Fractured formation leakage stoppage experiment simulation evaluation device and method

Abstract

The invention relates to a fractured formation leaking stoppage experiment simulation evaluation device, and belongs to the technical field of oil and gas field exploration and development, the fractured formation leaking stoppage experiment simulation evaluation device comprises a kettle body, a first space is defined in the kettle body, a stirring system is arranged in the first space, and the first space is connected to the top of the kettle body; the stratum simulation device comprises a seam plate assembly and a cylinder body, the seam plate assembly is arranged in the cylinder body, and the seam plate assembly is formed by combining seam plate groups; wherein an electric sealing device is arranged at the bottom of the kettle body, and the bottom of the electric sealing device is connected with a cylinder body. The invention further relates to a fractured formation leaking stoppage experiment simulation evaluation method. According to the invention, the conditions of formation temperature and formation pressure difference can be simulated, the stirring system is used for simulating the thickening maintenance process of cement paste, the flowing state of the plugging slurry in a shaft is really simulated, the influence of formation cracks with different crack widths and crack heights on the plugging performance of the plugging slurry is discussed, and a reference basis is provided for preferably selecting a proper plugging material on site.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas field exploration and development, and particularly relates to a fractured stratum plugging experiment simulation evaluation device and method. Background Art

[0002] Well leakage is a complex underground situation in which various working fluids (including mud, cement slurry, completion fluid and other liquids) flow into the formation (excluding permeate filtrate) under the action of pressure difference during various underground operations such as drilling, cementing, testing or well repair. Well leakage can easily cause underground operation safety accidents such as drill sticking, blowout, and well collapse, consume drilling time, and lose a large amount of drilling fluid and plugging materials. If multiple plugging attempts fail, the drilling safety risk is high, and the only choice is to abandon the well, causing serious economic losses. Studies have shown that formation fractures are an important cause of well leakage. Using experimental devices to simulate formation fracture conditions to evaluate the performance of plugging materials and select suitable plugging materials and processes is of great significance to improve the success rate and efficiency of plugging, and to achieve the purpose of plugging formations and safe drilling. However, there is still a big difference between the simulated fracture conditions of the existing evaluation device and the leakage channel of the real fracture of the formation. It cannot truly simulate the fluid state of the plugging slurry in the wellbore, resulting in poor on-site application of plugging materials and processes. It is necessary to repeatedly carry out plugging construction, and the formation fractures cannot be effectively plugged.

[0003] A domestic patent for an experimental device and experimental method for crack plugging simulation (CN 112326888B), the device includes a main circulation loop and a first branch, the main circulation loop includes a plugging slurry tank, a formation water tank, an upper circulation pipeline, a lower circulation pipeline, a crack plugging simulator and a pulse solenoid valve, which can perform positive and reverse pressure tests on the plugging layer formed in the penetrating crack and the pressure bearing capacity test under the alternating action of positive and reverse directions, and truly evaluate the plugging of the plugging slurry during the simulated drilling process and the continuous plugging capacity of the plugging layer after the plugging is completed, and then evaluate the plugging effect of the plugging material, but the device cannot change the length and width of the crack to simulate the leakage under different conditions, but the device cannot realize variable crack evaluation, and cannot simulate the plugging performance of the plugging material under high temperature.

[0004] Domestic patented multi-scale fracture plugging simulator and multi-scale fracture plugging simulation experimental device (CN114893147A), the device includes a plugging slurry tank, an agitator, a plugging slurry output pipe, a return pipe and a waste liquid pool and a medium multi-scale fracture plugging simulator, the device can optimize the design of multi-scale fracture formation plugging materials while conducting fracture plugging simulation experiments, and provide theoretical guidance for simulating the downhole plugging process under complex working conditions.

