Fracturing tracing experimental device and method considering fracturing dynamic process and formation energy

Abstract

The present invention discloses a fracturing tracing experimental device and method that take into account the dynamic process of fracturing and formation energy. The fracturing tracing experimental device that takes into account the dynamic process of fracturing and formation energy includes a pumping system, a fracture system, a filtration system, a pressure application system, and a flowback system; the pumping system is used to inject fracturing fluid with a preset sand ratio and a preset tracer concentration into the fracture system at a preset displacement; the fracture system is connected to the pumping system, and the fracture system includes two fracture plates, a first elastic member, two pressure-bearing columns, and a rigid shell, wherein a accommodating cavity is defined in the rigid shell; the filtration system is connected to the fracture system, and the filtration system is used to simulate the mixing of fracturing fluid and formation fluid in different areas of the matrix during the fracturing process; the pressure application system is respectively connected to the opposite ends of the two pressure-bearing columns and the two fracture plates.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas field exploitation, and in particular to a fracturing tracing experimental device and method taking into account a fracturing dynamic process and formation energy. Background Art

[0002] Hydraulic fracturing technology is currently a key technology for the development of unconventional oil and gas fields at home and abroad. Fracture morphology, proppant placement, etc. directly affect the single well production and recovery rate. Post-fracturing monitoring can guide fracturing design and construction optimization, thereby improving the overall development effect of the oil and gas field. Compared with high-end monitoring technologies such as microseismic and electromagnetic imaging, tracer injection costs are low and do not require complex ground equipment, showing good application prospects in fracture monitoring.

[0003] However, the current theoretical research on fracturing tracer monitoring technology is not mature enough. Experimental research on tracer fracturing monitoring technology at home and abroad is basically conducted using core displacement devices. However, there are many problems in using existing core displacement experimental devices for fracturing tracer technology research. First, it is impossible to simulate the mixing process of tracers and formation fluids caused by fracturing fluid loss and the production process of fluids under formation pressure during backflow. Second, when conducting fracturing tracer simulations considering proppants, the proppants need to be pre-placed in the splitting cracks of the core block, which cannot simulate the proppant migration effect during the actual fracturing process. The research results lack authenticity and cannot provide effective guidance for on-site fracturing design. Therefore, establishing a fracturing tracer experimental device and method that considers the fracturing dynamic process and formation energy, taking into account fracture opening, proppant migration, and formation energy, is of great significance for clarifying the fracturing tracer monitoring mechanism.

[0004] The above content is only used to assist in understanding the technical solution of the present invention and does not constitute an admission that the above content is prior art. Summary of the Invention

[0005] The main purpose of the present invention is to provide a fracturing tracing experimental device and method that take into account the fracturing dynamic process and formation energy, aiming to solve or partially solve the above problems.

[0006] To achieve the above objectives, the present invention provides a fracturing tracing experimental device that takes into account the dynamic process of fracturing and the energy of the formation. The fracturing tracing experimental device that takes into account the dynamic process of fracturing and the energy of the formation includes a pumping system, a fracture system, a filtration system, a pressure application system, and a flowback system.

[0007] The pumping system is used to inject fracturing fluid with a preset sand ratio and a preset tracer concentration into the fracture system at a preset displacement;

[0008] The fracture system is connected to the pumping system, and the fracture system includes two fracture plates, a first elastic member, two pressure-bearing columns, and a rigid shell. A housing is defined in the rigid shell, and the two fracture plates are accommodated in the housing and arranged opposite to each other. The two fracture plates can move in directions toward or away from each other. The side edges of the two fracture plates are sealed against the inner wall of the housing. Pressure-bearing columns are respectively provided on the opposite sides of the two fracture plates. The two pressure-bearing columns extend out of the housing. The first elastic member is provided between the opposite sides of the two fracture plates and the inner wall of the housing. The housing is provided with an injection port and an outlet between the two fracture plates. When fracturing fluid is injected between the two fracture plates, the two fracture plates move in directions away from each other and contact the corresponding pressure-bearing columns, and the first elastic member is squeezed and is in a compressed state.

[0009] The fluid loss system is connected to the fracture system, and the fluid loss system is used to simulate the mixing of fracturing fluid and formation fluid at different areas of the matrix during the fracturing process;

[0010] The pressure applying system is respectively connected to the ends of the two pressure-bearing columns opposite to the two crack plates;

[0011] The flowback system is connected to the fracture system and is used to simulate the fluid production process from the matrix to the fracture and from the fracture to the wellhead under the action of formation pressure.

