Experimental apparatus and method for evaluating the sand flushing and drilling effects of coiled tubing in horizontal wells

Abstract

This invention discloses an experimental apparatus and method for evaluating the sand flushing and drilling / grinding effects of coiled tubing in horizontal wells. The apparatus includes a coiled tubing sand flushing unit, a coiled tubing drilling / grinding unit, a wellbore structure simulation unit, a fluid circulation unit, a data measurement and processing unit, and a high-temperature, high-pressure simulation unit. It is used to simulate sand flushing and well washing conditions in long horizontal sections of oil wells and to conduct evaluation experiments on the removal of sediment using conventional sand flushing fluids. It features a function for visually observing and recording the effect of removing sediment from horizontal wells. By comparing sand flushing and drilling / grinding simulation experiments under various conditions such as wellbore structure, drilling displacement, sand flushing fluid type, sand flushing nozzle type, presence or absence of tubing centralizers, sand flushing method, grinding shoe type, drilling / grinding working fluid displacement, and drilling / grinding working fluid additives, the impact of these conditions on the effectiveness of coiled tubing sand flushing and drilling / grinding is evaluated, and the optimal combination of coiled tubing sand flushing and drilling / grinding engineering is selected. The apparatus is designed according to the actual sand flushing and well washing and drilling / grinding bridge plug conditions, and has a complete structure and is easy to operate.

Description

Technical Field

[0001] This invention relates to the field of oilfield well workover operation experimental simulation technology, and in particular to an experimental device and method for evaluating the sand flushing and drilling effects of coiled tubing in horizontal wells. Background Technology

[0002] Currently, the main technology for achieving volumetric fracturing in large-volume tight oil horizontal wells is pump-fed composite bridge plug staged fracturing technology. To achieve full-bore production after fracturing, it is crucial to promptly remove formation sand, fracturing sand deposits, and staged bridge plugs. Horizontal wells experience rapid sand and cuttings settling, making sand and cuttings removal difficult, especially in gas wells where pressurized sand washing and bridge plug drilling are challenging under non-killed conditions. Conventional equipment and threaded tubing are insufficient for pressurized sand washing and bridge plug drilling in horizontal wells. Horizontal well sand washing and drilling using coiled tubing technology is well-suited for pressurized operations.

[0003] Currently, most methods for horizontal well sand removal and bridge plug drilling are simulated using numerical simulation. The results provide some guidance for the design of coiled tubing sand removal and drilling, but field tests are still needed for evaluation. The actual effects of coiled tubing sand removal and drilling may differ significantly from the simulation results, and field verification experiments are costly in terms of manpower and resources.

[0004] Therefore, it is essential to evaluate the sand flushing and drilling effects of coiled tubing in horizontal wells. An experimental device is needed that can closely simulate the actual working conditions of the sand flushing and drilling process in coiled tubing in horizontal wells, so as to analyze and study the engineering factors that affect the sand flushing and drilling of coiled tubing in horizontal wells. Summary of the Invention

[0005] The technical problem this invention aims to solve is to provide an experimental apparatus and method for evaluating the sand flushing and drilling effects of coiled tubing in horizontal wells. By comprehensively considering factors such as wellbore structure, sand flushing fluid volume, sand flushing fluid type, sand flushing nozzle type, tubing centralizer, sand flushing method, grinding shoe type, drilling fluid volume, and drilling fluid additives, this method can effectively simulate the actual sand flushing and drilling conditions of coiled tubing in horizontal wells, enabling the study of factors influencing sand flushing and drilling in horizontal wells. In the laboratory setting, specific engineering parameters from field construction are used to control parameter variables, thereby simulating the relationship between sand flushing and drilling in coiled tubing and various parameters, allowing for targeted improvements to the coiled tubing process.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: an experimental device for evaluating the sand flushing and drilling effects of coiled tubing in horizontal wells, comprising a coiled tubing sand flushing unit, a coiled tubing drilling unit, a wellbore structure simulation unit, a fluid circulation unit, a data measurement and processing unit, and a high-temperature and high-pressure simulation unit. The coiled tubing sand flushing unit includes a working drum, a control device, an injector, a blowout preventer, coiled tubing, a tubing stabilizer, and a sand flushing nozzle. The coiled tubing drilling unit replaces the sand flushing nozzle in the coiled tubing sand flushing unit with drilling tools and a composite bridge plug. The drilling tools include a reverse circulation valve, a double-disc check valve, a screw drill, and a flat-bottomed grinding shoe. The wellbore structure simulation unit... The components include a transparent wellbore, wellbore couplings, high-temperature and high-pressure resistant rubber hoses, wellbore joints, a rotating shaft, a hydraulic cylinder, a slide rail trolley, and a pulley track; the liquid circulation unit includes a frequency converter, a bidirectional delivery pump A, a filter A, a storage tank, a filter B, a bidirectional delivery pump B, a continuous tubing line, a blowout preventer line, a shut-off valve C, a throttle valve A, a shut-off valve D, and a throttle valve B; the data measurement and processing unit includes a flow meter A, a flow meter B, a mobile ultrasonic probe, a computer, and a high-speed camera; the high-temperature and high-pressure simulation unit includes a nitrogen cylinder, a pressure regulator, a pressure sensor, a temperature controller, a temperature sensor, an electric heating film, shut-off valves A, B, E, and F;

[0007] The transparent wellbore consists of two sections: a vertical section and a horizontal section. The vertical section is set vertically, and the horizontal section is set horizontally. The high-temperature and high-pressure resistant rubber pipe is connected to the two transparent wellbore sections through wellbore couplings, respectively simulating the vertical section, directional section, and horizontal section of the wellbore on site.

[0008] The well shaft joint and the rotating shaft are located at the free end of the horizontal section of the transparent well shaft. The rotating shaft is hinged to the piston rod of the hydraulic cylinder, and the hydraulic cylinder is connected to the external hydraulic pump pipeline. The hydraulic cylinder is fixed on the slide rail trolley, and the slide rail trolley slides on the pulley track.

[0009] The blowout preventer is located at the top of the vertical section of the transparent wellbore and is connected to the blowout preventer pipeline; the working drum and injector are located at the upper vertical part of the blowout preventer.

[0010] The first end of the coiled tubing passes through the injector and blowout preventer box and enters the horizontal section of the transparent wellbore, and its tail end is connected to the coiled tubing line.

[0011] The continuous tubing line is sequentially equipped with a bidirectional delivery pump B, a shut-off valve D, a flow meter B, and a throttle valve B; the blowout preventer line is sequentially equipped with a bidirectional delivery pump A, a shut-off valve C, a flow meter A, and a throttle valve A; the frequency converter is connected to the bidirectional delivery pump A and the bidirectional delivery pump B.

[0012] The reverse circulation valve, double-disc check valve, screw drill, and flat-bottomed grinding shoe are sequentially connected to the end of the horizontal section of the transparent wellbore of the coiled tubing, and the composite bridge plug is set at the end of the horizontal section of the transparent wellbore.

[0013] The transparent wellbore is equipped with an electric heating film, a temperature controller, and a temperature sensor; the pressure regulator is connected to a nitrogen cylinder, a pressure sensor, and shut-off valves A and B; the pressure regulator is connected to the coiled tubing and blowout preventer lines, and is controlled by the shut-off valves.

[0014] The computer is installed outside the transparent well casing and is electrically connected to the high-speed camera, movable ultrasonic probe, pressure sensor, temperature controller, and temperature sensor, respectively.

[0015] The continuous tubing and blowout preventer tubing are connected together to the storage tank.

[0016] The injector consists of a locking groove, a clamping block, a clamping point, and a locking pin, and is used to clamp the continuous tubing. The working drum at the top of the injector is connected to the clamping point via a rope. Activating the working drum causes the injector and the continuous tubing to move in the vertical direction.

[0017] The blowout preventer consists of a sealing packing, a locking nut, a fluid delivery channel, a sealing ring, and a locking knob. The sealing packing and sealing ring form an annular seal around the coiled tubing, while also allowing the coiled tubing to move up and down.

