Water injection and production simulation experiment device considering crack deformation

Abstract

The application provides a water injection and production simulation experiment device considering crack deformation, comprising: a core clamping system; a liquid supply system; a monitoring system; a liquid production system; wherein the combined core has a plurality of deformable simulation cracks, the liquid supply system can inject water to the plurality of simulation cracks to make them deform, so as to simulate the deformation of the core cracks formed in the rock water injection and production process, the monitoring system is used for dynamically monitoring the changes of the pressure and oil saturation of the combined core in the rock water injection and production process simulated by the water injection and production simulation experiment device, and the liquid production system is used for collecting and metering the oil and water produced in the rock water injection and production process, so as to calculate the water injection and production recovery degree. In the application, the combined core is used in cooperation with the water injection and production simulation experiment device, so that the deformation of the core cracks formed in the rock water injection and production process can be simulated in the process of simulating the rock water injection and production. In this way, the influence of the core cracks on the rock water injection process in the water injection and production process is considered.

Description

Technical Field

[0001] This invention relates to the field of horizontal well water injection for replenishing formation energy, and in particular to a water injection simulation experimental device that takes into account fracture deformation. Background Technology

[0002] With the increasing demand for oil and gas resources and the limited availability of conventional oil and gas resources, tight oil is receiving more and more attention as a hot area of ​​unconventional oil and gas. Due to their typical geological characteristics, tight oil reservoirs generally lack natural production capacity in single wells. Currently, they are mostly developed using horizontal well volumetric fracturing depletion-type development. Due to formation energy depletion and rapid production decline, water injection huff and puff is widely used as a supplementary energy source for volumetric fracturing horizontal wells. The main problem currently facing water injection huff and puff is that the fracture network formed by volumetric fracturing is limited, and the swept area of ​​the injected water during the injection stage is fixed. With the increase of huff and puff cycles, the recovery rate of huff and puff decreases significantly. To address this issue, the field uses high-volume, high-pressure water injection during the injection stage of water injection huff and puff to induce the formation of complex fracture networks, thereby increasing the reservoir stimulation volume and improving the development effect of horizontal well water injection huff and puff. This method has achieved significant results in the Tuha Oilfield, Daqing Oilfield, and Changqing Oilfield. However, because the fractures formed by high-volume water injection are dynamic fractures with strong pressure sensitivity, there is a lack of understanding of the changes in oil saturation and fluid migration laws in the rock during the injection, well shut-in, and flowback stages of water injection huff and puff, which take into account fracture deformation. This results in a lack of theoretical guidance for current field applications and significant differences in effectiveness.

[0003] In other words, the existing technology lacks an understanding of the changes in oil saturation and fluid migration patterns within the rock during the water injection, well shut-in, and flowback stages, which take into account fracture deformation. That is, the influence of fracture deformation is not considered during the changes in oil saturation and fluid migration within the rock during the water injection, well shut-in, and flowback stages. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a water injection and backflow simulation experimental device that considers fracture deformation. This device solves the problem of lacking understanding of the changes in oil saturation and fluid transport patterns within rocks during the water injection, well shut-in, and backflow stages, taking into account fracture deformation.

[0005] This invention provides a water injection and churn simulation experimental device considering fracture deformation, comprising: a core clamping system for clamping a composite core; a fluid supply system connected to the core clamping system for applying confining pressure to the clamped composite core; a monitoring system electrically connected to the composite core within the core clamping system; and a fluid production system connected to the core clamping system. The composite core has multiple deformable simulated fractures. The fluid supply system injects water into the multiple simulated fractures to cause deformation, simulating the deformation of core fractures formed during rock water injection and churn. The monitoring system dynamically monitors the changes in pressure and oil saturation of the composite core during the simulated rock water injection and churn process. The fluid production system collects and measures the oil and water produced during the simulated rock water injection and churn process to calculate the degree of water injection and churn recovery.

[0006] In one embodiment, the composite core includes: a first core body with multiple first monitoring points spaced apart along a first direction, the first monitoring points being electrically connected to a monitoring system; a second core body with multiple second monitoring points spaced apart along the first direction, the second monitoring points being electrically connected to the monitoring system; and a third core body with multiple third monitoring points spaced apart along the first direction, the third monitoring points being electrically connected to the monitoring system; wherein the first core body, the second core body, and the third core body are arranged sequentially at intervals along a second direction, a first rubber sleeve is fitted on one end of the first core body near the second core body, a second rubber sleeve is fitted on one end of the third core body near the second core body, a third rubber sleeve is fitted on the outer periphery of the second core body, a confining pressure cavity is defined between the first rubber sleeve, the second rubber sleeve, and the third rubber sleeve and the core clamping system, the confining pressure cavity is connected to a liquid supply system, the liquid supply system applies confining pressure to the clamped composite core through the confining pressure cavity, and two deformable simulated cracks are formed between the first core body, the second core body, and the third core body.

[0007] In one embodiment, the first monitoring point includes at least one pressure test hole and at least one oil saturation measurement probe hole disposed on the first core body, and / or the second monitoring point includes at least one pressure test hole and at least one oil saturation measurement probe hole disposed on the second core body, and / or the third monitoring point includes at least one pressure test hole and at least one oil saturation measurement probe hole disposed on the third core body.

