An experimental device and method for simulating sanding pressure fracturing of casing hole of horizontal well

Abstract

This invention belongs to the field of laboratory physical simulation testing technology for hydraulic fracturing, and discloses an experimental apparatus and method for simulating casing perforation erosion in horizontal wells with proppant fracturing. The experimental apparatus includes a fracturing fluid delivery system, a proppant mixing system, an erosion testing system, a circulation and recovery system, and a monitoring and control system. The fracturing fluid delivery system includes a storage tank, a liquid turbine flow meter, and a plunger pump. The proppant mixing system includes a proppant addition system and a proppant mixing system. The erosion testing system includes simulated formation fractures, casing sub-sections, a constant pressure relief valve, and several erosion test sub-sections. The circulation and recovery system includes a separator, a proppant recovery tank, and fracturing fluid circulation pipelines. The monitoring and control system includes a PC terminal, a flow controller, a proppant concentration controller, and a phased-array ultrasonic detector. This invention, by testing the erosion of casing perforations during fracturing under simulated conditions, provides a basis for optimizing fracturing and temporary plugging processes, improving fracturing efficiency, and reducing the risk of casing damage in oil reservoirs.

Description

Technical Field

[0001] This invention belongs to the field of indoor physical simulation test technology for hydraulic fracturing, specifically relating to an experimental device and method for simulating the erosion of the casing orifice in horizontal wells by sand fracturing. Background Technology

[0002] With the continuous development and utilization of energy, conventional oil and gas energy is gradually failing to meet the needs, and traditional conventional energy development is gradually shifting towards unconventional oil and gas development, which is transforming into the "new conventional." To achieve large-scale and efficient development of unconventional oil and gas resources, horizontal well staged fracturing and volumetric fracturing technologies are necessary. High-volume, proppant-carrying fracturing operations are characterized by high displacement, high pump pressure, and long duration. Under sufficient pressure to break up the formation, high-volume proppant-carrying fracturing fluid is forced into the formation through the perforations of the oil and gas well, easily causing erosion and wear on the production casing string, especially at the perforations.

[0003] Currently, erosion and wear of the casing orifice during fracturing can reduce the strength of the casing string and may further induce casing deformation and failure. After large-scale fracturing, casing deformation and damage in the producing formation occur frequently, becoming one of the technical challenges restricting the safe and efficient development of unconventional oil and gas. However, the influence and mechanism of high-volume proppant fracturing on casing orifice erosion are still unclear. Research on solid-liquid phase erosion mainly focuses on surface pipelines and equipment, while research on wellbore erosion is scarce. Furthermore, physical simulation experimental devices for casing orifice erosion during high-volume proppant fracturing are rarely reported, failing to provide equipment support and evaluation basis for testing and researching the erosion behavior of casing orifices under actual working conditions.

[0004] Therefore, establishing an experimental device to simulate casing perforation erosion during horizontal well fracturing with proppant, and forming an experimental method for casing perforation erosion during proppant fracturing, is of great significance for the evaluation and control of casing perforation erosion during high-volume proppant fracturing. Summary of the Invention

[0005] This invention aims to address the technical problems existing in the prior art by providing an experimental apparatus and method for simulating casing perforation erosion during horizontal well fracturing with sand. It tests and evaluates the erosion of casing perforations during fracturing under simulated working conditions, provides a basis for optimizing fracturing and temporary plugging processes, improves fracturing effectiveness, and reduces the risk of casing damage in oil reservoirs.

[0006] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0007] An experimental apparatus for simulating the perforation erosion of a horizontal well casing in a sand-fracturing process, the apparatus comprising a fracturing fluid delivery system, a sand mixing system, an erosion testing system, and a monitoring and control system;

[0008] The fracturing fluid delivery system includes a storage tank, a liquid turbine flow meter, and a plunger pump, which are connected in sequence via a supply pipeline.

[0009] The sand addition and mixing system includes a sand addition system and a sand mixing system connected in sequence. The sand addition system includes a proppant storage tank, a high-pressure source, and a sand addition tank. The sand mixing system includes a premixing chamber, a sand mixing chamber, a mixing chamber, and a sand concentration monitor. The proppant storage tank and the sand addition tank are connected in sequence through a sand supply pipeline. The sand addition tank is connected to an external high-pressure source. A variable frequency motor is installed on the top of the sand addition tank to provide power to the sand conveying screw built into the sand addition tank. The lower part of the sand addition tank is connected to the premixing chamber. The premixing chamber is connected to the sand mixing chamber through a sand outlet at the bottom. The sand mixing chamber is connected to the mixing chamber.

[0010] The erosion testing system includes a simulated formation fracture, a casing short section, a constant pressure relief valve, and several erosion test short sections. The erosion test short sections and the casing short sections, as well as the erosion test short sections and the simulated formation fracture, are connected by flanges. The simulated formation fracture is connected to the constant pressure relief valve via an output pipeline. The sand mixing chamber and the plunger pump are connected by a liquid delivery pipeline, and the mixing chamber and the erosion test short sections are connected by a mixing and delivery pipeline.

[0011] The monitoring and control system includes a PC terminal, a flow controller, a sand concentration controller, and a phased-array ultrasonic detector. The PC terminal is connected to the flow controller, the sand concentration controller, and the phased-array ultrasonic detector. The flow controller is connected to a liquid turbine flow meter and a plunger pump. The sand concentration controller is connected to a variable frequency motor and a sand concentration monitor. The phased-array ultrasonic detector is connected to a phased-array ultrasonic probe installed on the erosion test section.

