Experimental device for simulating flow-limiting fracturing multi-cluster crack liquid inlet amount

Abstract

The invention provides an experimental device for simulating the flow-limiting fracturing multi-cluster fracture liquid inlet amount. The device comprises a liquid storage device, a pump injection system, a multi-cluster perforation unit and a data acquisition system. The pump injection system is connected between the liquid storage device and the multiple multi-cluster perforation units, and a liquid outlet of the multi-cluster perforation unit at the far end is closed. The multi-cluster perforation unit comprises a shell, a simulation sleeve, a simulation rock sleeve, a flow detection assembly and a confining pressure detection device. A liquid inlet and a liquid outlet are formed in two ends of the shell, and a pressure and flow detection port is formed in the peripheral surface. The simulation sleeve and the simulation rock sleeve are nested and arranged in the shell, two ends of the simulation sleeve are communicated with the liquid inlet and the liquid outlet, and the periphery of the simulation sleeve is provided with a perforation channel capable of being connected with a flow adjusting device. And a closed cavity is formed between the simulated rock sleeve and the shell. During an experiment, the data acquisition system can acquire pump injection parameters, the pressure in the closed cavity and the flow of liquid flowing out of the perforation channel so as to analyze the balance of the liquid inlet amount of the multi-cluster perforation unit.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas development, and particularly relates to an experimental device for simulating the liquid intake of multi-cluster fractures in limited-entry fracturing. Background Art

[0002] The multi-cluster perforation staged fracturing technology for horizontal wells is an effective way to improve the utilization degree of unconventional reservoirs. However, through monitoring by DTS (Distributed Temperature Sensing), DAS (Distributed Acoustic Sensing) or microseismic at home and abroad, it is found that effective extended fractures have not formed near the perforation cluster positions of some horizontal wells, and there are a large number of ineffective perforation clusters that do not produce oil and gas after fracturing. After multi-cluster perforation fracturing, the problem of low production contribution rate is generally faced. The limited-entry perforation technology can effectively promote the balanced initiation and extension of multiple clusters during fracturing in the horizontal well section. This technology arranges different numbers of perforations in different sections of the horizontal well, constructs with a large displacement, and uses the perforation friction to increase the bottom-hole construction pressure, forcing the fracturing fluid to be diverted and successively fracturing the sections with similar fracture pressures.

[0003] Scholars at home and abroad have carried out a large amount of theoretical research and numerical simulation work in aspects such as the optimization of limited-entry perforation parameters for fracturing and the analysis of flow distribution during the simultaneous extension of multiple fractures in horizontal wells. In terms of theoretical research, mainly the simultaneous calculation of multi-fracture propagation is carried out by using quasi-three-dimensional fracture parameters. Under the condition of obtaining ideal fracture parameters, the limited-entry perforation fracturing scheme is optimized, and factors such as induced stress and perforation erosion are considered to analyze the flow distribution during the simultaneous extension of multiple fractures in the fractured horizontal well. In terms of numerical simulation, mainly methods such as the Displacement Discontinuity Method (DDM), the Extended Finite Element Method (XFEM), and the Boundary Element Method (BEM) are used, and two-dimensional and three-dimensional models are used to study the fracture initiation and propagation morphology, fluid distribution, etc. under different perforation schemes.

[0004] Although scholars have done a lot of research on the relationship between limited-entry perforation and fracture propagation, no relevant physical simulation experiments have been carried out in the research, and the theoretical and numerical simulation results cannot be verified. Due to the difficulties in on-site testing and the inability to obtain the flow parameters of each cluster of fractures in the wellbore in a timely manner, it is crucial to carry out indoor simulation experiments on flow distribution during the extension of multiple clusters of fractures for verifying the current theoretical models and numerical simulation results and further studying the optimization method of limited-entry perforation parameters. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. For this reason, the present invention provides an experimental device for simulating the liquid intake of multi-cluster fractures in limited-entry fracturing, aiming to solve the problem that the parameters and results of limited-entry perforation fracturing experiments cannot be simulated and verified in the related art.