[0008] In one embodiment, the core clamping system includes: a housing having an open cavity into which the assembled core slides in a third direction; a water injection channel connected to a liquid supply system is provided within the housing for pressurizing two deformable simulated fractures; a pressure channel connected to the liquid supply system is also provided within the housing for pressurizing a confining pressure chamber, which is isolated from the two deformable simulated fractures; and a pressure cap, which is placed over the opening of the open cavity to clamp and fix the assembled core within the open cavity; wherein the pressure cap is provided with a plurality of first sliding holes, a plurality of second sliding holes, and a plurality of third sliding holes, the plurality of first sliding holes corresponding one-to-one with a plurality of first monitoring points, the plurality of second sliding holes corresponding one-to-one with a plurality of second monitoring points, and the plurality of third sliding holes corresponding one-to-one with a plurality of third monitoring points; the monitoring system includes a plurality of test connectors, each test connector extending into a corresponding first, second, or third sliding hole and inserted into a corresponding first, second, or third monitoring point, the test connector being able to slide within its corresponding first, second, or third sliding hole.

[0009] In one embodiment, a sliding pin is provided in the first, second, or third sliding hole, and a groove is provided on the inner wall surface of the first, second, or third sliding hole. The outer peripheral portion of the sliding pin is inserted into the groove and slidably connected with the groove. The test connector is inserted into the inner hole of the sliding pin. A spring is also provided between the inner wall surface and the sliding pin. When the simulated crack is deformed by pressure, the spring is compressed. When the simulated crack is not compressed, the simulated crack returns to its initial state under the action of the spring's restoring force.

[0010] In one embodiment, the test connector includes a pressure test probe and a dual-electrode oil saturation measurement probe, wherein the pressure test probe is inserted into the corresponding pressure test hole, and the dual-electrode oil saturation measurement probe is inserted into the corresponding oil saturation measurement probe hole.

[0011] In one embodiment, the monitoring system further includes a locking connector disposed within the inner hole of the sliding pin, which is used to lock the test connector within the inner hole.

[0012] In one embodiment, the monitoring system further includes: an oil saturation monitor for monitoring the oil saturation of the composite core; a pressure monitor for monitoring the pressure of the composite core; and conductive lines electrically connected to the oil saturation monitor, the pressure monitor, and multiple test connectors.

[0013] In one embodiment, the liquid supply system includes: a confining pressure pressurization line connected to a pressurization channel for pressurizing the confining pressure chamber; and a crack pressurization line connected to a water injection channel for pressurizing two deformable simulated cracks.

[0014] In one embodiment, the fluid collection system includes: a collection pipe, one end of which is connected to two deformable simulated fractures; a measuring cylinder, corresponding to the other end of the collection pipe, for collecting and measuring the oil and water collected during the simulated water injection and churn process; a first valve, disposed on the collection pipe, for controlling the opening and closing of the collection pipe; and a first pressure gauge, disposed on the collection pipe, for monitoring the pressure of the collection pipe.

[0015] Compared with existing technologies, the beneficial effects of this invention are as follows: By combining core samples with a water injection and flow-through simulation experimental device, the deformation of core fractures formed during the water injection and flow-through process can be simulated. This takes into account the influence of core fractures on the injection, well-closing, and flowback stages of water injection and flow-through, thereby improving the accuracy of the simulation. This overcomes the lack of understanding in existing technologies regarding the changes in oil saturation and fluid transport patterns within the rock during the injection, well-closing, and flowback stages, which consider fracture deformation. It is closer to actual field conditions and is of great significance for optimizing key process parameters of water injection and flow-through in horizontal wells with volumetric fracturing at the field scale, maximizing the advantages of water injection and flow-through. It also provides an important reference for the development of horizontal well water injection and flow-through in tight oil reservoirs. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structural composition of the water injection and discharge simulation experimental device considering crack deformation in an embodiment of the present invention;

[0017] Figure 2 for Figure 1 A three-dimensional structural diagram of the core clamping system;

[0018] Figure 3 for Figure 2 Schematic diagram of the structure of the intermediate pressure cover;

[0019] Figure 4 for Figure 3 Cross-sectional view of the middle pressure cover AA;

[0020] Figure 5 for Figure 4 A magnified view of a portion of the pressure cover at point B;

[0021] Figure 6 for Figure 2 Sectional view at point BB;

[0022] Figure 7 This is a front view of the combined rock core in Embodiment 1 of the present invention (without the rubber sleeve installed);

[0023] Figure 8 for Figure 7 Top view of the middle composite core;

[0024] Figure 9 for Figure 8 Enlarged view at point A in the middle;

[0025] Figure 10 This is a front view of the combined rock core (equipped with a rubber sleeve) in Embodiment 1 of the present invention;

[0026] Figure 11 This is a schematic diagram of the assembly of the combined rock core installed in the rock core clamping system in an embodiment of the present invention;

[0027] Figure 12 This is a flowchart of the water injection and spitting simulation experiment method in Embodiment 2 of the present invention;

[0028] Figure 13 This is a map showing the oil saturation distribution of the rock sample after it was saturated with oil in Example 2 of the present invention.

