Simulation device and method for improving producing degree of tight reservoir by using inter-slit displacement and well sealing

Abstract

The application discloses a simulation device and method for improving the producing degree of a tight reservoir by using inter-fracture displacement and well sealing. The experimental device comprises a temperature and pressure loading module, a first core monitoring module, an automatic control module, a second core monitoring module, a liquid injection module and an inter-fracture displacement simulation module. The experimental method comprises a preparation step before the experiment, a data measurement step, and a real-time control step of the automatic control module, wherein the data measurement step comprises a reservoir environment simulation step, a liquid injection step, a well sealing and displacement step, and a data collection step. The experimental device and method consider actual factors such as the temperature and pressure environment of the reservoir, the flow rate of the fracturing fluid and the well sealing time, can realize the monitoring of the oil displacement amount and the semi-quantitative characterization of the fracturing fluid sweep efficiency, and thus provide a certain basis for the fracturing construction design of an oilfield.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of petroleum engineering, in particular to a simulation device and method for improving the producing degree of tight reservoirs by using inter-fracture displacement and well shut-in, and especially relates to an experimental device and method process capable of monitoring the oil displacement and semi-quantitatively representing the fracturing fluid sweep efficiency, by considering the actual factors such as reservoir temperature, confining pressure environment, fracturing fluid flow rate and well shut-in time. BACKGROUND

[0002] Horizontal wells have the advantages of large contact area with the formation, long penetration into the reservoir, large single-well controlled reserves and high oil production rate, and are widely used in various oil and gas reservoirs. After the horizontal well is modified by fracturing technology, artificial fractures are formed in the formation, and the fluid in the fractures enters the surrounding rock under the action of pressure difference, thereby displacing the crude oil in the rock. It is shown by relevant scholars that with the increasing of artificial fracture density, the field mining technology is gradually upgraded, and the inter-well displacement problem is transformed into the inter-fracture displacement problem in the same well, and the inter-fracture displacement and well shut-in for improving the producing degree of tight reservoirs have become an effective means for oil and gas exploitation.

[0003] However, there is little research on the inter-fracture displacement of horizontal wells in the existing data, and the law of improving the producing degree of reservoirs by inter-fracture displacement is not clear. Through the investigation of the existing technology, it is found that the displacement devices include conventional clamp displacement experimental device, microwave heating displacement experimental device, gas-water alternating displacement experimental device and the like. These devices can monitor the oil displacement of the fracturing fluid in the core under certain conditions, but cannot carry out the simulation of improving the producing degree of tight reservoirs by inter-fracture displacement. At present, there is no simulation device and method for improving the producing degree of tight reservoirs by inter-fracture displacement and well shut-in. SUMMARY

[0004] The present application aims to provide a simulation device and method for improving the producing degree of tight reservoirs by using inter-fracture displacement and well shut-in, which can consider the actual factors such as reservoir temperature, confining pressure environment, fracturing fluid flow rate and well shut-in time, and realize the monitoring of oil displacement and the semi-quantitative representation of the fracturing fluid sweep efficiency, thereby providing the best well shut-in time for the fracturing construction design of oilfields and providing theoretical guidance and technical support for the field application of the inter-fracture injection and production technology between the same well segments of horizontal wells.

[0005] The technical scheme adopted by the present application is as follows:

[0006] The simulation device for improving the producing degree of tight reservoirs by using inter-fracture displacement and well shut-in comprises an inter-fracture displacement simulation module, a temperature and pressure loading module, a first core monitoring module, a second core monitoring module and a liquid injection module.

[0007] The intercrack displacement simulation module comprises a shell, a first core and a second core are fixedly arranged in the inner cavity of the shell, and a gap is left between the first core and the second core; a sand prevention net is wrapped around the periphery of the whole body of the first core and the second core, a heat circulation layer is filled between the sand prevention net and the inner surface of the shell, and a first core liquid outlet and a second core liquid outlet are arranged on the shell;

[0008] The temperature and pressure loading module is connected with the intercrack displacement simulation module and is used for providing a preset temperature and pressure for the intercrack displacement simulation module to simulate a high-temperature and high-pressure environment of a reservoir;

[0009] The first core monitoring module is connected with the first core liquid outlet and is used for controlling the discharge of the oil displacement amount of the first core and monitoring the fluid flow and pressure at the outlet end of the first core;

[0010] The second core monitoring module is connected with the second core liquid outlet and is used for controlling the discharge of the oil displacement amount of the second core and monitoring the fluid flow and pressure at the outlet end of the second core;

[0011] The liquid injection module is connected with the intercrack displacement simulation module and is used for providing a fracturing fluid for the intercrack displacement simulation module and monitoring the fluid flow and pressure at the inlet end.