[0005] A domestic patent for an experimental device that can be used for induced fracture plugging simulation evaluation (CN 110857943A), the device includes, including a high-pressure gas source, a fluid replenishment pool, a fluid replenishment tank, a plugging liquid tank, a plugging simulation chamber, a mud pump, a circulation pool, a metering cylinder, a valve and a pipeline, which can simulate the circulation of drilling fluid to flush the formed plugging layer, so as to evaluate the continuous plugging ability of the plugging layer in the subsequent drilling process after the plugging is completed; it can also evaluate the reverse pressure bearing capacity of the plugging material; at the same time, the crack size of the crack module can change according to the pressure size, simulating the induced crack changes in the formation, and then used to evaluate the plugging effect of the plugging material on the induced cracks, but the device cannot simulate the formation temperature and pressure conditions.

[0006] Domestic patent fractured formation plugging simulation evaluation device and evaluation method (CN 114198084A), the device includes a simulated wellbore, a fracture model, a pumping assembly and a stirring container, the top of the simulated wellbore is detachably connected to a simulated drill pipe, a plurality of first visualization windows are provided on the wall of the simulated wellbore, and a first camera is provided at some of the first visualization windows. There are simulated fractures inside the fracture model, a plurality of second visualization windows are provided on the fracture model, and a second camera is provided at some of the second visualization windows. The device can realistically simulate the actual plugging construction situation, and can quantitatively evaluate the degree of mixing of plugging materials and formation fluids and the retention performance of plugging materials in the leaking layer. The device has insufficient pressure bearing capacity and cannot meet the needs of formation plugging simulation under high temperature conditions.

[0007] As for plugging leaks in fractured formations, the underground is facing high temperature and high pressure. The plugging slurry needs to flow through the wellbore to reach the leaking layer. Taking cement slurry as an example, before reaching the leaking layer, the cement slurry thickening process needs to be considered, the thickening state of cement slurry in the wellbore needs to be simulated, and the influence of formation temperature on plugging materials needs to be considered. At the same time, the formation crack morphology will also affect the plugging performance. It can be seen from the above-mentioned prior art that there is currently no simulation evaluation device for plugging leaks in fractured formations that takes into account temperature, simulates actual plugging construction and crack morphology. The device of the present invention can simulate the thickening process of cement slurry in the wellbore, realize variable crack width and crack height simulation, realize the evaluation of plugging effects under various complex formation crack conditions, guide the application of plugging materials, reduce plugging costs, and improve plugging efficiency. Summary of the invention

[0008] In view of the above problems, the present invention can simulate the formation fracture conditions to experimentally evaluate the plugging performance of plugging slurry and cement slurry. The device can simulate the formation temperature and formation pressure difference conditions, simulate the cement slurry in the thickening and curing process through the stirring system, and truly simulate the flow state of the plugging slurry in the wellbore. The influence of formation fracture conditions with different fracture widths and fracture heights on the plugging performance of the plugging slurry is discussed, so as to optimize the plugging system suitable for different conditions, and provide a reference basis for the on-site optimization of suitable plugging materials.

[0009] In order to overcome the problems existing in the prior art, the present invention provides the following technical solutions:

[0010] A fractured formation plugging experiment simulation evaluation device, comprising:

[0011] A kettle body, wherein a first space is defined in the kettle body, and a stirring system is arranged in the first space and connected to the top of the kettle body;

[0012] A formation simulation device, the formation simulation device comprises a seam plate assembly and a cylinder body, the seam plate assembly is arranged in the cylinder body, the seam plate assembly is composed of a seam plate group, and simulates leakage channels under different formation conditions;

[0013] Wherein, an electric sealing device is provided at the bottom of the kettle body, and the bottom of the electric sealing device is connected to the cylinder body.

[0014] Furthermore, the simulation evaluation device also includes a control system, which includes a setting system and a display system. The setting system collects experimental parameters and data and is connected to the display system. The display system sets experimental parameters, connects and displays data, and records experimental data through computer operation and displays them in graphic form.

