Experimental device and method for evaluating sand washing and drilling and grinding effects of coiled tubing of horizontal well

Abstract

The invention discloses an experimental device and method for evaluating sand washing and drilling and grinding effects of a coiled tubing of a horizontal well, and the experimental device comprises a coiled tubing sand washing unit, a coiled tubing drilling and grinding unit, a well body structure simulation unit, a liquid circulation unit, a data measuring and processing unit and a high-temperature and high-pressure simulation unit, and is used for simulating working conditions of sand washing and well washing of a long horizontal section of petroleum. And carrying out a conventional sand washing fluid settled sand removal evaluation experiment. The device has the function of visually observing, recording and removing the sand setting effect of the horizontal well, and sand washing and drilling and grinding simulation experiments under the working conditions of comparing the well body structure, the construction displacement, the sand washing fluid type, the sand washing nozzle type, the existence or absence of an oil pipe centralizer, the sand washing mode, the grinding shoe type, the drilling and grinding working fluid displacement, the drilling and grinding working fluid additive and the like are carried out. And the influence of the working conditions on the sand washing and drilling and grinding effects of the coiled tubing is evaluated, and the optimal sand washing and drilling and grinding engineering combination of the coiled tubing is optimized. The device is designed according to on-site sand washing and well washing and bridge plug drilling and grinding working conditions, and is complete in structure and convenient to operate.

Description

Technical Field

[0001] The invention relates to the technical field of experimental simulation of oilfield well repairing operations, in particular to an experimental device and method for evaluating sand flushing and drilling and grinding effects of a coiled tubing in a horizontal well. Background Art

[0002] At present, the main technology that can achieve large-volume tight oil horizontal well volume fracturing is the pumped composite bridge plug staged fracturing technology. In order to achieve full-bore production after fracturing transformation, it is necessary to promptly remove the formation sand, fracturing sand deposition and staged bridge plugs. The horizontal wellbore has a fast sand and debris deposition rate, and it is difficult to carry sand and debris, especially for gas wellbore under pressure sand washing and drilling and grinding bridge plugs without well pressure. Conventional equipment and threaded connection strings are difficult to meet the requirements of horizontal well pressure sand washing and drilling and grinding bridge plugs. Horizontal well sand washing and drilling and grinding using continuous tubing technology can well adapt to pressure operations.

[0003] At present, the methods of horizontal well sand removal and bridge plug drilling and grinding are mostly simulated through numerical simulation. The results have certain guiding significance for the design of coiled tubing sand flushing and drilling and grinding, but field tests are still needed for evaluation. The actual effect of coiled tubing sand flushing and drilling and grinding may be quite different from the simulation, and field verification experiments consume manpower and material resources.

[0004] Therefore, it is very necessary to evaluate and study the effects of sand flushing and drilling and grinding of horizontal well coiled tubing. An experimental device is needed that can fit the horizontal well coiled tubing sand flushing and drilling and grinding process as closely as possible under actual working conditions, and to analyze and study the engineering factors that affect the horizontal well coiled tubing sand flushing and drilling and grinding. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide an experimental device and method for evaluating the sand flushing and drilling and grinding effects of coiled tubing in horizontal wells. Under the condition of comprehensively considering the wellbore structure, sand flushing fluid displacement, sand flushing fluid type, sand flushing nozzle type, tubing centralizer, sand flushing method, grinding shoe type, drilling and grinding working fluid displacement, drilling and grinding working fluid additives and other related factors, the actual horizontal well coiled tubing sand flushing and drilling and grinding working conditions can be effectively simulated to realize the research on the factors affecting the sand flushing and drilling and grinding of coiled tubing in horizontal wells. Indoors, the specific engineering parameters in the field construction are used to control the parameter variables therein to achieve the relationship between the simulated coiled tubing sand flushing and drilling and grinding and various parameters, so that the coiled tubing process can be targetedly improved.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: an experimental device for evaluating the sand flushing and drilling and grinding effects of horizontal well coiled tubing, including a coiled tubing sand flushing unit, a coiled tubing drilling and grinding unit, a wellbore structure simulation unit, a liquid 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, a coiled tubing, a tubing centralizer, and a sand flushing nozzle; the coiled tubing drilling and grinding unit replaces the sand flushing nozzle in the coiled tubing sand flushing unit with a drilling and grinding tool and a composite bridge plug, and the drilling and grinding tool includes a reverse circulation valve, a double-flap check valve, a screw drill, and a flat-bottomed grinding shoe; the wellbore structure simulation unit The element includes a transparent wellbore, a wellbore coupling, a high-temperature and high-pressure resistant rubber tube, a wellbore joint, a rotating shaft, a hydraulic cylinder, a slide rail car, and a pulley track; the liquid circulation unit includes a frequency converter, a two-way delivery pump A, a filter A, a liquid storage tank, a filter B, a two-way delivery pump B, an oil pipe sand flushing pipeline, a blowout prevention box pipeline, a stop valve C, a throttle valve A, a stop 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 bottle, a voltage stabilizer, a pressure sensor, a temperature controller, a temperature sensor, an electric heating film, a stop valve A, a stop valve B, a stop valve E, and a stop valve F;

[0007] The transparent wellbore has two sections, namely a vertical section and a horizontal section. The vertical section is arranged vertically, and the horizontal section is arranged horizontally. The high temperature and high pressure resistant rubber tube is connected to the two sections of the transparent wellbore through a wellbore coupling, respectively simulating the vertical section, the deflection section and the horizontal section of the on-site wellbore.

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

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

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

[0011] The oil pipe sand flushing pipeline is provided with a two-way delivery pump B, a stop valve D, a flow meter B and a throttle valve B in sequence; the blowout prevention box pipeline is provided with a two-way delivery pump A, a stop valve C, a flow meter A and a throttle valve A in sequence; the frequency converter is connected to the two-way delivery pump A and the two-way delivery pump B;

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

[0013] The transparent wellbore is provided with an electric heating film on the outside, a temperature controller and a temperature sensor are provided; the voltage stabilizer is connected to the nitrogen bottle, the pressure sensor, the stop valve A and the stop valve B; the voltage stabilizer is connected to the coiled tubing line and the blowout prevention box line, and is controlled by the stop valve and the stop valve;

[0014] The computer is arranged outside the transparent wellbore and is electrically connected to the high-speed camera, the movable ultrasonic probe, the pressure sensor, the temperature controller, and the temperature sensor respectively;

[0015] The coiled tubing line and the blowout preventer box line are connected to the liquid storage tank.

[0016] The injector is composed of a locking groove, a clamping block, a clamping suspension point, and a locking pin, and is used to clamp the coiled tubing. The working drum on the injector is connected to the clamping suspension point through a twisted rope. Starting the working drum allows the injector and the coiled tubing to move in a vertical direction.

[0017] The blowout prevention box is composed of a sealing packing, a locking nut, an infusion channel, a sealing ring, and a locking knob. The sealing packing and the sealing ring form an annular seal around the coiled tubing and allow the coiled tubing to move up and down.

[0018] The blowout prevention box pipeline is connected to the infusion channel, and the sand flushing liquid enters and exits the transparent wellbore through the infusion channel.