[0006] The present invention provides an experimental device for simulating the liquid injection volume of multiple clusters of fractures in limited-entry fracturing, which includes a liquid storage device, a pumping system, multiple multi-cluster perforation units, and a data acquisition system. The liquid inlet end of the pumping system is connected to the liquid storage device, and multiple multi-cluster perforation units are connected in series at the liquid outlet end of the pumping system. The pumping parameters of the pumping system are adjustable, and the pumping parameters at least include pumping displacement and pumping pressure. The downstream end of the multi-cluster perforation unit far from the pumping system is closed. The data acquisition system is connected to the pumping system for collecting the pumping parameters. Among them, the multi-cluster perforation unit includes: A housing with a hollow interior. An inlet and an outlet are respectively provided at both ends of the housing. Pressure detection ports and flow detection ports communicating the inside and outside of the housing are provided on the outer peripheral surface of the housing. A simulated casing is inserted into the housing, and both ends of the simulated casing are respectively communicated with the inlet and the outlet. The end of the simulated casing is in sealed contact with the inner end face of the housing. Multiple perforation channels communicating the inside and outside of the simulated casing are provided on the outer peripheral surface of the simulated casing, and flow regulating devices with different flow cross-sectional areas are detachably connected to the perforation channels. A simulated rock casing is sleeved outside the simulated casing, and the inner side wall of the simulated rock casing is in contact with the inner side wall of the simulated casing. A closed chamber is provided between the outer peripheral surface of the simulated rock casing and the inner peripheral surface of the housing. The end face of the simulated rock casing is in sealed contact with the inner end face of the housing. A flow detection assembly is connected between the flow detection port and the liquid storage device, and the flow detection assembly is connected to the data acquisition system. A confining pressure detection device, the detection end of which 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 device for simulating the liquid injection volume of multiple clusters of fractures in limited-entry fracturing provided by the present invention, the pumping system includes an inlet pipeline, an injection pipeline, a liquid pump, and a pumping parameter control cabinet. The inlet pipeline is connected between the liquid storage device and the liquid inlet end of the liquid pump. The injection pipeline is connected between the liquid outlet end of the liquid pump and the inlet of the multi-cluster perforation unit located upstream. The pumping parameter control cabinet is electrically connected to the liquid pump for adjusting the pumping parameters.

[0008] According to the experimental device for simulating the liquid injection volume of multiple clusters of fractures in limited-entry fracturing provided by the present invention, the liquid pump is a piston pump.

[0009] According to the experimental device for simulating the liquid injection volume of multiple clusters of fractures in limited-entry fracturing provided by the present invention, a flow valve and a first flowmeter are arranged on the liquid injection pipeline.

[0010] According to the experimental device for simulating the liquid injection volume of multiple clusters of fractures in limited-entry fracturing provided by the present invention, a pipeline friction regulating valve is also arranged on the liquid injection pipeline.

[0011] According to the experimental device for simulating the liquid injection volume of multiple clusters of fractures in limited-entry fracturing provided by the present invention, the housing includes: a cylinder body, on which the pressure detection port and the flow detection port are both arranged; two end covers, which are respectively detachably connected to both ends of the cylinder body, and a liquid inlet is arranged on one of the end covers, and a liquid outlet is arranged on the other end cover. A positioning groove is arranged at one end of the end cover close to the inner side of the cylinder body, and the inner diameter of the positioning groove is equal to the outer diameter of the simulated rock casing, and the end of the simulated rock casing is inserted into the positioning groove.

[0012] According to the experimental device for simulating the liquid injection volume of multiple clusters of fractures in limited-entry fracturing provided by the present invention, a guiding groove is also arranged at one end of the positioning groove close to the inside of the cylinder body. The inner diameter of the guiding groove at the end connected to the positioning groove is equal to the inner diameter of the positioning groove, and the inner diameter of the guiding groove gradually increases from the positioning groove towards the direction close to the inside of the cylinder body.

[0013] According to the experimental device for simulating the liquid injection volume of multiple clusters of fractures in limited-entry fracturing provided by the present invention, a first limiting step is arranged at one end of the perforation channel close to the inside of the simulated casing. The flow regulating device includes: a flow-limiting ring, which is arranged in the perforation channel, and the bottom end of the flow-limiting ring contacts the top end of the first limiting step; a shunt compression cap, in which a plurality of shunt channels are arranged. The shunt compression cap is detachably connected to one end of the perforation channel far from the first limiting step. After the shunt compression cap is connected to the perforation channel, the flow-limiting ring is squeezed between the first limiting step and the shunt compression cap. The flow-limiting holes of the flow-limiting ring are communicated with the plurality of shunt channels to connect the inside and outside of the simulated casing, and the top surface of the shunt compression cap is entirely located inside the cylinder surrounded by the outer peripheral surface of the simulated casing.