[0018] The blowout preventer is connected to the fluid delivery channel, through which the flushing fluid enters and exits the transparent wellbore.

[0019] When the hydraulic cylinder adjusts the length of the piston rod, the horizontal section of the transparent well shaft can steplessly change its inclination, with a change angle of 0° to 90°; at the same time, it will generate a component force parallel to the horizontal section of the transparent well shaft on the slide rail car, so that the slide rail car slides parallel to the horizontal section of the transparent well shaft on the pulley track.

[0020] The connection point between the continuous oil pipeline and the blowout preventer pipeline connected to the storage tank is equipped with filter A and filter B. When the frequency converter is controlled to change the conveying direction of the bidirectional conveying pump A and the bidirectional conveying pump B, it can complete both forward and reverse sand flushing. The two filters can better perform the function of filtering sand and maintaining a low solid content in the storage tank.

[0021] A temperature sensor is set up to measure the temperature inside the transparent wellbore. A temperature controller is used to adjust the temperature to a preset value as needed to simulate the high-temperature environment of the formation. The pressure regulator is connected to a nitrogen cylinder and shut-off valve A. The internal pressure of the nitrogen cylinder is used to inject nitrogen into the pressure regulator. The pressure regulator is connected to the coiled tubing and blowout preventer lines respectively to simulate the system pressure of the wellbore environment during conventional sand flushing and drilling bridge plug completion processes.

[0022] The high-speed camera is used to capture and record the movement of sand particles in the vertical, inclined, and horizontal sections, and to record the time it takes for the settled sand to be completely removed.

[0023] The transparent well casing is made of high-temperature and high-pressure resistant fiberglass. The sand flushing fluid used in the experiment is clean water, linear adhesive and low-density foam liquid; the experimental sediment is made of ceramsite; the sand flushing nozzles are jet nozzles and rotating nozzles.

[0024] The experimental method using the above-mentioned experimental apparatus for evaluating the sand flushing and drilling effects of coiled tubing in horizontal wells includes the following steps:

[0025] A. Procedure for Sand Flushing Test of Coiled Tubing

[0026] (i) After the coiled tubing passes through the injector and blowout preventer, secure the coiled tubing to them. Then connect the coiled tubing to the centralizer and the sand-flush nozzle in sequence. After the blowout preventer and the transparent tubing are secured, insert them into the transparent wellbore until the horizontal section is reached.

[0027] (ii) Remove the wellbore connector of the horizontal well section, push the amount of sand to be tested into the horizontal well section, and then install the wellbore connector to make it completely sealed with the horizontal well section.

[0028] (iii) If the well structure really needs to be tested, adjust the well structure simulation unit, use an external hydraulic pump to change the injection volume, adjust the extension and retraction length of the hydraulic cylinder piston rod and its position on the pulley track, and change the well inclination angle of the horizontal section of the transparent well barrel.

[0029] (iv) Load the experimental fluid for sand flushing into the storage tank, then seal it, and open the shut-off valve C, shut-off valve D, throttle valve A and throttle valve B;

[0030] (v) Adjust the temperature controller to heat the horizontal section of the transparent well barrel with the electric heating film, read the value on the temperature sensor, and make the temperature of the transparent well barrel reach the preset experimental value;

[0031] (vi) When conducting a positive sand flushing simulation experiment, open the shut-off valve C, shut-off valve D, throttle valve A and throttle valve B, start the liquid circulation unit, use the frequency converter to control the bidirectional delivery pump B to deliver sand flushing fluid to the continuous oil pipeline, record the value on the flow meter B, adjust the throttle valve B to control the sand flushing fluid discharge, and control the bidirectional delivery pump A to extract the sand flushing fluid from the blowout box pipeline, pass through the filter A and return to the storage tank to form a positive sand flushing circulation;

[0032] (vii) When conducting the backwash sand simulation experiment, open the shut-off valve C, shut-off valve D, throttle valve A and throttle valve B, start the liquid circulation unit, use the frequency converter to adjust the bidirectional delivery pump A to deliver sand flushing fluid to the blowout box pipeline, record the value on the flow meter A, adjust the throttle valve A to control the sand flushing fluid discharge, and the bidirectional delivery pump B draws the sand flushing fluid from the continuous oil pipeline, passes through the filter B and returns to the storage tank to form a backwash sand circulation;

[0033] (viii) Open the shut-off valve A on the nitrogen cylinder to inject nitrogen into the pressure regulator, and then close the shut-off valve A; at this time, the liquid circulation is positive sand flushing circulation, then close the shut-off valve E and open the shut-off valve F; at this time, the liquid circulation is negative sand flushing circulation, then close the shut-off valve F and open the shut-off valve E; adjust the shut-off valve B on the pressure regulator and read the value on the pressure sensor to simulate the system pressure of the wellbore environment during conventional coiled tubing sand flushing completion.

[0034] (ix) Operate the control device to control the winding and unwinding of the winch, and drive the injector to move in the vertical direction. At this time, one end of the sand-flushing nozzle of the coiled tubing will also move forward and backward in the horizontal section of the transparent wellbore, which can achieve a better sand-flushing effect.

[0035] (x) A high-speed camera takes photos of the continuous tubing sand flushing experiment and uploads them to a computer. An ultrasonic probe detects the thickness of the sand. The computer records and displays the migration pattern and trajectory of the sand particles, as well as the thickness, width and length of the sand and the time it takes for the sand to be completely removed.

[0036] B. Coiled tubing drilling and grinding test procedures

[0037] (i) After the coiled tubing passes through the injector and blowout preventer, secure the coiled tubing to them. Then, connect the coiled tubing to the centralizer, reverse circulation valve, double-disc check valve, screw drill, and flat-bottomed grinding shoe in sequence. After the blowout preventer and the transparent tubing are secured, control the insertion of the coiled tubing into the transparent wellbore until it reaches the horizontal section.

[0038] (ii) Remove the wellbore connector from the horizontal section, set the composite bridge plug to be tested at the end of the horizontal section, and then install the wellbore connector to ensure a complete seal with the horizontal section.

[0039] (iii) If the well structure really needs to be tested, adjust the well structure simulation unit, use an external hydraulic pump to change the injection volume, adjust the extension and retraction length of the hydraulic cylinder piston rod and its position on the pulley track, and change the well inclination angle of the horizontal section of the transparent well barrel.

[0040] (iv) Load the experimental fluid for sand flushing into the storage tank, then seal it, and open the shut-off valve C, shut-off valve D, throttle valve A and throttle valve B;

[0041] (v) Adjust the temperature controller to heat the horizontal section of the transparent well barrel with the electric heating film, read the value on the temperature sensor, and make the temperature of the transparent well barrel reach the preset experimental value;

[0042] (vi) Open shut-off valves C and D, throttle valves A and B to start the liquid circulation unit. Use the frequency converter to control the bidirectional delivery pump B to deliver the descaling fluid to the continuous tubing line. Record the value on the flow meter B. Adjust the throttle valve B to control the discharge rate of the drilling fluid, thereby controlling the working torque of the screw drill. Control the bidirectional delivery pump A to extract the drilling fluid from the blowout preventer line, and return it to the storage tank through filter A.

[0043] (vii) Open the shut-off valve A on the nitrogen cylinder to inject nitrogen into the pressure regulator, and then close the shut-off valve A; close the shut-off valve E and open the shut-off valve F; adjust the shut-off valve B on the pressure regulator and read the value on the pressure sensor to simulate the system pressure of the wellbore environment during conventional coiled tubing drilling and finishing.

[0044] (viii) Operate the control device to control the winding and unwinding of the winch, and drive the injector to move in the vertical direction. At this time, one end of the flat-bottomed grinding shoe of the coiled tubing will move forward and backward in the horizontal section of the transparent wellbore. In order to better transmit drilling pressure in the flat-bottomed grinding shoe, a weight is added to the injector so that more drilling pressure can be transmitted in the flat-bottomed grinding shoe to achieve a better drilling effect.