[0012] Preferably, the temperature and pressure loading module comprises a screw pump, a pressure sensor, a heat circulation system and a temperature sensor.

[0013] The screw pump is communicated with the inner cavity of the shell of the intercrack displacement simulation module through a pipeline; the pressure sensor and the temperature sensor are connected with the intercrack displacement simulation module and are respectively used for measuring the pressure and the temperature in the inner cavity of the shell of the intercrack displacement simulation module; and the heat circulation system is connected with the heat circulation layer through a pipeline.

[0014] Preferably, the first core monitoring module comprises a first core liquid outlet valve, a first core pressure gauge, a first core flowmeter and a first core metering device.

[0015] The first core metering device is communicated with the first core liquid outlet through a pipeline, and the first core liquid outlet valve, the first core pressure gauge and the first core flowmeter are sequentially arranged on the pipeline along the fluid flow direction.

[0016] Preferably, the second core monitoring module comprises a second core liquid outlet valve, a second core pressure gauge, a second core flowmeter and a second core metering device.

[0017] The second core metering device is communicated with the second core liquid outlet through a pipeline, and the second core liquid outlet valve, the second core pressure gauge and the second core flowmeter are sequentially arranged on the pipeline along the fluid flow direction.

[0018] Preferably, the liquid injection module comprises a fracturing fluid tank, a fracturing fluid tank valve, a compression pump, a compression pump valve, an injection flow meter and an injection pressure gauge.

[0019] The inlet of the compression pump is connected with the fracturing fluid tank through a pipeline, and the fracturing fluid tank valve is arranged at the outlet of the fracturing fluid tank.

[0020] The outlet of the compression pump is communicated with the inner cavity of the intercrack displacement simulation module shell through a pipeline, the compression pump valve is arranged at the outlet of the compression pump, the injection flow meter is arranged at the outlet of the compression pump valve, and the injection pressure gauge is arranged at the outlet of the injection flow meter.

[0021] Preferably, fixed blocks are arranged at two ends of the fracture between the first core and the second core, and the fixed blocks are used to fix the first core and the second core and ensure that a crack with a preset width is left between the first core and the second core.

[0022] The application further provides a simulation method for improving the producing degree of a dense reservoir by using intercrack displacement and well blanking, which is performed by using the simulation device as described above and comprises the following steps.

[0023] S1, cracks are pressed out of the first core and the second core to form a heterogeneous core, and then the first core and the second core are subjected to an oil saturation experiment, and then the first core and the second core are loaded into the intercrack displacement simulation module shell;

[0024] S2, the intercrack displacement simulation module is subjected to confining pressure by the temperature and pressure loading module until mechanical equilibrium is reached in the intercrack displacement simulation module, and then the inner cavity of the intercrack displacement simulation module is heated by the temperature and pressure loading module until the temperature of the inner cavity of the intercrack displacement simulation module reaches a preset value;

[0025] S3, fracturing fluid is injected into the intercrack displacement simulation module by the liquid injection module until the first core and the second core are filled with the fracturing fluid, and after the pressure in the inner cavity of the intercrack displacement simulation module is stabilized, the injection flow and the injection pressure of the liquid injection module are obtained;

[0026] S4, then the process of well blanking and displacement is alternately performed on the intercrack displacement simulation module until the fluid flow at the outlet end of the first core monitored by the first core monitoring module is stable and the fluid flow at the outlet end of the second core monitored by the second core monitoring module is stable, and the outlet pressure and the outlet flow of the first core and the outlet pressure and the outlet flow of the second core under different well blanking times are recorded, and the simulation is ended.

[0027] Preferably, 5 to 8 cracks are pressed out of the first core, and 5 to 8 cracks are pressed out of the second core.

[0028] Preferably, in S2, the pressure of the pressure position 25 MPa-30 MPa is applied to the inter-fracture displacement simulation module, and the temperature and pressure loading module heats the inner cavity of the inter-fracture displacement simulation module to 60-100 DEG C.

[0029] Preferably, in S3, the flow rate of the liquid injection module when injecting the fracturing fluid into the inter-fracture displacement simulation module is 3-6 mL / min, and the pressure is 15-20 MPa.

[0030] The present application has the following beneficial effects

[0031] Through the simulation device, the influence of the well soaking time on the displacement effect can be studied under the environment of simulating the reservoir temperature and pressure, the best well soaking time of the reservoir can be determined, the sweep efficiency of the fracturing fluid in different reservoirs is clear, and the sweep efficiency of the fracturing fluid is semi-quantitatively characterized.