[0014] According to the experimental device for simulating the liquid injection volume of multiple clusters of fractures in limited-entry fracturing provided by the present invention, each shunt compression cap includes four shunt channels.

[0015] According to the experimental device for simulating the liquid injection volume of multiple clusters of fractures in limited-entry fracturing provided by the present invention, the flow detection assembly includes a second flowmeter and a flowmeter control valve.

[0016] Due to the above technical solutions adopted by the present invention, it has the following advantages: The experimental device for simulating the liquid intake of multiple clusters of fractures in limited-entry fracturing provided by the present invention includes a liquid storage device, a pumping system, multiple multi-cluster perforation units, and a data acquisition system. The liquid inlet end of the pumping system is connected to the liquid storage device, and multiple multi-cluster perforation units are connected in series at the liquid outlet end of the pumping system. The pumping parameters of the pumping system are adjustable, and the pumping parameters at least include pumping displacement and pumping pressure. The liquid outlet of the multi-cluster perforation unit far from the pumping system is 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 a housing, a simulated casing, a simulated rock casing, a flow detection component, and a confining pressure detection device. The interior of the housing is hollow, and a liquid inlet and a liquid outlet are respectively arranged at both ends of the housing. Pressure detection ports and flow detection ports communicating the inside and outside of the housing are arranged on the outer peripheral surface of the housing. The simulated casing is arranged inside the housing, and both ends of the simulated casing are respectively communicated with the liquid inlet and the liquid outlet. The end of the simulated casing is in sealing contact with the inner side end surface of the housing. Perforation channels communicating the inside and outside of the simulated casing are arranged on the outer peripheral surface of the simulated casing, and flow regulating devices with different flow cross-sectional areas are detachably connected to the perforation channels. The simulated rock casing is sleeved outside the simulated casing, and the inner side wall of the simulated rock casing is in contact with the inner side wall of the simulated casing. A closed chamber is arranged between the outer peripheral surface of the simulated rock casing and the inner peripheral surface of the housing. The end surface of the simulated rock casing is in sealing contact with the inner side end surface of the housing. The upstream end of the flow detection component is connected to the flow detection port, the downstream end of the flow detection component 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, according to the limited-entry fracturing perforation scheme, calculate the flow cross-sectional areas of multiple multi-cluster perforation units, select flow regulating devices with different flow cross-sectional areas for assembly, and ensure that the total flow cross-sectional area of each multi-cluster perforation unit is the calculated value of the above flow cross-sectional area. Then, after adjusting the pumping parameters of the pumping system, start the pumping system to convey the fracturing fluid in the liquid storage device into multiple multi-cluster perforation units. The fracturing fluid flows through the flow regulating device in the perforation channel to the simulated rock casing, and enters the closed chamber between the housing and the simulated rock casing through the pores or fractures of the simulated rock casing, and finally flows back to the liquid storage device through the flow detection component. During the fluid flow process, the data acquisition system real-time collects the pressure in the closed chamber between the housing and the simulated rock casing, the flow value detected by the flow detection component, and the pumping parameters. Based on the data collected by the data acquisition system, the flow of multiple multi-cluster perforation units under the control of the set pumping parameters of the perforation scheme can be analyzed, and further the balance of the liquid intake of multiple multi-cluster perforation units can be analyzed. Description of the Drawings

[0017] To more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0018] Figure 1 It is a schematic structural diagram of an experimental device for simulating the liquid injection volume of multi-cluster fractures with current-limiting fracturing provided by an embodiment of the present invention; Figure 2 It is a schematic structural diagram of a multi-cluster perforation unit provided by an embodiment of the present invention; Figure 3 It is an explosion diagram of a flow regulating device and a perforation channel provided by an embodiment of the present invention; Figure 4 It is a top view of a flow splitting pressure cap provided by an embodiment of the present invention; Figure 5 It is a side view of an end cap provided by an embodiment of the present invention.

[0019] Reference numerals: 100: liquid storage tank; 210: plunger pump; 220: liquid inlet pipeline; 230: injection pipeline; 231: flow valve; 232: first flowmeter; 233: pipeline friction regulating valve; 240: pump injection parameter control cabinet; 300: multi-cluster perforation unit; 311: cylinder body; 312: threaded joint; 3121: positioning groove; 3122: guiding groove; 313: sealing joint; 314: liquid inlet; 315: liquid outlet; 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 flowmeter; 352: flowmeter control valve; 360: closed chamber; 371: current-limiting ring; 372: flow splitting pressure cap; 3721: flow splitting channel; 3722: limiting block; 400: liquid return pipeline. Detailed implementation manners

[0020] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions in the present invention with reference to the drawings in the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments in the present invention belong to the scope of protection of the present invention.