[0045] (ix) A high-speed camera takes photos of the continuous tubing drilling and grinding experiment and uploads them to a computer. An ultrasonic probe detects the length of the bridge plug. The computer records and displays the movement pattern and trajectory of the drill cuttings, and shows the time it takes for the bridge plug and drill cuttings to be completely removed.

[0046] Compared with existing technologies, the above technical solution has the following advantages:

[0047] 1. The wellbore's directional drilling section is made of high-temperature and high-pressure resistant rubber tubing with a certain degree of elasticity. Under the action of the hydraulic cylinder's telescopic piston rod, the rubber tubing bends, allowing the horizontal section of the transparent wellbore to change its inclination to achieve the required inclination angle for the experiment. This ensures that the sand-laden tubing and coiled tubing in the transparent wellbore are consistent with the actual downhole operation, as are the composite bridge plugs and drilling tools in the wellbore, thus obtaining an accurate evaluation of the coiled tubing's sand-laden tubing and drilling effects.

[0048] 2. The injector is fixed to the coiled tubing and is connected to the winch of the working drum. When the control device is used to control the winding and unwinding of the winch, it actually controls the forward and backward movement of one end of the coiled tubing sand-flush nozzle in the horizontal section of the transparent wellbore. At the same time, the blowout preventer box and the transparent wellbore can form a sealed space, while still allowing the coiled tubing to move up and down. This is consistent with the on-site sand-flushing, drilling and well completion operation procedures.

[0049] 3. Coiled tubing and blowout preventer (BOP) lines are connected to both ends of the storage tank. These two sand flushing lines are connected to the coiled tubing and the BOP respectively. When the delivery direction of the two bidirectional delivery pumps is controlled by a frequency converter, it can simulate both forward and reverse sand flushing methods, which is more in line with the on-site coiled tubing sand flushing operation conditions.

[0050] 4. The movable ultrasonic probe can measure the thickness of sand and drill cuttings at different locations, and the high-speed camera can record the movement of sand particles and drill cuttings, enabling a more in-depth and effective evaluation of factors affecting the sand flushing and drilling effect of coiled tubing.

[0051] 5. This device establishes evaluation methods for wellbore structure, sand flushing fluid discharge rate, sand flushing fluid type, sand flushing nozzle type, tubing centralizer, sand flushing method - sand carrying - influencing factors, and evaluation methods for drilling fluid discharge rate, grinding shoe type, drilling fluid additives - cuttings carrying - influencing factors. It uses construction parameters and tools that are easily obtained in the field as the main indicators for evaluating the sand flushing and drilling effects of coiled tubing. The changes in the above factors can reflect the relationship between the sand flushing and drilling effects and them. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of the continuous tubing sand-flushing connection structure of the device of the present invention;

[0053] Figure 2 This is a schematic diagram of the continuous tubing drilling and milling connection structure of the device of the present invention;

[0054] Figure 3 This is a schematic diagram of the injector structure in this invention;

[0055] Figure 4 This is a schematic diagram of the spray guard structure in this invention;

[0056] Figure 5 This is a schematic diagram of the drilling tool structure in this invention;

[0057] In the diagram: 1 Working drum, 2 Injector, 2-1 Locking groove, 2-2 Clamping block, 2-3 Clamping point, 2-4 Locking pin, 3 Blowout preventer, 3-1 Sealing packing, 3-2 Locking nut, 3-3 Fluid delivery channel, 3-4 Sealing ring, 3-5 Locking knob, 4 Coiled tubing, 5 Transparent wellbore, 6 Wellbore coupling, 7 High-temperature and high-pressure resistant rubber hose, 8 Tubing centralizer, 9A Sandblasting nozzle, 9B Drilling tool, 9B-1 Reverse circulation valve, 9B-2 Double-disc check valve, 9B-3 Screw drill, 9B-4 Flat-bottomed grinding shoe, 10 Wellbore connector, 11 Rotating shaft, 12 Control device, 13 Mobile ultrasonic probe, 14 Calculator 15. High-speed camera, 16. Hydraulic cylinder, 17. Slide rail carriage, 18. Nitrogen cylinder, 19. Shut-off valve A, 20. Pressure regulator, 21. Shut-off valve B, 22. Pressure sensor, 23. Pulley rail, 24. Temperature controller, 25. Temperature sensor, 26. Flow meter A, 27. Shut-off valve C, 28. Bidirectional transfer pump A, 29. Filter A, 30. Liquid storage tank, 31. Throttling valve A, 32. Electric heating membrane, 33. Filter B, 34. Frequency converter, 35. Bidirectional transfer pump B, 36. Shut-off valve D, 37. Flow meter B, 38. Throttling valve B, 39. Continuous oil pipeline, 40. Blowout preventer pipeline, 41. Shut-off valve E, 42. Shut-off valve F, 43. Composite bridge plug. Detailed Implementation

[0058] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings.

[0059] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 a part of the embodiments of the present invention, not all of them. 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. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0060] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

[0061] Example:

[0062] See Figure 1 — Figure 4An experimental device for evaluating the sand flushing effect of coiled tubing in horizontal wells is provided. The well structure includes a transparent wellbore 5 with vertical and horizontal sections, a wellbore coupling 6, a high-temperature and high-pressure rubber sleeve 7, and a wellbore joint 10. The high-temperature and high-pressure rubber sleeve 7 is connected to the transparent wellbore 5 with vertical and horizontal sections through the wellbore coupling 6. The high-temperature and high-pressure rubber sleeve 7 meets the bending and tensile requirements of the directional drilling section and can withstand the high-temperature and high-pressure sand flushing fluid and drilling working fluid. It can simulate the wellbore structure in actual working conditions and is highly similar to it.

[0063] If simulating a continuous tubing sand flushing test, remove the wellbore connector 10, add the simulated sand for the test into the horizontal section of the transparent wellbore 5, and after the sand is added, install the wellbore connector 10 and the blowout preventer 3 to ensure that the two connections can be effectively sealed.

[0064] If simulating a coiled tubing drilling experiment, remove the wellbore connector 10, set the experimental composite bridge plug into the horizontal section of the transparent wellbore 5, and then install the wellbore connector 10 and blowout preventer 3 to ensure effective sealing of the two connections.

[0065] The top of the vertical section of the transparent wellbore 5 is equipped with a working drum 1, an injector 2, and a blowout preventer 3. The first end of the coiled tubing 4 is inserted from the injector 2 and the blowout preventer 3. If simulating a coiled tubing sand flushing device, a tubing centralizer 8 and a sand flushing nozzle 9 are installed, and the transparent tubing 5 is introduced until it reaches the horizontal section. If simulating a coiled tubing drilling device, a centralizer 8, a reverse circulation valve 9B-1, a double-lobe check valve 9B-2, a screw drill 9B-3, and a flat-bottomed grinding shoe 9B-4 are installed, and the tail end of the coiled tubing 4 is connected to the coiled tubing line 39.

[0066] The injector 2 has a locking pin 2-4. After tightening the locking pin 2-4, the clamping block 2-2 slides through the locking groove 2-1 and then clamps the continuous tubing. When simulating the continuous tubing drilling experiment, if it is necessary to control the drilling pressure on the drilling tool 9B, weights can be added or removed from the injector 2.

[0067] The blowout preventer 3 has a locking nut 3-2. When the locking nut 3-2 applies pressure to the sealing packing 3-1, the sealing packing 3-1 expands and deforms to form a seal, while allowing the continuous tubing to move up and down. The blowout preventer line 40 is connected to the infusion channel 3-3.

[0068] The winch on the working drum 1 is connected to the clamping point 2-3 on the injector 2. The operation control device 12 controls the winding and unwinding of the winch, which can control the up and down movement of the coiled tubing 4. That is, it controls the forward and backward movement of the sand-flush nozzle and the drilling tool in the horizontal section of the transparent wellbore 5, and can also control the drilling pressure applied to the composite bridge plug by the drilling tool, completely simulating the sand-flush and drilling operation of the coiled tubing in actual working conditions.