[0032] The simulation method is simple in operation, has important significance for unconventional reservoir fracturing design and post-fracturing evaluation, and provides theoretical guidance and technical support for the field application of the inter-well and inter-fracture injection-production technology of the horizontal well. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0034] Figure 1 is a structure schematic diagram of the simulation device for improving the producing degree of the tight reservoir by inter-fracture displacement and well soaking according to the present application;

[0035] Figure 2 is a structure schematic diagram of the liquid injection module in the simulation device for improving the producing degree of the tight reservoir by inter-fracture displacement and well soaking according to the present application;

[0036] Figure 3 is a structure schematic diagram of the inter-fracture displacement simulation module in the simulation device for improving the producing degree of the tight reservoir by inter-fracture displacement and well soaking according to the present application;

[0037] Figure 4 is a flow chart of the test method for improving the producing degree of the tight reservoir by inter-fracture displacement and well soaking according to the present application.

[0038] Wherein, 11-warm pressure loading module; 111-screw pump; 112-pressure sensor; 113-heating cycle system; 114-temperature sensor; 12-first core monitoring module; 121-first core outlet valve; 122-first core pressure gauge; 123-first core flow meter; 124-first core metering beaker; 13-automatic control module; 14-second core monitoring module; 141-second core outlet valve; 142-second core pressure gauge; 143-second core flow meter; 144-second core metering beaker; 15-liquid injection module; 151-fracturing fluid tank; 152-fracturing fluid tank valve; 153-compression pump; 154-compression pump valve; 155-injection flow meter; 156-injection pressure gauge; 16-interstitial displacement simulation module; 161-first core; 162-second core; 163-fixed block; 164-sand control net; 165-heating cycle layer; 166-first core outlet; 167-second core outlet. DETAILED DESCRIPTION

[0039] The method flow in the embodiment of the present application is described clearly and completely below in combination with the drawings in the embodiment of the present application, but should not be interpreted as the limitation of the embodiment of the present application. All other embodiments obtained by those skilled in the art without creative labor based on the embodiment in the present application belong to the protection scope of the present application.

[0040] Reference Figure 1 , Figure 1 It is the simulation device structure schematic diagram of the present application for improving the producing degree of the tight reservoir by interstitial displacement and well plugging. As shown in Figure 1As shown, the device of the present application comprises a temperature and pressure loading module 11, a first core monitoring module 12, an automatic control module 13, a second core monitoring module 14, a liquid injection module 15 and an interfracture displacement simulation module 16. The temperature and pressure loading module 11 is connected to the interfracture displacement simulation module 16 by pipeline, and the main function of the temperature and pressure loading module 11 is to provide a certain temperature and pressure for the interfracture displacement simulation module 16 to simulate the high temperature and high pressure environment of the reservoir. The first core monitoring module 12 is connected to the interfracture simulation module 16 by pipeline, and the main function of the first core monitoring module 12 is to control the discharge of the first core oil displacement volume and monitor the fluid flow and pressure at the outlet end of the first core. The automatic control module 13 is connected to the first core monitoring module 12, the second core monitoring module 14 and the interfracture displacement simulation module 16 by pipeline, and the main function of the automatic control module 13 is to monitor the temperature and confining pressure inside the interfracture displacement simulation module 16, measure the injection flow rate of the fracturing fluid, the displacement flow rate, the well shut-in time and the pressure difference between the two ends of the interfracture displacement simulation module 16, etc. The second core monitoring module 14 is connected to the interfracture displacement simulation module 16 by pipeline, and the main function of the second core monitoring module 14 is to control the discharge of the second core oil displacement volume and monitor the fluid flow and pressure at the outlet end of the second core. The liquid injection module 15 is connected to the interfracture displacement simulation module 16 by pipeline, and the main function of the liquid injection module 15 is to provide injection of fracturing fluid for the interfracture displacement simulation module 16 and monitor the fluid flow and pressure at the inlet end. The interfracture displacement simulation module 16 is connected to the temperature and pressure loading module 11, the first core monitoring module 12, the automatic control module 13, the second core monitoring module 14 and the liquid injection module 15 by pipeline, and the main function of the interfracture displacement simulation module 16 is to realize interfracture displacement test experiment under reservoir conditions.

