Experimental device for simulating fluid intake of multiple-cluster fractures in limited-entry fracturing

Abstract

The application provides an experimental device for simulating the liquid intake of multi-cluster fractures in limited flow fracturing. The device comprises a liquid storage device, a pumping system, a multi-cluster perforation unit and a data acquisition system. The pumping system is connected between the liquid storage device and the multi-cluster perforation unit, and the liquid outlet of the distal multi-cluster perforation unit is closed. The multi-cluster perforation unit comprises a shell, a simulation casing, a simulation rock casing, a flow detection assembly and a confining pressure detection device. The shell is provided with a liquid inlet and a liquid outlet at both ends and is provided with pressure and flow detection ports on the outer circumferential surface. The simulation casing and the simulation rock casing are nested and placed in the shell, the simulation casing is communicated with the liquid inlet and the liquid outlet at both ends, and the outer circumferential surface has a perforation channel connected with a flow adjusting device. The simulation rock casing and the shell form a closed chamber. During the experiment, the data acquisition system can collect the pumping parameters, the pressure in the closed chamber and the flow of the outflowing liquid in the perforation channel to analyze the uniformity of the liquid intake of the multi-cluster perforation unit.

Description

Technical Field

[0001] This invention relates to the field of oil and gas development technology, and in particular to an experimental device for simulating the fluid inflow of multiple clusters of fractures in flow-limited fracturing. Background Technology

[0002] Multi-cluster perforation fracturing technology in horizontal wells is an effective way to improve the utilization of unconventional reservoirs. However, monitoring by domestic and international researchers using methods such as DTS (Distributed Fiber Optic Thermometry), DAS (Distributed Noise Measurement), or microseismic monitoring has revealed that some horizontal wells do not form effective extended fractures near the perforation cluster locations, and a large number of ineffective perforation clusters that do not produce oil and gas remain after fracturing. Multi-cluster perforation fracturing generally faces the problem of low production contribution. Flow-limited perforation technology can effectively promote balanced fracture initiation and propagation within horizontal well sections during fracturing. This technology involves arranging different numbers of perforations at different locations in the horizontal well, performing high-volume fracturing, and utilizing perforation friction to increase the bottomhole fracturing pressure, forcing the fracturing fluid to divert and sequentially fracturing sections with similar fracturing pressures.

[0003] Domestic and international scholars have conducted extensive theoretical research and numerical simulations in areas such as the optimization of perforation parameters in flow-limited fracturing and the analysis of flow distribution when multiple fractures extend simultaneously in horizontal wells. In theoretical research, the main approach involves using quasi-three-dimensional fracture parameter simultaneous calculations to assess the propagation of multiple fractures. This optimizes flow-limited fracturing perforation schemes under ideal fracture parameters, considering factors such as induced stress and perforation erosion, and analyzes the flow distribution when multiple fractures extend simultaneously in fracturing horizontal wells. In numerical simulation, methods such as the displacement discontinuity method (DDM), extended finite element method (XFEM), and boundary element method (BEM) are primarily employed. Two-dimensional and three-dimensional models are used to study fracture initiation and propagation morphology and fluid distribution under different perforation schemes.

[0004] Although scholars have conducted extensive research on the relationship between flow-limited perforations and fracture propagation, the lack of related physical simulation experiments has prevented the verification of theoretical and numerical simulation results. Due to difficulties in field testing and the inability to obtain flow parameters for each cluster of fractures in the well in a timely manner, conducting indoor simulation experiments on flow distribution during the propagation of multiple fracture clusters is crucial for verifying current theoretical models and numerical simulation results, and for further research on methods to optimize flow-limited perforation parameters. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention provides an experimental apparatus for simulating the fluid inflow rate of multi-cluster fractures in flow-limited fracturing, aiming to solve the problem in related technologies that cannot simulate and verify the parameters and results of flow-limited fracturing perforation experiments.