[0012] In order to achieve the above-mentioned object, the present invention further provides 9. An experimental method using the fracturing tracing experimental device according to any one of claims 3 to 8 that takes into account the fracturing dynamic process and formation energy, characterized in that it comprises:

[0013] The control pumping system starts working, valves 1 to 3 are all closed, and the pumping system begins to inject fracturing fluid mixed with tracers and proppants into the fracture system. At this time, the space between the two fracture plates is gradually filled with liquid and proppant, and the fracturing fluid enters the filtration system through the fracture system;

[0014] When the pressure in the No. 1 liquid storage tank reaches a first pressure value, the No. 1 valve and the No. 2 valve are opened to allow the fracturing fluid to enter the No. 2 liquid storage tank; when the pressure in the No. 2 liquid storage tank reaches a second pressure value, the No. 3 valve and the No. 4 valve are opened to allow the fracturing fluid to enter the No. 3 liquid storage tank; when the pressure in the No. 3 liquid storage tank reaches a third pressure value, the No. 2 valve and the No. 4 valve are closed to terminate the filtration, wherein the first pressure value is less than the second pressure value and is less than the third pressure value.

[0015] When the two crack plates abut against the two pressure columns respectively, the crack opens to the maximum extent, the pumping system is closed, and the pumping process ends;

[0016] When the pumping process is completed, the pressure application system starts and applies closing pressure to the two fracture plates through the two pressure columns. When the pressure on the two fracture plates reaches the set value, the pressure application system stops applying pressure and maintains the pressure, and the pressure application is completed.

[0017] When the pressure application is completed, the No. 2 reversing valve is opened to control the opening of the production outlet, and the backflow system starts to operate. The first piston in the No. 1 liquid storage tank is displaced upward under the action of the second spring, and the mixed liquid in the No. 1 liquid storage tank begins to flow back. When the pressure in the No. 1 liquid storage tank drops to 0, the backflow of the mixed liquid in the No. 1 liquid storage tank is completed; the No. 2 valve is opened, and the mixed liquid in the No. 2 liquid storage tank begins to flow back. When the pressure in the No. 2 liquid storage tank drops to 0, the backflow of the mixed liquid in the No. 2 liquid storage tank is completed; the No. 4 valve is opened, and the mixed liquid in the No. 3 liquid storage tank begins to flow back. When the pressure in the No. 3 liquid storage tank drops to 0, the backflow of the mixed liquid in the No. 3 liquid storage tank is completed; wherein, during the entire backflow process, samples are taken at the production outlet and the samples are tested for tracer concentration;

[0018] Draw the tracer concentration-time variation curve during the flowback process.

[0019] The present invention has at least the following beneficial effects:

[0020] The present invention provides a fracturing tracing experimental device that takes into account the dynamic process of fracturing and the energy of the formation. The fracturing tracing experimental device that takes into account the dynamic process of fracturing and the energy of the formation comprises a pumping system, a fracture system, a filtration system, a pressure application system, and a flowback system; the pumping system is used to inject a fracturing fluid with a preset sand ratio and a preset tracer concentration into the fracture system at a preset displacement; the fracture system is connected to the pumping system, and the fracture system comprises two fracture plates, a first elastic member, two pressure-bearing columns, and a rigid shell. A accommodating cavity is defined in the rigid shell, and the two fracture plates are accommodated in the accommodating cavity and are arranged relative to each other. The two fracture plates can move in directions toward or away from each other, and the sides of the two fracture plates are sealed with the inner wall of the accommodating cavity, and the opposite sides of the two fracture plates are respectively provided with pressure-bearing The first elastic member is provided between the opposing sides of the two fracture plates and the inner wall of the fracture plate. The fracture plate is provided with an injection port and an outlet port. When the fracturing fluid is injected between the two fracture plates, the two fracture plates move in opposing directions and contact the corresponding pressure-bearing member, and the first elastic member is squeezed and placed in a compressed state. The filtration system is connected to the fracture system and is used to simulate the mixing of fracturing fluid and formation fluid in different areas of the matrix during the fracturing process. The pressure application system is respectively connected to the opposite ends of the two pressure-bearing members and the two fracture plates. The flowback system is connected to the fracture system and is used to simulate the fluid production process from the matrix to the fracture and from the fracture to the wellhead under the action of formation pressure. In this way, a fracturing tracing experimental device that considers the fracturing dynamic process and formation energy, including fracture opening, proppant migration, and formation energy, can be provided.