[0041] Specifically, as shown in the figure, Figure 1 The temperature and pressure loading module 11 comprises a screw pump 111, a pressure sensor 112, a heating circulation system 113 and a temperature sensor 114. The screw pump 111 is connected to the interfracture displacement simulation module 16 by pipeline, and is mainly used for simulating a high pressure environment of the reservoir to provide pressure for the interfracture displacement simulation module 16. The pressure sensor 112 is fixedly connected to the interfracture displacement simulation module 16, and is mainly used for real-time monitoring of the pressure information in the cavity of the interfracture displacement simulation module 16. The heating circulation system 113 is connected to the interfracture displacement simulation module 16 by pipeline, and is mainly used for providing a closed circulation pipeline to provide heating liquid for the displacement simulation and ensure the temperature in the cavity of the interfracture displacement simulation module 16. The temperature sensor 114 is fixed by the heating circulation layer 165, and is mainly used for real-time monitoring of the temperature information of the interfracture displacement simulation module.

[0042] As shown in the figure, Figure 1As shown, the first core monitoring module 12 includes: a first core discharge valve 121, a first core pressure gauge 122, a first core flow meter 123, and a first core metering beaker 124. The left end of the first core discharge valve 121 is connected to the first core pressure gauge 122, and the right end is connected to the inter-slot displacement simulation module 16, mainly used to control the outflow of oil from the first core. The left end of the first core pressure gauge 122 is connected to the first core flow meter 123, and the right end is connected to the first core discharge valve 121, mainly used to measure the displacement outflow pressure of the first core. The right end of the first core flow meter 123 is connected to the first core pressure gauge 122, mainly used to measure the displacement flow rate of the first core. The first core metering beaker 124 is placed directly below the outlet of the first core monitoring module 12, mainly used to recover the crude oil after displacement from the first core.

[0043] like Figure 1 As shown, the second core monitoring module 14 includes: a second core discharge valve 141, a second core pressure gauge 142, a second core flow meter 143, and a second core metering beaker 144. The left end of the second core discharge valve 141 is connected to the inter-slot displacement simulation module 16, and the right end is connected to the second core pressure gauge 142, mainly used to control the outflow of oil from the second core. The left end of the second core pressure gauge 142 is connected to the second core discharge valve 141, and the right end is connected to the second core flow meter 143, mainly used to measure the displacement outflow pressure of the second core. The left end of the second core flow meter 143 is connected to the second core pressure gauge 142, mainly used to measure the displacement flow rate of the second core. The second core metering beaker 144 is placed directly below the outlet of the second core monitoring module 14, mainly used to recover the crude oil after displacement from the second core.

[0044] Reference Figure 3The injection module 15 comprises a fracturing fluid tank 151, a fracturing fluid tank valve 152, a compression pump 153, a compression pump valve 154, an injection flow meter 155 and an injection pressure gauge 156. The fracturing fluid tank 151 is connected to the fracturing fluid tank valve 152 at the left end, mainly used for storing prepared fracturing fluid and providing injection fluid for inter-fracture displacement; the fracturing fluid tank valve 152 is connected to the compression pump 153 at the left end and to the fracturing fluid tank 151 at the right end, mainly used for controlling the inflow of fracturing fluid; the compression pump 153 is connected to the compression pump valve 154 at the left end and to the fracturing fluid tank valve 152 at the right end, mainly used for mixing fracturing fluid and providing additional displacement pressure to provide power for fracturing fluid displacement; the compression pump valve 154 is connected to the injection flow meter 155 at the left end and to the compression pump 153 at the right end, mainly used for controlling the opening and closing of the compression pump 153; the injection flow meter 155 is connected to the injection pressure gauge 156 at the left end and to the compression pump valve 154 at the right end, mainly used for measuring the volume flow rate of injection; and the injection pressure gauge 156 is connected to the inter-fracture displacement simulation module 16 at the left end and to the injection flow meter 155 at the right end, mainly used for measuring the injection pressure.