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

[0020] Filters A and B are provided at the connection points of the coiled tubing line and the blowout preventer box line connected to the liquid storage tank. When the frequency converter is controlled to change the delivery direction of the bidirectional delivery pump A and the bidirectional delivery pump B, two sand flushing modes, forward sand flushing and reverse sand flushing, can be completed. The two filters can better filter the sedimentation sand and maintain a low solid content in the liquid storage tank.

[0021] A temperature sensor is set to measure the temperature inside the transparent wellbore, and the temperature is adjusted to the preset value using a temperature controller as needed to simulate the high-temperature environment of the formation; the pressure regulator is connected to the nitrogen bottle and the stop valve A, and the nitrogen is injected into the pressure regulator using the internal pressure of the nitrogen bottle. The pressure regulator is connected to the coiled tubing pipeline and the blowout preventer box pipeline respectively to simulate the system pressure of the wellbore environment during conventional sand flushing fluid sand flushing and drilling and grinding bridge plug completion.

[0022] The high-speed camera is used to photograph and record the migration status of sand in the vertical well section, the inclined well section and the horizontal section, and to record the time when the sediment is completely removed.

[0023] The transparent shaft is made of high temperature and high pressure resistant fiberglass. The sand flushing fluid used in the experiment is clean water, linear glue and low-density foam liquid. Expanded clay is used for experimental sand settling. The sand flushing nozzles are jet nozzles and rotary nozzles.

[0024] The experimental method using the above experimental device for evaluating the sand flushing and drilling and grinding effects of horizontal well coiled tubing includes the following steps:

[0025] A. Coiled Tubing Sand Flushing Test Procedure

[0026] (i) After the coiled tubing passes through the injector and the blowout preventer, fix the coiled tubing to them well, then connect the coiled tubing to the centralizer and the sand flushing nozzle in sequence. After the blowout preventer and the transparent tubing are fixed, insert them into the transparent wellbore until they reach the horizontal section;

[0027] (ii) Remove the wellbore joint of the horizontal well section, push the sand settling amount required for the test into the horizontal well section, and then install the wellbore joint so that it is completely sealed with the horizontal well section;

[0028] (iii) For wellbore structures that really need to be tested, adjust the wellbore structure simulation unit, use an external hydraulic pump to change the injection volume, adjust the telescopic length of the hydraulic cylinder piston rod and its position on the pulley track, and change the well inclination angle of the horizontal well section of the transparent wellbore;

[0029] (iv) Place the experimental fluid for sand washing into the liquid reservoir, seal it, and open stop valve C, stop valve D, throttle valve A, and throttle valve B;

[0030] (V) adjusting the temperature controller so that the electric heating film heats the horizontal section of the transparent shaft, reading the value on the temperature sensor, and making the temperature of the transparent shaft reach the preset experimental value;

[0031] (VI) When conducting a positive sand flushing simulation experiment, open the stop valve C, stop valve D, throttle valve A and throttle valve B, start the liquid circulation unit, use the frequency converter to control the two-way delivery pump B to deliver the sand flushing liquid to the oil pipe sand flushing pipeline, record the value on the flow meter B, adjust the throttle valve B to control the sand flushing liquid displacement, control the two-way delivery pump A to extract the sand flushing liquid from the blowout box pipeline, and return it to the liquid storage tank through the filter A to form a positive sand flushing cycle;

[0032] (VII) When conducting the backwash simulation experiment, open the stop valve C, stop valve D, throttle valve A and throttle valve B, start the liquid circulation unit, use the frequency converter to adjust the two-way delivery pump A to deliver the sand flushing liquid to the direction of the blowout box pipeline, record the value on the flow meter A, adjust the throttle valve A to control the discharge of the sand flushing liquid, and the two-way delivery pump B extracts the sand flushing liquid from the oil pipe sand flushing pipeline and returns it to the liquid storage tank through the filter B, forming a backwash circulation;

[0033] (VIII) Open the stop valve A on the nitrogen bottle, inject nitrogen into the pressure regulator, and then close the stop valve A; at this time, the liquid circulation is a positive sand flushing circulation, so close the stop valve E and open the stop valve F; at this time, the liquid circulation is a reverse sand flushing circulation, so close the stop valve F and open the stop valve E; adjust the stop valve B on the pressure regulator and read the value on the pressure sensor to simulate the system pressure of the wellbore environment during the conventional coiled tubing sand flushing completion process;

[0034] (IX) Operate the control device to control the retraction and extension of the winch rope to 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] (10) 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 sediment. The computer records and displays the migration form and trajectory of the sediment particles, the thickness, width and length of the sediment, and the time when the sediment is completely removed;

[0036] B. Coiled Tubing Drilling and Grinding Experiment Steps

[0037] (i) After the coiled tubing passes through the injector and the blowout preventer, fix the coiled tubing to them well, then connect the coiled tubing to the centralizer, reverse circulation valve, double-flap check valve, screw drill, flat-bottom grinding shoe in sequence. After the blowout preventer and the transparent tubing are fixed, control the coiled tubing to be inserted into the transparent wellbore until it reaches the horizontal section;

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

[0039] (iii) For wellbore structures that really need to be tested, adjust the wellbore structure simulation unit, use an external hydraulic pump to change the injection volume, adjust the telescopic length of the hydraulic cylinder piston rod and its position on the pulley track, and change the well inclination angle of the horizontal well section of the transparent wellbore;

[0040] (iv) Place the experimental fluid for sand washing into the liquid reservoir, seal it, and open stop valve C, stop valve D, throttle valve A, and throttle valve B;

[0041] (V) adjusting the temperature controller so that the electric heating film heats the horizontal section of the transparent shaft, reading the value on the temperature sensor, and making the temperature of the transparent shaft reach the preset experimental value;

[0042] (VI) Open stop valve C, stop valve D, throttle valve A and throttle valve B, start the liquid circulation unit, use the frequency converter to control the two-way delivery pump B to deliver the chip removal fluid to the direction of the coiled tubing line, record the value on the flow meter B, adjust the throttle valve B to control the displacement of the drilling and grinding working fluid to control the working torque of the screw drill. Control the two-way delivery pump A to extract the drilling and grinding working fluid from the blowout preventer box pipeline and return it to the liquid storage tank through the filter A;

[0043] (VII) Open the stop valve A on the nitrogen bottle, inject nitrogen into the regulator, and then close the stop valve A; close the stop valve E and open the stop valve F; adjust the stop valve B on the regulator and read the value on the pressure sensor to simulate the system pressure of the wellbore environment during conventional coiled tubing drilling and completion;

[0044] (VIII) Operate the control device to control the retraction and release of the winch rope to drive the injector to move in the vertical direction. At this time, one end of the flat-bottomed mill shoe of the coiled tubing will move forward and backward in the horizontal section of the transparent wellbore. In order to better allow the flat-bottomed mill shoe to transmit drilling pressure, a heavy object is added to the injector to transmit more drilling pressure at the flat-bottomed mill shoe to achieve a better drilling and grinding 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 migration pattern and trajectory of the drill cuttings, and displays the time when the bridge plug and drill cuttings are completely removed.