[0021] Furthermore, the present invention utilizes reservoirs No. 1, No. 2, and No. 3 to represent the matrix near the fracture, the matrix in the middle region, and the matrix in the distal region, respectively. Each of the three reservoirs contains varying amounts of brine to simulate formation water. The stiffness coefficient of the second elastic member in each reservoir is related to the desired formation pressure. The stiffness coefficient of the second elastic member increases with increasing formation pressure. This means that the second elastic member can be replaced based on the desired stiffness coefficient. The amount of brine in the three reservoirs is related to the water content of the near-fracture, middle, and distal regions of the formation and can be adjusted based on experimental needs. Therefore, the device can also be used to study tracer flowback characteristics in formations with varying formation pressures and water saturations.

[0022] Furthermore, the pumping system injects fracturing fluid with a specific sand ratio and tracer concentration into the fracture system at a specific flow rate. The fracture system simulates the crack opening, proppant placement, and crack closure during the post-fracturing flowback process. After passing through the fracture system, the injected fracturing fluid enters the filtration system and mixes with the formation fluid in the fluid storage tank. It is then returned through the flowback system, and the flowback fluid is sampled. This allows for a fracturing tracer experimental method that takes into account fracture opening, proppant migration, and formation energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of an embodiment of a fracturing tracing experimental device provided by the present invention that takes into account the fracturing dynamic process and formation energy;

[0024] Figure 2 This is a schematic diagram of the crack system in the closed state;

[0025] Figure 3 Schematic diagram of the crack system in the open state;

[0026] Figure 4 Schematic diagram of the status of each liquid storage tank at the initial moment;

[0027] Figure 5 This is the status diagram of each liquid storage tank after the pumping stage is completed.

[0028] 1-Mixing tank; 2-Injection pump; 3-Injection pipeline; 4-Drain port; 5-Reversing valve No. 1; 6-Crack plate; 7-First spring; 8-Pressure column; 9-Rigid shell; 10-Liquid storage tank No. 1; 11-Liquid storage tank No. 2; 12-Liquid storage tank No. 3; 13-Pipeline No. 1; 14-Pipeline No. 2; 15-Pipeline No. 3; 16-Valve No. 1; 17-Valve No. 2; 18-Valve No. 3; 19-Valve No. 4; 20-Hydraulic device; 21-Reversing valve No. 2; 22-Production outlet.

[0029] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0030] In embodiments of the present invention, the term "and / or" describes the association relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0031] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0032] In the embodiments of the present invention, the term "plurality" refers to two or more than two, and other quantifiers are similar.

[0033] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, it will be understood by those skilled in the art that in the embodiments of the present invention, many technical details are provided to enable the reader to better understand the present invention. However, even without these technical details and the various changes and modifications based on the following embodiments, the technical solutions claimed in the present invention can be implemented. The division of the following embodiments is for convenience of description and should not constitute any limitation on the specific implementation of the present invention. The various embodiments can be combined with each other and referenced to each other under the premise that there is no contradiction.

[0034] The present invention provides a fracturing tracing experimental device that takes into account the fracturing dynamic process and formation energy. Figures 1 to 3 As shown, the fracturing tracing experimental device considering the fracturing dynamic process and formation energy includes a pumping system, a fracture system, a filtration system, a pressure application system, and a flowback system.

[0035] The fracture system is used to simulate the opening of fractures, the placement of proppant, and the closure of fractures during post-fracturing flowback during a real fracturing process. The fracture system is connected to the pumping system and includes two fracture plates 6, a first elastic member, two pressure-bearing columns 8, and a rigid housing 9. The rigid housing 9 defines a housing cavity within which the two fracture plates 6 are housed and arranged relative to each other. The two fracture plates 6 can move in directions toward or away from each other. The sides of the two fracture plates 6 are sealed against the inner wall of the housing cavity. Pressure-bearing columns 8 are provided on the opposing sides of the two fracture plates 6, extending out of the housing cavity. The first elastic member is provided between the opposing sides of the two fracture plates 6 and the inner wall of the housing cavity. The housing cavity has an injection port and an outlet between the two fracture plates 6. When fracturing fluid is injected between the two fracture plates 6, the two fracture plates 6 move in opposing directions and contact the corresponding pressure-bearing columns 8, squeezing the first elastic member and placing it in a compressed state.

[0036] The function of the fracture system is to simulate the opening of fractures, the laying of proppants, and the closure of fractures during the actual fracturing process. The injected fracturing fluid passes through the fracture system and enters the filtration system and mixes with the formation fluid in the storage tank. It is then returned through the flowback system and the return fluid is sampled.