[0021] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0022] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means more than two unless otherwise specifically defined.

[0023] In the present invention, unless otherwise clearly defined and limited, the terms "mounted", "connected", "coupled", "fixed", etc. should be construed broadly. For example, it may be a fixed connection, a detachable connection, or an integral body; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] In the present invention, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0025] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc., mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0026] The experimental device for simulating the liquid intake of multiple clusters of fractures in limited-entry fracturing provided by the present invention includes a liquid storage device, a pumping system, multiple multi-cluster perforation units, and a data acquisition system. The liquid intake end of the pumping system is connected to the liquid storage device, and multiple multi-cluster perforation units are connected in series at the liquid outlet end of the pumping system. The pumping parameters of the pumping system are adjustable, and the pumping parameters at least include the pumping displacement and the pumping pressure. The liquid outlet of the multi-cluster perforation unit far from the pumping system is 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 a housing, a simulated casing, a simulated rock casing, a flow detection component, and a confining pressure detection device. The interior of the housing is hollow, and a liquid inlet and a liquid outlet are respectively arranged at both ends of the housing. Pressure detection ports and flow detection ports communicating the inside and outside of the housing are arranged on the outer peripheral surface of the housing. The simulated casing is arranged inside the housing, and both ends of the simulated casing are respectively communicated with the liquid inlet and the liquid outlet. The end of the simulated casing is in sealed contact with the inner end surface of the housing. Perforation channels communicating the inside and outside of the simulated casing are arranged on the outer peripheral surface of the simulated casing, and flow regulating devices with different flow cross-sectional areas are detachably connected in the perforation channels. The simulated rock casing is sleeved outside the simulated casing, and the inner side wall of the simulated rock casing is in contact with the inner side wall of the simulated casing. A closed chamber is arranged between the outer peripheral surface of the simulated rock casing and the inner peripheral surface of the housing. The end surface of the simulated rock casing is in sealed contact with the inner end surface of the housing. The upstream end of the flow detection component is connected to the flow detection port, the downstream end of the flow detection component 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, according to the limited-entry fracturing perforation scheme, calculate the flow cross-sectional areas of multiple multi-cluster perforation units, select flow regulating devices with different flow cross-sectional areas for assembly, and ensure that the total flow cross-sectional area of each multi-cluster perforation unit is the calculated value of the above flow cross-sectional area. Then, after adjusting the pumping parameters of the pumping system, start the pumping system to transport the fracturing fluid in the liquid storage device into multiple multi-cluster perforation units. The fracturing fluid flows through the flow regulating device in the perforation channel to the simulated rock casing, and enters the closed chamber between the housing and the simulated rock casing through the pores or fractures of the simulated rock casing, and finally flows back to the liquid storage device through the flow detection component. During the fluid flow process, the data acquisition system real-time collects the pressure in the closed chamber between the housing and the simulated rock casing, the flow value detected by the flow detection component, and the pumping parameters. Based on the data collected by the data acquisition system, the flow of multiple multi-cluster perforation units under the control of the set pumping parameters of the perforation scheme can be analyzed, and further the balance of the liquid intake of multiple multi-cluster perforation units can be analyzed.

[0027] The following will describe the experimental device for simulating the liquid intake of multiple clusters of fractures in limited-entry fracturing of the present invention in conjunction with Figures 1 to 5 the drawings.

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

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

[0030] The pumping and injection system includes a liquid inlet pipeline 220, a liquid injection pipeline 230, a liquid pump, and a pumping and injection parameter control cabinet 240. Among them, the liquid pump can be a piston pump 210.

[0031] One end of the liquid inlet pipeline 220 is connected to the bottom of the liquid storage tank 100, and the other end of the liquid inlet pipeline 220 is connected to the liquid inlet end of the piston pump 210. The piston pump 210 sucks the fracturing fluid in the liquid storage tank 100 through the liquid inlet pipeline 220.