[0006] This invention provides an experimental apparatus for simulating the fluid inflow rate of multi-cluster fractures in flow-limited fracturing, comprising a liquid storage device, a pumping system, multiple multi-cluster perforation units, and a data acquisition system. The inlet end of the pumping system is connected to the liquid storage device, and the multiple multi-cluster perforation units are connected in series at the outlet end of the pumping system. The pumping parameters of the pumping system are adjustable, and the pumping parameters include at least pumping flow rate and pumping pressure. The downstream ends of the multi-cluster perforation units away from the pumping system are closed. The data acquisition system is connected to the pumping system and is used to collect the pumping parameters. The multi-cluster perforation unit includes: The outer shell is hollow inside, and has an inlet and an outlet at each end. A pressure detection port and a flow detection port connecting the inner and outer sides of the outer shell are provided on the outer peripheral surface of the outer shell. A simulated sleeve is inserted inside the outer shell, and both ends of the simulated sleeve are connected to the liquid inlet and the liquid outlet, respectively. The end of the simulated sleeve is in sealed contact with the inner end face of the outer shell. Multiple perforation channels connecting the inner and outer sides of the simulated sleeve are provided on the outer circumferential surface of the simulated sleeve. The perforation channels are used to detachably connect to flow regulating devices with different flow cross-sectional areas. A simulated rock casing is sleeved on the outside of the simulated casing, and the inner wall of the simulated rock casing is in contact with the inner wall of the simulated casing. A closed cavity is provided between the outer peripheral surface of the simulated rock casing and the inner peripheral surface of the outer shell. The end face of the simulated rock casing is in sealed contact with the inner end face of the outer shell. A flow detection component is connected between the flow detection port and the liquid storage device, and the flow detection component is connected to the data acquisition system; A confining pressure detection device, wherein the detection end of the confining pressure detection device is connected to the pressure detection port, and the confining pressure detection device is connected to the data acquisition system.

[0007] According to the experimental apparatus for simulating the injection rate of multi-cluster fractures under limited flow fracturing provided by the present invention, the pumping system includes an inlet pipeline, an injection pipeline, a pump, and a pumping parameter control cabinet. The inlet pipeline is connected between the liquid storage device and the inlet end of the pump. The injection pipeline is connected between the outlet end of the pump and the inlet of the multi-cluster perforation unit located upstream. The pumping parameter control cabinet is electrically connected to the pump and is used to adjust the pumping parameters.

[0008] According to the experimental apparatus for simulating the inflow of fluid into multiple clusters of fractures in flow-limited fracturing provided by the present invention, the pump is a plunger pump.

[0009] According to the experimental apparatus for simulating the injection volume of multiple clusters of fractures under flow restriction provided by the present invention, a flow valve and a first flow meter are provided on the injection pipeline.

[0010] According to the experimental apparatus for simulating the injection volume of multiple clusters of fractures under limited flow fracturing provided by the present invention, a pipeline friction regulating valve is also provided on the injection pipeline.

[0011] The experimental apparatus for simulating the influx of fluid into multiple clusters of fractures in flow-limited fracturing according to the present invention includes, in its outer shell: The cylinder body, wherein both the pressure detection port and the flow detection port are disposed on the cylinder body; Two end caps are detachably connected to both ends of the cylinder. One end cap has a liquid inlet and the other end cap has a liquid outlet. The end of the end cap near the inner side of the cylinder has a positioning groove. The inner diameter of the positioning groove is equal to the outer diameter of the simulated rock sleeve. The end of the simulated rock sleeve is inserted into the positioning groove.

[0012] According to the experimental apparatus for simulating the inflow of fluid into multiple clusters of fractures in flow-limited fracturing provided by the present invention, a guide groove is also provided at one end of the positioning groove near the inside of the cylinder. The inner diameter of the end of the guide groove connected to the positioning groove is equal to the inner diameter of the positioning groove, and the inner diameter of the guide groove gradually increases from the positioning groove toward the inside of the cylinder.

[0013] According to the experimental apparatus for simulating the inflow rate of multi-cluster fractures under flow-limited fracturing provided by the present invention, a first limiting step is provided at one end of the perforation channel near the interior of the simulated casing, and the flow regulation device includes: A flow-limiting ring is disposed within the perforation channel, and the bottom end of the flow-limiting ring contacts the top end of the first limiting step. The flow-diverting cap has multiple flow-diverting channels inside. The flow-diverting cap is detachably connected to the end of the perforation channel away from the first limiting step. When the flow-diverting cap is connected to the perforation channel, the flow-limiting ring is squeezed between the first limiting step and the flow-diverting cap. The flow-limiting hole of the flow-limiting ring and the multiple flow-diverting channels connect the inner and outer sides of the simulated sleeve. The top surface of the flow-diverting cap is entirely located inside the cylinder enclosed by the outer circumference of the simulated sleeve.

[0014] According to the experimental apparatus for simulating the inflow of fluid into multiple clusters of fractures in flow-limited fracturing provided by the present invention, each of the flow-diverting caps includes four flow-diverting channels.

[0015] The experimental apparatus for simulating the inflow of fluid into multiple clusters of fractures in flow-limited fracturing according to the present invention includes a flow detection component comprising a second flow meter and a flow meter control valve.