[0069] A parallel pulley track 23 is provided vertically below the horizontal section of the transparent well shaft 5. The slide rail 17 can slide freely on the pulley track 23. The hydraulic cylinder 16 is fixed on the slide rail 17. The piston rod of the hydraulic cylinder 16 and the well shaft joint 10 are hinged to the rotating shaft 11. The hydraulic cylinder 16 is connected to the external hydraulic pump pipeline. The external hydraulic pump can control the extension and retraction length of the piston rod of the hydraulic cylinder 16, so that the rotating shaft 11 hinged to the piston rod rotates in an arc with a point on the inclined section as the center. At this time, under the action of the horizontal component force of the horizontal section of the transparent well shaft 5, the slide rail slides horizontally on the pulley track and drives the horizontal section of the transparent well shaft 5 to steplessly change the tilt angle within the range of 0° to 90°, so as to achieve the purpose of adjusting the angle of the horizontal section.

[0070] Pour the sand-flushing fluid or drilling fluid to be used in the experiment into the storage tank 30, and then seal the storage tank 30. The two ends of the storage tank are connected to the coiled tubing line 39 and the blowout preventer line 40. The connection is equipped with filter A 29 and filter B 33. The coiled tubing line 39 is equipped with a bidirectional transfer pump B 35, a shut-off valve D 36, a flow meter B 37 and a throttle valve B 38 in sequence. The blowout preventer line 40 is equipped with a bidirectional transfer pump A 28, a shut-off valve C 27, a flow meter A 26 and a throttle valve A 31 in sequence. After multiple cycles, a large amount of sand or drill cuttings will accumulate in the horizontal section and the directional section of the wellbore structure, which will reduce the discharge rate of the sand-flushing fluid and drilling fluid returning to the storage tank 30 and easily cause blockage of the pipeline. Therefore, when the sand-flushing fluid or drilling fluid circulation begins, both bidirectional transfer pumps should be turned on at the same time.

[0071] Filters A 29 and B 33 are installed at the connection between the reservoir 30 and the continuous tubing 39 and the blowout preventer 40 to collect the sand and drill cuttings carried into the reservoir 30, ensuring the quality of the flushing fluid and drilling fluid during circulation.

[0072] If a continuous tubing sand flushing experiment is simulated, when the liquid circulation is a positive sand flushing circulation, the frequency converter 34 needs to control the bidirectional delivery pump B35 to deliver the sand flushing fluid to the continuous tubing line 39, and control the bidirectional delivery pump A28 to extract the sand flushing fluid from the blowout box line 40. The sand flushing fluid carrying the sediment returns to the storage tank 30 through the filter A29, forming a closed positive sand flushing circulation.

[0073] If a continuous tubing sand flushing experiment is simulated, when the liquid circulation is a backflush sand circulation, the frequency converter 34 needs to control the bidirectional delivery pump A 28 to deliver the sand flushing fluid to the blowout preventer line 40, and control the bidirectional delivery pump B 35 to extract the sand flushing fluid from the continuous tubing line 39. The sand flushing fluid carrying the sediment passes through the filter B 33 and returns to the storage tank 30, forming a closed backflush sand circulation.

[0074] If a continuous tubing drilling experiment is simulated, the frequency converter 34 controls the bidirectional delivery pump B35 to deliver drilling fluid to the continuous tubing line 39, and the bidirectional delivery pump A28 controls the pump A28 to extract the drilling fluid from the blowout preventer line 40. The drilling fluid carrying drill cuttings returns to the storage tank 30 through the filter A29, forming a closed-loop drilling fluid circulation.

[0075] The drilling fluid discharge rate is controlled by controlling the valves. The drilling fluid can control the rotation speed of the flat-bottomed grinding shoe 9B-4 by using the reverse circulation valve 9B-1, the double-lobe check valve 9B-2, and the screw drill 9B-3.

[0076] The computer 14 is set outside the transparent wellbore 5 to collect and process data from the high-speed camera 15, the mobile ultrasonic probe 13, the temperature sensor 25, and the pressure sensor 22 in the experimental device; the mobile ultrasonic probe 13 set on the outer wall of the horizontal section of the wellbore can monitor the thickness of the sediment and the length of the composite bridge plug at different locations in the well structure.

[0077] The pressure regulator 20 is connected to the nitrogen cylinder 18, shut-off valve A19, shut-off valve B21 and pressure sensor 22. When shut-off valve A19 is opened, nitrogen is injected into the pressure regulator 20 using the internal pressure of the nitrogen cylinder 18. Then shut-off valve A19 is closed. The pressure regulator 20 is connected to the continuous oil line 39 and the blowout preventer line 40 respectively.

[0078] If it is a forward sand circulation, close the stop valve E 41 and open the stop valve F 42; if it is a reverse sand circulation, open the stop valve E 41 and close the stop valve F 42; if it is a drill-grind bridge plug, close the stop valve E 41 and open the stop valve F 42.

[0079] By adjusting the shut-off valve B 21, the value of the pressure sensor 22 is read. The shut-off valve B 21 is adjusted to control the pressure in the pressure regulator 20. At this time, the reading on the pressure sensor 22 is the system pressure in the well structure. The horizontal section of the transparent wellbore 5 is equipped with a heating device, which includes an electric heating film 32, a temperature sensor 25, and a temperature controller 24. The electric heating film 32 is in close contact with the outer wall of the horizontal section. Electrodes are plated at both ends of the electric heating film 32 and are electrically connected to the temperature sensor 25 and the temperature controller 24, respectively. The temperature sensor 25 and the temperature controller 24 are electrically connected to the computer 14, respectively. The electric heating film 32 is used to heat the horizontal section. The heating process is monitored by the temperature sensor 25 and displayed by the connected computer 14. By adjusting the heating temperature of the electric heating film 32, the temperature inside the transparent wellbore 5 is controlled, simulating the high temperature and high pressure environment of deep well sand flushing and drilling completion operations.

[0080] The transparent wellbore 5 is made of high-temperature and high-pressure resistant fiberglass, with a diameter of 127mm and a wall thickness of 6mm; the coiled tubing 4 is made of a special micro-alloy material with a diameter of 38.1mm; both jet nozzles and rotating nozzles are used for sand flushing; the liquids used in the experiment are clean water, linear adhesive, and low-density foam liquid, all of which are conventional sand flushing fluids; the experimental sediment is 1m thick. 3 The 0.3-0.6mm ceramic particles ensure that the sand flushing simulation experiment of the horizontal well coiled tubing is consistent with the actual field conditions.

[0081] The diameters of the reverse circulation valve 9B-1, the double-disc check valve 9B-2, and the screw drill 9B-3 are 73mm, and the diameter of the flat-bottomed grinding shoe is 108mm. All drilling and grinding tools selected are field continuous tubing drilling and grinding tools. The selected composite bridge plug is suitable for 5-inch (127mm) casing and is made of high-grade composite material.

[0082] The specific implementation method of this embodiment is as follows:

[0083] 1. Simulation experiment of sand flushing in coiled tubing

[0084] After the coiled tubing 4 is passed through the injector 2 and blowout preventer 3, it is secured to them. Then, the coiled tubing 4 is connected to the tubing centralizer 8 and the sand flushing nozzle 9 in sequence, and then inserted into the transparent wellbore 5 until it reaches the horizontal section. The sand flushing nozzles are jet nozzles and rotary nozzles. If the effect of the tubing centralizer 8 on the sand flushing effect of the coiled tubing is to be tested, the tubing centralizer 8 is not installed, and the sand flushing effect of the coiled tubing without the centralizer 8 is tested. The wellbore joint 10 of the horizontal section is removed, the amount of sand to be tested is pushed into the horizontal section, and then the wellbore joint 10 is installed to ensure that it is completely sealed with the horizontal section.