[0032] The upstream end of the liquid injection pipeline 230 is connected to the liquid outlet end of the piston pump 210 for outputting the fracturing fluid sucked by the piston pump 210. A flow valve 231, a first flowmeter 232, and a pipeline friction regulating valve 233 are sequentially arranged on the liquid injection pipeline 230. The flow valve 231 is used to adjust the flow rate of the fracturing fluid in the liquid injection pipeline 230. The first flowmeter 232 can be an electromagnetic flowmeter for measuring the flow rate of the fracturing fluid in the liquid injection pipeline 230. Experimental personnel can calculate the pipeline friction according to the simulated horizontal wellbore length and adjust the pipeline friction regulating valve 233 based on the calculated value of the pipeline friction.

[0033] The pumping and injection parameter control cabinet 240 is electrically connected to the piston pump 210 for adjusting the pumping and injection parameters of the piston pump 210. The pumping and injection parameters at least include the pumping and injection flow rate and the pumping and injection pressure.

[0034] There are multiple multi-cluster perforation units 300, and each multi-cluster perforation unit 300 includes a liquid inlet 314, a liquid outlet 315, a pressure detection port, and a flow rate detection port. The multiple multi-cluster perforation units 300 are connected in series in sequence, that is, the liquid outlet 315 of the previous multi-cluster perforation unit 300 is connected to the liquid inlet 314 of the subsequent multi-cluster perforation unit 300. The liquid inlet 314 of the multi-cluster perforation unit 300 at the upstream end is connected to the downstream end of the liquid injection pipeline 230, and the liquid outlet 315 of the multi-cluster perforation unit 300 at the downstream end is closed.

[0035] A confining pressure detection device 340 is connected to the pressure detection port of each multi-cluster perforation unit 300. The confining pressure detection device 340 is communicatively connected to the data acquisition system for transmitting the detected pressure signal to the data acquisition system.

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

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

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

[0039] The housing includes a cylinder body 311 and two end covers. The inside of the cylinder body 311 is hollow and both ends are through. The pressure detection port and the flow detection port are both arranged on the outer peripheral surface of the cylinder body 311 and communicate with the inside and outside of the cylinder body 311.

[0040] There are two end covers, which are respectively arranged at both ends of the cylinder body 311. The end cover includes a threaded joint 312 and a sealing joint 313. One end of the threaded joint 312 is provided with an external thread, and the other end is provided with an internal thread. The outside of the sealing joint 313 is provided with an external thread, and the end of the cylinder body 311 is provided with an internal thread. The external thread of the threaded joint 312 is threadedly connected to the internal thread of the cylinder body 311, and the external thread of the sealing joint 313 is threadedly connected to the internal thread of the threaded joint 312.

[0041] Among them, a liquid inlet 314 is arranged on one end cover, and a liquid outlet 315 is arranged on the other end cover. Specifically, both the liquid inlet 314 and the liquid outlet 315 are arranged on the sealing joint 313 of the corresponding end cover, and both the liquid inlet 314 and the liquid outlet 315 communicate with the inside of the cylinder body 311.

[0042] A positioning groove 3121 is also arranged at the inner end of the end cover close to the cylinder body 311. The inner diameter of the positioning groove 3121 is equal to the outer diameter of the end of the simulated rock casing 330. The end of the simulated rock casing 330 is inserted into the positioning groove 3121, and the simulated casing 320 is sleeved inside the simulated rock casing 330.

[0043] In order to facilitate the insertion of the simulated rock casing 330 into the positioning groove 3121, a guiding groove 3122 is also arranged at the inner end of the positioning groove 3121 close to the inside of the cylinder body 311. The guiding groove 3122 may be a flared structure. The inner diameter of the end connected to the positioning groove 3121 is equal to the inner diameter of the positioning groove 3121, and the inner diameter of the end far from the positioning groove 3121 is larger than the inner diameter of the positioning groove 3121, and the two ends are transitioned by an inclined plane.

[0044] Specifically, the inner diameter of the positioning groove 3121 is equal to the outer diameter of the simulated rock casing 330. After the simulated rock casing 330 is inserted into the positioning groove 3121, the outer peripheral surface of the end of the simulated rock casing 330 contacts the inner wall of the positioning groove 3121, and the end face of the simulated rock casing 330 contacts the end face of the sealing joint 313, so as to realize the sealing inside the simulated rock casing 330.

[0045] The inner diameter of the position where the guiding groove 3122 is connected to the positioning groove 3121 is equal to the inner diameter of the positioning groove 3121. The inner diameter of the guiding groove 3122 gradually increases from the positioning groove 3121 towards the direction close to the inside of the cylinder body 311, forming a flared structure. In this way, the inner diameter of the opening at the end of the guiding groove 3122 is larger than the outer diameter of the simulated rock casing 330, which is convenient for the insertion of the simulated rock casing 330. During the insertion process, the inner side surface of the guiding groove 3122 guides the simulated rock casing 330 into the positioning groove 3121.