[0016] The present invention has the following advantages due to the adoption of the above technical solutions: The present invention provides an experimental apparatus for simulating the influx of fluid into multiple clusters of fractures in flow-limited fracturing. The apparatus includes a liquid storage device, a pumping system, multiple cluster perforation units, and a data acquisition system. The inlet of the pumping system is connected to the liquid storage device. Multiple cluster perforation units are connected in series at the outlet of the pumping system. The pumping parameters of the pumping system are adjustable, including at least the pumping flow rate and pumping pressure. The outlets of the cluster perforation units located away from the pumping system are closed. The data acquisition system is connected to the pumping system to collect the pumping parameters. Each cluster perforation unit includes a shell, a simulated casing, a simulated rock casing, a flow detection component, and a confining pressure detection device. The shell is hollow internally, with an inlet and an outlet at each end. Pressure and flow detection ports connecting the inner and outer sides of the shell are located on its outer circumference. A simulated sleeve is installed inside the outer casing, with its two ends connected to the inlet and outlet respectively. The end of the simulated sleeve is in sealed contact with the inner end face of the outer casing. Perforation channels connecting the inner and outer sides of the simulated sleeve are provided on its outer circumference, allowing for detachable connection to flow regulating devices with different flow cross-sectional areas. A simulated rock sleeve is fitted outside the simulated sleeve, with its inner wall in contact with the inner wall of the simulated casing. A closed chamber is provided between the outer circumference of the simulated rock sleeve and the inner circumference of the outer casing. The end face of the simulated rock sleeve is in sealed contact with the inner end face of the outer casing. The upstream end of the flow detection component is connected to the flow detection port, the downstream end is connected to the liquid storage device, and the flow detection component is connected to the data acquisition system. The detection end of the confining pressure detection device is connected to the pressure detection port, and the confining pressure detection device is connected to the data acquisition system. During the experiment, based on the flow-limited fracturing perforation scheme, the flow cross-sectional area of ​​multiple multi-cluster perforation units was calculated. Flow regulating devices with different flow cross-sectional areas were selected and combined to ensure that the total flow cross-sectional area of ​​each multi-cluster perforation unit was the calculated value. Then, after adjusting the pumping parameters of the pumping system, the pumping system was started, delivering fracturing fluid from the liquid storage device to the multiple multi-cluster perforation units. The fracturing fluid flows through the flow regulating device in the perforation channel to the simulated rock casing, and then enters the closed chamber between the outer shell and the simulated rock casing through the pores or fractures of the simulated rock casing. Finally, it flows back to the liquid storage device via the flow detection component. During the fluid flow process, the data acquisition system collects the pressure in the closed chamber between the outer shell and the simulated rock casing, the flow rate value detected by the flow detection component, and the pumping parameters in real time. Based on the data collected by the data acquisition system, the flow rate of the multiple multi-cluster perforation units under the control of the set pumping parameters can be analyzed, thereby analyzing the balance of the fluid inflow to the multiple multi-cluster perforation units. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of an experimental device for simulating the fluid inflow of multiple clusters of fractures in flow-limited fracturing, according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the structure of a multi-cluster perforation unit provided in an embodiment of the present invention; Figure 3 This is an exploded view of the flow regulating device and the perforation channel provided in an embodiment of the present invention; Figure 4 This is a top view of a shunt cap provided in an embodiment of the present invention; Figure 5 This is a side view of an end cap provided in an embodiment of the present invention.

[0019] Figure label: 100: Liquid storage tank; 210: Plunger pump; 220: Inlet pipeline; 230: Injection pipeline; 231: Flow valve; 232: First flow meter; 233: Pipeline friction regulating valve; 240: Pump injection parameter control cabinet; 300: Multi-cluster perforation unit; 311: Cylinder; 312: Threaded joint; 3121: Positioning groove; 3122: Guide groove; 313: Sealing joint; 314: Inlet; 315: 320: Simulated casing; 321: Perforation channel; 3211: First limiting step; 3212: Second limiting step; 330: Simulated rock casing; 340: Confining pressure detection device; 351: Second flow meter; 352: Flow meter control valve; 360: Closed chamber; 371: Flow limiting ring; 372: Diverting cap; 3721: Diverting channel; 3722: Limiting block; 400: Return pipeline. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0021] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element 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.