[0012] Furthermore, the experimental apparatus also includes a circulation and recovery system, which includes a separator, a proppant recovery tank, and a fracturing fluid circulation pipeline. The first end of the separator is connected to a constant pressure overflow valve, the second end of the separator is connected to the proppant recovery tank through the recovery pipeline, and the third end of the separator is connected to the storage tank of the fracturing fluid delivery system through the fracturing fluid circulation pipeline.

[0013] Furthermore, in the fracturing fluid delivery system, a supply valve is installed on the pipeline between the storage tank and the liquid turbine flow meter; a pressure gauge is installed on the plunger pump.

[0014] Furthermore, in the sand mixing system, the upper part of the sand tank is provided with a sand inlet and a high-pressure injection port; the sand inlet is connected to the proppant storage tank through a sand supply pipeline, and a proppant supply valve is provided on the sand supply pipeline near the proppant storage tank, and a sand inlet valve is provided on the sand supply pipeline near the sand inlet; the high-pressure injection port is connected to a high-pressure source through a high-pressure pipeline, and a high-pressure injection valve is provided on the high-pressure pipeline near the high-pressure injection port.

[0015] Furthermore, in the sand mixing system, a sand stop valve is provided above the sand outlet of the premixing chamber; a turbine is provided in the mixing chamber, and the turbine is made of wear-resistant material.

[0016] Furthermore, in the erosion testing system, the erosion test section is assembled from a test tube body, an O-ring seal, and a test sample; the O-ring seal is placed between the test tube body and the test sample; a first connecting flange is provided on the test tube body surrounding the test sample, which is used to fix it to a second connecting flange provided at the end of the simulated formation fracture, and a gasket is provided between the test sample and the simulated formation fracture.

[0017] Furthermore, the experimental tube is equipped with flanges at both ends with adjustable installation angles, which can simulate the erosion of the aperture at phase angles of 0 to 360°.

[0018] Furthermore, the experimental specimen is cylindrical and stepped, with a simulated perforation hole in the center; the experimental specimen is also provided with a sealing groove for installing an O-ring.

[0019] Furthermore, the curvature of the inner wall surface of the experimental sample is consistent with the curvature of the inner wall of the experimental tube, and the sleeve short section is the same as the inner diameter of the experimental tube.

[0020] Furthermore, the infusion tube is a high-pressure tube, and the mixing tube is a high-pressure flexible tube resistant to erosion and wear; the sand conveying screw, sand mixing chamber, stirring chamber, experimental tube body, gasket, simulated formation fracture, and output pipeline are all made of wear-resistant materials; the sand adding tank is a pressure vessel.

[0021] This invention also provides an experimental method for simulating the perforation erosion of a horizontal well casing under sand fracturing, employing any of the experimental apparatus described above for simulating the perforation erosion of a horizontal well casing under sand fracturing. The experimental method includes the following steps:

[0022] Step S01: Processing the experimental sample;

[0023] Step S02: Assemble the experimental section and connect one or more experimental sections to the erosion test system via flanges according to the experimental requirements;

[0024] Step S03: Prepare a sufficient amount of experimental fracturing fluid in the reservoir and a sufficient amount of experimental proppant in the proppant storage tank. Open the proppant supply valve and the sand inlet valve to add a certain amount of proppant to the sand addition tank. Check and close all instruments and valves.

[0025] Step S04: Open the PC terminal to check the operation of the controller and sensor. After ensuring that the controller and sensor are working properly, operate the PC terminal to control the phased ultrasonic detector to perform ultrasonic detection on the hole before the experiment through the phased ultrasonic probe to obtain the morphology of the hole that has not been eroded so as to compare and analyze it with the morphology of the hole after erosion.

[0026] Step S05: After the ultrasonic detection is completed, open the liquid supply valve, operate the PC terminal to start the plunger pump through the flow controller and control the pump displacement to reach the required displacement Q for the experiment. P Simultaneously, the flow controller will receive flow data Q from the liquid turbine flow meter. R And the pressure data P received from the pressure gauge b Returning to the PC terminal, the PC terminal automatically compares Q. P and Q R The size of the pump is determined, and the pump displacement is automatically fine-tuned via a flow controller according to the required displacement for the experiment, until the flow rate Q measured by the liquid turbine flow meter is reached. R The required displacement Q for the experiment P To ensure equal pressure, adjust the opening pressure threshold P0 of the constant pressure relief valve to set the simulated formation pressure.

[0027] Step S06: After the pump discharge stabilizes, operate the PC terminal to adjust the output pressure P of the high-pressure source. g Open the high-pressure injection valve and the sand stop valve, operate the PC terminal to control the variable frequency motor to drive the sand conveying screw to rotate, pump the proppant into the sand mixing chamber to mix with the fracturing fluid, and after being evenly mixed in the mixing chamber, it enters the mixing and conveying pipe. The sand concentration monitor monitors the sand concentration C in the mixed solution in real time. R The data is then returned to the PC terminal, which automatically compares it with C. R and the required sand concentration C for the experiment P The size of the pump is adjusted, and the pump displacement is automatically fine-tuned via a flow controller according to the required discharge volume for the experiment. The frequency of the variable frequency motor is also automatically fine-tuned until the sand concentration C detected by the sand concentration monitor reaches the specified value. R and the required sand concentration C for the experiment P equal;

[0028] Step S07: Turn on the separator to start working. The proppant-carrying fracturing fluid enters the experimental pipe from the mixing pipe and is ejected at high speed from the simulated perforation holes on the experimental sample into the simulated formation fracture, causing erosion around the simulated perforation holes on the experimental sample. The proppant-carrying fracturing fluid flowing out of the simulated formation fracture enters the separator after passing through the constant pressure overflow valve for separation. The separated fracturing fluid enters the storage tank through the circulation pipeline for circulation. The separated proppant enters the proppant recovery tank for treatment and reuse.