[0046] Compared with the prior art, the above technical solution has the following advantages:

[0047] 1. The inclination section of the wellbore structure is a high-temperature and high-pressure resistant rubber tube with a certain degree of elasticity. Under the action of the telescopic piston rod of the hydraulic cylinder, the rubber tube bends, so that the horizontal section of the transparent wellbore can change the well inclination to achieve the well inclination angle required for the experiment. This can make the sand settling and continuous tubing in the transparent wellbore consistent with the state in the actual downhole construction, and also make the composite bridge plug and drilling and grinding tools in the wellbore consistent with the state in the actual downhole construction, thereby obtaining an accurate evaluation of the sand flushing and drilling and grinding effects of the continuous tubing.

[0048] 2. The injector is fixed to the coiled tubing, which is in turn connected to the twisted rope of the working drum. When the control device is used to control the retraction and extension of the twisted rope, it actually controls the forward and backward movement of one end of the coiled tubing sand flushing nozzle in the horizontal section of the transparent wellbore. At the same time, the blowout preventer box and the transparent wellbore can form a closed space and still meet the up and down movement of the coiled tubing, which is consistent with the on-site sand flushing and drilling and grinding completion operation procedures.

[0049] 3. Continuous tubing lines and blowout preventer box lines are connected to both ends of the liquid storage tank. These two sand flushing pipelines are connected to the continuous tubing and the blowout preventer box respectively. When the frequency converter is used to control the delivery direction of the two bidirectional delivery pumps, the two sand flushing methods of forward sand flushing and reverse sand flushing can be simulated, which is more in line with the on-site continuous tubing sand flushing operation conditions.

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

[0051] 5. The device established an evaluation method for wellbore structure, sand flushing fluid displacement, sand flushing fluid type, sand flushing nozzle type, tubing centralizer, sand flushing method-sand carrying-influencing factors and an evaluation method for drilling and grinding working fluid displacement, grinding shoe type, drilling and grinding working fluid additives-chip carrying-influencing factors. The construction parameters and construction tools that can be easily obtained during on-site construction are used as the main indicators for evaluating the sand flushing and drilling and grinding effects of continuous tubing. The changes in the above factors can reflect the relationship between the sand flushing and drilling and grinding effects and them. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0055] Figure 4 It is a schematic diagram of the structure of the blowout prevention box in the present invention;

[0056] Figure 5 It is a schematic diagram of the structure of the drilling and grinding tool in the present invention;

[0057] In the figure: 1 working drum, 2 injector, 2-1 locking groove, 2-2 clamping block, 2-3 clamping device hanging point, 2-4 locking pin, 3 blowout box, 3-1 sealing packing, 3-2 locking nut, 3-3 infusion channel, 3-4 sealing ring, 3-5 locking knob, 4 continuous tubing, 5 transparent wellbore, 6 wellbore coupling, 7 high temperature and high pressure resistant rubber tube, 8 tubing centralizer, 9A sandblasting nozzle, 9B drilling and grinding tool, 9B-1 reverse circulation valve, 9B-2 double disc one-way valve, 9B-3 screw drill, 9B-4 flat bottom grinding shoe, 10 wellbore joint, 11 rotating shaft, 12 control device, 13 mobile ultrasonic probe, 14 calculation machine, 15 high-speed camera, 16 hydraulic cylinder, 17 slide car, 18 nitrogen bottle, 19 stop valve A, 20 regulator, 21 stop valve B, 22 pressure sensor, 23 pulley track, 24 temperature controller, 25 temperature sensor, 26 flow meter A, 27 stop valve C, 28 two-way delivery pump A, 29 filter A, 30 liquid storage tank, 31 throttle valve A, 32 electric heating film, 33 filter B, 34 inverter, 35 two-way delivery pump B, 36 stop valve D, 37 flow meter B, 38 throttle valve B, 39 continuous oil pipeline, 40 blowout preventer pipeline, 41 stop valve E, 42 stop valve F, 43 composite bridge plug. DETAILED DESCRIPTION

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

[0059] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work 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 drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention.

[0060] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and thus, once an item is defined in one drawing, it may not be further defined or explained in the subsequent drawings.

[0061] Example:

[0062] See also Figure 1 — Figure 4An experimental device for evaluating the sand flushing effect of a coiled tubing in a horizontal well, wherein the wellbore structure includes a vertical section and a horizontal section of a transparent wellbore 5, a wellbore coupling 6, a high-temperature and high-pressure rubber tube 7, and a wellbore joint 10. The high-temperature and high-pressure rubber tube 7 is connected to the vertical section and the horizontal section of the transparent wellbore 5 through the wellbore coupling 6. The high-temperature and high-pressure rubber tube 7 meets the bending and stretching of the deflection section and the ability to withstand high-temperature and high-pressure sand flushing fluid and drilling and grinding working fluid, and can simulate the wellbore structure in actual working conditions and is highly similar to it;

[0063] If the coiled tubing sand flushing experiment is simulated, the wellbore joint 10 is removed and the simulated sand for the experiment is added into the horizontal section of the transparent wellbore 5. After the sand is added, the wellbore joint 10 and the blowout prevention box 3 are installed so that the two connections can be effectively sealed.

[0064] If the coiled tubing drilling and grinding experiment is simulated, the wellbore joint 10 is removed, the composite bridge plug for the experiment is set in the horizontal section of the transparent wellbore 5, and then the wellbore joint 10 and the blowout preventer box 3 are installed so that the two connections can be effectively sealed.

[0065] A working drum 1, an injector 2 and a blowout preventer 3 are arranged on the top of the vertical section of the transparent wellbore 5. The head end of the coiled tubing 4 is inserted from the injector 2 and the blowout preventer 3. If a coiled tubing sand flushing device is simulated, an upper tubing centralizer 8 and a sand flushing nozzle 9 are installed to pass the transparent tubing 5 to the horizontal section; if a coiled tubing drilling and grinding device is simulated, an upper centralizer 8, a reverse circulation valve 9B-1, a double-flap check valve 9B-2, a screw drill 9B-3, and a flat-bottomed grinding shoe 9B-4 are installed, and then the tail end of the coiled tubing 4 is connected to the upper tubing sand flushing pipeline 39.

[0066] The injector 2 is provided with 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 coiled tubing. When the drilling and grinding experiment of the coiled tubing is simulated, if the drilling pressure on the drilling and grinding tool 9B needs to be controlled, the weight can be added or removed from the injector 2.

[0067] The blowout preventer box 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 swells and deforms to form a seal, while allowing the coiled tubing to move up and down. The blowout preventer box pipeline 40 is connected to the infusion channel 3-3.

[0068] The twist rope on the working drum 1 is connected to the clamp hanging point 2-3 on the injector 2. The control device 12 is operated to control the retraction and extension of the twist rope, so as to control the up and down movement of the coiled tubing 4, that is, to control the forward and backward movement of the sand flushing nozzle and the drilling and grinding tool in the horizontal section of the transparent wellbore 5, and also to control the drilling pressure applied by the drilling and grinding tool on the composite bridge plug, which completely simulates the sand flushing and drilling and grinding operations of the coiled tubing in actual working conditions.