[0085] Determine the wellbore structure for the experiment. If the well inclination angle needs to be changed, adjust the wellbore structure simulation unit, use an external hydraulic pump to change the injection volume, and adjust the piston rod of hydraulic cylinder 16 to retract downward. At this time, the horizontal section of transparent wellbore 5 will give the slide rail 17 a horizontal force to the left, pushing the slide rail 17 to slide to the left on the pulley track 23 to obtain a stable wellbore structure until the well inclination angles for the experiment are 30°, 60° and 90°.

[0086] Add clean water, linear adhesive, and low-density foam liquid to the storage tank 30 as experimental sand flushing fluids, then seal it and open the shut-off valve C 27, shut-off valve D 36, throttle valve A 31, and throttle valve B 38.

[0087] Adjust the temperature controller 24 to heat the horizontal section of the transparent well tube 5 with the electric heating film 32, read the value on the temperature sensor 25, and when the temperature value reaches 50℃, adjust the temperature controller 24 to stabilize the temperature of the transparent well tube 5 at the experimental temperature of 50℃.

[0088] During the positive sand flushing simulation experiment, shut-off valves C27, D36, A31, and B38 are opened to activate the liquid circulation unit. The frequency converter 34 controls the bidirectional pump B35 to deliver flushing fluid to the continuous tubing line 39. The value on the flow meter B37 is recorded. The flow meter B38 and frequency converter 34 are adjusted to control the flushing fluid discharge rate. The experimental flushing fluid discharge rates are set to 285 L / min, 325 L / min, and 385 L / min, respectively. The bidirectional pump A28 is controlled to extract flushing fluid from the blowout preventer line 40 with the same power and discharge rate. If the value on the flow meter A26 is the same as the value on the flow meter B37, it indicates that the entire positive sand flushing circulation has not been blocked, and the flushing fluid returns to the storage tank 30 after passing through the filter A29.

[0089] When conducting the backwash simulation experiment, open the shut-off valve C 27, shut-off valve D 36, throttle valve A 31, and throttle valve B 38 to start the liquid circulation unit. Use the frequency converter 34 to adjust the bidirectional delivery pump A 28 to deliver the backwash fluid to the blowout preventer line 40. Record the value on the flow meter A 26. Adjust the throttle valve A 31 and the frequency converter 34 to control the discharge rate of the backwash fluid. The experimental discharge rates of the backwash fluid are set to 285 L / min, 325 L / min, and 385 L / min, respectively. Control the bidirectional delivery pump B 35 to extract the backwash fluid from the continuous tubing line 39 with the same power and discharge rate. If the value of the flow meter B 37 is the same as the value of the flow meter A 26, it indicates that the entire backwash circulation has not been blocked. The fluid returns to the storage tank 30 after passing through the filter B 33.

[0090] Open the shut-off valve A19 on the nitrogen cylinder 18 to inject nitrogen into the pressure regulator 20, and then close the shut-off valve A19; at this time, the liquid circulation is in forward sand circulation, so close the shut-off valve E 41 and open the shut-off valve F 42; at this time, the liquid circulation is in reverse sand circulation, so close the shut-off valve F 42 and open the shut-off valve E 41; adjust the shut-off valve B 21 on the liquid storage tank 20 to control the value on the pressure sensor 22 to 5MPa;

[0091] The operation control device 12 controls the lowering of the winch rope, which drives the sand-flushing nozzle 9 on the coiled tubing 4 to advance at a speed of 5 m / min until the sediment in the horizontal section of the transparent wellbore 5 is washed clean.

[0092] The high-speed camera 15 captures the morphology of the sand particles moving in the horizontal section of the transparent well shaft 5 during the experiment, and then uploads the experimental photos to the computer 14. The ultrasonic probe 13 can monitor and detect the thickness of the sand particles. The computer 14 records and displays the morphology and trajectory of the sand particles, as well as the thickness, width and length of the sand particles and the time required for the sand particles to be completely removed.

[0093] To illustrate the experimental role of this device in evaluating the effect of sand flushing during coiled tubing sand flushing, the device was used to evaluate the relationship between the effect of coiled tubing sand flushing and the above-mentioned factors under different well structure, sand flushing fluid discharge rate, sand flushing fluid type, sand flushing nozzle type, presence or absence of tubing centralizer, and sand flushing method.

[0094] The flushing solution used in the experiment was clean water, and the sediment used was 1m thick. 3 The wellbore contains 0.3-0.6mm ceramic particles, has a transparent wellbore temperature of 50℃, a pressure of 5MPa, a sand flushing fluid discharge rate of 285L / min, a sand flushing nozzle that is a jet nozzle, and is equipped with a tubing centralizer.

[0095] Well structure:

[0096] With other factors remaining constant, the well inclination angle in the well structure was changed to 30°, 60° and 90° respectively, and the experimental data and results were obtained.

[0097] As can be seen from the data in Table 1, when the well inclination angle is increased to 60° and 90°, compared with the well inclination angle of 30°, the sand flushing time of the coiled tubing increases significantly, and the sand-carrying fluid in the horizontal well section has difficulty carrying sand.

[0098] Table 1. Sand flushing time at different well inclination angles

[0099]

[0100]

[0101] Sand flushing fluid discharge rate:

[0102] With other parameters unchanged, the flushing fluid flow rate was adjusted to 285 L / min, 325 L / min and 385 L / min respectively, and the experimental data and results were measured.

[0103] Table 2. Flushing Time under Different Flushing Fluid Discharge Rates

[0104] Types of sand flushing fluid Sand particle size Well inclination angle Sand flushing fluid discharge Sandblasting nozzle types central stabilizer Sand washing time Clear water 0.3-0.6mm 90° 285L / min jet nozzle have 12min Clear water 0.3-0.6mm 90° 325L / min jet nozzle have 9min Clear water 0.3-0.6mm 90° 385L / min jet nozzle have 7min

[0105] As can be seen from the data in Table 2, increasing the flushing fluid flow rate can significantly improve the flushing efficiency of coiled tubing. When the flushing fluid flow rate is 325 L / min and 385 L / min, the flushing time is reduced by about 25% and 42% respectively compared to the flushing fluid flow rate of 285 L / min.

[0106] Type of sand-washing fluid:

[0107] With other parameters unchanged, the sand flushing fluid was changed to water, linear adhesive and low-density foam liquid, and the experimental data and results were measured.

[0108] As shown in Table 3, water has the worst sand-carrying capacity and the longest flushing time when used as the flushing fluid. When linear adhesive and low-density foam liquid are used as flushing fluids, the sand-carrying capacity is enhanced, the sand-carrying efficiency is roughly the same, and the flushing time is reduced by approximately 33.3% and 50%, respectively.

[0109] Table 3. Flushing Time for Different Flushing Fluid Types

[0110] Types of sand flushing fluid Sand particle size Well inclination angle Sand flushing fluid discharge Sandblasting nozzle types central stabilizer Sand washing time Clear water 0.3-0.6mm 90° 285L / min jet nozzle have 12min Linear adhesive 0.3-0.6mm 90° 285L / min jet nozzle have 8min Low-density foam liquid 0.3-0.6mm 90° 285L / min jet nozzle have 6min

[0111] Sandblasting nozzle type:

[0112] With other parameters remaining unchanged, the type of sand-flushing nozzle was changed to either a jet nozzle or a rotating nozzle, and experimental data and results were obtained.

[0113] Table 4. Sand flushing time for different sand flushing nozzle types

[0114] Types of sand flushing fluid Sand particle size Well inclination angle Sand flushing fluid discharge Sandblasting nozzle types central stabilizer Sand washing time Clear water 0.3-0.6mm 90° 285L / min jet nozzle have 12min Clear water 0.3-0.6mm 90° 285L / min Rotary nozzle have 9min

[0115] As can be seen from the data in Table 4, when the sand-carrying nozzle is a rotating nozzle, the sand-carrying capacity is greatly enhanced, and the sand-carrying time of the rotating nozzle is reduced by about 25% compared with that of the jet nozzle.

[0116] Tubing centralizer:

[0117] With other parameters remaining unchanged, the tubing stabilizer was removed, and the experimental data and results were measured.