[0029] Step S08: During the experiment, the pressure changes on each experimental section are monitored in real time by a pressure sensor, and the flow rate changes through each simulated orifice are monitored by a flow sensor. After a certain time interval t0, the variable frequency motor, sand stop valve and plunger pump are turned off in sequence to stop the experiment.

[0030] The PC terminal is used to control the phased ultrasonic detector to perform ultrasonic detection on the hole after the experiment, and the morphology of the hole after erosion is obtained. The evolution of the hole erosion morphology and erosion degree is analyzed by comparison.

[0031] After the detection is completed, change the experimental discharge rate and sand concentration parameters, and repeat steps S05, S06 and S08 in sequence to continue the experiment until the experiment ends, and then proceed to step S09.

[0032] Step S09: At the end of the experiment, record the experiment duration t, turn off the variable frequency motor to stop sand feeding, and close the plunger pump, separator and all valves;

[0033] Step S10: After the experiment, remove the experimental samples, clean and dry them, and then weigh each sample again. i1 The macroscopic morphology of the samples was photographed and analyzed using a camera, and the microscopic morphology of the samples after erosion was observed and analyzed using a scanning electron microscope. The average erosion rate of each sample was calculated using the following formula.

[0034]

[0035] In the above formula: The average erosion rate is expressed in g / min; w i0 Let g be the mass of the i-th sample before the experiment; w be the mass of the i-th sample before the experiment. i1 t represents the mass of the i-th sample after the experiment, in g; t represents the duration of the erosion experiment, in min.

[0036] Further, step S01 specifically includes:

[0037] The test tube was fabricated according to the specifications of the oil layer casing, ensuring that its inner diameter was the same as that of the oil layer casing. Test specimens were fabricated using the same material as the oil layer casing, and simulated perforation holes were machined on the specimens based on the perforation conditions. Each test specimen was numbered, cleaned, dried, and then its mass w was measured. i0 .

[0038] Further, in step S02, according to experimental requirements, one or more experimental sections are connected to the erosion testing system via flanges, specifically including:

[0039] When testing the erosion of a single perforation hole, only one experimental section is connected;

[0040] When testing the erosion of perforations in a single cluster at different phases, multiple experimental sections are connected sequentially to the erosion testing system at different phases.

[0041] When testing the difference in perforation erosion between two clusters, multiple experimental short sections are connected to a casing short section in the erosion testing system.

[0042] Furthermore, in step S08, if the amount of proppant in the sand adding tank is insufficient for the experiment, the experiment is stopped, and then the proppant supply valve and sand inlet valve are opened to add a certain amount of proppant to the sand adding tank. Steps S05, S06 and S08 are repeated in sequence to continue the experiment until the experiment ends, and then the experiment proceeds to step S09.

[0043] Furthermore, in step S09, shutting off the variable frequency motor to stop sand feeding, and shutting off the plunger pump, separator, and all valves specifically includes: shutting off the variable frequency motor to stop sand feeding, the plunger pump continuing to operate to pump fracturing fluid into the erosion test system to flush it, and shutting off the plunger pump, separator, and all valves after there is no residual proppant.

[0044] Compared with the prior art, the beneficial effects of the present invention are:

[0045] (1) The present invention provides an experimental device and method for simulating casing hole erosion during horizontal well sand fracturing. The experimental pipe body and experimental sample are processed according to the actual working conditions on site to truly restore the erosion of casing hole under actual fracturing conditions.

[0046] (2) The present invention uses a PC terminal to precisely control parameters such as experimental discharge rate and sand concentration, ensuring the accuracy and reliability of the experiment;

[0047] (3) The present invention realizes real-time monitoring of hole erosion through a monitoring and control system, and can explore the evolution process of erosion behavior of casing holes during sand fracturing.

[0048] (4) The experimental tube of the present invention is provided with flanges at both ends with adjustable installation angles. When testing the erosion of a single perforation hole, only one experimental section is connected sequentially. When testing the erosion of perforations in different phases of a single cluster, multiple experimental sections can be connected sequentially to the erosion test system at different phases. When testing the difference in erosion of perforations between two clusters, multiple experimental sections and one sleeve section can be connected to the erosion test system. In the above manner, the erosion behavior of perforations at different phase angles (0 to 360°) and between different clusters can be simulated.