[0037] Specifically, the rigid housing 9 is made of steel. The gap between the fracture plates 6 and the containment chamber can be sealed with a rubber strip. The two fracture plates 6 move toward and away from each other to simulate fracture closure and opening, respectively. A filter screen is installed at the injection port to prevent proppant from entering the filtration system during fracturing.

[0038] Before the fracture plates 6 come into contact with the pressure-bearing columns 8, the first elastic member applies pressure to the fracture plates 6, ensuring contact (i.e., fracture closure). Initially, the pressure-bearing columns 8 and the fracture plates 6 are not in contact, and the two fracture plates 6 are in contact, closing the fracture. When the pumping system begins operation, the fracture opens, and the two fracture plates 6 move in opposite directions. The first elastic member is compressed, and the space between the two fracture plates 6 gradually fills with liquid and proppant. When the two fracture plates 6 contact their corresponding pressure-bearing columns 8, the fracture opens to its maximum extent.

[0039] In some embodiments, the crack plate 6 is made of phenolic resin and can withstand a maximum pressure of 50 MPa. The inner wall thereof is designed to have a certain degree of roughness to simulate the rough wall surface of a real crack.

[0040] In some embodiments, the first elastic member is a first spring 7 .

[0041] The first elastic member and pressure-bearing column 8 are located on the same side of the crack plate 6, with the other side of the first elastic member contacting the inner wall of the chamber. The pressure-bearing column 8 is used to transmit pressure from the pressure-applying system to the two crack plates 6. Once the pressure on the two crack plates 6 reaches the set value, the pressure-applying system stops applying pressure and maintains it until the end of the experiment.

[0042] The pressure-applying system is connected to the ends of the two pressure-bearing columns 8 opposite the two fracture plates 6. The pressure-applying system is used to simulate the closing pressure on the fracture. After the pumping phase is completed, the pressure-applying system begins to operate, applying closing pressure to the two fracture plates 6. In some embodiments, the pressure-applying system is a hydraulic device 20.

[0043] The fluid loss system is used to simulate the mixing of fracturing fluid and formation fluid in different areas of the matrix during fracturing and to prepare for the operation of the flowback system. The fluid loss system is connected to the fracture system and is used to simulate the mixing of fracturing fluid and formation fluid in different areas of the matrix during fracturing.

[0044] During the pumping stage, the fracturing fluid enters the filtration system through the fracture system, mixes with the original fluid in the formation and maintains a certain pressure, preparing for the operation of the backflow system.

[0045] The filtration system includes multiple liquid storage tanks connected in series and a No. 1 pipeline 13. Each liquid storage tank is provided with a second elastic member and a piston. The second elastic member is arranged between the bottom of the liquid storage tank and the piston. The top of the liquid storage tank is connected to a connecting pipeline for connecting multiple liquid storage tanks. A control valve is provided on the connecting pipeline. One end of the No. 1 pipeline 13 is connected to the outlet, and the other end is connected to one of the multiple liquid storage tanks.

[0046] More specifically, multiple liquid storage tanks include a No. 1 liquid storage tank 10, a No. 2 liquid storage tank 11, and a No. 3 liquid storage tank 12. The filtration loss system also includes a No. 2 pipeline 14 and a No. 3 pipeline 15. The control valves include a No. 1 valve 16, a No. 2 valve 17, a No. 3 valve 18, and a No. 4 valve 19. The other end of the No. 1 pipeline 13 is connected to the top of the No. 1 liquid storage tank 10, one end of the No. 2 pipeline 14 is connected to the top of the No. 1 liquid storage tank 10, the other end of the No. 2 pipeline 14 is connected to the top of the No. 2 liquid storage tank 11, one end of the No. 3 pipeline 15 is connected to the top of the No. 2 liquid storage tank 11, and the other end of the No. 3 pipeline 15 is connected to the top of the No. 3 liquid storage tank 12. The No. 1 valve 16 and the No. 2 valve 17 are respectively connected to the two ends of the No. 2 pipeline 14, and the No. 3 valve 18 and the No. 4 valve 19 are respectively connected to the two ends of the No. 3 pipeline 15.

[0047] The second elastic member includes a second spring, a third spring, and a fourth spring. The piston includes a first piston, a second piston, and a third piston. The first fluid reservoir 10 is provided with a second spring and a first piston. The second fluid reservoir 11 is provided with a third spring and a second piston. The third fluid reservoir 12 is provided with a fourth spring and a third piston. The spring coefficients of the springs (the second spring, the third spring, and the fourth spring) in each fluid reservoir are related to the formation pressure to be simulated. The greater the formation pressure to be simulated, the greater the spring coefficients of the springs (the second spring, the third spring, and the fourth spring). In other words, the springs (the second spring, the third spring, and the fourth spring) can be replaced according to the spring coefficients required for the experiment.