[0022] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0023] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0024] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0025] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example 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. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0026] The present invention provides an experimental apparatus for simulating the influx of fluid into multiple clusters of fractures in flow-limited fracturing. The apparatus includes a liquid storage device, a pumping system, multiple cluster perforation units, and a data acquisition system. The inlet of the pumping system is connected to the liquid storage device. Multiple cluster perforation units are connected in series at the outlet of the pumping system. The pumping parameters of the pumping system are adjustable, including at least the pumping flow rate and pumping pressure. The outlets of the cluster perforation units located away from the pumping system are closed. The data acquisition system is connected to the pumping system to collect the pumping parameters. Each cluster perforation unit includes a shell, a simulated casing, a simulated rock casing, a flow detection component, and a confining pressure detection device. The shell is hollow internally, with an inlet and an outlet at each end. Pressure and flow detection ports connecting the inner and outer sides of the shell are located on its outer circumference. A simulated sleeve is installed inside the outer casing, with its two ends connected to the inlet and outlet respectively. The end of the simulated sleeve is in sealed contact with the inner end face of the outer casing. Perforation channels connecting the inner and outer sides of the simulated sleeve are provided on its outer circumference, allowing for detachable connection to flow regulating devices with different flow cross-sectional areas. A simulated rock sleeve is fitted outside the simulated sleeve, with its inner wall in contact with the inner wall of the simulated casing. A closed chamber is provided between the outer circumference of the simulated rock sleeve and the inner circumference of the outer casing. The end face of the simulated rock sleeve is in sealed contact with the inner end face of the outer casing. The upstream end of the flow detection component is connected to the flow detection port, the downstream end is connected to the liquid storage device, and the flow detection component is connected to the data acquisition system. The detection end of the confining pressure detection device is connected to the pressure detection port, and the confining pressure detection device is connected to the data acquisition system. During the experiment, based on the flow-limited fracturing perforation scheme, the flow cross-sectional area of ​​multiple multi-cluster perforation units was calculated. Flow regulating devices with different flow cross-sectional areas were selected and combined to ensure that the total flow cross-sectional area of ​​each multi-cluster perforation unit was the calculated value. Then, after adjusting the pumping parameters of the pumping system, the pumping system was started, delivering fracturing fluid from the liquid storage device to the multiple multi-cluster perforation units. The fracturing fluid flows through the flow regulating device in the perforation channel to the simulated rock casing, and then enters the closed chamber between the outer shell and the simulated rock casing through the pores or fractures of the simulated rock casing. Finally, it flows back to the liquid storage device via the flow detection component. During the fluid flow process, the data acquisition system collects the pressure in the closed chamber between the outer shell and the simulated rock casing, the flow rate value detected by the flow detection component, and the pumping parameters in real time. Based on the data collected by the data acquisition system, the flow rate of the multiple multi-cluster perforation units under the control of the set pumping parameters can be analyzed, thereby analyzing the balance of the fluid inflow to the multiple multi-cluster perforation units.

[0027] The following is combined with Figures 1 to 5 The present invention describes an experimental apparatus for simulating the influx of fluid into multiple clusters of fractures in flow-limited fracturing.

[0028] An embodiment of the present invention provides an experimental apparatus for simulating the liquid inflow of multi-cluster fractures in flow-limited fracturing, including a liquid storage device, a pumping system, multiple multi-cluster perforation units 300, and a data acquisition system.

[0029] The liquid storage device can be a liquid storage tank 100, which can be used to store fracturing fluid.

[0030] The pumping system includes an inlet line 220, an injection line 230, a pump, and a pumping parameter control cabinet 240. The pump can be a plunger pump 210.

[0031] One end of the inlet pipe 220 is connected to the bottom of the liquid storage tank 100, and the other end of the inlet pipe 220 is connected to the inlet end of the plunger pump 210. The plunger pump 210 draws fracturing fluid from the liquid storage tank 100 through the inlet pipe 220.

[0032] The upstream end of the injection line 230 is connected to the outlet end of the plunger pump 210 for discharging the fracturing fluid pumped by the plunger pump 210. A flow valve 231, a first flow meter 232, and a line friction regulating valve 233 are sequentially installed on the injection line 230. The flow valve 231 regulates the flow rate of the fracturing fluid in the injection line 230, and the first flow meter 232, which can be an electromagnetic flow meter, measures the flow rate of the fracturing fluid in the injection line 230. The experimenter can calculate the line friction based on the simulated horizontal wellbore length and adjust the line friction regulating valve 233 based on the calculated value of the line friction.

[0033] The pumping parameter control cabinet 240 is electrically connected to the plunger pump 210 and is used to adjust the pumping parameters of the plunger pump 210. The pumping parameters include at least the pumping flow rate and the pumping pressure.