[0049] (5) The experimental apparatus of the present invention comprehensively considers the influence of parameters such as perforation phase angle, fracturing fluid type, proppant type and particle size, experimental discharge rate, and sand concentration on erosion. The factors considered are relatively comprehensive and accurate. It tests and evaluates the erosion of casing holes during fracturing under simulated working conditions, provides a basis for optimizing fracturing process and temporary plugging process, improves fracturing effect, and reduces the risk of oil layer casing damage. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the overall experimental apparatus according to an embodiment of the present invention;

[0051] Figure 2 This is a schematic diagram of the sand mixing device according to an embodiment of the present invention;

[0052] Figure 3 This is a schematic diagram of the erosion test section according to an embodiment of the present invention;

[0053] Figure 4 This is a schematic diagram of the structure of the experimental sample in an embodiment of the present invention;

[0054] Explanation of markings in the diagram:

[0055] 1-Accumulation tank; 2-Supply pipeline; 3-Liquid turbine flow meter; 4-Plunger pump; 5-Infusion pipe; 6-Sand concentration monitor; 7-Mixed delivery pipe; 8-Constant pressure overflow valve; 9-Separator; 10-Proppant recovery tank; 11-Proppant storage tank; 12-Proppant supply valve; 13-Sand supply pipeline; 14-Recovery pipeline; 15-Fracturing fluid circulation pipeline; 16-Supply valve; 17-PC terminal; 18-High pressure source;

[0056] 401 - Pressure gauge;

[0057] 501-Sand tank; 502-Variable frequency motor; 503-Sand inlet valve; 504-Sand inlet; 505-Turbine; 506-Mixing chamber; 507-Sand mixing chamber; 508-Sand conveying screw; 509-Sand outlet; 510-Premixing chamber; 511-Sand particle shut-off valve; 512-High pressure injection port; 513-High pressure injection valve; 514-High pressure pipeline;

[0058] 701 - Adjustable mounting angle flange; 702 - Erosion test sub; 703 - Simulated formation fracture; 704 - Casing sub; 705 - Pressure sensor; 706 - Output line; 707 - Flow sensor; 710 - Test tube body; 711 - Test specimen; 712 - Gasket; 713 - O-ring seal; 722 - Sealing groove; 721 - Simulated perforation orifice;

[0059] 171-Flow controller; 172-Sand concentration controller; 173-Phase-controlled ultrasonic detector; 174-Phase-controlled ultrasonic probe. Detailed Implementation

[0060] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0061] Example 1

[0062] An experimental apparatus for simulating casing perforation erosion during horizontal well fracturing with sand addition consists of a fracturing fluid delivery system, a sand addition and mixing system, an erosion testing system, a circulation and recovery system, and a monitoring and control system.

[0063] like Figure 1 As shown, the fracturing fluid delivery system includes a storage tank 1, a supply valve 16, a liquid turbine flow meter 3, and a plunger pump 4. The storage tank 1, the supply valve 16, the liquid turbine flow meter 3, and the plunger pump 4 are connected in sequence through a supply pipeline 2. The plunger pump 4 is equipped with a pressure gauge 401.

[0064] Combination Figure 2 As shown, the sand adding and mixing system includes a sand adding system and a sand mixing system connected in sequence. The sand adding system includes a proppant storage tank 11, a proppant supply valve 12, a high-pressure source 18, and a sand adding tank 501. The sand mixing system includes a premixing chamber 510, a sand mixing chamber 507, a mixing chamber 506, and a sand concentration monitor 6. The proppant storage tank 11, the proppant supply valve 12, and the sand adding tank 501 are connected in sequence via a sand supply pipeline 13. The sand adding tank 501 is provided with a sand inlet 504 and a high-pressure injection port 512 at its upper part. The sand inlet 504 is connected to the proppant storage tank 11 via the sand supply pipeline 13, and a proppant supply valve is provided on the sand supply pipeline 13 near the proppant storage tank 11. 12. A sand inlet valve 503 is provided on the sand supply pipeline 13 near the sand inlet 504; the high pressure injection port 512 is connected to the high pressure source 18 through the high pressure pipeline 514, and a high pressure injection valve 513 is provided on the high pressure pipeline 514 near the high pressure injection port 512; a variable frequency motor 502 is installed on the top of the sand adding tank 501 to provide power to the sand conveying screw 508 built into the sand adding tank 501; the lower part of the sand adding tank 501 is connected to the premixing chamber 510, the premixing chamber 510 is connected to the sand mixing chamber 507 through the sand outlet 509 at the bottom, a sand particle shut-off valve 511 is provided on the upper part of the sand outlet 509, the sand mixing chamber is connected to the stirring chamber 506, and a turbine 505 is provided in the stirring chamber 506;

[0065] The erosion testing system includes a simulated formation fracture 703, a casing section 704, a constant pressure relief valve 8, and several erosion test sections 702. The erosion test sections 702 and the casing section 704, and the erosion test sections 702 and the simulated formation fracture 703 are connected by flanges. The simulated formation fracture 703 is connected to the constant pressure relief valve 8 via an output pipeline 706. The sand mixing chamber 507 and the plunger pump 4 are connected via a liquid delivery pipe 5, and the mixing chamber 506 and the erosion test sections 702 are connected via a mixing and delivery pipeline 7.

[0066] The recycling system includes a separator 9, a proppant recovery tank 10, and a fracturing fluid circulation pipeline 15. The first end of the separator 9 is connected to a constant pressure overflow valve 8, the second end of the separator 9 is connected to the proppant recovery tank 10 through the recovery pipeline 14 for recovering the separated proppant, and the third end of the separator 9 is connected to the storage tank 1 of the fracturing fluid delivery system through the fracturing fluid circulation pipeline 15 for recycling the separated fracturing fluid.