[0029] Figure 14 This is a map showing the oil saturation distribution after the well-clogging stage in Embodiment 2 of the present invention.

[0030] Figure 15 This is a pressure distribution diagram after the well-sealing stage in Embodiment 2 of the present invention;

[0031] Figure 16 This is a pressure distribution diagram after 2 hours of backflow in Embodiment 2 of the present invention.

[0032] In the diagram: 10. Core clamping system; 11. Box body; 111. Opening; 112. Water injection channel; 1121. First injection port; 1122. Second injection port; 113. Pressure testing channel; 12. Pressure cap; 121. First sliding hole; 122. Second sliding hole; 123. Third sliding hole; 13. Sliding pin; 131. Inner hole; 132. Cylindrical body; 133. Sliding rod; 14. Spring; 20. Liquid supply system; 21. Confining pressure testing pipeline; 211. Confining pressure pump; 212. Third pressure gauge; 22. Fracturing pressure testing pipeline; 221. Constant speed pump; 222. Second valve; 223. First intermediate container; 224. Third valve; 225. Second pressure gauge; 226. Fourth valve ; 227. Second intermediate container; 228. Fifth valve; 30. Monitoring system; 31. Locking joint; 311. Locking nut; 32. Test joint; 321. Pressure test probe; 322. Dual-pole oil saturation measurement probe; 33. Oil saturation monitor; 34. Pressure monitor; 35. Conductive circuit; 351. Wire; 40. Fluid sampling system; 41. Produced pipeline; 42. Measuring cylinder; 43. First valve; 44. First pressure gauge; 100. Composite core; 101. First core body; 102. Second core body; 103. Third core body; 1041. First rubber sleeve; 1042. Second rubber sleeve; 1043. Third rubber sleeve; 105. Simulated fracture. Detailed Implementation

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] Example 1

[0035] like Figure 1 As shown, this invention provides a water injection and pumping simulation experimental device considering fracture deformation, comprising a core clamping system 10, a fluid supply system 20, a monitoring system 30, and a fluid sampling system 40. The core clamping system 10 is used to clamp a composite core 100. The fluid supply system 20 is connected to the core clamping system 10 and is used to apply confining pressure to the clamped composite core 100. The monitoring system 30 is electrically connected to the composite core 100 within the core clamping system 10. The fluid sampling system 40 is connected to the core clamping system 10. The composite core 100 has multiple deformable simulated fractures 105. The fluid supply system 20 can inject water into the multiple simulated fractures 105 to cause them to deform, so as to simulate the deformation of the core fractures formed during the rock water injection process. The monitoring system 30 is used to dynamically monitor the changes in pressure and oil saturation of the composite core 100 during the simulated rock water injection process in the water injection simulation experimental device. The fluid production system 40 is used to collect and measure the oil and water produced during the simulated rock water injection process in order to calculate the degree of water injection production.

[0036] In the above setup, by using the combined core 100 with the water injection and flowback simulation experimental device, the deformation of core fractures formed during the rock water injection and flowback process can be simulated. This takes into account the impact of core fractures on the injection, shut-in, and flowback stages of the water injection and flowback process, thereby improving the accuracy of the simulation. This overcomes the lack of understanding in existing technologies regarding the changes in oil saturation and fluid transport patterns within the rock during the injection, shut-in, and flowback stages, which are influenced by fracture deformation. It is closer to actual field conditions and is of great significance for optimizing key process parameters of water injection and flowback in horizontal wells at the field scale, maximizing the advantages of water injection and flowback. It also provides an important reference for the development of horizontal well water injection and flowback in tight oil reservoirs.

[0037] Specifically, such as Figure 1 , Figure 7 and Figure 8As shown, in one embodiment, the composite core 100 includes a first core body 101, a second core body 102, and a third core body 103. The first core body 101 has multiple first monitoring points spaced apart along a first direction, and these first monitoring points are electrically connected to the monitoring system 30. The second core body 102 has multiple second monitoring points spaced apart along the first direction, and these second monitoring points are electrically connected to the monitoring system 30. The third core body 103 has multiple third monitoring points spaced apart along the first direction, and these third monitoring points are electrically connected to the monitoring system 30. The first core body 101, the second core body 102, and the third core body 103 are arranged sequentially at intervals in the second direction. A first rubber sleeve 1041 is fitted on the end of the first core body 101 near the second core body 102, a second rubber sleeve 1042 is fitted on the end of the third core body 103 near the second core body 102, and a third rubber sleeve 1043 is fitted on the outer periphery of the second core body 102. The first rubber sleeve 1041, the second rubber sleeve 1042, and the third rubber sleeve 1043 define a confining pressure cavity with the core clamping system 10. The confining pressure cavity is connected to the liquid supply system 20. The liquid supply system 20 applies confining pressure to the clamped core assembly 100 through the confining pressure cavity. Two deformable simulated cracks 105 are formed between the first core body 101, the second core body 102, and the third core body 103.

[0038] Specifically, such as Figure 8 As shown, in one embodiment, the first core body 101, the second core body 102, and the third core body 103 are cuboids.

[0039] Specifically, in one embodiment, the first core body 101 has the following dimensions (length x width x height): 10cm × 10cm × 3cm. The third core body 103 has the following dimensions: 10cm × 10cm × 3cm. The second core body 102 has the following dimensions: 20cm × 10cm × 3cm.