[0046] It should be noted that the internal thread of the above-mentioned threaded joint 312 is provided on the inner side wall of the positioning groove 3121. When the simulated rock casing 330 is inserted into the positioning groove 3121 and the threaded joint 312 is connected to the cylinder body 311, the part of the threaded joint 312 where the positioning groove 3121 and the guiding groove 3122 are located is clamped between the cylinder body 311 and the simulated rock casing 330, so as to form a closed chamber 360 between the outer side wall of the simulated rock casing 330 and the inner side wall of the cylinder body 311.

[0047] The simulated casing 320 is arranged inside the simulated rock casing 330, and the outer diameter of the simulated casing 320 is equal to the inner diameter of the simulated rock casing 330. After the simulated casing 320 is arranged inside the simulated rock casing 330, the outer side wall of the simulated casing 320 contacts the inner wall of the simulated rock casing 330. At this time, after the simulated rock casing 330 with the simulated casing 320 arranged inside is installed in the outer shell, due to the existence of the positioning groove 3121 on the threaded joint 312, the threaded joint 312, the simulated rock casing 330 and the simulated casing 320 can be coaxially arranged, so that the internal channel of the simulated casing 320 communicates with the liquid inlet 314 and the liquid outlet 315 of the outer shell.

[0048] A plurality of perforation channels 321 communicating the inside and outside of the simulated casing 320 are arranged on the outer peripheral surface of the simulated casing 320. The perforation channels 321 are used for detachably connecting with flow regulating devices with different flow cross-sectional areas. The fracturing fluid flowing into the simulated casing 320 from the liquid 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 through 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 cracks and pores of the simulated rock casing 330 and reaches the closed chamber 360 between the simulated rock casing 330 and the cylinder body 311, and then flows out through the flow detection port. A flow detection assembly connecting the flow detection port and the liquid storage tank 100 is provided at the flow detection port, and the flow detection assembly is used to detect the flow rate of the fracturing fluid flowing out of the flow detection port.

[0050] A pressure detection port is further provided on the cylinder body 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 body 311.

[0051] The data acquisition system is used to connect to the pumping system, the flow detection assembly, 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 side wall of the perforation channel 321 close to the inside of the simulated casing 320. The flow regulating device includes a flow limiting ring 371 and a shunt pressing cap 372.

[0053] The flow limiting ring 371 is of a ring structure, and its interior is a flow limiting hole. The difference in the flow cross-sectional area of the flow regulating valve is reflected in the difference in the inner diameter of the flow limiting ring 371. The larger the inner diameter size, the larger its 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 used to be placed in the perforation channel 321, and the top surface of the first limiting step 3211 supports the bottom surface of the flow limiting ring 371. At this time, the flow limiting hole 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 achieve the effect of restricting the flow rate, the inner diameter of the flow limiting hole is smaller than the inner diameter of the first limiting step 3211. If the inner diameter of the flow limiting hole is larger than the inner diameter of the first limiting step 3211, then no matter how the aperture of the flow limiting hole changes, its flow cross-sectional area is the flow cross-sectional area of the first limiting step 3211.

[0055] The flow splitting pressure cap 372 is used to be installed in the perforation channel 321. After the flow splitting pressure cap 372 is connected to the perforation channel 321, it presses against the top surface of the flow limiting ring 371 and, together with the first limiting step 3211, restricts the axial movement of the flow limiting ring 371. The flow splitting pressure cap 372 can be threadedly connected to the inner side wall of the perforation channel 321. Or it can be directly inserted. When the simulation casing 320 installed with the flow splitting pressure cap 372 is inserted into the simulation rock casing 330, the inner wall of the simulation rock casing 330 presses against the top of the flow splitting pressure cap 372, which can also achieve the purpose of restricting the axial movement of the flow splitting pressure cap 372 and the flow limiting ring 371. However, for this kind of limiting method, it is necessary to ensure that when the bottom surface of the flow splitting pressure cap 372 contacts the top surface of the flow limiting ring 371, the top surface of the flow splitting pressure cap 372 just contacts the inner side wall of the simulation rock casing 330.