[0067] The monitoring and control system includes a PC terminal 17, a flow controller 171, a sand concentration controller 172, and a phased-array ultrasonic detector 173. The PC terminal 17 is connected to the flow controller 171, the sand concentration controller 172, and the phased-array ultrasonic detector 173. The flow controller 171 is connected to the liquid turbine flow meter 3 and the plunger pump 4. The sand concentration controller 172 is connected to the variable frequency motor 502 and the sand concentration monitor 6. The phased-array ultrasonic detector 173 is connected to the phased-array ultrasonic probe 174 installed on the erosion test section 702.

[0068] In this embodiment of the invention, combined with Figure 3 As shown, the erosion test section 702 is assembled from an experimental tube body 710, an O-ring seal 713, and an experimental sample 711. The O-ring seal 713 is placed between the experimental tube body 710 and the experimental sample 711 to provide a seal. A first connecting flange is provided on the experimental tube body 710 around the experimental sample 711 for fixed connection with a second connecting flange provided at the end of the simulated formation fracture 703. A gasket is provided between the experimental sample 711 and the simulated formation fracture 703. The experimental tube body 710 has adjustable flanges 701 at both ends. By adjusting the installation angle of the flanges 701, the erosion of the pore at a phase angle of 0 to 360° can be simulated.

[0069] Combination Figure 4As shown, the experimental specimen 711 is a cylindrical stepped shape with a simulated perforation hole 721 in the center. The experimental specimen 711 is also provided with a sealing groove 722 for installing an O-ring seal 713. The O-ring seal 713 is used to seal the gap between the experimental specimen 711 and the experimental tube 710, preventing the sand-carrying fracturing fluid from overflowing from the gap during the erosion simulation experiment and causing erosion damage to the outer wall of the experimental specimen 711 and the experimental tube. At the same time, it ensures that the force of erosion of the perforation hole is not weakened, making the erosion experiment more realistic and improving the accuracy of the erosion evaluation results. The curvature of the inner wall surface of the experimental specimen 711 is consistent with the curvature of the inner wall of the experimental tube 710, and the sleeve short section 704 has the same inner diameter as the experimental tube 710.

[0070] Furthermore, in this embodiment of the invention, the infusion pipe 5 is a high-pressure pipe, and the mixing pipe 7 is a high-pressure flexible hose resistant to erosion and wear; the sand conveying screw 508, the sand mixing chamber 507, the stirring chamber 506 and the turbine 505, the experimental pipe body 710, the gasket 712, the simulated formation fracture 703, and the output pipeline 706 in the sand mixing system are all made of wear-resistant materials; the sand adding tank 501 is a pressure vessel.

[0071] Example 2

[0072] An experimental method for simulating casing perforation erosion during horizontal well fracturing with proppant, using the experimental apparatus described in Example 1, includes the following steps:

[0073] Step S01: Based on the field data: the oil layer casing specifications are 5-inch TP125V, wall thickness 11.1mm, inner diameter 104.8mm, using an 86-type perforation gun, phase angle 60°, and perforation hole diameter 10mm; process the experimental tube 710 so that its inner diameter is the same as that of the oil layer casing, which is 108mm; process the experimental sample 711 using the same material as the oil layer casing, and process a simulated perforation hole 721 with a diameter of 10mm on the experimental sample; number each experimental sample, clean and dry the experimental sample, and then weigh the mass w of each sample. i0 ;

[0074] Step S02: Assemble the experimental tube 710, experimental sample 711, gasket 712 and simulated formation fracture 703 into a erosion test section 702; to simulate the erosion of a single cluster of holes with different phase angles, connect the three experimental sections 702 to the erosion test system through flanges at 90°, 150° and 210° phases.

[0075] Step S03: Prepare a sufficient amount of experimental fracturing fluid in the reservoir 1, and prepare a sufficient amount of experimental proppant in the proppant storage tank 11. Open the proppant supply valve 12 and the sand inlet valve 503 to add a certain amount of proppant to the sand addition tank 501. Check and close all instruments and valves.

[0076] Step S04: Open the PC terminal to check the operation of the controller and sensors, including the flow controller 171, sand concentration controller 172, phased-array ultrasonic detector 173, pressure sensor 705 and flow sensor 707. After ensuring that the controller and sensors are working properly, operate the PC terminal 17 to control the phased-array ultrasonic detector 173 to perform ultrasonic detection on the hole before the experiment through the phased-array ultrasonic probe 174 to obtain the morphology of the hole that has not been eroded.

[0077] Step S05: After the ultrasonic detection is completed, open the liquid supply valve 16, operate the PC terminal 17 to start the plunger pump 4 through the flow controller 171 and control the pump displacement to reach the required displacement Q for the experiment. P At the same time, the flow controller 171 will receive flow data Q from the liquid turbine flow meter 3. R And the pressure data P received from pressure gauge 401 b Return to PC Terminal 17, PC Terminal 17 automatically compares Q. P and Q R The size of the pump is determined, and the pump displacement is automatically fine-tuned via the flow controller 171 according to the required displacement for the experiment, until the flow rate Q measured by the liquid turbine flow meter 3 is reached. R The required displacement Q for the experiment P Equal to the opening pressure threshold P0 of the constant pressure relief valve 8, thereby setting the simulated formation pressure;