[0040] Specifically, such as Figure 8 As shown, in one embodiment, a first core 101 has four first monitoring points spaced apart along a first direction, and the first monitoring points are electrically connected to the monitoring system 30. A second core 102 has eight second monitoring points spaced apart along the first direction, and the second monitoring points are electrically connected to the monitoring system 30. The two second monitoring points are grouped into sets of four and spaced apart along the second direction. A third core 103 has four third monitoring points spaced apart along the first direction, and the third monitoring points are electrically connected to the monitoring system 30.

[0041] Specifically, in one embodiment, the first monitoring point includes a pressure test hole and two oil saturation measurement probe holes disposed on the first core body 101, the second monitoring point includes a pressure test hole and two oil saturation measurement probe holes disposed on the second core body 102, and the third monitoring point includes a pressure test hole and two oil saturation measurement probe holes disposed on the third core body 103.

[0042] Specifically, such as Figure 3 and Figure 6 as well as Figure 11 As shown, in one embodiment, the core clamping system 10 includes a housing 11 and a pressure cap 12. The housing 11 has an opening 111 at the top, through which the assembled core 100 is positioned along a third direction (…). Figure 11 The core 100 (perpendicular to the plane of the paper) slides into the opening 111. The box 11 has a water injection channel 112 connected to the liquid supply system 20, used to pressurize the two deformable simulated cracks 105. The box 11 also has a pressure channel 113 connected to the liquid supply system 20, used to pressurize the confining pressure chamber, which is isolated from and not connected to the two deformable simulated cracks 105. A pressure cap 12 is placed over the opening of the opening 111 to clamp and fix the composite core 100 within the opening 111. The pressure cap 12 is provided with four first sliding holes 121, eight second sliding holes 122, and four third sliding holes 123. The four first sliding holes 121 are set one-to-one with the four first monitoring points, the eight second sliding holes 122 are set one-to-one with the eight second monitoring points, and the four third sliding holes 123 are set one-to-one with the four third monitoring points. The monitoring system 30 includes sixteen test connectors 32. Each test connector 32 extends into the corresponding first sliding hole 121, second sliding hole 122, or third sliding hole 123 and is inserted into the corresponding first monitoring point, second monitoring point, or third monitoring point. The test connector 32 can slide within its corresponding first sliding hole 121, second sliding hole 122, or third sliding hole 123.

[0043] Specifically, such as Figure 6 and Figure 11 As shown, in one embodiment, a water injection channel 112 is opened from one side of the box body 11. It is a water injection hole that extends along the second direction. A first injection port 1121 and a second injection port 1122 are provided at intervals on the outer periphery of the water injection hole. The first injection port 1121 and the second injection port 1122 are respectively connected to two deformable simulated cracks 105.

[0044] Specifically, such as Figure 10 and Figure 11 As shown, in one embodiment, the first rubber sleeve 1041, the second rubber sleeve 1042, and the third rubber sleeve 1043 have the same structure.

[0045] Specifically, such as Figure 10 and Figure 11 As shown, in one embodiment, the first rubber sleeve 1041 includes a rubber collar and sealing rings disposed at both ends of the rubber collar, the outer diameter of the two sealing rings being larger than the outer diameter of the rubber collar. A sealing groove is formed on the inner wall of the housing 11 along the third direction, and the sealing ring of the assembled core 100 slides into the opening 111 along the third direction. The sealing rings, the rubber collar, and the inner wall surface of the housing 11 define a confining cavity.

[0046] Specifically, such as Figure 6 and Figure 11 As shown, in one embodiment, the pressure channel 113 includes three pressure holes arranged along the second direction, one end of each of the three pressure holes being connected to one of the three confining pressure chambers. The other end of each of the three pressure holes is connected to the liquid supply system 20.

[0047] Specifically, such as Figure 4 and Figure 5 As shown, in one embodiment, a sliding pin 13 is provided in the first sliding hole 121, the second sliding hole 122, or the third sliding hole 123. A groove is provided on the inner wall surface of the first sliding hole 121, the second sliding hole 122, or the third sliding hole 123. The outer peripheral part of the sliding pin 13 is inserted into the groove and slidably connected with the groove. The test connector 32 passes through the inner hole 131 of the sliding pin 13. A spring 14 is also provided between the inner wall surface and the sliding pin 13. When the simulated crack 105 is deformed by pressure (water pressure), the spring 14 is compressed. When the simulated crack 105 is not compressed, the simulated crack 105 returns to its initial state under the action of the spring restoring force.

[0048] Specifically, such as Figure 5 As shown, in one embodiment, the sliding pin 13 includes a cylindrical body 132 and a slide rod 133, the slide rod 133 being disposed on the outer periphery of the cylindrical body 132. The slide rod 133 is inserted into a sliding groove and slidably connected to the sliding groove.

[0049] Specifically, such as Figure 9 As shown, in one embodiment, the test connector 32 includes a pressure test probe 321 and a dual-electrode oil saturation measurement probe 322. The pressure test probe 321 is inserted into the corresponding pressure test hole, and the dual-electrode oil saturation measurement probe 322 is inserted into the corresponding oil saturation measurement probe hole.