[0069] A parallel pulley track 23 is provided vertically below the horizontal section of the transparent wellbore 5, and the slide rail car 17 can slide freely on the pulley track 23. The hydraulic cylinder 16 is fixed on the slide rail car 17, and the piston rod of the hydraulic cylinder 16 and the wellbore joint 10 are hinged to the rotating shaft 11. The hydraulic cylinder 16 is connected to the external hydraulic pump pipeline, and the external hydraulic pump can control the telescopic 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 force component of the horizontal section of the transparent wellbore 5, the slide rail car slides horizontally on the pulley track, and drives the horizontal section of the transparent wellbore 5 to steplessly change the inclination angle within the range of 0°-90°, so as to achieve the purpose of adjusting the angle of the horizontal section;

[0070] The sand flushing fluid or drilling and grinding working fluid required for the experiment is poured into the liquid reservoir 30, and then the liquid reservoir 30 is sealed. The two ends of the liquid reservoir are connected to the coiled tubing line 39 and the blowout prevention box line 40, and filters A 29 and B 33 are provided at the connection points; the coiled tubing line 39 is provided with a two-way delivery pump B 35, a stop valve D 36, a flow meter B 37 and a throttle valve B 38 in sequence; the blowout prevention box line 40 is provided with a two-way delivery pump A 28, a stop valve C 27, a flow meter A 26 and a throttle valve A 31 in sequence; after multiple cycles, a large amount of sediment or drilling cuttings will accumulate in the horizontal section and the deflection section of the wellbore structure, so that the displacement of the pipeline from which the sand flushing fluid and the drilling and grinding working fluid return to the liquid reservoir 30 decreases, which is easy to cause the pipeline to be blocked. Therefore, when the sand flushing fluid or the drilling and grinding working fluid is circulated, two two-way delivery pumps should be turned on at the same time;

[0071] Filter A 29 and filter B 33 are provided at the connection between the liquid reservoir 30 and the coiled tubing line 39 and the blowout prevention box line 40, for collecting the sediment and drill cuttings brought into the liquid reservoir 30, and ensuring the quality of the sand flushing fluid and the drilling and grinding working fluid during the circulation process;

[0072] If the coiled tubing sand flushing experiment is simulated, when the liquid circulation is a positive sand flushing circulation, the frequency converter 34 is required to control the bidirectional delivery pump B35 to deliver the sand flushing liquid to the tubing sand flushing pipeline 39, and control the bidirectional delivery pump A 28 to extract the sand flushing liquid from the blowout prevention box pipeline 40, and the sand flushing liquid carrying the sediment returns to the liquid storage tank 30 through the filter A 29, forming a closed positive sand flushing circulation;

[0073] If the coiled tubing sand flushing experiment is simulated, when the liquid circulation is a backwashing circulation, the frequency converter 34 is required to control the bidirectional delivery pump A 28 to deliver the sand flushing liquid to the blowout box pipeline 40, and control the bidirectional delivery pump B 35 to extract the sand flushing liquid from the tubing sand flushing pipeline 39, and the sand flushing liquid carrying the sediment returns to the liquid storage tank 30 through the filter B 33, forming a closed backwashing circulation;

[0074] If the coiled tubing drilling and grinding experiment is simulated, the inverter 34 controls the bidirectional delivery pump B35 to deliver the drilling and grinding working fluid to the coiled tubing pipeline 39, and controls the bidirectional delivery pump A28 to extract the drilling and grinding working fluid from the blowout prevention box pipeline 40, and the drilling and grinding working fluid carrying the drill cuttings returns to the liquid storage tank 30 through the filter A29, forming a closed drilling and grinding working fluid circulation;

[0075] By controlling the valve, the displacement of the drilling and grinding working fluid is controlled. The drilling and grinding working fluid can control the rotation speed of the flat-bottomed grinding shoe 9B-4 through the reverse circulation valve 9B-1, the double-flap check valve 9B-2, and the screw drill 9B-3;

[0076] The computer 14 is arranged outside the transparent wellbore 5, and collects and processes the data of 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 arranged on the outer wall of the wellbore in the horizontal section can monitor the sand thickness and the length of the composite bridge plug at different positions in the wellbore structure;

[0077] The pressure regulator 20 is connected to the nitrogen cylinder 18, the stop valve A19, the stop valve B21 and the pressure sensor 22. The stop valve A19 is opened, and the nitrogen is injected into the pressure regulator 20 by using the internal pressure of the nitrogen cylinder 18. Then the stop valve A19 is closed. The pressure regulator 20 is connected to the coiled tubing line 39 and the blowout preventer box line 40 respectively.

[0078] If it is a positive sand flushing cycle, close the stop valve E 41 and open the stop valve F 42; if it is a reverse sand flushing cycle, open the stop valve E 41 and close the stop valve F 42; if it is a drilling and grinding bridge plug, close the stop valve E 41 and open the stop valve F 42;

[0079] By adjusting the stop valve B 21, the value of the pressure sensor 22 is read, and the stop valve B 21 is adjusted to control the pressure in the regulator 20. At this time, the reading on the pressure sensor 22 is the system pressure in the wellbore structure; the horizontal section of the transparent wellbore 5 is provided with a heating device, the heating device includes an electric heating film 32, a temperature sensor 25, and a temperature controller 24. The electric heating film 32 is close to the outer wall of the horizontal section. Electrodes are plated at both ends of the electric heating film 32, which 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 in the transparent wellbore 5 is controlled to simulate the high temperature and high pressure environment of deep well sand flushing and drilling and grinding completion operations;

[0080] The transparent wellbore 5 is made of high temperature and high pressure resistant fiberglass with a diameter of 127 mm and a wall thickness of 6 mm. The coiled tubing 4 is made of special microalloy material with a diameter of 38.1 mm. The sand flushing nozzles are jet nozzles and rotary nozzles. The liquids used in the experiment are clean water, linear glue and low-density foam liquid, all of which are conventional sand flushing liquids. The experimental sand settling uses a 1m 3 0.3-0.6mm ceramsite; it can ensure that the horizontal well coiled tubing sand flushing simulation experiment is consistent with the actual working conditions on site.

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

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

[0083] 1. Coiled tubing sand flushing simulation experiment

[0084] After the coiled tubing 4 is passed through the injector 2 and the blowout preventer box 3, the coiled tubing 4 is fixed to them well, and 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 types of the sand flushing nozzles are jet nozzles and rotary nozzles. If the influence 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 well section is removed, and the amount of sand settling required for the experiment is pushed into the horizontal well section, and then the wellbore joint 10 is installed to make it completely sealed with the horizontal well 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 the hydraulic cylinder 16 to retract downward. At this time, the horizontal section of the transparent wellbore 5 will give the slide rail car 17 a horizontal force to the left, pushing the slide rail car 17 to slide to the left on the pulley track 23 to obtain a stable wellbore structure until the well inclination angles used in the experiment are 30°, 60° and 90°;

[0086] Clean water, linear glue and low-density foam liquid for sand washing are added into the liquid storage tank 30 as experimental sand washing liquid, and then the liquid storage tank 30 is sealed, and the stop valve C 27, the stop valve D 36, the throttle valve A 31 and the throttle valve B 38 are opened;

[0087] The temperature controller 24 is adjusted to make the electric heating film 32 heat the horizontal section of the transparent shaft 5, and the value on the temperature sensor 25 is read. When the temperature value reaches 50°C, the temperature controller 24 is adjusted to stabilize the temperature of the transparent shaft 5 at the experimental temperature of 50°C.