[0078] Step S06: After the pump discharge rate stabilizes, the PC terminal 17 adjusts the output pressure P of the high-pressure source 18 through the sand concentration controller 172. g Slightly higher than P b The high-pressure injection valve 513 and the sand stop valve 511 are opened. The PC terminal 17 controls the variable frequency motor 502 to drive the sand conveying screw 508 to rotate through the sand concentration controller 172, pumping the proppant into the sand mixing chamber 507 to mix with the fracturing fluid. After being stirred by the turbine 505 in the stirring chamber 506, the mixture is uniformly mixed and then enters the mixing and delivery pipe 7. The sand concentration monitor 6, located in the middle of the mixing and delivery pipe 7, monitors the sand concentration C in the mixed solution in real time. R The data is then returned to PC terminal 17, which automatically compares it with C. R and the required sand concentration C for the experiment P The pump displacement is automatically fine-tuned via flow controller 171 according to the required discharge volume for the experiment, and the frequency of variable frequency motor 502 is also automatically fine-tuned until the sand concentration C detected by sand concentration monitor 6 is reached. R and the required sand concentration C for the experiment P equal;

[0079] Step S07: Turn on the separator 9 to start working. The proppant-carrying fracturing fluid enters the experimental pipe from the mixing pipe 7 and is ejected at high speed from the simulated perforation hole 721 on the experimental sample 711 into the simulated formation fracture 703, causing erosion around the simulated perforation hole 721 on the experimental sample 711. The proppant-carrying fracturing fluid flowing out of the simulated formation fracture 703 enters the separator 9 for separation after passing through the constant pressure overflow valve 8. The separated fracturing fluid enters the storage tank 1 through the circulation pipeline 15 for circulation. The separated proppant enters the proppant recovery tank 10 and is reused after treatment.

[0080] Step S08: During the experiment, the pressure change on each experimental section 702 is monitored in real time by pressure sensor 705, and the flow rate change through each simulated orifice is monitored by flow sensor 707. After a certain time interval t0, the variable frequency motor 502, sand stop valve 511 and plunger pump 4 are turned off in sequence to stop the experiment.

[0081] The PC terminal 17 controls the phased ultrasonic detector 173 to perform ultrasonic detection on the hole after the experiment through the phased ultrasonic probe 174, and obtains the morphology of the hole after erosion. The evolution of the hole erosion morphology and erosion degree is analyzed by comparison.

[0082] After the detection is completed, repeat steps S05, S06 and S08 in sequence to continue the experiment until the experiment ends, and then proceed to step S09.

[0083] If the amount of proppant in the sand tank is insufficient for the experiment, the experiment must be stopped. Then, the proppant supply valve 12 and the sand inlet valve 503 are opened to add a certain amount of proppant to the sand tank 501. Steps S05, S06 and S08 are repeated in sequence to continue the experiment until the experiment ends. Then, proceed to step S09.

[0084] Step S09: At the end of the experiment, record the experiment duration t, turn off the variable frequency motor 502 to stop the sand feeding, and continue to work the plunger pump 4 to pump the fracturing fluid into the erosion test system to flush it. After there is no residual proppant, turn off the plunger pump 4, separator 9 and all valves.

[0085] Step S10: After the experiment, remove the experimental sample 711, clean and dry it, and then weigh each sample again. i1 The macroscopic morphology of the samples can be photographed and analyzed using a camera, and the microscopic morphology of the samples after erosion can be observed and analyzed using a scanning electron microscope. The average erosion rate of each sample can be calculated using formula (1).

[0086]

[0087] In the formula: The average erosion rate is expressed in g / min; wi0 Let g be the mass of the i-th sample before the experiment; w be the mass of the i-th sample before the experiment. i1 t represents the mass of the i-th sample after the experiment, in g; t represents the duration of the erosion experiment, in min.

[0088] The above description is merely an embodiment of this application and is not intended to limit the invention. Any modifications, equivalent substitutions, and improvements made within the scope of this application should be included within the protection scope of this invention.

Claims

1. An experimental apparatus for simulating perforation erosion of a horizontal well casing under fracturing with added sand, the apparatus comprising a fracturing fluid delivery system, a sand mixing system, an erosion testing system, and a monitoring and control system, characterized in that: The fracturing fluid delivery system includes a storage tank (1), a liquid turbine flow meter (3), and a plunger pump (4), which are connected in sequence through a supply pipeline (2). The sand addition and mixing system includes a sand addition system and a sand mixing system connected in sequence. The sand addition system includes a proppant storage tank (11), a high-pressure source (18), and a sand addition tank (501). The sand mixing system includes a premixing chamber (510), a sand mixing chamber (507), a mixing chamber (506), and a sand concentration monitor (6). The proppant storage tank (11) and the sand addition tank (501) are connected in sequence through a sand supply pipe (13). The sand addition tank (501) is connected to a high-pressure source (18). A variable frequency motor (502) is installed on the top of the sand addition tank (501) to provide power to the sand conveying screw (508) built into the sand addition tank (501). The lower part of the sand addition tank (501) is connected to the premixing chamber (510). The premixing chamber (510) is connected to the sand mixing chamber (507) through the sand outlet (509) at the bottom. The sand mixing chamber (507) is connected to the mixing chamber (506). The erosion testing system includes a simulated formation fracture (703), a casing short section (704), a constant pressure relief valve (8), and several erosion test short sections (702). The erosion test short sections (702) and the casing short section (704), as well as the erosion test short sections (702) and the simulated formation fracture (703), are connected by flanges. The simulated formation fracture (703) is connected to the constant pressure relief valve (8) through an output pipeline (706). The sand mixing chamber (507) and the plunger pump (4) are connected by a liquid delivery pipe (5), and the mixing chamber (506) and the erosion test short section (702) are connected by a mixing delivery pipe (7). The monitoring and control system includes a PC terminal (17), a flow controller (171), a sand concentration controller (172), and a phased-array ultrasonic detector (173). The PC terminal (17) is connected to the flow controller (171), the sand concentration controller (172), and the phased-array ultrasonic detector (173). The flow controller (171) is connected to the liquid turbine flow meter (3) and the plunger pump (4). The sand concentration controller (172) is connected to the variable frequency motor (502) and the sand concentration monitor (6). The phased-array ultrasonic detector (173) is connected to the phased-array ultrasonic probe (174) installed on the erosion test section (702). The erosion test section (702) is assembled from an experimental tube (710), an O-ring (713), and an experimental specimen (711). The O-ring (713) is positioned between the experimental tube (710) and the experimental specimen (711). A first connecting flange is provided on the experimental tube (710) surrounding the experimental specimen (711) for fixed connection with a second connecting flange at the end of the simulated formation fracture (703). A gasket (712) is provided between the experimental specimen (711) and the simulated formation fracture (703). The experimental tube (710) is equipped with flanges (701) at both ends with adjustable installation angles, which can simulate the erosion of the hole at a phase angle of 0~360°.