[0034] The multi-cluster perforation unit 300 includes multiple units, each of which includes an inlet 314, an outlet 315, a pressure detection port, and a flow detection port. Multiple multi-cluster perforation units 300 are connected in series, meaning the outlet 315 of the preceding multi-cluster perforation unit 300 is connected to the inlet 314 of the following multi-cluster perforation unit 300. The inlet 314 of the upstream multi-cluster perforation unit 300 is connected to the downstream end of the injection pipeline 230, while the outlet 315 of the downstream multi-cluster perforation unit 300 is closed.

[0035] Each multi-cluster perforation unit 300 is connected to a confining pressure detection device 340 at its pressure detection port. The confining pressure detection device 340 is connected to the data acquisition system and is used to transmit the detected pressure signal to the data acquisition system.

[0036] A flow detection component is connected to the flow detection port of each multi-cluster perforation unit 300, and the downstream end of each flow detection component is connected to the liquid storage tank 100. Specifically, the downstream ends of multiple flow detection components are connected to the liquid storage tank 100 through the return liquid pipeline 400.

[0037] The flow detection assembly may include a second flow meter 351 and a flow meter control valve 352, wherein the second flow meter 351 may be a glass rotor flow meter.

[0038] The aforementioned multi-cluster perforation unit 300 includes a housing, a simulated casing 320, a simulated rock casing 330, a flow detection component, and a confining pressure detection device 340.

[0039] The outer casing includes a cylindrical body 311 and two end caps. The cylindrical body 311 is hollow inside and has two through ends. The pressure detection port and the flow detection port are both located on the outer circumferential surface of the cylindrical body 311 and connect the inner and outer sides of the cylindrical body 311.

[0040] The end caps include two end caps, which are respectively disposed at both ends of the cylinder 311. Each end cap includes a threaded connector 312 and a sealing connector 313. One end of the threaded connector 312 has an external thread, and the other end has an internal thread. The sealing connector 313 has an external thread on its outer side, and the end of the cylinder 311 has an internal thread. The external thread of the threaded connector 312 is threadedly connected to the internal thread of the cylinder 311, and the external thread of the sealing connector 313 is threadedly connected to the internal thread of the threaded connector 312.

[0041] One end cap is provided with a liquid inlet 314, and the other end cap is provided with a liquid outlet 315. Specifically, the liquid inlet 314 and the liquid outlet 315 are both provided on the sealing joint 313 of the corresponding end cap, and both the liquid inlet 314 and the liquid outlet 315 are connected to the interior of the cylinder 311.

[0042] A positioning groove 3121 is provided at one end of the end cap near the inner side of the cylinder 311. The inner diameter of the positioning groove 3121 is equal to the outer diameter of the end of the simulated rock sleeve 330. The end of the simulated rock sleeve 330 is inserted into the positioning groove 3121, and the simulated sleeve 320 is inserted into the simulated rock sleeve 330.

[0043] To facilitate the insertion of the simulated rock casing 330 into the positioning groove 3121, a guide groove 3122 is provided at one end of the positioning groove 3121 near the inside of the cylinder 311. The guide groove 3122 can be a flared structure, with the inner diameter of the end connected to the positioning groove 3121 being equal to the inner diameter of the positioning groove 3121, and the inner diameter of the end away from the positioning groove 3121 being greater than the inner diameter of the positioning groove 3121. The two ends are connected by a slope.

[0044] Specifically, the inner diameter of the positioning groove 3121 is equal to the outer diameter of the simulated rock sleeve 330. When the simulated rock sleeve 330 is inserted into the positioning groove 3121, the outer circumferential surface of the end of the simulated rock sleeve 330 contacts the inner wall of the positioning groove 3121, and the end face of the simulated rock sleeve 330 contacts the end face of the sealing joint 313, so as to achieve the sealing of the interior of the simulated rock sleeve 330.

[0045] The inner diameter of the position where the guide groove 3122 connects with the positioning groove 3121 is equal to the inner diameter of the positioning groove 3121. The inner diameter of the guide groove 3122 gradually increases from the positioning groove 3121 toward the inside of the cylinder 311, forming a flared structure. Thus, the inner diameter of the opening at the end of the guide groove 3122 is larger than the outer diameter of the simulated rock sleeve 330, which facilitates the insertion of the simulated rock sleeve 330. During the insertion process, the inner side of the guide groove 3122 guides the simulated rock sleeve 330 into the positioning groove 3121.