[0088] When conducting the positive sand flushing simulation experiment, the stop valve C 27, the stop valve D 36, the throttle valve A 31 and the throttle valve B 38 are opened, the liquid circulation unit is turned on, and the frequency converter 34 is used to control the two-way delivery pump B 35 to deliver the sand flushing liquid to the oil pipe sand flushing pipeline 39, and the value on the flow meter B 37 is recorded. The throttle valve B 38 and the frequency converter 34 are adjusted to control the sand flushing liquid displacement. The experimental sand flushing liquid displacement is set to 285L / min, 325L / min and 385L / min respectively; the two-way delivery pump A 28 is controlled to extract the sand flushing liquid from the blowout prevention box pipeline 40 with the same power and displacement. If the value of the flow meter A 26 is the same as the value of the flow meter B 37, it indicates that the entire positive sand flushing cycle is not blocked, and the sand flushing liquid returns to the liquid storage tank 30 through the filter A 29;

[0089] When conducting the backwash simulation experiment, open the stop valve C 27, the stop valve D 36, the throttle valve A 31 and the throttle valve B 38, start the liquid circulation unit, use the frequency converter 34 to adjust the two-way delivery pump A 28 to deliver the sand flushing liquid to the blowout box pipeline 40, record the value on the flow meter A 26, adjust the throttle valve A 31 and the frequency converter 34 to control the sand flushing liquid displacement, and the experimental sand flushing liquid displacement is set to 285L / min, 325L / min and 385L / min respectively; control the two-way delivery pump B 35 to extract the sand flushing liquid from the oil pipe sand flushing pipeline 39 with the same power and displacement. 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 cycle is not blocked and the sand returns to the liquid storage tank 30 through the filter B 33;

[0090] Open the stop valve A19 on the nitrogen bottle 18, inject nitrogen into the regulator 20, and then close the stop valve A19; at this time, the liquid circulation is a positive sand flushing circulation, so the stop valve E 41 is closed and the stop valve F 42 is opened; at this time, the liquid circulation is a reverse sand flushing circulation, so the stop valve F 42 is closed and the stop valve E 41 is opened; adjust the stop valve B 21 on the liquid storage tank 20, and control the value on the pressure sensor 22 to be 5MPa;

[0091] The operation control device 12 controls the lowering of the winch rope, driving the sand flushing nozzle 9 on the coiled tubing 4 to move forward at a speed of 5 m / min until the sediment in the horizontal section of the transparent wellbore 5 is flushed clean;

[0092] The high-speed camera 15 photographs the migration morphology of the sand particles 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 be used to monitor and detect the thickness of the sand, and the computer 14 records and displays the migration morphology and trajectory of the sand particles, and displays the thickness, width and length of the sand and the time when the sand is completely removed.

[0093] In order to illustrate the experimental role of the device in evaluating the effect of sand flushing during coiled tubing sand flushing, the relationship between the coiled tubing sand flushing effect and the above factors was evaluated by using the device under different experimental conditions such as wellbore structure, sand flushing fluid displacement, sand flushing fluid type, sand flushing nozzle type, presence or absence of tubing centralizer and sand flushing method.

[0094] The sand flushing liquid used in the experiment was clean water, and the sand settling was 1m 3 The transparent wellbore temperature is 50℃, the pressure is set to 5MPa, the sand flushing fluid displacement is 285L / min, the sand flushing nozzle is a jet nozzle, and a tubing centralizer is installed.

[0095] Well structure:

[0096] When other factors remain unchanged, the well inclination angle in the wellbore structure is changed to 30°, 60° and 90° respectively, and the experimental data and results are tested;

[0097] From the data in Table 1, it can be seen that when the well inclination angle is increased to 60° and 90°, the sand flushing time of the coiled tubing is greatly increased compared with the well inclination angle of 30°, and it is difficult for the sand flushing fluid to carry sand in the horizontal well section.

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

[0099]

[0100]

[0101] Flushing fluid displacement:

[0102] With other parameters unchanged, the discharge volume of the sand flushing fluid was adjusted to 285L / min, 325L / min and 385L / min respectively, and the experimental data and results were measured;

[0103] Table 2 Sand flushing time under different sand flushing fluid displacement

[0104] Flushing fluid type Sand particle size Well inclination angle Flushing fluid volume Sandblasting nozzle type Centralizer Sand washing time Shimizu 0.3-0.6mm 90° 285L / min Jet nozzle have 12min Shimizu 0.3-0.6mm 90° 325L / min Jet nozzle have 9min Shimizu 0.3-0.6mm 90° 385L / min Jet nozzle have 7min

[0105] From the data in Table 2, it can be seen that increasing the flushing fluid displacement can significantly improve the flushing efficiency of the coiled tubing. When the flushing fluid displacement is 325L / min and 385L / min, the flushing time is reduced by about 25% and 42% compared with the flushing fluid displacement of 285L / min.

[0106] Flushing fluid type:

[0107] With other parameters unchanged, the sand washing fluid was changed to water, linear glue and low-density foam fluid, and the experimental data and results were measured;

[0108] From the data in Table 3, it can be seen that when water is used as the sand flushing fluid, the sand carrying capacity is the worst and the sand flushing time is the longest. When linear glue and low-density foam liquid are used as the sand flushing fluid, the sand carrying capacity is enhanced, the sand carrying efficiency is roughly the same, and the sand flushing time is reduced by about 33.3% and 50%, respectively.

[0109] Table 3 Sand flushing time under different types of sand flushing fluid

[0110] Flushing fluid type Sand particle size Well inclination angle Flushing fluid volume Sandblasting nozzle type Centralizer Sand washing time Shimizu 0.3-0.6mm 90° 285L / min Jet nozzle have 12min Linear glue 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] When other parameters remain unchanged, change the type of sandblasting nozzle to jet nozzle or rotary nozzle, and measure the experimental data and results;

[0113] Table 4 Sand blasting time under different sand blasting nozzle types

[0114] Flushing fluid type Sand particle size Well inclination angle Flushing fluid volume Sandblasting nozzle type Centralizer Sand washing time Shimizu 0.3-0.6mm 90° 285L / min Jet nozzle have 12min Shimizu 0.3-0.6mm 90° 285L / min Rotating sprinkler have 9min

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

[0116] Tubing Centralizer:

[0117] With other parameters unchanged, remove the tubing centralizer and measure the experimental data and results;

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

[0119] Flushing fluid type Sand particle size Well inclination angle Flushing fluid volume Sandblasting nozzle type Centralizer Sand washing time Shimizu 0.3-0.6mm 90° 285L / min Jet nozzle have 12min Shimizu 0.3-0.6mm 90° 285L / min Jet nozzle none 10min

[0120] From the data in Table 5, it can be seen that without installing the tubing centralizer, the sand flushing efficiency of the jet nozzle is significantly reduced, and the sand flushing time is increased by about 17%.

[0121] Sand blasting method:

[0122] With other parameters unchanged, a single inclined hole nozzle was installed, and two sand flushing methods, positive sand flushing and reverse sand flushing, were used to measure the experimental data and results.