[0048] The No. 1 fluid storage tank 10 is used to simulate the mixing of fracturing fluid and formation fluid in the matrix near the fracture area. The No. 2 fluid storage tank 11 is used to simulate the mixing of fracturing fluid and formation fluid in the matrix in the middle area. The No. 3 fluid storage tank 12 is used to simulate the mixing of fracturing fluid and formation fluid in the matrix at the far end.

[0049] Liquid storage tanks 10, 11, and 12 are each equipped with a pressure gauge and a pressure display. The three tanks are connected via pipelines 14 and 15. Valve 16 and valve 18 are located on pipelines 14 and 15, respectively. Initially, the three tanks are filled with varying amounts of brine to simulate formation fluid. Because the area near the fracture is small, fracturing fluid filtration is high, and tracer concentration is high during flowback, the amount of brine in tank 10 is ≤ the amount of brine in tank 2 11 ≤ the amount of brine in tank 3 12.

[0050] Liquid storage tanks 10, 11, and 12 are initially filled with varying amounts of brine to simulate formation fluid. The amount of brine initially contained in each of these tanks 10, 11, and 12 is related to the water content of the near-fracture, mid-fracture, and distal regions of the formation and can be adjusted based on experimental needs. In some embodiments, the brine is a 2 wt% calcium chloride or potassium chloride solution.

[0051] When the pumping system begins operation, valve 16 opens and valve 3 closes. Fracturing fluid enters reservoir 10 through pipeline 13 and mixes with formation fluid. The first piston in reservoir 10 moves downward, compressing first spring 7. When the pressure in reservoir 10 reaches a first preset value (e.g., 1 MPa), the spring in reservoir 10 is compressed to its limit. Since valve 16 is open, the fluid in reservoir 10 enters reservoir 2. When the pressure in reservoir 11 reaches a second preset value (e.g., 3 MPa), the second spring in reservoir 11 is compressed to its limit. Valve 3 opens, allowing the fluid in reservoir 11 to enter reservoir 3. When the pressure in reservoir 12 reaches a third preset value (e.g., 5 MPa), the third spring in reservoir 12 is compressed to its limit. Valve 2 and valve 4 close.

[0052] The flowback system is connected to the fracture system and is used to simulate the fluid production process from the matrix to the fracture and from the fracture to the wellhead under the action of formation pressure. The flowback system includes the No. 1 liquid storage tank 10, the No. 2 liquid storage tank 11, the No. 3 liquid storage tank 12, the No. 1 pipeline 13, the No. 2 pipeline 14, the No. 3 pipeline 15, the No. 2 valve 17, the No. 4 valve 19, the No. 2 reversing valve 21, and the production outlet 22. The production outlet 22 is connected to the injection pipeline 3, and the No. 2 reversing valve 21 is connected to the production outlet 22 and is used to control the opening or closing of the production outlet 22. Liquid storage tank No. 1 10, liquid storage tank No. 2 11, and liquid storage tank No. 3 12 have stored a certain amount of liquid and pressure during the filtration stage. When the flowback system is working, the No. 2 reversing valve 21 controls the opening of the production port 22, samples are taken at the production port 22, and the tracer concentration test is performed on the samples taken to draw a tracer concentration-time change curve during the flowback process.

[0053] The pumping system is used to inject fracturing fluid with a preset sand ratio and a preset tracer concentration into the fracture system at a preset displacement. The pumping system includes a mixing tank 1, an injection pump 2, an injection pipeline 3, a discharge port 4, and a No. 1 reversing valve 5. The outlet of the mixing tank 1 is connected to one end of the injection pump 2, the other end of the injection pump 2 is connected to one end of the injection pipeline 3, and the other end of the injection pipeline 3 is connected to the injection port; the discharge port 4 is connected to the No. 1 pipeline 13, and the No. 1 reversing valve 5 is arranged at the discharge port 4 and is used to control the opening or closing of the discharge port 4.

[0054] The function of the mixing tank 1 is to mix the fracturing fluid, tracer, and proppant uniformly before injecting them into the fracture system via the injection pump 2. After a set of experiments, clean water is pumped into the fracture through the mixing tank 1 to flush out the fracturing fluid, proppant, and tracer from the fracture and the pipeline, and then drain them through the drain port 4 to avoid affecting the next set of experiments.