[0046] It should be noted that the internal thread of the aforementioned threaded connector 312 is located on the inner side wall of the positioning groove 3121. When the simulated rock sleeve 330 is inserted into the positioning groove 3121 and the threaded connector 312 is connected to the cylinder 311, the portion of the threaded connector 312 with the positioning groove 3121 and the guide groove 3122 is clamped between the cylinder 311 and the simulated rock sleeve 330, thereby forming a closed cavity 360 between the outer side wall of the simulated rock sleeve 330 and the inner side wall of the cylinder 311.

[0047] The simulated sleeve 320 is inserted inside the simulated rock sleeve 330, and the outer diameter of the simulated sleeve 320 is equal to the inner diameter of the simulated rock sleeve 330. After the simulated sleeve 320 is inserted into the simulated rock sleeve 330, the outer wall of the simulated sleeve 320 contacts the inner wall of the simulated rock sleeve 330. At this time, after the simulated rock sleeve 330 with the simulated sleeve 320 inserted is installed in the outer shell, the threaded joint 312 has a positioning groove 3121, which makes the threaded joint 312, the simulated rock sleeve 330 and the simulated sleeve 320 coaxial, so that the internal channel of the simulated sleeve 320 connects the liquid inlet 314 and the liquid outlet 315 of the outer shell.

[0048] Multiple perforation channels 321 are provided on the outer circumferential surface of the simulated casing 320, connecting the inner and outer sides of the simulated casing 320. The perforation channels 321 are detachably connected to flow regulating devices with different flow cross-sectional areas. The fracturing fluid flowing into the simulated casing 320 from the inlet 314 can flow out through the perforation channels 321. The flow regulating device can be used to control the flow rate of the fracturing fluid discharged from the perforation channels 321. In other words, the larger the flow cross-sectional area of ​​the flow regulating device, the larger the flow rate of the fracturing fluid discharged through the perforation channels 321, and vice versa.

[0049] The fracturing fluid discharged through the perforation channel 321 passes through the fractures and pores of the simulated rock casing 330 to reach the closed chamber 360 between the simulated rock casing 330 and the cylinder 311, and then flows out through the flow detection port. A flow detection component is provided at the flow detection port, connecting the flow detection port to the liquid storage tank 100, and the flow detection component is used to detect the flow rate of the fracturing fluid flowing out of the flow detection port.

[0050] A pressure detection port is also provided on the cylinder 311, and a confining pressure detection device 340 is connected to the pressure detection port. The confining pressure detection device 340 is used to detect the pressure in the closed chamber 360 between the simulated rock casing 330 and the cylinder 311.

[0051] The data acquisition system is used to connect with the pumping system, the flow detection component, and the confining pressure detection device 340. The data acquisition system is used to collect the pumping parameters of the pumping system, the flow rate of the fracturing fluid discharged through the flow detection port, and the pressure value in the closed chamber 360.

[0052] In some embodiments, a first limiting step 3211 is provided at one end of the inner wall of the perforation channel 321 near the interior of the simulated sleeve 320, and the flow regulating device includes a flow limiting ring 371 and a flow diversion cap 372.

[0053] The flow-limiting ring 371 has a ring-shaped structure with a flow-limiting orifice inside. The different flow cross-sectional areas of the flow regulating valve are reflected in the different inner diameters of the flow-limiting ring 371; the larger the inner diameter, the larger the flow cross-sectional area, and vice versa. The outer diameter of the flow-limiting ring 371 is equal to the diameter of the top surface of the first limiting step 3211. The flow-limiting ring 371 is placed inside the perforation channel 321, and the top surface of the first limiting step 3211 is supported on the bottom surface of the flow-limiting ring 371. At this time, the flow-limiting orifice of the flow-limiting ring 371 is coaxial with the perforation channel 321.

[0054] It should be noted that, in order for the flow-limiting ring 371 to effectively limit the flow rate, the inner diameter of the flow-limiting orifice is smaller than the inner diameter of the first limiting step 3211. If the inner diameter of the flow-limiting orifice is larger than the inner diameter of the first limiting step 3211, then regardless of how the diameter of the flow-limiting orifice changes, its flow cross-sectional area will always be the flow cross-sectional area of ​​the first limiting step 3211.