[0123] Table 6 Sand blasting time under different sand blasting methods

[0124] Sand blasting method Flushing fluid type Well inclination angle Flushing fluid volume Sandblasting nozzle type Centralizer Sand washing time Sand washing Shimizu 90° 285L / min Single inclined hole nozzle have 14min Backwash sand Shimizu 90° 285L / min Single inclined hole nozzle have 11min

[0125] From the data in Table 6, it can be seen that when using a single oblique air nozzle, the efficiency of backwashing is significantly improved compared with the efficiency of forward sandwashing, and the sand washing time is reduced by about 21.4%.

[0126] 1. Coiled tubing drilling and grinding simulation experiment

[0127] After the coiled tubing 4 is passed through the injector 2 and the blowout preventer box 3, the coiled tubing 4 is well fixed thereto, and then the coiled tubing 4 is sequentially connected to the tubing centralizer 8, the reverse circulation valve 9B-1, the double-flap 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 it reaches the horizontal section. The types of the flat-bottomed grinding shoe are four-blade high-efficiency grinding shoe and six-blade high-efficiency grinding shoe; the wellbore joint 10 of the horizontal well section is removed, the composite bridge plug used for the experiment is set in the horizontal well section, and then the wellbore joint 10 is installed to make it completely sealed with the horizontal well 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 the hydraulic cylinder 16 to retract downward. At this time, the horizontal section of the transparent wellbore 5 will give the slide rail car 17 a horizontal force to the left, pushing the slide rail car 17 to slide to the left on the pulley track 23 to obtain a stable wellbore structure until the well inclination angles used in the experiment are 30°, 60° and 90°;

[0129] Add drilling and grinding working fluid into the fluid reservoir 30, the working fluid formula is electric pump fluid plus resistance reducing agent, and then seal it, open the stop valve C 27, stop valve D 36, throttle valve A 31 and throttle valve B 38;

[0130] To test whether there is an effect of drilling and grinding working fluid additives on the drilling and grinding effect, KCl solution can be added to the reservoir 30 and the reservoir 30 can be sealed, and the coiled tubing drilling and grinding bridge plug experiment can be performed again;

[0131] The temperature controller 24 is adjusted to make the electric heating film 32 heat the horizontal section of the transparent shaft 5, and the value on the temperature sensor 25 is read. When the temperature value reaches 50°C, the temperature controller 24 is adjusted to stabilize the temperature of the transparent shaft 5 at the experimental temperature of 50°C.

[0132] When conducting the drilling and grinding simulation experiment, the stop valve C 27, the stop valve D 36, the throttle valve A 31 and the throttle valve B 38 are opened, the liquid circulation unit is turned on, and the frequency converter 34 is used to control the two-way delivery pump B 35 to deliver the sand flushing liquid to the direction of the coiled tubing pipeline 39, and the value on the flow meter B 37 is recorded. The throttle valve B 38 and the frequency converter 34 are adjusted to control the displacement of the drilling and grinding working fluid, and the displacement of the drilling and grinding working fluid is set to 350L / min, 420L / min and 500L / min respectively; the two-way delivery pump A 28 is controlled to extract the drilling and grinding working fluid from the blowout prevention box pipeline 40 with the same power and displacement. If the value of the flow meter A 26 is the same as the value of the flow meter B 37, it indicates that the entire liquid circulation is not blocked, and the drilling and grinding working fluid returns to the liquid storage tank 30 through the filter A 29;

[0133] Open the stop valve A19 on the nitrogen bottle 18, inject nitrogen into the regulator 20, and then close the stop valve A19; at this time, the liquid circulation is a positive sand flushing circulation, so the stop valve E 41 is closed and the stop valve F 42 is opened; at this time, the liquid circulation is a reverse sand flushing circulation, so the stop valve F 42 is closed and the stop valve E 41 is opened; adjust the stop valve B 21 on the liquid storage tank 20, and control the value on the pressure sensor 22 to be 5MPa;

[0134] The operation control device 12 controls the lowering of the twisted 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 and ground cleanly;

[0135] The high-speed camera 15 photographs the migration morphology of drill cuttings particles 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 be used to monitor and detect the length of the composite bridge plug 43, and the computer 14 records and displays the migration morphology and trajectory of the drill cuttings particles, and displays the length of the composite bridge plug 43 and the time of complete removal.

[0136] In order to illustrate the experimental role of the device in evaluating the effect of drilling and grinding bridge plugs during coiled tubing drilling and grinding, the relationship between the coiled tubing drilling and grinding effect and the above factors was evaluated by using the device under different experimental conditions such as different grinding shoe types, drilling and grinding working fluid displacement, and drilling and grinding working fluid additives.

[0137] The drilling and grinding working fluid formula used in the experiment is electric pump fluid plus drag reducing agent, the material of the composite bridge plug is advanced composite material, the transparent wellbore temperature is 50°C, the pressure is set to 5MPa, the drilling and grinding working fluid displacement is 350L / min, 420L / min and 500L / min, the flat-bottomed mill shoe uses four-blade high-efficiency mill shoe and six-blade high-efficiency mill shoe, and the wellbore inclination is 30 degrees.

[0138] Mill shoe type:

[0139] With other factors unchanged, four-blade high-efficiency grinding shoes and six-blade high-efficiency grinding shoes were used to test the experimental data and results.

[0140] Table 7 Drilling and grinding time under different grinding shoe types

[0141] Drilling and grinding fluid displacement Mill shoe type KCl solution Drilling and grinding time 420L / min Four-blade high-efficiency grinding shoe none 36min 420L / min Six-blade high-efficiency grinding shoe none 49min

[0142] From the data in Table 7, it can be seen that the four-edge high-efficiency grinding shoe has higher drilling and grinding bridge plug efficiency than the six-edge high-efficiency grinding shoe. The four-edge high-efficiency grinding shoe can be used as much as possible in on-site working conditions.

[0143] Drilling and grinding fluid displacement:

[0144] The grinding shoe uses a four-edge high-efficiency grinding shoe. When other parameters remain unchanged, the displacement of the drilling and grinding working fluid is adjusted to 350L / min, 420L / min and 500L / min respectively, and the experimental data and results are measured;

[0145] Table 8 Drilling and grinding time under different drilling and grinding working fluid displacement

[0146] Drilling and grinding fluid displacement Mill shoe type KCl solution Drilling and grinding time 350L / min Four-blade high-efficiency grinding shoe none 54min 420L / min Four-blade high-efficiency grinding shoe none 36min 500L / min Four-blade high-efficiency grinding shoe none 32min

[0147] During the experiment, when the drilling and grinding fluid displacement was 350L / min, the drilling and grinding blocked the wellbore. The wellbore became unobstructed only after increasing the displacement. From the data in Table 8, it can be seen that increasing the drilling and grinding fluid displacement can significantly improve the drilling and grinding efficiency of the coiled tubing.

[0148] Drilling and grinding fluid additives:

[0149] When other parameters remain unchanged, KCl solution is added to the drilling and grinding working fluid, and the experimental data and results are measured;

[0150] It can be seen from the data in Table 9 that after adding KCl solution to the drilling and grinding working fluid, the drilling and grinding time is significantly reduced.