[0045] Referring to Figures 1-3 The inter-fracture displacement simulation module 16 comprises an outer shell, a first core 161, a second core 162, a fixing block 163, a sand control screen 164, a heating circulation layer 165, a first core outlet 166 and a second core outlet 167. The first core 161 is fixed at the left end of the inner cavity of the outer shell of the inter-fracture displacement simulation module 16, designed in a block shape, and the size is determined according to the control module and the inter-fracture displacement simulation module, and is the experimental object to be measured; the second core 162 is fixed at the right end of the inner cavity of the outer shell of the inter-fracture displacement simulation module 16, designed in a block shape, and the size is determined according to the control module and the inter-fracture displacement simulation module, and is the experimental object to be measured; the fixing block 163 is fixed at the upper and lower ends of the inner cavity of the outer shell of the inter-fracture displacement simulation module 16, and is fixed in the middle of the first core 161 and the second core 162, designed in a block shape, and is mainly used for fixing the first core and the second core; the sand control screen 164 is fixed around the whole mechanism formed by the first core 161 and the second core 162, and wraps the first core 161 and the second core 162, and the main function is to prevent the migration of micro-particles generated by the fracturing of the reservoir from blocking the inlet of the monitoring module; the heating circulation layer 165 is fixed around the sand control screen 164, and is mainly used for providing a circulation channel for the heating fluid of the inter-fracture displacement simulation, and ensuring that the inter-fracture displacement simulation is controlled at the reservoir temperature; the first core outlet 166 is connected to the first core monitoring module 12, and is mainly used for facilitating the discharge of the displacement fluid of the first core in the displacement simulation; and the second core outlet 167 is connected to the second core monitoring module 14, and is mainly used for facilitating the discharge of the displacement fluid of the second core in the displacement simulation.

[0046] Referring to Figure 4The application utilizes the simulation method of inter-slit displacement synergy well plugging to improve the producing degree of tight reservoirs, which is used in the above-mentioned testing device and comprises the following steps:

[0047] S1, preparation before experiment: the preparation before experiment includes: assembling the experimental device according to the experimental device schematic diagram; checking whether the temperature and pressure loading module 11, the automatic control module 13, the compression pump 153, the injection pressure gauge 156, the first core pressure gauge 122, the second core pressure gauge 142, the injection flowmeter 155, the first core flowmeter 123 and the second core flowmeter 143 work normally; ensuring that the flowmeters (the injection flowmeter 155, the first core flowmeter 123 and the second core flowmeter 143), the pressure gauges (the injection pressure gauge 156, the first core pressure gauge 122 and the second core pressure gauge 142) and the valves (the fracturing fluid tank valve 152, the compression pump valve 154, the first core outlet valve 121 and the second core outlet valve 141) are in the closed state before the experiment; filling the fracturing fluid tank 151 with water, checking the sealing property of the fracturing fluid tank 151, specifically, closing the fracturing fluid tank valve 152 and observing whether there is fluid leakage around the fracturing fluid tank 151, if not, the sealing property is good; using the triaxial compression machine to press out 5-8 cracks at different positions of the first core 161 and the second core 162 respectively, so that the two cores are non-homogeneous cores, and then performing the oil saturation experiment; pretreating the inter-slit displacement simulation module 16, that is, first displacing the simulation module with water, observing whether there is fluid flowing out of the first core outlet 166 and the second core outlet 167, if there is fluid flowing out, the inter-slit displacement simulation module 16 works normally; checking whether each pipeline keeps unobstructed and the like, as shown in S1 of the specification. Figure 4

[0048] S2, data measurement: the data measurement step refers to the whole displacement testing process, including the reservoir environment simulation step S21, the liquid injection step S22, the well plugging and displacement step S23 and the data collection step S24, as shown in S2 of the specification. Figure 4

[0049] Specifically, the data measurement step comprises:

[0050] S21, reservoir environment simulation: first, the prepared non-homogeneous oil-saturated first core 161 and the second core 162 (A and B anastomosis cutting) are placed in the inter-slit displacement simulation module 16 according to the experimental requirements; then, the inter-slit displacement simulation module 16 is sealed, the screw pump 111 is adjusted to increase the core confining pressure to 25-30 MPa, until the mechanical equilibrium in the inter-slit displacement simulation module 16 is reached; then, the heating circulation system 113 is started, until the temperature of the inter-slit displacement simulation module 16 reaches 60-100℃, as shown in S21 of the specification. Figure 4

[0051] ​​​S22, liquid injection step: open the fracturing fluid tank valve 152 and the compressor valve 154, so that the fracturing fluid enters the displacement simulation device 16 at a flow rate of 3-6 mL / min and a pressure of 15-20 MPa, until the core is filled with the fracturing fluid; in order to avoid errors caused by uneven mixing of the fracturing fluid, the injection pressure and the injection flow rate must be obtained by the automatic control module 13 when the readings of the injection flow meter 155 and the injection pressure gauge 156 are stable, as shown in S22 of FIG. 8. Figure 4

[0052] S23, well soaking and displacement: close the fracturing fluid tank valve 152, and start the whole well soaking process simulation; after soaking for 1 day, open the first core outlet valve 121 and the second core outlet valve 141, repeat the reservoir environment simulation step S21 and the liquid injection step S22, and then close the fracturing fluid tank valve 152 again; after soaking for N days, open the first core outlet valve 121 and the second core outlet valve 141. When the readings of the first core pressure gauge 122, the second core pressure gauge 142 and the first core flow meter 123, the second core flow meter 143 are stable, record the outlet pressure and the outlet flow rate of the first core and the second core at different soaking times by the automatic control module 13, as shown in S23 of FIG. 9. Figure 4