[0050] Specifically, such as Figure 2 As shown, in one embodiment, the monitoring system 30 further includes a locking connector 31 disposed within the inner hole of the sliding pin 13, which is used to lock the test connector 32 within the inner hole.

[0051] Specifically, such as Figure 2 and Figure 7As shown, in one embodiment, the inner hole 131 of the sliding pin 13 is a threaded hole. The locking connector 31 includes a locking sleeve 311, which is inserted into the composite core 100 and respectively sleeved on the outer periphery of the first monitoring point, the second monitoring point, and the third monitoring point. The locking sleeve 311 extends completely into the threaded hole. A circular double-threaded nut is sleeved on the test connector 32. The external thread of the circular double-threaded nut mates with the threaded hole, and its internal thread mates with the external thread of the locking sleeve 311. Thus, the test connector 32 is fixed in the inner hole 131 of the sliding pin 13.

[0052] Specifically, such as Figure 1 As shown, in one embodiment, the monitoring system 30 further includes an oil saturation monitor 33, a pressure monitor 34, and a conductive line 35. The oil saturation monitor 33 is used to monitor the oil saturation of the composite core 100, the pressure monitor 34 is used to monitor the pressure of the composite core 100, and the conductive line 35 is electrically connected to the oil saturation monitor 33, the pressure monitor 34, and multiple test connectors 32.

[0053] Specifically, such as Figure 1 As shown, in one embodiment, the liquid supply system 20 includes a confining pressure pressurization pipeline 21 and a crack pressurization pipeline 22. The confining pressure pressurization pipeline 21 is connected to the pressurization channel 113 and is used to pressurize the confining pressure chamber, while the crack pressurization pipeline 22 is connected to the water injection channel 112 and is used to pressurize two deformable simulated cracks 105.

[0054] Specifically, such as Figure 1 As shown, in one embodiment, the fluid collection system 40 includes a collection pipe 41, a measuring cylinder 42, a first valve 43, and a first pressure gauge 44. One end of the collection pipe 41 is connected to two deformable simulated cracks 105; the measuring cylinder 42 is correspondingly positioned at the other end of the collection pipe 41 to collect and measure the oil and water collected during the simulated water injection and discharge process; the first valve 43 is located on the collection pipe 41 to control the opening and closing of the collection pipe 41; and the first pressure gauge 44 is located on the collection pipe 41 to monitor the pressure of the collection pipe 41.

[0055] The following is combined with Figures 1 to 11 Here is a more specific embodiment of this application:

[0056] This invention provides a water injection and pumping experimental device considering crack deformation, comprising an injection system (liquid supply system 20), a core clamping system 10, a monitoring system 30, and a liquid sampling system 40. The core clamping system 10 includes rubber sleeves (including the aforementioned first to third rubber sleeves), a lower cavity (box 11), and a pressure cap 12. The lower cavity and the pressure cap 12 are connected by a screw through a series of threaded holes on the edge, and by a series of threaded movable monitoring points (including monitoring points and locking sleeves 311 set on the outer periphery of the monitoring points) distributed inside the pressure cap 12 through a series of threaded movable monitoring points distributed inside the pressure cap 12 using round double-threaded nuts. The water injection channel 112 and the pressure-pressurizing channel 113 are located on both sides outside the lower cavity.

[0057] Specifically, the fluid supply system 20 is connected to the core clamping system 10 via the water injection channel 112 and the pressure testing channel 113. In the fluid supply system 20, the constant-speed pump 221 is connected to the water injection channel 112 via the second valve 222, the first intermediate container 223, the third valve 224, and the second pressure gauge 225, forming line one. Simultaneously, the constant-speed pump 221 is also connected to the water injection channel 112 via the fourth valve 226, the second intermediate container 227, and the fifth valve 228, forming line two. Line one and line two are connected in parallel. The fracture pressure testing pipeline 22 includes line one and line two.

[0058] Specifically, the confining pressure pump 211 is connected to the third pressure gauge 212 and the three pressure holes of the pressure channel 113 through pipelines, forming a confining pressure and pressure-pressurizing pipeline 21.

[0059] Specifically, the fluid collection system 40 is connected to the core clamping system 10 through the water injection channel 112. The measuring cylinder 42 in the fluid collection system 40 is connected to the water injection channel 112 through the first valve 43 and the first pressure gauge 44 to measure the collected fluid.

[0060] Specifically, the monitoring system 30 is connected to the core clamping system 10 through threaded movable monitoring points. The oil saturation monitor 33 and the pressure monitor 34 in the monitoring system 30 are connected to a series of threaded movable monitoring points through electrode sleeves via wires 351. The conductive line 35 includes wires 351 and electrode sleeves.

[0061] Specifically, four monitoring points are evenly distributed in the first core body 101 and the third core body 103, and eight second monitoring points are evenly distributed in the second core body 102. A single pressure test hole and two dual-electrode oil saturation measurement probe holes are arranged at each monitoring point as required. Each monitoring point is located inside the corresponding locking sleeve 311 with external thread.