[0055] The viscosity of the fracturing fluid, the concentration of the tracer, the sand ratio of the proppant, and the particle size can be adjusted based on specific experiments. In some embodiments, the fracturing fluid can be a water-based or oil-based fracturing fluid, the tracer can be a trace element tracer, a chemical tracer, a carbon quantum dot tracer, etc., and the proppant can be quartz sand or ceramsite, etc.

[0056] After pressure application is complete, the flowback system begins operation. Valve No. 2 (17) and Valve No. 4 (19) are closed, and reversing valve No. 2 (21) opens. As pressure decreases, the first piston in tank No. 1 (10) displaces upward under the action of the second spring, and the mixed liquid in tank No. 1 (10) begins to flow back. When the pressure in tank No. 1 (10) drops to 0 MPa, the flowback of the mixed liquid in tank No. 1 (10) is complete. Valve No. 2 (17) opens, and the fluid in tank No. 2 (11) begins to flow back. The second piston in tank No. 2 (11) displaces upward under the action of the third spring, and the mixed liquid in tank No. 2 (11) begins to flow back. When the pressure in tank No. 2 (11) drops to 0 MPa, the flowback of the mixed liquid in tank No. 2 (11) is complete. Valve No. 4 (19) opens, and the fluid in tank No. 3 (12) begins to flow back. The third piston in tank No. 3 (12) displaces upward under the action of the fourth spring, and the mixed liquid in tank No. 3 (12) begins to flow back. When the pressure in the No. 3 liquid storage tank 12 drops to 0 MPa, the mixed liquid in the No. 3 liquid storage tank 12 is completely returned.

[0057] The present invention also provides an experimental method using the above-mentioned fracturing tracing experimental device that takes into account the fracturing dynamic process and formation energy, the experimental method comprising:

[0058] (1) The control pumping system starts working, valves 16 to 18 are all closed, and the pumping system starts to inject fracturing fluid mixed with tracers and proppants into the fracture system. At this time, the space between the two fracture plates 6 is gradually filled with liquid and proppants, and the fracturing fluid enters the filtration system through the fracture system. Figure 2 This is a schematic diagram of the crack system in the closed state; Figure 3 Schematic diagram of the crack system in an open state

[0059] (2) When the pressure in the No. 1 liquid storage tank 10 reaches a first pressure value, the No. 1 valve 16 and the No. 2 valve 17 are opened to allow the fracturing fluid to enter the No. 2 liquid storage tank 11; when the pressure in the No. 2 liquid storage tank 11 reaches a second pressure value, the No. 3 valve 18 and the No. 4 valve 19 are opened to allow the fracturing fluid to enter the No. 3 liquid storage tank 12; when the pressure in the No. 3 liquid storage tank 12 reaches a third pressure value, the No. 2 valve 17 and the No. 4 valve 19 are closed, and the filtration loss ends.

[0060] (3) When the two crack plates 6 respectively abut against the two pressure columns 8, the cracks open to the maximum extent, the pumping system is closed, and the pumping process ends. Figure 4 Schematic diagram of the status of each liquid storage tank at the initial moment; Figure 5 This is the status diagram of each liquid storage tank after the pumping stage is completed.

[0061] (4) When the pumping process is completed, the pressure application system is started and a closing pressure is applied to the two crack plates 6 respectively through the two pressure-bearing columns 8; when the pressure on the two crack plates 6 is loaded to the set value, the pressure application system stops applying pressure and maintains the pressure, and the pressure application is completed.

[0062] (5) When the pressure is applied, the No. 2 reversing valve 21 is opened to control the opening of the production port 22, and the backflow system starts to operate. The first piston in the No. 1 liquid storage tank 10 is displaced upward under the action of the second spring, and the mixed liquid in the No. 1 liquid storage tank 10 starts to flow back. When the pressure in the No. 1 liquid storage tank 10 drops to 0, the backflow of the mixed liquid in the No. 1 liquid storage tank 10 is completed; the No. 2 valve 17 is opened, and the mixed liquid in the No. 2 liquid storage tank 11 starts to flow back. When the pressure in the No. 2 liquid storage tank 11 drops to 0, the backflow of the mixed liquid in the No. 2 liquid storage tank 11 is completed; the No. 4 valve 19 is opened, and the mixed liquid in the No. 3 liquid storage tank 12 starts to flow back. When the pressure in the No. 3 liquid storage tank 12 drops to 0, the backflow of the mixed liquid in the No. 3 liquid storage tank 12 is completed. During the entire backflow process, samples are taken at the production port 22 and the tracer concentration of the samples is tested.