[0053] S24, data collection: after the step of one well soaking and displacement experiment, the next test point is required, and the outlet pressure and the outlet flow rate of the first core and the second core are required to be no less than 3 each time, so as to ensure the accuracy of the experimental data, as shown in S25 of FIG. 10. Figure 4

[0054] Real-time control of the automatic control module: in the whole data measurement process, the temperature and the pressure of the inter-fracture displacement simulation module 16 are controlled by the automatic control module 13, the injection flow rate and the pressure of the fracturing fluid are measured, the outlet flow rate and the outlet pressure of the first core and the second core are monitored, and the temperature value of the heating circulation system 113 is controlled, so as to ensure the normal operation of the experiment, as shown in S3 of FIG. 7. Figure 4

[0055] Embodiment

[0056] Based on the above device and method of the present application, displacement experiments are carried out on two cores at different depths in the Sulige gas field, the influence of different soaking times on the displacement of the cores, and the sweep efficiency of the fracturing fluid in different cores are studied, so as to achieve the goal of determining the best soaking time of the reservoir and semi-quantitatively characterizing the sweep efficiency of the fracturing fluid.

[0057] The specific test process includes the following steps:

[0058] ​​​​First, according to the experimental device schematic diagram to set up the experimental device; check the temperature and pressure loading module 11, automatic control module 13, compression pump 153, injection pressure gauge 156, the first core pressure gauge 122, the second core pressure gauge 142, injection flow meter 155, the first core flow meter 123, the second core flow meter 143 whether normal work; ensure that the experiment before each flowmeter (injection flow meter 155, the first core flow meter 123, the second core flow meter 143), pressure gauge (injection pressure gauge 156, the first core pressure gauge 122, the second core pressure gauge 142), valve (fracturing fluid tank valve 152, compression pump valve 154, the first core outlet valve 121, the second core outlet valve 141) in the closed state; the fracturing fluid tank 151 filled with water, check the fracturing fluid tank 151 sealing, the specific operation has closed fracturing fluid tank valve 152, observe whether there is fluid leakage around the fracturing fluid tank 151, if not, the sealing is good; using triaxial compression machine, respectively, on the first core 161 and the second core 162 in different positions to 5-8 cracks, so that the two cores for heterogeneous core, then saturated oil experiment; on the intercrack displacement simulation module 16 pretreatment, that is, first with water on the simulation module displacement, observe whether there is fluid flow out of the first core outlet 166, the second core outlet 167, if there is fluid flow, the intercrack displacement simulation module 16 work normally; check whether each pipeline keep unobstructed, etc.

[0059] Then according to the experimental requirements in the intercrack intercrack displacement simulation module 16 put in the prepared heterogeneous saturated oil after the first core 161 and the second core 162 (A and B anastomosis cutting); then seal the intercrack displacement simulation module 16, adjust the screw pump 111 so that the core confining pressure increases to 25 MPa, until the intercrack displacement simulation module 16 reaches mechanical equilibrium; then start heating cycle system 113, to the intercrack displacement simulation module 16 temperature to 90 DEG C.

[0060] Open fracturing fluid tank valve 152 and compressor valve 154, so that the fracturing fluid at 4 mL / min flow rate, 20 MPa pressure into the displacement simulation device 16, until the core is full of fracturing fluid; in order to avoid the error caused by the uneven mixing of fracturing fluid on the experiment, must when observed injection flow meter 155 and injection pressure gauge 156 show stable, then by the automatic control module 13 to get the injection pressure and injection flow.

[0061] After the liquid injection is completed, the fracturing fluid tank valve 152 is closed, the whole well soaking process simulation is started, the first core liquid outlet valve 121 and the second core liquid outlet valve 141 are opened after the well is soaked for 1 day; the reservoir environment simulation step S21 and the liquid injection step S22 are repeated, the fracturing fluid tank valve 152 is closed again, the first core liquid outlet valve 121 and the second core liquid outlet valve 141 are opened after the well is soaked for 3 days; the reservoir environment simulation step S21 and the liquid injection step S22 are repeated, the fracturing fluid tank valve 152 is closed again, the first core liquid outlet valve 121 and the second core liquid outlet valve 141 are opened after the well is soaked for 5 days; the reservoir environment simulation step S21 and the liquid injection step S22 are repeated, the fracturing fluid tank valve 152 is closed again, the first core liquid outlet valve 121 and the second core liquid outlet valve 141 are opened after the well is soaked for 7 days. When the first core pressure gauge 122, the second core pressure gauge 142 and the first core flowmeter 123, the second core flowmeter 143 are stable, the first core outlet pressure, the outlet flow and the second core outlet pressure, the outlet flow under different soaking times are recorded by the automatic control module 13.