2. The experimental setup of claim 1, wherein, It also includes a circulation and recovery system, which includes a separator (9), a proppant recovery tank (10), and a fracturing fluid circulation pipeline (15). The first end of the separator (9) is connected to a constant pressure overflow valve (8), the second end of the separator (9) is connected to the proppant recovery tank (10) through the recovery pipeline (14), and the third end of the separator (9) is connected to the reservoir (1) of the fracturing fluid delivery system through the fracturing fluid circulation pipeline (15).

3. The experimental setup of claim 1, wherein, In the fracturing fluid delivery system, a supply valve (16) is installed on the pipeline between the storage tank (1) and the liquid turbine flow meter (3); a pressure gauge (401) is installed on the plunger pump (4).

4. The experimental setup of claim 1, wherein, In the sand mixing system, the sand tank (501) is provided with a sand inlet (504) and a high-pressure injection port (512) at the top. The sand inlet (504) is connected to the proppant storage tank (11) through the sand supply pipeline (13), and a proppant supply valve (12) is provided on the sand supply pipeline (13) near the proppant storage tank (11), and a sand inlet valve (503) is provided on the sand supply pipeline (13) near the sand inlet (504). The high-pressure injection port (512) is connected to the high-pressure source (18) through the high-pressure pipeline (514), and a high-pressure injection valve (513) is provided on the high-pressure pipeline (514) near the high-pressure injection port (512).

5. The experimental setup of claim 1, wherein, In the sand mixing system, a sand stop valve (511) is provided on the upper part of the sand outlet (509) of the premixing chamber (510); a turbine (505) is provided in the mixing chamber (506), and the turbine (505) is made of wear-resistant material.

6. The experimental setup of claim 1, wherein, The experimental specimen (711) is cylindrical and stepped, with a simulated perforation hole (721) in the center; the experimental specimen (711) is also provided with a sealing groove (722) for installing an O-ring (713).

7. The experimental setup of claim 1, wherein, The inner wall curvature of the experimental sample (711) is consistent with the inner wall curvature of the experimental tube (710), and the sleeve short section (704) has the same inner diameter as the experimental tube (710).

8. The experimental setup of claim 1, wherein, The infusion tube (5) is a high-pressure tube, and the mixing tube (7) is a high-pressure hose resistant to erosion and wear; the sand conveying screw (508), sand mixing chamber (507), stirring chamber (506), experimental tube body (710), gasket (712), simulated formation fracture (703), and output pipeline (706) are all made of wear-resistant materials; the sand adding tank (501) is a pressure vessel.