[0151] Table 9 Drilling time after adding KCL solution

[0152] Drilling and grinding fluid displacement Mill shoe type KCl solution Drilling and grinding time 420L / min Four-blade high-efficiency grinding shoe none 36min 420L / min Four-blade high-efficiency grinding shoe have 29min

[0153] It can be seen that the device can be effectively used in the study of evaluating the effects of sand flushing and drilling and grinding on coiled tubing.

[0154] In the description of the present invention, it should be pointed out that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside" and "outside" etc. indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and should not be understood as a limitation on the present invention.

Claims

1. An experimental device for evaluating the sand flushing and drilling and grinding effects of coiled tubing in horizontal wells, comprising a coiled tubing sand flushing unit, a coiled tubing drilling and grinding unit, a wellbore structure simulation unit, a liquid 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 comprises a working drum (1), a control device (12), an injector (2), a blowout prevention box (3), a coiled tubing (4), a tubing centralizer (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) comprises a reverse circulation valve (9B-1), a double-flap check valve (9B-2), a screw drill (9B-3), and a flat-bottomed grinding shoe (9B-4); the wellbore structure simulation unit comprises a transparent wellbore (5), a wellbore coupling (6), a high-temperature and high-pressure resistant rubber tube (7), a wellbore joint (10), a rotating shaft (11), a hydraulic cylinder (16), a slide rail car (17), and a pulley track (23); the liquid circulation unit comprises a frequency converter (3 4), a two-way delivery pump A (28), a filter A (29), a liquid storage tank (30), a filter B (33), a two-way delivery pump B (35), an oil pipe sand flushing pipeline (39), a blowout prevention box pipeline (40), a stop valve C (27), a throttle valve A (31), a stop valve D (36), and a throttle valve B (38); the data measurement and processing unit includes a flow meter A (26), a flow meter B (37), a mobile ultrasonic probe (13), a computer (14), and a high-speed camera (15); the high-temperature and high-pressure simulation unit includes a nitrogen bottle (18), a regulator (20), a pressure sensor (22), a temperature controller (24), a temperature sensor (25), an electric heating film (32), a stop valve A (19), a stop valve B (21), a stop valve E (41), and a stop valve F (42); The transparent wellbore (5) has two sections, namely a vertical section and a horizontal section, the vertical section is arranged vertically, and the horizontal section is arranged horizontally; the high temperature and high pressure resistant rubber tube (7) is connected to the two sections of the transparent wellbore (5) through a wellbore collar (6), respectively simulating the vertical section, the deflection section and the horizontal section of the on-site wellbore; The shaft joint (10) and the rotating shaft (11) are at the free end of the horizontal section of the transparent shaft (5); the rotating shaft (11) is hinged to the piston rod of the hydraulic cylinder (16); the hydraulic cylinder (16) is connected to an external hydraulic pump pipeline; the hydraulic cylinder (16) is fixed on a slide rail vehicle (17); and the slide rail vehicle (17) slides on a pulley track (23); The blowout prevention box (3) is arranged at the top of the vertical section of the transparent wellbore (5) and is connected to the blowout prevention box pipeline (40); the working roller (1) and the injector (2) are arranged at the vertical upper part of the blowout prevention box (3); The head end of the coiled tubing (4) passes through the injector (2) and the blowout preventer box (3) and enters the horizontal section of the transparent wellbore (5), and the tail end is connected to the coiled tubing line (39); The oil pipe sand flushing pipeline (39) is provided with a bidirectional delivery pump B (35), a stop valve D (36), a flow meter B (37) and a throttle valve B (38) in sequence; the blowout prevention box pipeline (40) is provided with a bidirectional delivery pump A (28), a stop valve C (27), a flow meter A (26) and a throttle valve A (31) in sequence; the frequency converter (34) is connected to the bidirectional delivery pump A (28) and the bidirectional delivery pump B (35); The reverse circulation valve (9B-1), the double-flap 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 coiled tubing at the horizontal section of the transparent wellbore (5), and the composite bridge plug (43) is sealed at the end of the horizontal section of the transparent wellbore (5); The transparent wellbore (5) is provided with an electric heating film (32) on the outside, and is provided with a temperature controller (24) and a temperature sensor (25); the voltage stabilizer (20) is connected to a nitrogen bottle (18), a pressure sensor (22), a stop valve A (19) and a stop valve B (21); the voltage stabilizer (20) is connected to a coiled tubing line (39) and a blowout prevention box line (40), and is controlled by a stop valve (41) and a stop valve (42); The computer (14) is arranged outside the transparent wellbore (5) and is electrically connected to the high-speed camera (15), the movable ultrasonic probe (13), the pressure sensor (22), the temperature controller (24), and the temperature sensor (25) respectively; The coiled tubing line (39) and the blowout preventer box line (40) are connected to the liquid storage tank (30).

2. The experimental device for evaluating the sand flushing and drilling and grinding effects of coiled tubing in horizontal wells according to claim 1 is characterized in that: The injector (2) is composed of a locking groove (2-1), a clamping block (2-2), a clamping suspension point (2-3), and a locking pin (2-4), and is used to clamp the coiled tubing (4). The working drum (1) on the upper part of the injector (2) is connected to the clamping suspension point (2-3) through a twisted rope. When the working drum (1) is started, the injector (2) and the coiled tubing (4) move in a vertical direction.

3. The experimental device for evaluating the sand flushing and drilling and grinding effects of horizontal well coiled tubing according to claim 1 is characterized in that: The blowout prevention box (3) is composed 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), and at the same time allow the coiled tubing to move up and down.

4. The experimental device for evaluating the sand flushing and drilling and grinding effects of coiled tubing in horizontal wells according to claim 3 is characterized in that: The blowout prevention box pipeline (40) is connected to the infusion channel (3-3), and the sand flushing liquid enters and exits the transparent wellbore (5) through the infusion channel (3-3).

5. The experimental device for evaluating the sand flushing and drilling and grinding 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 shaft (5) can change its inclination steplessly, and the change angle is 0°-90°; at the same time, a component force parallel to the horizontal section of the transparent shaft (5) is generated on the slide rail vehicle (17), so that the slide rail vehicle (17) slides on the pulley track (23) parallel to the horizontal section of the transparent shaft (5).

6. The experimental device for evaluating the sand flushing and drilling and grinding effects of coiled tubing in horizontal wells according to claim 1, characterized in that: A filter A (29) and a filter B (33) are provided at the connection point of the coiled tubing line (39) and the blowout prevention box line (40) connected to the liquid storage tank (30). When the frequency converter (34) is controlled to change the delivery direction of the bidirectional delivery pump A (28) and the bidirectional delivery pump B (35), two sand flushing modes, namely, forward sand flushing and reverse sand flushing, can be completed. The two filters can better complete the function of filtering and settling sand, thereby maintaining a low solid content in the liquid storage tank (30).

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

8. The experimental device for evaluating the sand flushing and drilling and grinding 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 migration status of sand particles in the vertical well section, the inclined well section and the horizontal well section, and to record the time when the sediment is completely cleared.

9. The experimental device for evaluating the sand flushing and drilling and grinding 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 glass fiber reinforced plastic; the sand flushing liquid used in the experiment is clean water, linear glue and low density foam liquid; ceramsite is used for sand settling in the experiment; and the sand flushing nozzle (9) is a jet nozzle and a rotary nozzle.