[0062] After the one-time soaking and displacement experiment step is completed, the next test point is carried out, and the first core outlet pressure and the first core outlet flow and the second core outlet pressure and the second core outlet flow data are required to be not less than 3 each time, so as to ensure the accuracy of the experimental data.

[0063] During the whole data measurement process, the temperature and pressure of the inter-fracture displacement simulation module 16 are controlled by the automatic control module 13, the fracturing fluid injection flow and pressure are measured, the first core and the second core outlet flow and outlet pressure are monitored, and the temperature value of the heating circulation system 113 is controlled, so as to ensure the normal operation of the experiment.

[0064] It is found through monitoring that the oil displacement amount of the first core and the second core is greatly increased, the fracturing fluid sweep degree is greatly improved, and the oil and gas recovery is obviously improved by using the method of the present application. According to the experimental test data, the best soaking time of the first core is 3 days, the best soaking time of the second core is 5 days, and the oil displacement amount and the fracturing fluid sweep degree of the first core are higher than those of the second core.

[0065] According to the above-mentioned field examples, the inter-fracture displacement and soaking method provided by the present application effectively improves the development degree of the tight reservoir, communicates more natural fractures and unproduced areas of the reservoir, and improves the oil and gas recovery. The experimental device and method of the present application considers the actual factors such as the reservoir temperature and pressure environment, the fracturing fluid flow rate and the soaking time, can realize the monitoring of the oil displacement amount and the semi-quantitative characterization of the fracturing fluid sweep degree, and thus provides a certain basis for the fracturing construction design of the oil field.

Claims

1. A simulation device for improving the producing degree of tight reservoirs by using inter-slug displacement and cooperative huff and puff, characterized in that, The intercrack displacement simulation module (16), the temperature and pressure loading module (11), the first core monitoring module (12), the second core monitoring module (14) and the liquid injection module (15) are included. The intercrack displacement simulation module (16) comprises a shell, a first core (161) and a second core (162) are fixedly arranged in the inner cavity of the shell, and a gap is left between the first core (161) and the second core (162); the periphery of the whole body of the first core (161) and the second core (162) is covered with a sand prevention net (164), the sand prevention net (164) and the inner surface of the shell are filled with a heating circulation layer (165), and the shell is provided with a first core liquid outlet (166) and a second core liquid outlet (167); The temperature and pressure loading module (11) is connected with the intercrack displacement simulation module (16) and is used for providing a preset temperature and pressure for the intercrack displacement simulation module (16) to simulate a high-temperature and high-pressure environment of a reservoir. The first core monitoring module (12) is connected with the first core liquid outlet (166) and is used for controlling the discharge of the first core oil displacement amount and monitoring the fluid flow and pressure at the outlet end of the first core; The second core monitoring module (14) is connected with the second core liquid outlet (167) and is used for controlling the discharge of the second core oil displacement amount and monitoring the fluid flow and pressure at the outlet end of the second core; The liquid injection module (15) is connected with the intercrack displacement simulation module (16) and is used for providing a fracturing fluid for the intercrack displacement simulation module (16) and monitoring the fluid flow and pressure at the inlet end; The first core (161) and the second core (162) are fixed with fixing blocks (163) at both ends of the gap, and the fixing blocks (163) are used to fix the first core (161) and the second core (162) and ensure that a crack with a preset width is formed between the first core (161) and the second core (162); The preparation process of the first core (161) and the second core (162) comprises the following steps: forming a heterogeneous core by pressing a crack on the first core (161) and the second core (162), and then performing an oil saturation experiment on the first core (161) and the second core (162) to obtain the first core (161) and the second core (162).

2. The simulation device for improving the producing degree of tight reservoirs by using inter-slug displacement synergy and well killing according to claim 1, characterized in that, The temperature and pressure loading module (11) comprises a screw pump (111), a pressure sensor (112), a heating circulation system (113) and a temperature sensor (114); The screw pump (111) is communicated with the inner cavity of the shell of the intercrack displacement simulation module (16) through a pipeline; the pressure sensor (112) and the temperature sensor (114) are connected with the intercrack displacement simulation module (16) and are respectively used for measuring the pressure and temperature in the inner cavity of the shell of the intercrack displacement simulation module (16); and the heating circulation system (113) is connected with the heating circulation layer (165) through a pipeline.

