve 206, and the seventh valve 207, and open the first valve 201, the fourth valve 204, the fifth valve 205, and the eighth valve 208.

[0065] (f) Observe the values of the first pressure sensor 401, the second pressure sensor 402, and the third pressure sensor 403. When the value of the second pressure sensor 402 is greater than the value of the third pressure sensor 403, and the difference between the two starts to gradually increase, it indicates that the gap in the lost physical model 101 has begun to be blocked. When the plugging agent blocks the gap in the lost physical model 101, backpressure is generated. When the pressure reaches the specified pressure, the system will automatically stop the operation of the high-pressure injection pump 105, thus meeting the test requirements.

[0066] (g) Open the leak valve 305 and collect the liquid leaking from it with a container.

[0067] (h) When the value of the second pressure sensor 402 is greater than the value of the third pressure sensor 403, and the difference between the two continues to rise and then rapidly drops after reaching a certain value, at this time, turn off the test device to stop its operation. Open the software and export the experimental data.

[0068] (i) Turn off the heating of the simulation kettle 102 and the stirrer in the simulation kettle 102. After the temperature drops to room temperature, remove the plugging nut on the lost physical model 1, pull out the inner cylinder and the cylinder cover, disassemble the cylinder cover and record the distribution of the plugging material in the gap. Then clean the cylinder. Measure the liquid collected with a container from the leak valve 305.

[0069] (j)Open the software for manual control. After opening the first valve 201, the second valve 202, the third valve 203, the fourth valve 204, the liquid replenishing valve 301, the cleaning valve 303 and the exhaust valve 304, turn on the high-pressure injection pump 105 to flush the pipeline and the simulation kettle clean.

[0070] (k)Install the removed cylinder body back to its original position and fix it on the outer cylinder body of the lost physical model 1 with a plug pressing cap.

[0071] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A circulating lost circulation testing device, characterized in that, It includes a lost circulation formation model, a first piston container, a second piston container, and a high-pressure injection pump; the lost circulation formation model includes a simulation kettle and a lost circulation physical model, and the lost circulation physical model includes a cylinder body, a pull rod, and a pressing plate; one end of the cylinder body is the liquid inlet end, and the other end is the liquid outlet end; the liquid outlet end is provided with a liquid outlet hole and a pull rod hole, and the liquid outlet hole communicates with the liquid inlet end; a pressing plate groove is provided at one end of the liquid outlet hole close to the pull rod hole; the pull rod is slidably inserted into the pull rod hole; the pressing plate is in sliding and sealing cooperation with the inner wall of the pressing plate groove, and one side of the pressing plate is in clearance fit with the inner wall of the liquid outlet hole; at least one connecting rod is arranged between the pull rod and the pressing plate, one end of the connecting rod is hinged to the pull rod, and the other end is hinged to the pressing plate; a liquid leakage pipe is communicated with the liquid outlet hole of the lost circulation physical model, and a liquid leakage valve is arranged on the liquid leakage pipe; The simulation kettle is respectively communicated with the first end of the first piston container and the first end of the second piston container through a first valve and a second valve; the liquid inlet end of the lost circulation physical model is communicated with the simulation kettle, and the liquid outlet hole is respectively communicated with the first end of the first piston container and the first end of the second piston container through a third valve and a fourth valve; The liquid outlet of the high-pressure injection pump is respectively communicated with the second end of the first piston container and the second end of the second piston container through a fifth valve and a sixth valve; the liquid inlet of the high-pressure injection pump is respectively communicated with the second end of the first piston container and the second end of the second piston container through a seventh valve and an eighth valve.

2. The cyclic plugging leakage test device according to claim 1, characterized in that, Electromagnetic induction switches are arranged at both ends of the first piston container and the second piston container, and the electromagnetic induction switches are respectively adapted to the pistons in the first piston container or the second piston container, and are used to automatically control the opening and closing of the first valve, the second valve, the third valve, the fourth valve, the fifth valve, the sixth valve, the seventh valve, and the eighth valve.

3. The cyclic plugging leakage test device according to claim 1, characterized in that, The liquid outlet end of the high-pressure injection pump is communicated with the lost circulation formation model through a cleaning valve.

4. The cyclic plugging leakage test device according to claim 1, wherein It further includes a buffer container, and a piston plate that is in sealed and sliding cooperation with the inner wall of the buffer container is arranged in the buffer container. The piston plate divides the buffer container into two sections, one section is filled with gas, and the other section is communicated with the liquid outlet end of the high-pressure injection pump.

5. The cyclic plugging leakage test device according to claim 1, wherein It further includes a liquid storage tank, and the liquid storage tank is communicated with the liquid inlet of the high-pressure injection pump through a liquid replenishing valve.

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