[0063] (6) Draw the tracer concentration-time curve during the flowback process.

[0064] Obviously, the embodiments described above are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, those skilled in the art may make other different forms of changes or modifications without making any creative work, and all of these should fall within the scope of protection of the present invention.

Claims

1. A fracturing tracing experimental device that takes into account the dynamic process of fracturing and formation energy, characterized in that: Including pump injection system, fracture system, filtration system, pressure application system, and flowback system; The pumping system is used to inject fracturing fluid with a preset sand ratio and a preset tracer concentration into the fracture system at a preset displacement; The fracture system is connected to the pumping system, and the fracture system includes two fracture plates, a first elastic member, two pressure-bearing columns, and a rigid shell. A housing is defined in the rigid shell, and the two fracture plates are accommodated in the housing and arranged opposite to each other. The two fracture plates can move in directions toward or away from each other. The side edges of the two fracture plates are sealed against the inner wall of the housing. Pressure-bearing columns are respectively provided on the opposite sides of the two fracture plates. The two pressure-bearing columns extend out of the housing. The first elastic member is provided between the opposite sides of the two fracture plates and the inner wall of the housing. The housing is provided with an injection port and an outlet between the two fracture plates. When fracturing fluid is injected between the two fracture plates, the two fracture plates move in directions away from each other and contact the corresponding pressure-bearing columns, and the first elastic member is squeezed and is in a compressed state. The fluid loss system is connected to the fracture system, and the fluid loss system is used to simulate the mixing of fracturing fluid and formation fluid at different areas of the matrix during the fracturing process; The pressure applying system is respectively connected to the ends of the two pressure-bearing columns opposite to the two crack plates; The flowback system is connected to the fracture system and is used to simulate the fluid production process from the matrix to the fracture and from the fracture to the wellhead under the action of formation pressure.

2. The fracturing tracing experimental device considering the fracturing dynamic process and formation energy according to claim 1, characterized in that: The filtration system includes multiple liquid storage tanks connected in series and a No. 1 pipeline. Each liquid storage tank is provided with a second elastic member and a piston. The second elastic member is arranged between the bottom of the liquid storage tank and the piston. The top of the liquid storage tank is connected to a connecting pipeline for connecting multiple liquid storage tanks. A control valve is provided on the connecting pipeline. One end of the No. 1 pipeline is connected to the outlet, and the other end is connected to one of the multiple liquid storage tanks.

3. The fracturing tracing experimental device considering the fracturing dynamic process and formation energy according to claim 2, characterized in that: The plurality of liquid storage tanks include a No. 1 liquid storage tank, a No. 2 liquid storage tank, and a No. 3 liquid storage tank. The filtration system further includes a No. 2 pipeline and a No. 3 pipeline. The control valves include a No. 1 valve, a No. 2 valve, a No. 3 valve, and a No. 4 valve. The other end of the No. 1 pipeline is in communication with the top of the No. 1 liquid storage tank, one end of the No. 2 pipeline is in communication with the top of the No. 1 liquid storage tank, the other end of the No. 2 pipeline is in communication with the top of the No. 2 liquid storage tank, one end of the No. 3 pipeline is in communication with the top of the No. 2 liquid storage tank, the other end of the No. 3 pipeline is in communication with the top of the No. 3 liquid storage tank, the No. 1 valve and the No. 2 valve are respectively connected to both ends of the No. 2 pipeline, and the No. 3 valve and the No. 4 valve are respectively connected to both ends of the No. 3 pipeline; Among them, the No. 1 liquid storage tank is used to simulate the mixing of fracturing fluid and formation fluid in the matrix near the fracture area, the No. 2 liquid storage tank is used to simulate the mixing of fracturing fluid and formation fluid in the matrix in the middle area, and the No. 3 liquid storage tank is used to simulate the mixing of fracturing fluid and formation fluid in the matrix in the distal area; the amount of brine in the No. 1 liquid storage tank is ≤ the amount of brine in the No. 2 liquid storage tank ≤ the amount of brine in the No. 3 liquid storage tank.

4. The fracturing tracing experimental device considering the fracturing dynamic process and formation energy according to claim 3, characterized in that: The second elastic member includes a second spring, a third spring, and a fourth spring; the piston includes a first piston, a second piston, and a third piston; a second spring and a first piston are provided in the No. 1 liquid storage tank, and the second spring is provided between the first piston and the bottom wall of the No. 1 liquid storage tank; a third spring and a second piston are provided in the No. 2 liquid storage tank, and the third spring is provided between the second piston and the bottom wall of the No. 2 liquid storage tank; a fourth spring and a third piston are provided in the No. 3 liquid storage tank, and the fourth spring is provided between the third piston and the bottom wall of the No. 3 liquid storage tank.