9. An experimental method for simulating sand erosion in a horizontal well sand fracturing casing hole, using the experimental device according to any one of claims 1-8, characterized in that, The experimental method includes the following steps: Step S01: Processing the experimental sample; Step S02: Assemble the experimental section (702) and connect one or more experimental sections (702) to the erosion test system via flanges according to the experimental requirements; Step S03: Prepare a sufficient amount of experimental fracturing fluid in the reservoir (1), and prepare a sufficient amount of experimental proppant in the proppant storage tank (11). Open the proppant supply valve (12) and sand inlet valve (503) to add a certain amount of proppant to the sand addition tank (501). Check and close all instruments and valves. Step S04: Open the PC terminal to check the operation of the controller and sensor. After ensuring that the controller and sensor are working properly, operate the PC terminal (17) to control the phased ultrasonic detector (173) to perform ultrasonic detection on the hole before the experiment through the phased ultrasonic probe (174) to obtain the morphology of the hole that has not been eroded so as to compare and analyze it with the morphology of the hole after erosion. Step S05: After the ultrasonic detection is completed, open the liquid supply valve (16), operate the PC terminal (17) to start the plunger pump (4) through the flow controller (171) and control the pump displacement to reach the required displacement Q for the experiment. P Meanwhile, the flow controller (171) will receive flow data Q from the liquid turbine flow meter (3). R and the pressure data P received from pressure gauge (401) b Return to PC terminal (17), PC terminal (17) automatically compares Q P and Q R The size of the pump is determined, and the pump displacement is automatically fine-tuned by the flow controller (171) according to the required displacement for the experiment, until the flow rate Q measured by the liquid turbine flow meter (3) is reached. R The required displacement Q for the experiment P Equal to the opening pressure threshold P0 of the constant pressure relief valve (8), set the simulated formation pressure; Step S06: After the pump displacement stabilizes, operate the PC terminal (17) to adjust the output pressure P of the high-pressure source (18). g Open the high-pressure injection valve (513) and the sand stop valve (511), operate the PC terminal (17) to control the variable frequency motor (502) to drive the sand conveying screw (508) to rotate, pump the proppant into the sand mixing chamber (507) to mix with the fracturing fluid, and after being stirred evenly through the stirring chamber (506), enter the mixing and conveying pipe (7). The sand concentration monitor (6) monitors the sand concentration C in the mixed solution in real time. R The data is then returned to the PC terminal (17), and the PC terminal (17) automatically compares it with C. R and the required sand concentration C for the experiment P The size of the pump is adjusted, and the pump displacement is automatically fine-tuned by the flow controller (171) according to the required displacement for the experiment, and the frequency of the variable frequency motor (502) is also fine-tuned until the sand concentration C detected by the sand concentration monitor (6) reaches the specified value. R and the required sand concentration C for the experiment P equal; Step S07: Turn on the separator (9) to start working. The proppant-carrying fracturing fluid enters the experimental tube from the mixing pipe (7) and is ejected at high speed from the simulated perforation hole (721) on the experimental sample (711) into the simulated formation fracture (703). It causes erosion around the simulated perforation hole (721) on the experimental sample (711). The proppant-carrying fracturing fluid flowing out of the simulated formation fracture (703) enters the separator (9) for separation after passing through the constant pressure overflow valve (8). The separated fracturing fluid enters the storage tank (1) through the circulation pipeline (15) for circulation. The separated proppant enters the proppant recovery tank (10) for treatment and reuse. Step S08: During the experiment, the pressure changes on each experimental section (702) are monitored in real time by the pressure sensor (705), and the flow rate changes through each simulated orifice are monitored by the flow sensor (707); after a certain time interval t0, the variable frequency motor (502), sand stop valve (511) and plunger pump (4) are turned off in turn to stop the experiment. The PC terminal (17) controls the phased ultrasonic detector (173) to perform ultrasonic detection on the hole after the experiment through the phased ultrasonic probe (174) to obtain the morphology of the hole after erosion. The evolution of the hole erosion morphology and erosion degree is analyzed by comparison. After the detection is completed, change the experimental discharge rate and sand concentration parameters, and repeat steps S05, S06 and S08 in sequence to continue the experiment until the experiment ends, and then proceed to step S09. Step S09: At the end of the experiment, record the experiment duration t, turn off the variable frequency motor (502) to stop sand feeding, and close the plunger pump (4), separator (9) and all valves; Step S10: After the experiment, the experimental sample (711) is removed and cleaned and dried, and then the mass of each sample is weighed again A camera is used to take pictures and analyze the macroscopic morphology of the sample, and a scanning electron microscope is used to observe and analyze the microscopic morphology of the sample after erosion, and the average erosion rate of each sample is calculated by the following formula ; In the above formula: The average erosion rate is expressed in g / min. w i0 For the first i The mass of each sample before the experiment, in grams; w i1 For the first i Mass of each sample after the experiment, in grams; t The duration of the erosion experiment is in minutes.

10. The experimental method according to claim 9, characterized in that, Step S01 specifically includes: The test tube (710) is fabricated according to the specifications of the oil layer casing, so that the inner diameter of the test tube (710) is the same as that of the oil layer casing. The test specimen (711) is fabricated using the same material as the oil layer casing, and simulated perforation holes (721) are fabricated on the test specimen according to the perforation situation. Each test specimen is numbered, cleaned and dried, and then the mass of each specimen is weighed. .

11. The experimental method according to claim 9, characterized in that, In step S02, according to the experimental requirements, one or more experimental sections (702) are connected to the erosion testing system via flanges, specifically including: When testing the erosion of a single perforation hole, only one experimental section (702) is connected. When testing the erosion of perforations with different phases in a single cluster, multiple experimental sections (702) are connected sequentially to the erosion testing system with different phases. When testing the difference in perforation erosion between two clusters, multiple experimental short sections (702) are connected to a casing short section (704) in the erosion testing system.

12. The experimental method according to claim 9, characterized in that, In step S08, if the amount of proppant in the sand tank is insufficient for the experiment, the experiment is stopped. Then, the proppant supply valve (12) and sand inlet valve (503) are opened to add a certain amount of proppant to the sand tank (501). Steps S05, S06 and S08 are repeated in sequence to continue the experiment until the experiment ends, and then the experiment proceeds to step S09.

13. The experimental method according to claim 9, characterized in that, In step S09, the variable frequency motor (502) is turned off to stop sand feeding, and the plunger pump (4), separator (9) and all valves are closed. Specifically, the variable frequency motor (502) is turned off to stop sand feeding, the plunger pump (4) continues to work to pump fracturing fluid into the erosion test system to flush it, and the plunger pump (4), separator (9) and all valves are closed after there is no residual proppant.

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