3. The simulation device for improving the producing degree of tight reservoirs by using inter-slug displacement synergy and well killing according to claim 1, characterized in that, The first core monitoring module (12) comprises a first core liquid valve (121), a first core pressure gauge (122), a first core flowmeter (123) and a first core metering device. The first core metering device is communicated with the first core outlet (166) through a pipeline, and the pipeline is sequentially provided with the first core outlet valve (121), the first core pressure gauge (122) and the first core flow meter (123) along the fluid flow direction.

4. The simulation device for improving the producing degree of tight reservoirs by using inter-slug displacement synergy and well killing according to claim 1, characterized in that, The second core monitoring module (14) comprises a second core outlet valve (141), a second core pressure gauge (142), a second core flow meter (143) and a second core metering device. The second core metering device is communicated with the second core outlet (167) through a pipeline, and the pipeline is sequentially provided with the second core outlet valve (141), the second core pressure gauge (142) and the second core flow meter (143) along the fluid flow direction.

5. The simulation device for improving the producing degree of tight reservoirs by using inter-slug displacement synergy and well killing according to claim 1, characterized in that, The injection module (15) comprises a fracturing fluid tank (151), a fracturing fluid tank valve (152), a compression pump (153), a compression pump valve (154), an injection flow meter (155) and an injection pressure gauge (156). The inlet of the compression pump (153) is connected with the fracturing fluid tank (151) through a pipeline, and the fracturing fluid tank valve (152) is arranged at the outlet of the fracturing fluid tank (151). The outlet of the compression pump (153) is communicated with the inner cavity of the housing of the interfracture displacement simulation module (16) through a pipeline, the compression pump valve (154) is arranged at the outlet of the compression pump (153), the injection flow meter (155) is arranged at the outlet of the compression pump valve (154), and the injection pressure gauge (156) is arranged at the outlet of the injection flow meter (155).

6. A simulation method for improving the producing degree of tight reservoirs by using inter-slug displacement and coordinated huff and puff, characterized in that, The simulation method is performed by using the simulation device of claims 1-5, and comprises the following steps: S1, the first core (161) and the second core (162) are pressed out of the fracture to form a heterogeneous core, and then the first core (161) and the second core (162) are saturated with oil; then the first core (161) and the second core (162) are loaded into the housing of the interfracture displacement simulation module (16); S2, the interfracture displacement simulation module (16) is subjected to confining pressure by the temperature and pressure loading module (11) until mechanical equilibrium is reached in the interfracture displacement simulation module (16); then the inner cavity of the interfracture displacement simulation module (16) is heated by the temperature and pressure loading module (11) until the temperature of the inner cavity of the interfracture displacement simulation module (16) reaches a preset value; S3, the interfracture displacement simulation module (16) is injected with fracturing fluid by the injection module (15) until the first core (161) and the second core (162) are filled with fracturing fluid; after the pressure in the inner cavity of the interfracture displacement simulation module (16) is stabilized, the injection flow and injection pressure information of the injection module (15) are obtained; S4, then the interfracture displacement simulation module (16) is subjected to the process of alternating well killing and displacement until the fluid flow at the outlet of the first core monitored by the first core monitoring module (12) is stable and the fluid flow at the outlet of the second core monitored by the second core monitoring module (14) is stable; the first core outlet pressure, the first core outlet flow, the second core outlet pressure and the second core outlet flow under different well killing times are recorded, and the simulation is ended.

7. The simulation method for improving the producing degree of tight reservoirs by using inter-slug displacement synergy and well killing according to claim 6, characterized in that, 5-8 fractures were pressed out for the first core (161), and 5-8 fractures were pressed out for the second core (162).

8. The simulation method for improving the producing degree of tight reservoirs by using inter-slug displacement synergy and well killing according to claim 6, characterized in that, In S2, the pressure of the confining pressure applied to the inter-fracture displacement simulation module (16) is 25-30 MPa, and the temperature and pressure loading module (11) heats the inner cavity of the inter-fracture displacement simulation module (16) to 60-100 ℃.

9. The simulation method for enhancing the producing degree of tight reservoirs by using inter-slug displacement synergy and well killing according to claim 6, characterized in that, In S3, the flow rate of the liquid injection module (15) when injecting fracturing fluid into the inter-fracture displacement simulation module (16) is 3-6 mL / min, and the pressure is 15-20 MPa.

Images