[0118] Table 5. Sand flushing time after removing the tubing centralizer

[0119] Types of sand flushing fluid Sand particle size Well inclination angle Sand flushing fluid discharge Sandblasting nozzle types central stabilizer Sand washing time Clear water 0.3-0.6mm 90° 285L / min jet nozzle have 12min Clear water 0.3-0.6mm 90° 285L / min jet nozzle none 10min

[0120] As can be seen from the data in Table 5, without the installation of the tubing centralizer, the sand flushing efficiency of the jet nozzle decreases significantly, and the sand flushing time increases by about 17%.

[0121] Sand washing method:

[0122] With other parameters unchanged, a single oblique nozzle was installed, and both forward and reverse sand flushing methods were used to measure experimental data and results.

[0123] Table 6. Sand flushing time under different sand flushing methods

[0124] Sand washing method Types of sand flushing fluid Well inclination angle Sand flushing fluid discharge Sandblasting nozzle types central stabilizer Sand washing time Sand washing Clear water 90° 285L / min Single angled nozzle have 14min Backwash Sand Clear water 90° 285L / min Single angled nozzle have 11min

[0125] As can be seen from the data in Table 6, when using a single-angled air nozzle, the sand flushing efficiency of backflush is significantly improved compared to that of forward flush, and the sand flushing time is reduced by about 21.4%.

[0126] 1. Simulation Experiment of Coiled Tubing Drilling

[0127] After the coiled tubing 4 is passed through the injector 2 and blowout preventer 3, it is secured to them. Then, the coiled tubing 4 is sequentially connected to the tubing stabilizer 8, the reverse circulation valve 9B-1, the double-disc check valve 9B-2, the screw drill 9B-3, and the flat-bottomed grinding shoe 9B-4, and then inserted into the transparent wellbore 5 until the horizontal section is reached. The flat-bottomed grinding shoe is of the four-blade high-efficiency type and the six-blade high-efficiency type. The wellbore connector 10 of the horizontal section is removed, and the composite bridge plug used for the experiment is set in the horizontal section. Then, the wellbore connector 10 is installed to ensure a complete seal with the horizontal section.

[0128] Determine the wellbore structure for the experiment. If the well inclination angle needs to be changed, adjust the wellbore structure simulation unit, use an external hydraulic pump to change the injection volume, and adjust the piston rod of hydraulic cylinder 16 to retract downward. At this time, the horizontal section of transparent wellbore 5 will give the slide rail 17 a horizontal force to the left, pushing the slide rail 17 to slide to the left on the pulley track 23 to obtain a stable wellbore structure until the well inclination angles for the experiment are 30°, 60° and 90°.

[0129] Drilling working fluid for drilling is added to the storage tank 30. The working fluid formula is electric pump fluid plus drag reducer. Then the tank is sealed and the shut-off valves C 27, D 36, A 31 and B 38 are opened.

[0130] To investigate the effect of drilling and grinding working fluid additives on drilling and grinding performance, KCl solution can be added to the reservoir 30 and then sealed before conducting a continuous tubing drilling and grinding bridge plug experiment again.

[0131] Adjust the temperature controller 24 to heat the horizontal section of the transparent well tube 5 with the electric heating film 32, read the value on the temperature sensor 25, and when the temperature value reaches 50℃, adjust the temperature controller 24 to stabilize the temperature of the transparent well tube 5 at the experimental temperature of 50℃.

[0132] During the drilling simulation experiment, shut-off valves C27, D36, A31, and B38 are opened to activate the liquid circulation unit. The frequency converter 34 controls the bidirectional pump B35 to deliver flushing fluid to the continuous tubing line 39. The value on the flow meter B37 is recorded. The flow meter B38 and the frequency converter 34 are adjusted to control the drilling fluid discharge rate, which is set to 350 L / min, 420 L / min, and 500 L / min. The bidirectional pump A28 is controlled to extract the drilling fluid from the blowout preventer line 40 with the same power and discharge rate. If the value on the flow meter A26 is the same as the value on the flow meter B37, it indicates that the entire liquid circulation is not blocked, and the drilling fluid returns to the storage tank 30 through the filter A29.

[0133] Open the shut-off valve A19 on the nitrogen cylinder 18 to inject nitrogen into the pressure regulator 20, and then close the shut-off valve A19; at this time, the liquid circulation is in forward sand circulation, so close the shut-off valve E 41 and open the shut-off valve F 42; at this time, the liquid circulation is in reverse sand circulation, so close the shut-off valve F 42 and open the shut-off valve E 41; adjust the shut-off valve B 21 on the liquid storage tank 20 to control the value on the pressure sensor 22 to 5MPa;

[0134] The operation control device 12 controls the lowering of the winch rope and controls the drilling pressure of the flat-bottomed grinding shoe 9B-4 on the composite bridge plug 43 until the composite bridge plug 43 in the horizontal section of the transparent wellbore 5 is drilled clean.

[0135] The high-speed camera 15 captures the morphology of the drill cuttings movement in the horizontal section of the transparent wellbore 5 during the experiment, and then uploads the experimental photos to the computer 14. The ultrasonic probe 13 can monitor and detect the length of the composite bridge plug 43. The computer 14 records and displays the morphology and trajectory of the drill cuttings movement, the length of the composite bridge plug 43, and the time required for complete removal.

[0136] To illustrate the experimental role of this device in evaluating the effect of drilling bridge plugs during coiled tubing drilling, the device was used to evaluate the relationship between the coiled tubing drilling effect and the above-mentioned factors under different drilling shoe types, drilling fluid flow rates, and drilling fluid additives.

[0137] The drilling fluid used in the experiment was formulated as an electric pump fluid with a drag-reducing agent. The composite bridge plug was made of high-grade composite material. The transparent wellbore temperature was 50℃, the pressure was set to 5MPa, and the drilling fluid flow rate was 350L / min, 420L / min and 500L / min. The flat-bottomed grinding shoes were four-blade high-efficiency grinding shoes and six-blade high-efficiency grinding shoes. The wellbore inclination was 30 degrees.

[0138] Shoe type:

[0139] With other factors remaining constant, experimental data and results were obtained by using four-blade high-efficiency grinding shoes and six-blade high-efficiency grinding shoes respectively.

[0140] Table 7 Drilling Time for Different Shoe Types

[0141] Drilling working fluid discharge Types of shoes KCl solution Drilling time 420L / min Four-blade high-efficiency shoe polishing none 36min 420L / min Six-blade high-efficiency shoe polishing none 49min

[0142] The data in Table 7 shows that the four-blade high-efficiency grinding shoe is more efficient at drilling and grinding bridge plugs than the six-blade high-efficiency grinding shoe. Therefore, the four-blade high-efficiency grinding shoe should be selected as much as possible in field conditions.

[0143] Drilling fluid displacement:

[0144] Four-blade high-efficiency grinding shoes were selected for grinding. With other parameters unchanged, the drilling and grinding working fluid flow rate was adjusted to 350L / min, 420L / min and 500L / min respectively, and the experimental data and results were measured.

[0145] Table 8. Drilling time under different drilling fluid discharge rates

[0146] Drilling working fluid discharge Types of shoes KCl solution Drilling time 350L / min Four-blade high-efficiency shoe polishing none 54min 420L / min Four-blade high-efficiency shoe polishing none 36min 500L / min Four-blade high-efficiency shoe polishing none 32min

[0147] During the experiment, when the drilling fluid flow rate was 350 L / min, wellbore blockage occurred. The wellbore only became clear after increasing the flow rate. Table 8 shows that increasing the drilling fluid flow rate significantly improves the drilling efficiency of coiled tubing.

[0148] Drilling fluid additives:

[0149] With other parameters remaining constant, KCl solution was added to the drilling working fluid, and experimental data and results were measured.

[0150] As can be seen from the data in Table 9, the drilling time was significantly reduced after adding KCl solution to the drilling working fluid.