[0062] Specifically, the core clamping system 10 includes a pressure cap 12 and a box body 11. The box body 11 and pressure cap 12 have a series of internally threaded holes around their perimeters. Sixteen internally threaded movable monitoring points are evenly distributed inside the pressure cap 12. Each threaded movable monitoring point includes a sliding pin 13 with internal threads and a spring 14. The sliding pin 13 is partially positioned in a groove, and the two are connected by the spring 14, allowing the sliding pin 13 to slide under external force. The simulated fracture 105 is connected through an infinite flow channel (water injection channel 112) inside the edge of the box body 11, with an injection port (first injection port 1121) at 10cm (vertical distance from the end face where the opening of the water injection channel 112 is located) and an injection port (second injection port 1122) at 30cm (vertical distance from the end face where the opening of the water injection channel 112 is located).

[0063] It should be noted that the water injection channel 112 and the pressure testing channel 113 are staggered and not connected, and the height of the water injection channel 112 is slightly higher than that of the pressure testing channel 113.

[0064] Specifically, each artificially cemented core (first to third core bodies) is fitted with a corresponding rubber sleeve, and after assembly, it is inserted into the opening 111 through the sealing groove at the edge of the cavity. The locking sleeve 311 with external threads on the artificially cemented core passes through the sliding pin 13 with internal threads. The two are connected by a circular double-threaded nut (with external threads on its outer circumferential wall and internal threads on its inner circumferential wall), so that the core monitoring point is tightly connected to the threaded movable monitoring point on the gland. The gaps between each pair of artificially cemented cores are simulated cracks, which are connected to the liquid supply system 20 through the first injection port 1121, the second injection port 1122, and the infinite flow injection channel. Because the monitoring point of the artificially cemented rock core with external threaded screw is connected to the sliding pin 13 with internal thread, during the injection stage, the fluid pressure inside the simulated fracture increases, causing the artificially cemented rock core to slide and compress the spring 14, thus increasing the simulated fracture opening between each pair of artificially cemented rock cores. During the runoff stage, the fluid pressure inside the simulated fracture decreases, and the artificially cemented rock core slides under the action of the spring 14, decreasing the fracture opening between each pair of artificially cemented rock cores. The change in fluid pressure inside the simulated fracture during the injection and runoff stages causes a change in the fracture opening between each pair of artificially cemented rock cores, thereby simulating fracture deformation during the rock water injection and runoff simulation experiment.

[0065] Example 2

[0066] This invention provides an experimental method for a water injection and discharge experimental device that considers crack deformation, comprising the following steps:

[0067] Step S1: Prepare artificial cemented rock cores (first to third core bodies) containing pressure and oil saturation monitoring points, put rubber sleeves (first to third rubber sleeves) on the artificial cemented rock cores, assemble them and put them into the core clamping system;

[0068] Step S2: Apply confining pressure to the artificially cemented core using a confining pressure pump, and then use pressure measurement points to perform multi-point vacuum saturation water extraction to measure the core porosity.

[0069] Step S3: Using four rows of pressure test holes, simulate oil saturation is established by using row injection and sampling (first and second rows for injection, third and fourth rows for extraction) and cross injection and sampling (first and third rows for injection, second and fourth rows for extraction).

[0070] Step S4: Use the monitoring system to measure the oil saturation at various points in the core after oil saturation, and clarify the initial oil saturation distribution map of the rock sample;

[0071] Step S5, injection stage: Water is injected into the inner cavity of the core clamping system using a constant speed pump. When the injection pressure stabilizes at the preset value, the corresponding valve is closed.

[0072] Step S6: Use the monitoring system to determine the pressure and oil saturation distribution of the core at any injection moment;

[0073] Step S7, well shut-off stage: close all valves and use the monitoring system to determine the changes in core pressure and oil saturation at any well shut-off time;

[0074] Step S8, backflow stage: Open the valve of the fluid collection system and use a measuring cylinder to measure the volume of collected oil and water;

[0075] Step S9: When the outlet backflow pressure is less than the predetermined value, close the valve of the liquid sampling system, the drainage ends, and repeat steps S5-S8 to perform the next round of throughput.

[0076] Step S10: Calculate the degree of water injection recovery based on the ratio of water injection and saturated oil production to the volume of saturated oil in the core.

[0077] Based on the pressure and oil saturation distribution maps of each core sample at different times before water injection, during the injection stage, during the well-closing stage, and during the flowback stage, the study investigated the changes in pressure and oil saturation at various locations in the rock samples during water injection, well-closing, and flowback processes, further clarifying the fluid transport patterns within the rock.

[0078] like Figure 12 As shown, a more specific embodiment is described below:

[0079] This embodiment considers a water injection and flushing test method for crack deformation, including the following steps:

[0080] First, the core is prepared and then loaded into the core clamping system:

[0081] Epoxy resin and quartz sand are bonded together in a certain proportion, along with threaded screws used for pressure and oil saturation measurement probes, under the pressure of a press plate to form an artificially cemented core. This core consists of two 10cm×10cm×3cm cores and one 20cm×10cm×3cm core. The 10cm×10cm×3cm core has four evenly distributed monitoring points (four first monitoring points and four second monitoring points), while the 20cm×10cm×3cm core has eight evenly distributed monitoring points. Each core is fitted with a rubber sleeve and inserted into the core clamping system in the order of 10cm×10cm×3cm, 20cm×10cm×3cm, and 10cm×10cm×3cm cores, along the sealing groove. The two injection ports on the injection channel are aligned with the simulated cracks at the contact point of two adjacent cores, and the pressure channel is aligned with the corresponding confining pressure chamber.