10. An experimental method using the experimental device for evaluating the sand flushing and drilling and grinding effects of horizontal well coiled tubing according to any one of claims 1 to 9, characterized in that: The following steps are involved: A. Coiled Tubing Sand Flushing Test Procedure (i) After the coiled tubing (4) passes through the injector (2) and the blowout preventer box (3), the coiled tubing (4) is fixed to the injector (2) and the blowout preventer box (3), and then the coiled tubing (4) is connected to the centralizer (8) and the sand flushing nozzle (9A) in sequence. After the blowout preventer box (3) and the transparent tubing (5) are fixed, they are inserted into the transparent wellbore (5) until they reach the horizontal section; (ii) removing the wellbore joint (10) of the horizontal well section, pushing the amount of sand settling required for the experiment into the horizontal well section, and then installing the wellbore joint (10) so that it is completely sealed with the horizontal well section; (iii) For the wellbore structure that really needs to be tested, the wellbore structure simulation unit is adjusted, the injection volume is changed using an external hydraulic pump, the telescopic length of the piston rod of the hydraulic cylinder (16) and the position on the pulley track (23) are adjusted, and the well inclination angle of the horizontal well section of the transparent wellbore (5) is changed; (iv) placing the experimental fluid for sand washing into the liquid storage tank (30), sealing it, and opening the stop valve C (27), stop valve D (36), throttle valve A (31) and throttle valve B (38); (5) adjusting the temperature controller (24) so ​​that the electric heating film (32) heats the horizontal section of the transparent shaft (5), reading the value on the temperature sensor (25), and making the temperature of the transparent shaft (5) reach a preset experimental value; (VI) When conducting a positive sand flushing simulation experiment, the stop valve C (27), the stop valve D (36), the throttle valve A (31) and the throttle valve B (38) are opened, the liquid circulation unit is turned on, the frequency converter (34) is used to control the bidirectional delivery pump B (35) to deliver the sand flushing liquid to the oil pipe sand flushing pipeline (39), the value on the flow meter B (37) is recorded, the throttle valve B (38) is adjusted to control the discharge volume of the sand flushing liquid, and the bidirectional delivery pump A (28) is controlled to extract the sand flushing liquid from the blowout prevention box pipeline (40), and return the sand flushing liquid to the liquid storage tank (30) through the filter A (29), thereby forming a positive sand flushing cycle; (VII) When conducting a backwash simulation experiment, the stop valve C (27), the stop valve D (36), the throttle valve A (31) and the throttle valve B (38) are opened, the liquid circulation unit is turned on, the frequency converter (34) is used to adjust the bidirectional delivery pump A (28) to deliver the sand flushing liquid to the blowout prevention box pipeline (40), the value on the flow meter A (26) is recorded, the throttle valve A (31) is adjusted to control the discharge volume of the sand flushing liquid, and the bidirectional delivery pump B (35) draws the sand flushing liquid from the oil pipe sand flushing pipeline (39), and returns it to the liquid storage tank (30) through the filter B (33), thereby forming a backwash circulation; (VIII) Open the stop valve A (19) on the nitrogen bottle (18), inject nitrogen into the pressure regulator (20), and then close the stop valve A (19); at this time, the liquid circulation is a positive sand flushing circulation, then close the stop valve E (41) and open the stop valve F (42); at this time, the liquid circulation is a reverse sand flushing circulation, then close the stop valve F (42) and open the stop valve E (41); adjust the stop valve B (21) on the pressure regulator (20), read the value on the pressure sensor (22), so as to simulate the system pressure of the wellbore environment during the conventional coiled tubing sand flushing completion process; (IX) operating the control device (12) to control the retraction and extension of the winch rope, thereby driving the injector (2) to move in the vertical direction. At this time, one end of the sand flushing nozzle (9) of the coiled tubing (4) will also move forward and backward in the horizontal section of the transparent wellbore (5), thereby achieving a better sand flushing effect; (10) A high-speed camera (15) takes photos of the continuous tubing sand flushing experiment and uploads them to a computer (14), an ultrasonic probe (13) detects the thickness of the sediment, and the computer (14) records and displays the migration form and trajectory of the sediment particles, and displays the thickness, width and length of the sediment and the time when the sediment is completely cleared; B. Coiled Tubing Drilling and Grinding Experiment Steps (i) After the coiled tubing (4) passes through the injector (2) and the blowout preventer box (3), the coiled tubing (4) is fixed to the injector (2) and the blowout preventer box (3). Then, the coiled tubing (4) is connected to the centralizer (8), the reverse circulation valve (9B-1), the double-flap check valve (9B-2), the screw drill (9B-3), and the flat-bottom grinding shoe (9B-4) in sequence. After the blowout preventer box (3) and the transparent tubing (5) are fixed, the coiled tubing is controlled to be inserted into the transparent wellbore (5) until it reaches the horizontal section. (ii) removing the wellbore joint (10) of the horizontal well section, setting the composite bridge plug (43) to be tested at the end of the horizontal well section, and then installing the wellbore joint (10) to ensure a complete seal with the horizontal well section; (iii) For the wellbore structure that really needs to be tested, the wellbore structure simulation unit is adjusted, the injection volume is changed using an external hydraulic pump, the telescopic length of the piston rod of the hydraulic cylinder (16) and the position on the pulley track (23) are adjusted, and the well inclination angle of the horizontal well section of the transparent wellbore (5) is changed; (iv) placing the experimental fluid for sand washing into the liquid storage tank (30), sealing it, and opening the stop valve C (27), stop valve D (36), throttle valve A (31) and throttle valve B (38); (5) adjusting the temperature controller (24) so ​​that the electric heating film (32) heats the horizontal section of the transparent shaft (5), reading the value on the temperature sensor (25), and making the temperature of the transparent shaft (5) reach a preset experimental value; (VI) Open the stop valve C (27), stop 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 two-way delivery pump B (35) to deliver the chip removal liquid to the direction of the coiled tubing pipeline (39), record the value on the flow meter B (37), adjust the throttle valve B (38) to control the displacement of the drilling and grinding working fluid to control the working torque of the screw drill. Control the two-way delivery pump A (28) to extract the drilling and grinding working fluid from the blowout prevention box pipeline (40) and return it to the liquid storage tank (30) through the filter A (29); (VII) Opening the stop valve A (19) on the nitrogen bottle (18), injecting nitrogen into the pressure regulator (20), and then closing the stop valve A (19); closing the stop valve E (41), and opening the stop valve F (42); adjusting the stop valve B (21) on the pressure regulator (20), and reading the value on the pressure sensor (22) to simulate the system pressure of the wellbore environment during conventional coiled tubing drilling and completion; (VIII) operating the control device (12) to control the retraction and extension of the winch rope, driving 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 allow the flat-bottomed grinding shoe (9B-4) to transmit drilling pressure, a heavy object is added to the injector, so that more drilling pressure can be transmitted at the flat-bottomed grinding shoe (9B-4) to achieve a better drilling and grinding effect; (IX) A high-speed camera (15) takes photos of the continuous tubing drilling and grinding experiment and uploads them to a computer (14), an ultrasonic probe (13) detects the length of the bridge plug, and a computer (14) records and displays the migration form and trajectory of the drill cuttings, and displays the time when the bridge plug and drill cuttings are completely removed.

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