[0151] Table 9 Drilling time after adding KCl solution

[0152] Drilling working fluid discharge Types of shoes KCl solution Drilling time 420L / min Four-blade high-efficiency shoe polishing none 36min 420L / min Four-blade high-efficiency shoe polishing have 29min

[0153] This demonstrates that this device can be effectively used in studies that evaluate the effects of sand flushing and drilling in coiled tubing.

[0154] In the description of this invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limitations on this invention.

Claims

1. An experimental apparatus for evaluating the sand flushing and drilling effects of coiled tubing in horizontal wells, comprising a coiled tubing sand flushing unit, a coiled tubing drilling unit, a wellbore structure simulation unit, a fluid circulation unit, a data measurement and processing unit, and a high-temperature and high-pressure simulation unit, characterized in that, The coiled tubing sand flushing unit includes a working drum (1), a control device (12), an injector (2), a blowout preventer (3), coiled tubing (4), a tubing stabilizer (8), and a sand flushing nozzle (9A); the coiled tubing drilling and grinding unit replaces the sand flushing nozzle (9A) in the coiled tubing sand flushing unit with a drilling and grinding tool (9B) and a composite bridge plug (43). The drilling and grinding tool (9B) includes a reverse circulation valve (9B-1), a double-lobe check valve (9B-2), a screw drill (9B-3), and a flat-bottomed grinding shoe (9B-4); the well structure simulation unit includes a transparent wellbore (5), a wellbore coupling (6), a high-temperature and high-pressure resistant rubber hose (7), a wellbore joint (10), a rotating shaft (11), a hydraulic cylinder (16), a slide rail (17), and a pulley track (23); the liquid circulation unit includes a frequency converter (3) 4) Two-way transfer pump A (28), filter A (29), liquid storage tank (30), filter B (33), two-way transfer pump B (35), continuous oil pipeline (39), blowout preventer pipeline (40), shut-off valve C (27), throttle valve A (31), shut-off valve D (36), throttle valve B (38); The data measurement and processing unit includes flow meter A (26), flow meter B (37), mobile ultrasonic probe (13), computer (14), high-speed camera (15); The high temperature and high pressure simulation unit includes nitrogen cylinder (18), pressure regulator (20), pressure sensor (22), temperature controller (24), temperature sensor (25), electric heating film (32), shut-off valve A (19), shut-off valve B (21), shut-off valve E (41) and shut-off valve F (42); The transparent wellbore (5) has two sections, namely a vertical section and a horizontal section. The vertical section is set vertically and the horizontal section is set horizontally. The high temperature and high pressure resistant rubber pipe (7) is connected to the two transparent wellbore sections (5) through wellbore coupling (6) to simulate the vertical section, skew section and horizontal section of the wellbore on site, respectively. The well joint (10) and the rotating shaft (11) are at the free end of the horizontal section of the transparent well (5). The rotating shaft (11) is hinged to the piston rod of the hydraulic cylinder (16). The hydraulic cylinder (16) is connected to the external hydraulic pump pipeline. The hydraulic cylinder (16) is fixed on the slide rail (17). The slide rail (17) slides on the pulley track (23). The blowout preventer (3) is located at the top of the vertical section of the transparent wellbore (5) and is connected to the blowout preventer pipeline (40); the working drum (1) and the injector (2) are located at the vertical upper part of the blowout preventer (3); The first end of the coiled tubing (4) passes through the injector (2) and the blowout preventer (3) and enters the horizontal section of the transparent wellbore (5), and its tail end is connected to the coiled tubing line (39); The continuous tubing line (39) is sequentially equipped with a bidirectional transfer pump B (35), a shut-off valve D (36), a flow meter B (37), and a throttle valve B (38); the blowout preventer line (40) is sequentially equipped with a bidirectional transfer pump A (28), a shut-off valve C (27), a flow meter A (26), and a throttle valve A (31); the frequency converter (34) is connected to the bidirectional transfer pump A (28) and the bidirectional transfer pump B (35); The reverse circulation valve (9B-1), the double-lobe check valve (9B-2), the screw drill (9B-3), and the flat-bottomed grinding shoe (9B-4) are sequentially connected to the end of the horizontal section of the continuous tubing in the transparent wellbore (5), and the composite bridge plug (43) is set at the end of the horizontal section of the transparent wellbore (5). The transparent wellbore (5) is equipped with an electric heating film (32) on the outside, and a temperature controller (24) and a temperature sensor (25) are installed; the pressure regulator (20) is connected to a nitrogen cylinder (18), a pressure sensor (22), a shut-off valve A (19) and a shut-off valve B (21); the pressure regulator (20) is connected to the coiled tubing line (39) and the blowout preventer line (40), and is controlled by shut-off valve E (41) and shut-off valve F (42); The computer (14) is located outside the transparent well shaft (5) and is electrically connected to the high-speed camera (15), the mobile ultrasonic probe (13), the pressure sensor (22), the temperature controller (24), and the temperature sensor (25), respectively. The continuous tubing line (39) and the blowout preventer line (40) are connected together to the reservoir (30).

2. The experimental apparatus for evaluating the sand flushing and drilling effects of coiled tubing in horizontal wells according to claim 1, characterized in that, The injector (2) consists of a locking groove (2-1), a clamping block (2-2), a clamping point (2-3), and a locking pin (2-4), and is used to clamp the continuous tubing (4). The working drum (1) at the top of the injector (2) is connected to the clamping point (2-3) by a rope. Starting the working drum (1) causes the injector (2) and the continuous tubing (4) to move in the vertical direction.

3. The experimental apparatus for evaluating the sand flushing and drilling effects of coiled tubing in horizontal wells according to claim 1, characterized in that, The blowout preventer (3) consists of a sealing packing (3-1), a locking nut (3-2), an infusion channel (3-3), a sealing ring (3-4), and a locking knob (3-5). The sealing packing (3-1) and the sealing ring (3-4) form an annular seal around the coiled tubing (4), while allowing the coiled tubing to move up and down.

4. The experimental apparatus for evaluating the sand flushing and drilling effects of coiled tubing in horizontal wells according to claim 3, characterized in that, The blowout preventer pipeline (40) is connected to the fluid delivery channel (3-3), and the sand flushing fluid enters and exits the transparent wellbore (5) through the fluid delivery channel (3-3).

5. The experimental apparatus for evaluating the sand flushing and drilling effects of coiled tubing in horizontal wells according to claim 1, characterized in that, When the hydraulic cylinder (16) adjusts the length of the piston rod, the horizontal section of the transparent well shaft (5) can be infinitely changed in slope, with a change angle of 0° to 90°; at the same time, it will generate a component force parallel to the horizontal section of the transparent well shaft (5) on the slide rail (17), so that the slide rail (17) slides parallel to the horizontal section of the transparent well shaft (5) on the pulley track (23).

6. The experimental apparatus for evaluating the sand flushing and drilling effects of coiled tubing in horizontal wells according to claim 1, characterized in that, The connection point of the continuous oil pipeline (39) and the blowout preventer pipeline (40) connected to the liquid storage tank (30) is equipped with filter A (29) and filter B (33). When the frequency converter (34) changes the conveying direction of the bidirectional conveying pump A (28) and bidirectional conveying pump B (35), it can complete both forward and reverse sand flushing. The two filters can better perform the function of filtering sand and maintain a low solid content in the liquid storage tank (30).

7. The experimental apparatus for evaluating the sand flushing and drilling effects of coiled tubing in horizontal wells according to claim 1, characterized in that, A temperature sensor (25) is set to measure the temperature inside the transparent wellbore (5). The temperature is adjusted to the preset value using a temperature controller (24) as needed to simulate the high temperature environment of the formation. The pressure regulator (20) is connected to the nitrogen cylinder (18) and the shut-off valve A (19). The nitrogen is injected into the pressure regulator (20) using the internal pressure of the nitrogen cylinder (18). The pressure regulator (20) is connected to the coiled tubing line (39) and the blowout preventer line (40) respectively to simulate the system pressure of the wellbore environment during the conventional sand flushing fluid flushing and drilling bridge plug completion process.