[0082] Step 2, Device Connection:

[0083] The fluid supply system, monitoring system, and core clamping system are connected by pipelines, the monitoring system and core clamping system are connected by wires, and the core clamping system is tightly connected by threaded connections.

[0084] Step 3: After applying confining pressure, use the pressure measurement holes to perform multi-point vacuum saturation water extraction on the rock sample and determine the core porosity.

[0085] The pipeline of the fluid sampling system is inserted into the water container. A vacuum pump is used to saturate the water at multiple points from near to far through the pressure monitoring points of the model. The porosity of the core is determined by the mass of the core clamping system before and after saturation.

[0086] Step 4: Using pressure measurement points (holes) and employing a row-like and cross-injection method, simulate oil saturation to establish bound water saturation and monitor initial oil saturation:

[0087] For the two 10cm×10cm×3cm core samples at the edge, saturated oil was displaced through two adjacent pressure monitoring points. For the 20cm×10cm×3cm core sample in the middle, saturated oil was first displaced through two adjacent pressure monitoring points, and then through two diagonally opposite pressure monitoring points. Each time saturated oil was displaced, the pressure at the injection end and the production end was stabilized, and another set of pressure monitoring points was used to ensure that the core was fully saturated with oil. The pump was then stopped and aged for 72 hours. By measuring the amount of water displaced, the initial oil saturation and bound water saturation of the core sample were determined. Furthermore, the oil saturation distribution of the core was measured through the monitoring system to determine the initial oil saturation distribution map.

[0088] Step 5: Simulation of water injection and discharge considering crack deformation:

[0089] During the injection phase, all control valves are closed, and only the liquid supply valve (second pressure gauge) is opened. Water is injected into the core clamping system using a constant speed pump. When the pressure gauge on the injection pipeline stabilizes at 10 MPa, the liquid supply valve is closed. During the injection process, the pressure and oil saturation distribution at various points in the core are measured using a monitoring system when the pressure gauge reads 2 MPa, 5 MPa, and 10 MPa.

[0090] During the well-sealing stage, keep all control valves closed and use the monitoring system to measure the pressure and oil saturation distribution at various points in the core at 12h, 24h, 36h, 48h, 60h and 72h of the well-sealing time, until the set well-sealing time of 72h is reached, and then enter the flowback stage.

[0091] During the flowback stage, the control valves of the fluid production system are opened, the volume of produced oil and water is measured using a graduated cylinder, and the pressure and oil saturation distribution at various points in the core are measured using a monitoring system after the flowback stage.

[0092] Step Six: Determine the recovery rate and the pressure and oil saturation distribution maps:

[0093] Based on the difference between the water injection and saturated oil production and the core saturated oil production, the water injection recovery rate was calculated to be 17.6% according to formula (1). The oil saturation distribution after the rock sample was saturated, the oil saturation distribution after the well-closing stage, the pressure distribution after the well-closing stage, and the pressure distribution after 2 hours of flowback are shown below. Figure 13 , 14 As shown in 15 and 16.

[0094]

[0095] In the formula, E r For harvesting degree, %; Q p To determine the amount of oil produced, m 3 Q s For saturated oil quantity, m 3 .

[0096] from Figure 13 , 14 Figures 15 and 16 show that during the injection phase, the pressure near the fracture rises rapidly, while during the well-closing phase, the pressure gradually diffuses, and the overall pressure distribution gradually becomes more uniform. After the well-closing phase ends, the pressure distribution in the model ultimately shows a high pressure in the middle and low pressure at both ends. During oil production, the pressure near the fracture decreases more rapidly, while the pressure decreases more slowly in areas far from the fracture. After the preset oil production time (usually 2 hours), the pressure near the fracture in the model is lower, while the pressure in areas far from the fracture is higher.

[0097] Furthermore, it can be seen that during the well-clogging process, due to the oil-water permeation between the fracture matrix, crude oil in the rock samples near the fracture is displaced into the fracture, leading to a decrease in the oil saturation of the rock samples near the fracture. After the well-clogging stage ends, the oil saturation of the rock samples near the fracture decreases significantly, while the crude oil in the central part is difficult to effectively utilize. The research results indicate that although capillary permeation is the main oil production mechanism of water injection huff and puff, the permeation and drainage effect is limited due to the limited distance of capillary permeation. The degree of fracture development is the key factor affecting the development effect of water injection huff and puff.