[0055] The diversion cap 372 is installed inside the perforation channel 321. After the diversion cap 372 is connected to the perforation channel 321, it presses against the top surface of the flow-limiting ring 371, restricting the axial movement of the flow-limiting ring 371 together with the first limiting step 3211. The diversion cap 372 can be threaded to the inner wall of the perforation channel 321. Alternatively, it can be directly inserted. When the simulated sleeve 320 with the diversion cap 372 installed is inserted into the simulated rock sleeve 330, the inner wall of the simulated rock sleeve 330 presses against the top of the diversion cap 372, which also serves to restrict the axial movement of the diversion cap 372 and the flow-limiting ring 371. However, this limiting method requires ensuring that when the bottom surface of the diversion cap 372 contacts the top surface of the flow-limiting ring 371, the top surface of the diversion cap 372 is in contact with the inner wall of the simulated rock sleeve 330.

[0056] A limiting block 3722 is provided at the bottom of the flow divider cap 372. The bottom surface of the limiting block 3722 contacts the top surface of the flow limiting ring 371. Thus, the limiting block 3722 allows a gap to exist between the main body of the flow divider cap 372 and the flow limiting ring 371. Multiple flow divider channels 3721 are also provided on the flow divider cap 372, all of which penetrate the flow divider cap 372 axially. When fracturing fluid passes through the flow limiting hole of the flow limiting ring 371, it will enter the flow divider channel 3721 through the gap between the main body of the flow divider cap 372 and the flow limiting ring 371.

[0057] To increase the coverage area after the fracturing fluid flows out, the cross-sectional area of ​​the diversion cap 372 can be appropriately increased. At this time, a second limiting step 3212 needs to be set in the perforation channel 321. The diameter of the top surface of the second limiting step 3212 is larger than the inner diameter of the top surface of the first limiting step 3211.

[0058] In a specific embodiment, the experimental procedure will be described as follows: This embodiment takes a horizontal well containing five perforation clusters as an example. According to the flow-limiting fracturing perforation scheme, the flow cross-sectional areas of the perforation channels 321 of the five multi-cluster perforation units 300 are A1, A2, A3, A4, and A5, respectively. Flow-limiting rings 371 with different diameters of flow-limiting holes are selected and assembled to ensure that the flow cross-sectional areas of the multiple perforation channels 321 in the five multi-cluster perforation units 300 are A1, A2, A3, A4, and A5, respectively.

[0059] Place the selected flow-limiting ring 371 into the corresponding perforation channel 321 and secure it with the flow-dividing cap 372. Then, insert the simulated sleeve 320 into the simulated rock sleeve 330 and install the simulated rock sleeve 330 into the outer shell. Finally, connect the other components of the experimental setup.

[0060] Pumping parameters such as pumping flow rate and pumping pressure are set via the pumping parameter control cabinet 240. At this time, the data acquisition system collects and records the above-mentioned pumping parameters. Then, the pipeline friction is calculated based on the length of the simulated horizontal wellbore, and the pipeline friction regulating valve 233 is adjusted.

[0061] When the plunger pump 210 is started, the fracturing fluid flows from the liquid storage tank 100 through multiple multi-cluster perforation units 300. During the flow, part of the fracturing fluid enters the closed chamber 360 between the simulated rock casing 330 and the cylinder 311 through the flow regulating device in the perforation channel 321 and the simulated rock casing 330. Then, it enters the return pipeline 400 through the second flow meter 351 and the flow meter control valve 352. The return pipeline 400 guides the fracturing fluid into the liquid storage tank 100 to complete the circulation.