8. The experimental apparatus for evaluating the sand flushing and drilling effects of coiled tubing in horizontal wells according to claim 1, characterized in that, The high-speed camera (15) is used to photograph and record the movement of sand particles in the vertical, inclined and horizontal sections, and to record the time when the settled sand is completely removed.

9. The experimental apparatus for evaluating the sand flushing and drilling effects of coiled tubing in horizontal wells according to claim 1, characterized in that, The transparent wellbore (5) is made of high-temperature and high-pressure resistant fiberglass. The sand flushing fluid used in the experiment is water, linear adhesive and low-density foam liquid. The sand used in the experiment is ceramsite. The sand flushing nozzle (9A) is a jet nozzle and a rotating nozzle.

10. An experimental method using the experimental apparatus for evaluating the sand flushing and drilling effects of coiled tubing in horizontal wells as described in any one of claims 1-9, characterized in that, Includes the following steps: A. Procedure for Sand Flushing Test of Coiled Tubing (i) After the coiled tubing (4) passes through the injector (2) and the blowout preventer (3), the coiled tubing (4) is fixed to them. Then the coiled tubing (4) is connected to the tubing stabilizer (8) and the sand spray nozzle (9A) in sequence. After the blowout preventer (3) and the transparent wellbore (5) are fixed, the coiled tubing (4) is inserted into the transparent wellbore (5) until the horizontal section is reached. (ii) Remove the wellbore connector (10) of the horizontal well section, push the amount of sand to be tested into the horizontal well section, and then install the wellbore connector (10) to make it completely sealed with the horizontal well section. (iii) If the well structure really needs to be tested, adjust the well structure simulation unit, use an external hydraulic pump to change the injection volume, adjust the extension length of the piston rod of the hydraulic cylinder (16) and its position on the pulley rail (23), and change the well inclination angle of the horizontal section of the transparent well barrel (5). (iv) Load the experimental fluid for sand flushing into the storage tank (30), then seal it, and open the shut-off valve C (27), shut-off valve D (36), throttle valve A (31) and throttle valve B (38). (V) Adjust the temperature controller (24) to heat the horizontal section of the transparent well tube (5) with the electric heating film (32), read the value on the temperature sensor (25), and make the temperature of the transparent well tube (5) reach the preset experimental value; (vi) When conducting the positive sand flushing simulation experiment, open the shut-off valve C (27), shut-off valve D (36), throttle valve A (31) and throttle valve B (38), start the liquid circulation unit, use the frequency converter (34) to control the bidirectional delivery pump B (35) to deliver sand flushing fluid to the continuous oil pipeline (39), record the value on the flow meter B (37), adjust the throttle valve B (38) to control the sand flushing fluid discharge, control the bidirectional delivery pump A (28) to extract the sand flushing fluid from the blowout box pipeline (40), pass through the filter A (29) and return to the storage tank (30) to form a positive sand flushing circulation; (vii) When conducting the backwash sand simulation experiment, open the shut-off valve C (27), shut-off valve D (36), throttle valve A (31) and throttle valve B (38), start the liquid circulation unit, use the frequency converter (34) to adjust the bidirectional delivery pump A (28) to deliver sand flushing fluid to the blowout box pipeline (40), record the value on the flow meter A (26), adjust the throttle valve A (31) to control the discharge of sand flushing fluid, and the bidirectional delivery pump B (35) draws sand flushing fluid from the continuous oil pipeline (39), passes through the filter B (33) and returns to the storage tank (30) to form a backwash sand circulation; (viii) Open the shut-off valve A (19) on the nitrogen cylinder (18) to inject nitrogen into the pressure regulator (20), and then close the shut-off valve A (19); at this time, the liquid circulation is positive sand flushing circulation, then close the shut-off valve E (41) and open the shut-off valve F (42); at this time, the liquid circulation is negative sand flushing circulation, then close the shut-off valve F (42) and open the shut-off valve E (41); adjust the shut-off valve B (21) on the pressure regulator (20) and read the value on the pressure sensor (22) to simulate the system pressure of the wellbore environment during conventional continuous tubing sand flushing completion; (ix) Operation control device (12) controls the winding and unwinding of the winch, driving the injector (2) to move in the vertical direction. At this time, one end of the sand flushing nozzle (9A) of the coiled tubing (4) will also move forward and backward in the horizontal section of the transparent wellbore (5), which can achieve a better sand flushing effect. (x) A high-speed camera (15) takes photos of the continuous tubing sand flushing experiment and uploads them to a computer (14). A mobile ultrasonic probe (13) detects the thickness of the sand. The computer (14) records and displays the migration pattern and trajectory of the sand particles, and displays the thickness, width and length of the sand and the time it takes for the sand to be completely removed. B. Coiled tubing drilling and grinding test procedures (i) After the coiled tubing (4) passes through the injector (2) and blowout preventer (3), the coiled tubing (4) is fixed to them. Then the coiled tubing (4) is connected in sequence to the tubing stabilizer (8), the reverse circulation valve (9B-1), the double-valve check valve (9B-2), the screw drill (9B-3), and the flat-bottomed grinding shoe (9B-4). After the blowout preventer (3) and the transparent tubing (5) are fixed, the coiled tubing is inserted into the transparent wellbore (5) until it reaches the horizontal section. (ii) Remove the wellbore connector (10) of the horizontal well section, set the composite bridge plug (43) to be tested at the end of the horizontal well section, and then install the wellbore connector (10) to make it completely sealed with the horizontal well section. (iii) If the well structure really needs to be tested, adjust the well structure simulation unit, use an external hydraulic pump to change the injection volume, adjust the extension length of the piston rod of the hydraulic cylinder (16) and its position on the pulley rail (23), and change the well inclination angle of the horizontal section of the transparent well barrel (5). (iv) Load the experimental fluid for sand flushing into the storage tank (30), then seal it, and open the shut-off valve C (27), shut-off valve D (36), throttle valve A (31) and throttle valve B (38). (V) Adjust the temperature controller (24) to heat the horizontal section of the transparent well tube (5) with the electric heating film (32), read the value on the temperature sensor (25), and make the temperature of the transparent well tube (5) reach the preset experimental value; (vi) Open shut-off valve C (27), shut-off valve D (36), throttle valve A (31) and throttle valve B (38), start the liquid circulation unit, use frequency converter (34) to control bidirectional delivery pump B (35) to deliver chip removal fluid to the continuous oil line (39), record the value on flow meter B (37), adjust throttle valve B (38) to control the discharge of drilling working fluid, so as to control the working torque of screw drill; control bidirectional delivery pump A (28) to extract drilling working fluid from blowout box line (40), and return it to the storage tank (30) through filter A (29); (vii) Open the shut-off valve A (19) on the nitrogen cylinder (18) to inject nitrogen into the pressure regulator (20), and then close the shut-off valve A (19); close the shut-off valve E (41) and open the shut-off valve F (42); adjust the shut-off valve B (21) on the pressure regulator (20) and read the value on the pressure sensor (22) to simulate the system pressure of the wellbore environment during conventional coiled tubing drilling and finishing process; (viii) Operate the control device (12) to control the winding and unwinding of the winch, and drive the injector (2) to move in the vertical direction. At this time, one end of the flat-bottomed grinding shoe (9B-4) of the coiled tubing (4) will move forward and backward in the horizontal section of the transparent wellbore (5). In order to better transmit drilling pressure in the flat-bottomed grinding shoe (9B-4), a heavy object is added to the injector, which can transmit more drilling pressure in the flat-bottomed grinding shoe (9B-4) to achieve a better drilling effect. (ix) A high-speed camera (15) takes photos of the continuous tubing drilling and grinding experiment and uploads them to a computer (14). A mobile ultrasonic probe (13) detects the length of the bridge plug. The computer (14) records and displays the movement pattern and trajectory of the drill cuttings, and displays the time when the bridge plug and drill cuttings are completely removed.

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