[0098] In this invention, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more unless otherwise explicitly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "link" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0099] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0100] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0101] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A water injection and production simulation experimental device considering fracture deformation, characterized in that, The device comprises: a core clamping system for clamping a combined core; a liquid supply system connected with the core clamping system for pressurizing the clamped combined core; a monitoring system electrically connected with the combined core in the core clamping system; and a liquid production system connected with the core clamping system. The combined core has a plurality of deformable simulated fractures, the liquid supply system can pressurize the plurality of simulated fractures to deform them to simulate the deformation of core fractures formed in the process of water injection and production of rocks, the monitoring system is used to dynamically monitor the changes of pressure and oil saturation of the combined core in the process of water injection and production simulation of rocks, and the liquid production system is used to collect and measure the produced oil and water in the process of water injection and production simulation of rocks to calculate the degree of water injection and production. The combined core comprises: a first core body provided with a plurality of first monitoring points at intervals in a first direction, the first monitoring points being electrically connected with the monitoring system; a second core body provided with a plurality of second monitoring points at intervals in the first direction, the second monitoring points being electrically connected with the monitoring system; and a third core body provided with a plurality of third monitoring points at intervals in the first direction, the third monitoring points being electrically connected with the monitoring system. The first core body, the second core body and the third core body are sequentially and intervaliy arranged in a second direction, a first rubber sleeve is sleeved on one end of the first core body close to the second core body, a second rubber sleeve is sleeved on one end of the third core body close to the second core body, and a third rubber sleeve is sleeved on the outer periphery of the second core body, the first rubber sleeve, the second rubber sleeve and the third rubber sleeve define a confining pressure cavity between the first core body, the second core body and the third core body, the confining pressure cavity is communicated with the liquid supply system, the liquid supply system pressurizes the clamped combined core through the confining pressure cavity, and two deformable simulated fractures are formed between the first core body, the second core body and the third core body. The first monitoring points comprise at least one pressure test hole and at least one oil saturation measurement probe hole arranged on the first core body, and / or the second monitoring points comprise at least one pressure test hole and at least one oil saturation measurement probe hole arranged on the second core body, and / or the third monitoring points comprise at least one pressure test hole and at least one oil saturation measurement probe hole arranged on the third core body. The core clamping system comprises: a box body having an open cavity, the combined core is slid into the open cavity in a third direction, the box body is provided with a water injection channel communicated with the liquid supply system for pressurizing the two deformable simulated fractures, the box body is further provided with a pressurizing channel communicated with the liquid supply system for pressurizing the confining pressure cavity, and the confining pressure cavity is separated from the two deformable simulated fractures; and a gland cap covering the opening of the open cavity to clamp and fix the combined core in the open cavity. ​ ​ ​ The plurality of first sliding holes, the plurality of second sliding holes and the plurality of third sliding holes are arranged on the gland, the plurality of first sliding holes are arranged in one-to-one correspondence with the plurality of first monitoring points, the plurality of second sliding holes are arranged in one-to-one correspondence with the plurality of second monitoring points, and the plurality of third sliding holes are arranged in one-to-one correspondence with the plurality of third monitoring points, and the monitoring system comprises a plurality of test joints, each of the test joints extends into the corresponding first sliding hole or second sliding hole or third sliding hole and is inserted into the corresponding first monitoring point or second monitoring point or third monitoring point, and the test joint can slide in the first sliding hole or second sliding hole or third sliding hole. A sliding bolt is arranged in the first sliding hole or second sliding hole or third sliding hole, a sliding groove is arranged on the inner wall surface of the first sliding hole or second sliding hole or third sliding hole, the outer peripheral part of the sliding bolt is inserted into the sliding groove and is in sliding connection with the sliding groove, the test joint is arranged in the inner hole of the sliding bolt, and a spring is further arranged between the inner wall surface and the sliding bolt; when the simulated crack is deformed under pressure, the spring is compressed, and when the simulated crack is not under pressure, the simulated crack returns to the initial state under the action of the spring restoring force.

2. The water injection huff and puff simulation experimental apparatus considering fracture deformation according to claim 1, characterized in that, The test joint comprises a pressure test probe and a double-electric-level oil saturation measurement probe, the pressure test probe is inserted into the corresponding pressure test hole, and the double-electric-level oil saturation measurement probe is inserted into the corresponding oil saturation measurement probe hole.

3. The water injection huff and puff simulation experimental apparatus considering fracture deformation according to claim 2, characterized by, The monitoring system further comprises a locking joint arranged in the inner hole of the sliding bolt, which is used to lock the test joint in the inner hole.

4. The water injection huff and puff simulation experimental apparatus considering fracture deformation according to claim 1, characterized in that, The monitoring system further comprises: an oil saturation monitor for monitoring the oil saturation of the combined core; and a pressure monitor for monitoring the pressure of the combined core; and a conductive circuit electrically connected with the oil saturation monitor, the pressure monitor and the plurality of test joints.

5. The water injection huff and puff simulation experimental apparatus considering fracture deformation according to claim 1, characterized in that, The liquid supply system comprises: a confining pressure pressing pipeline in communication with the pressing channel and used for pressing the confining pressure cavity; and a crack pressing pipeline in communication with the water injection channel and used for pressing the two deformable simulated cracks.

6. The water injection huff and puff simulation experimental apparatus considering fracture deformation according to claim 1, wherein, The liquid production system comprises: a production pipeline having one end in communication with the two deformable simulated cracks; and a measuring cylinder arranged in correspondence with the other end of the production pipeline and used for collecting and measuring the produced oil and water in the simulated water injection and huff and puff process; and a first valve arranged on the production pipeline and used for controlling the opening and closing of the production pipeline; and a first pressure gauge arranged on the production pipeline and used for monitoring the pressure of the production pipeline.

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