[0062] During the fracturing fluid circulation process, the data acquisition system collects the pressure value detected by the confining pressure detection device 340 and the flow rate value detected by the flow rate detection component. Based on the data collected by the data acquisition system, the experimenters can determine the balance of fluid inflow to the five multi-cluster perforation units 300 under the given pumping parameters.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An experimental apparatus for simulating the influx of fluid into multiple clusters of fractures in flow-limited fracturing, characterized in that, Includes a liquid storage device, a pumping system, multiple multi-cluster perforation units (300), and a data acquisition system, wherein: The pumping system includes an inlet pipe (220), an injection pipe (230), a pump, and a pumping parameter control cabinet (240). The inlet pipe (220) is connected between the liquid storage device and the inlet end of the pump. Multiple multi-cluster perforation units (300) are connected in series. The injection pipe (230) is connected between the outlet end of the pump and the inlet (314) of the upstream multi-cluster perforation unit (300). The downstream end of the multi-cluster perforation unit (300) away from the injection pipe (230) is closed. The pumping parameter control cabinet (240) is electrically connected to the pump and is used to adjust the pumping parameters. The pumping parameters include at least the pumping displacement and the pumping pressure. The data acquisition system is connected to the pump and is used to acquire the pumping parameters. The multi-cluster perforation unit (300) includes: The outer shell is hollow inside, and the two ends of the outer shell are respectively provided with the liquid inlet (314) and the liquid outlet (315). The outer peripheral surface of the outer shell is provided with a pressure detection port and a flow detection port that connect the inner and outer sides of the outer shell. A simulated sleeve (320) is inserted inside the outer shell, with both ends of the simulated sleeve (320) connected to the inlet (314) and the outlet (315) respectively. The end of the simulated sleeve (320) is in sealed contact with the inner end face of the outer shell. A plurality of perforation channels (321) connecting the inner and outer sides of the simulated sleeve (320) are provided on the outer circumferential surface of the simulated sleeve (320). A first limiting step (3211) is provided at one end of the perforation channel (321) near the inside of the simulated sleeve (320). The perforation channel (321) is detachably connected to a flow regulating device with different flow cross-sectional areas. The flow regulating device includes a flow limiting ring (371) and a flow dividing cap (372). The flow limiting ring (371) is disposed in the perforation channel. (321) Inside, and the bottom end of the flow limiting ring (371) is in contact with the top end of the first limiting step (3211), the flow dividing cap (372) is provided with multiple flow dividing channels (3721), the flow dividing cap (372) and the end of the perforation channel (321) away from the first limiting step (3211) are detachably connected, when the flow dividing cap (372) is connected to the perforation channel (321), the flow limiting ring (371) is squeezed between the first limiting step (3211) and the flow dividing cap (372), the flow limiting hole of the flow limiting ring (371) and the multiple flow dividing channels (3721) are connected to the inner and outer sides of the simulated sleeve (320), and the top surface of the flow dividing cap (372) is all located inside the cylinder surrounded by the outer circumference of the simulated sleeve (320); A simulated rock sleeve (330) is sleeved on the outside of the simulated sleeve (320), and the inner wall of the simulated rock sleeve (330) is in contact with the inner wall of the simulated sleeve (320). A closed chamber (360) is provided between the outer peripheral surface of the simulated rock sleeve (330) and the inner peripheral surface of the outer shell. The end face of the simulated rock sleeve (330) is in sealed contact with the inner end face of the outer shell. A flow detection component is connected between the flow detection port and the liquid storage device, and the flow detection component is connected to the data acquisition system; A confining pressure detection device (340) is provided, wherein the detection end of the confining pressure detection device (340) is connected to the pressure detection port, and the confining pressure detection device (340) is connected to the data acquisition system.

2. The experimental apparatus for simulating the influx of fluid into multiple clusters of fractures under limited flow fracturing according to claim 1, characterized in that, The pump is a plunger pump (210).

3. The experimental apparatus for simulating the influx of fluid into multiple clusters of fractures under limited flow fracturing according to claim 1, characterized in that, The injection pipeline (230) is equipped with a flow valve (231) and a first flow meter (232).

4. The experimental apparatus for simulating the influx of fluid into multiple clusters of fractures under limited flow fracturing according to claim 1, characterized in that, The injection pipeline (230) is also equipped with a pipeline friction regulating valve (233).

5. The experimental apparatus for simulating the influx of fluid into multiple clusters of fractures under limited flow fracturing according to claim 1, characterized in that, The outer casing includes: The cylinder (311) has both the pressure detection port and the flow detection port located on it. Two end caps are detachably connected to both ends of the cylinder (311), and one end cap is provided with the liquid inlet (314) and the other end cap is provided with the liquid outlet (315). A positioning groove (3121) is provided at one end of the end cap near the inner side of the cylinder (311). The inner diameter of the positioning groove (3121) is equal to the outer diameter of the simulated rock sleeve (330). The end of the simulated rock sleeve (330) is inserted into the positioning groove (3121).

6. The experimental apparatus for simulating the fluid inflow rate of multiple clusters of fractures in flow-limited fracturing according to claim 5, characterized in that, The positioning groove (3121) is further provided with a guide groove (3122) at one end near the inside of the cylinder (311). The inner diameter of the end of the guide groove (3122) connected to the positioning groove (3121) is equal to the inner diameter of the positioning groove (3121). The inner diameter of the guide groove (3122) gradually increases from the positioning groove (3121) toward the inside of the cylinder (311).

7. The experimental apparatus for simulating the influx of fluid into multiple clusters of fractures under limited flow fracturing according to claim 1, characterized in that, Each of the said shunt caps (372) includes four said shunt channels (3721).

8. The experimental apparatus for simulating the influx of fluid into multiple clusters of fractures under limited flow fracturing according to claim 1, characterized in that, The flow detection assembly includes a second flow meter (351) and a flow meter control valve (352).

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