5. The fracturing tracing experimental device considering the fracturing dynamic process and formation energy according to claim 3, characterized in that: The pump injection system includes a stirring tank, an injection pump, an injection pipe, a discharge port, and a No. 1 reversing valve, wherein the outlet of the stirring tank is connected to one end of the injection pump, the other end of the injection pump is connected to one end of the injection pipe, and the other end of the injection pipe is connected to the injection port; The drain port is connected to the No. 1 pipeline, and the No. 1 reversing valve is arranged at the drain port and is used to control the opening or closing of the drain port.

6. The fracturing tracing experimental device considering the fracturing dynamic process and formation energy according to claim 3, characterized in that: The flowback system includes the No. 1 liquid storage tank, the No. 2 liquid storage tank, the No. 3 liquid storage tank, the No. 1 pipeline, the No. 2 pipeline, the No. 3 pipeline, the No. 2 valve, the No. 4 valve, the No. 2 reversing valve, and a production outlet. The production outlet is connected to the injection pipeline, and the No. 2 reversing valve is connected to the production outlet and is used to control the opening or closing of the production outlet.

7. The fracturing tracing experimental device considering the fracturing dynamic process and formation energy according to claim 3, characterized in that: The pumping system includes a stirring tank, an injection pump, an injection pipe, a discharge port, and a No. 1 reversing valve. The outlet of the stirring tank is connected to one end of the injection pump, the other end of the injection pump is connected to one end of the injection pipe, and the other end of the injection pipe is connected to the injection port; the discharge port is connected to the No. 1 pipe, and the No. 1 reversing valve is arranged at the discharge port and is used to control the opening or closing of the discharge port.

8. The fracturing tracing experimental device considering the fracturing dynamic process and formation energy according to claim 3, characterized in that: The outlet is provided with a filter.

9. An experimental method using the fracturing tracing experimental device according to any one of claims 3 to 8 that takes into account the fracturing dynamic process and formation energy, characterized in that: include: The control pumping system starts working, valves 1 to 3 are all closed, and the pumping system begins to inject fracturing fluid mixed with tracers and proppants into the fracture system. At this time, the space between the two fracture plates is gradually filled with liquid and proppant, and the fracturing fluid enters the filtration system through the fracture system; When the pressure in the No. 1 liquid storage tank reaches a first pressure value, the No. 1 valve and the No. 2 valve are opened to allow the fracturing fluid to enter the No. 2 liquid storage tank; when the pressure in the No. 2 liquid storage tank reaches a second pressure value, the No. 3 valve and the No. 4 valve are opened to allow the fracturing fluid to enter the No. 3 liquid storage tank; when the pressure in the No. 3 liquid storage tank reaches a third pressure value, the No. 2 valve and the No. 4 valve are closed to terminate the filtration, wherein the first pressure value is less than the second pressure value and is less than the third pressure value. When the two crack plates abut against the two pressure columns respectively, the crack opens to the maximum extent, the pumping system is closed, and the pumping process ends; When the pumping process is completed, the pressure application system starts and applies closing pressure to the two fracture plates through the two pressure columns. When the pressure on the two fracture plates reaches the set value, the pressure application system stops applying pressure and maintains the pressure, and the pressure application is completed. When the pressure application is completed, the No. 2 reversing valve is opened to control the opening of the production outlet, and the backflow system starts to operate. The first piston in the No. 1 liquid storage tank is displaced upward under the action of the second spring, and the mixed liquid in the No. 1 liquid storage tank begins to flow back. When the pressure in the No. 1 liquid storage tank drops to 0, the backflow of the mixed liquid in the No. 1 liquid storage tank is completed; the No. 2 valve is opened, and the mixed liquid in the No. 2 liquid storage tank begins to flow back. When the pressure in the No. 2 liquid storage tank drops to 0, the backflow of the mixed liquid in the No. 2 liquid storage tank is completed; the No. 4 valve is opened, and the mixed liquid in the No. 3 liquid storage tank begins to flow back. When the pressure in the No. 3 liquid storage tank drops to 0, the backflow of the mixed liquid in the No. 3 liquid storage tank is completed; wherein, during the entire backflow process, samples are taken at the production outlet and the samples are tested for tracer concentration; Draw the tracer concentration-time variation curve during the flowback process.

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