[0056] A limiting block 3722 is provided at the bottom of the flow splitting pressure cap 372. The bottom surface of the limiting block 3722 contacts the top surface of the flow limiting ring 371. In this way, the limiting block 3722 can make a gap exist between the main body of the flow splitting pressure cap 372 and the flow limiting ring 371. A plurality of flow splitting channels 3721 are also provided on the flow splitting pressure cap 372. The plurality of flow splitting channels 3721 all penetrate through the flow splitting pressure cap 372 along the axial direction of the flow splitting pressure cap 372. When the fracturing fluid passes through the flow limiting holes of the flow limiting ring 371, it will enter the flow splitting channels 3721 through the gap between the main body of the flow splitting pressure cap 372 and the flow limiting ring 371.

[0057] In order to increase the coverage area after the fracturing fluid flows out, the cross-sectional area of the flow splitting pressure cap 372 can be appropriately increased. At this time, a second limiting step 3212 needs to be provided 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 process will be described: This embodiment takes a horizontal well with 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 A 1 、A 2 、A 3 、A 4 、A 5 , respectively. Flow limiting rings 371 with different aperture diameters of the flow limiting holes are selected for matching to ensure that the flow cross-sectional areas of the plurality of perforation channels 321 in the five multi-cluster perforation units 300 are A 1 、A 2 、A 3 、A 4 、A 5 .

[0059] Place the selected current-limiting ring 371 into the corresponding perforation channel 321 and fix it with a shunt gland 372. Then insert the simulated casing 320 into the simulated rock casing 330, and install the simulated rock casing 330 into the housing. Finally, connect the other components of the experimental device.

[0060] Set the pumping parameters such as pumping displacement and pumping pressure through the pumping parameter control cabinet 240. At this time, the data acquisition system collects and records the above-mentioned pumping parameters. Then calculate the pipeline friction according to the length of the simulated horizontal wellbore and adjust the pipeline friction regulating valve 233.

[0061] Start the piston pump 210. The fracturing fluid flows from the liquid storage tank 100 through multiple multi-cluster perforation units 300. During the flow process, part of the fracturing fluid enters the closed chamber 360 between the simulated rock casing 330 and the cylinder body 311 through the flow regulating device in the perforation channel 321 and the simulated rock casing 330, and then enters the return pipeline 400 through the second flowmeter 351 and the flowmeter control valve 352. The return pipeline 400 guides the fracturing fluid into the liquid storage tank 100 to complete the cycle.

[0062] During the cyclic flow of the fracturing fluid, the data acquisition system collects the pressure value detected by the confining pressure detection device 340 and the flow value detected by the flow detection component. The experimenter can judge the balance of the liquid intake of the five multi-cluster perforation units 300 under the pumping parameters according to the data collected by the data acquisition system.

[0063] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be covered by the scope of the claims and the description of the present application. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. An experimental device for simulating the amount of liquid inflow into multiple clusters of fractures during flow-limiting fracturing, characterized in that: The invention comprises a liquid storage device, a pumping system, a plurality of multi-cluster perforating units (300) and a data acquisition system, wherein the liquid inlet end of the pumping system is connected to the liquid storage device, the plurality of multi-cluster perforating units (300) are connected in series to the liquid outlet end of the pumping system, the pumping parameters of the pumping system are adjustable, the pumping parameters at least include the pumping displacement and the pumping pressure, the downstream end of the multi-cluster perforating unit (300) away from the pumping system is closed, the data acquisition system is connected to the pumping system and is used to collect the pumping parameters, wherein the multi-cluster perforating unit (300) comprises: An outer shell, wherein the interior of the outer shell is hollow, and two ends of the outer shell are respectively provided with a liquid inlet (314) and a liquid outlet (315), and an outer peripheral surface of the outer shell is provided with a pressure detection port and a flow detection port communicating with the inner and outer sides of the outer shell; a simulation sleeve (320), the simulation sleeve (320) being inserted into the outer shell, and the two ends of the simulation sleeve (320) being respectively connected to the liquid inlet (314) and the liquid outlet (315), the end of the simulation sleeve (320) being in sealing contact with the inner end surface of the outer shell, and a plurality of perforation channels (321) being connected to the inner and outer sides of the simulation sleeve (320) being arranged on the outer peripheral surface of the simulation sleeve (320), and the perforation channels (321) being used for detachably connecting to flow regulating devices with different flow cross-sectional areas; a simulated rock casing (330), the simulated rock casing (330) being sleeved on the outside of the simulated casing (320), the inner side wall of the simulated rock casing (330) being in contact with the inner side wall of the simulated casing (320), a closed chamber (360) being provided between the outer peripheral surface of the simulated rock casing (330) and the inner peripheral surface of the outer shell, and the end surface of the simulated rock casing (330) being in sealing contact with the inner end surface of the outer shell; A flow detection component, the 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), wherein a 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 device for simulating the liquid inflow of multiple clusters of fractures during flow-limiting fracturing according to claim 1, characterized in that: The pumping system comprises a liquid inlet pipeline (220), a liquid injection pipeline (230), a liquid pump and a pumping parameter control cabinet (240); the liquid inlet pipeline (220) is connected between the liquid storage device and the liquid inlet end of the liquid pump; the liquid injection pipeline (230) is connected between the liquid outlet end of the liquid pump and the liquid inlet (314) of the multi-cluster perforating unit (300) located upstream; and the pumping parameter control cabinet (240) is electrically connected to the liquid pump and is used to adjust the pumping parameters.

3. The experimental device for simulating the liquid inflow of multiple clusters of fractures during flow-limiting fracturing according to claim 2, characterized in that: The liquid pump is a plunger pump (210).

4. The experimental device for simulating the liquid inflow of multiple clusters of fractures during flow-limiting fracturing according to claim 2, characterized in that: The liquid injection pipeline (230) is provided with a flow valve (231) and a first flow meter (232).

5. The experimental device for simulating the liquid inflow of multiple clusters of fractures during flow-limiting fracturing according to claim 2, characterized in that: The liquid injection pipeline (230) is also provided with a pipeline friction regulating valve (233).

6. The experimental device for simulating the liquid inflow of multiple clusters of fractures during flow-limiting fracturing according to claim 1, characterized in that: The housing comprises: A cylinder (311), wherein the pressure detection port and the flow detection port are both arranged on the cylinder (311); Two end covers, the two end covers are detachably connected to the two ends of the cylinder (311), one of the end covers is provided with the liquid inlet (314), and the other end cover is provided with the liquid outlet (315), one end of the end cover close to the inner side of the cylinder (311) is provided with a positioning groove (3121), the inner diameter of the positioning groove (3121) is equal to the outer diameter of the simulated rock casing (330), and the end of the simulated rock casing (330) is inserted into the positioning groove (3121).

7. The experimental device for simulating the liquid inflow of multiple clusters of fractures during flow-limiting fracturing according to claim 6, characterized in that: A guide groove (3122) is further provided at one end of the positioning groove (3121) close to the interior of the cylinder (311); the inner diameter of one end of the guide groove (3122) connected to the positioning groove (3121) is equal to the inner diameter of the positioning groove (3121); and the inner diameter of the guide groove (3122) gradually increases from the positioning groove (3121) towards the interior of the cylinder (311).

8. The experimental device for simulating the liquid inflow of multiple clusters of fractures during flow-limiting fracturing according to claim 1, characterized in that: A first limiting step (3211) is provided at one end of the perforation channel (321) close to the interior of the simulated casing (320), and the flow regulating device comprises: A flow limiting ring (371), the flow limiting ring (371) being arranged in the perforation channel (321), and the bottom end of the flow limiting ring (371) being in contact with the top end of the first limiting step (3211); A flow-dividing pressure cap (372) is provided with a plurality of flow-dividing channels (3721) therein; the flow-dividing pressure cap (372) is detachably connected to an end of the perforating channel (321) away from the first limiting step (3211); when the flow-dividing pressure cap (372) is connected to the perforating channel (321), the flow-limiting ring (371) is squeezed between the first limiting step (3211) and the flow-dividing pressure cap (372); the flow-limiting hole of the flow-limiting ring (371) and the plurality of flow-dividing channels (3721) are connected to the inner and outer sides of the simulated casing (320); and the top surface of the flow-dividing pressure cap (372) is entirely located on the inner side of a cylinder surrounded by the outer peripheral surface of the simulated casing (320).

9. The experimental device for simulating the liquid inflow of multiple clusters of fractures during flow-limiting fracturing according to claim 8, characterized in that: Each of the flow-dividing pressure caps (372) includes four flow-dividing channels (3721).

10. The experimental device for simulating the liquid inflow of multiple clusters of fractures during flow-limiting fracturing according to claim 1, characterized in that: The flow detection component comprises a second flow meter (351) and a flow meter control valve (352).

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