[0015] Furthermore, the kettle body is provided with an upper kettle cover and a lower kettle cover, the upper kettle cover is connected to a pressure relief pipeline, a kettle body thermocouple, and a stirring system, the kettle body is connected to a pressure sensor and a pressure pump, the outside of the kettle body is wrapped with a kettle body heater and a kettle body cooler, the pressure sensor and the kettle body thermocouple are inserted into the kettle body for testing the pressure and temperature inside the kettle, the pressure sensor and the kettle body thermocouple are connected to a control system, the upper kettle cover and the kettle body are connected to a kettle body pressure pump and a kettle body pressure relief pump through a pressure relief pipeline and a pressure pipeline, respectively, and the kettle body pressure pump pressurizes the inside of the kettle body through a nitrogen source.

[0016] Furthermore, the stirring system includes a paddle, a magnetic drive, and a variable frequency motor. The paddle is located inside the kettle body. A gasket, a diaphragm, and a pressure cover are sequentially provided between the paddle and the magnetic drive to ensure the sealing of the kettle body. A magnetic drive is installed on the upper part of the upper kettle cover. The magnetic drive is interconnected with the variable frequency motor through a V-belt to achieve rotation at the same linear speed to provide power for the rotation of the paddle.

[0017] Furthermore, the bottom of the cylinder body is connected to a liquid collecting tank system, which includes a liquid collecting tank, an electronic balance, and a condenser. The liquid collecting tank is provided with a condenser, which is connected to the electronic balance, and the electronic balance is connected to a control system.

[0018] Furthermore, the electric sealing device includes an electric push rod, a stop pin, and a sealing disk. The sealing disk is arranged inside the kettle body, and the electric push rod is located below the sealing disk. The electric push rod is arranged outside the kettle body, and a stop pin is arranged on the electric push rod. The kettle body and the formation simulation device are connected or disconnected through the electric sealing device, and the electric sealing device is switched on and off through the electric push rod.

[0019] Furthermore, the seam plate group of the formation simulation device is composed of a plurality of seam plates with different seam widths and seam heights. The formation simulation device simulates formation fractures through the gaps of the seam plate group. The seam plate group is connected by seam plate group fixing bolts to form one to four layers of seam plate body combinations. A single seam plate body is composed of axially symmetrical seam plates connected by seam plate body fixing bolts.

[0020] Furthermore, the formation simulation device also includes a lower heater, which is arranged outside the cylinder body, and the lower heater is also connected to a temperature sensor and connected to a control system.

[0021] The fractured formation plugging experiment simulation evaluation method uses the above-mentioned simulation evaluation device to simulate and evaluate the temperature and flow state changes of the wellbore plugging working fluid during the plugging process, including the following steps:

[0022] Assemble the seam plate group according to the requirements of simulating fracture conditions, fix the seam plate group in the cylinder of the formation simulation device, close the connecting valve of the formation simulation device, close the electric sealing device, and connect the formation simulation device and the electric sealing device through threads;

[0023] Pour the prepared plugging slurry into the kettle, put in the blades, install the gaskets, diaphragm and gland, connect the kettle cover to the variable frequency motor, set the blade speed and kettle temperature in the control system, and allow the plugging slurry to cure in the kettle;

[0024] After the maintenance is completed, the electric sealing device is opened, the connecting valve of the formation simulation device is opened, and the formation pressure difference is set to allow the plugging slurry to enter the seam plate group. As the slurry continues to enter the seam plate group, the pressure continues to drop. At the same time, the lost slurry in the formation simulation device will flow into the liquid collecting tank. The volume and weight of the lost slurry are read by the electronic balance and measuring cylinder, and the kettle body is continuously pressurized by the kettle body pressure pump to maintain the pressure difference;

[0025] If the differential pressure value cannot reach the set value or the slurry is completely lost, the experiment will be stopped. If the slurry can withstand a certain pressure in the seam plate group to form an effective plugging, the kettle pressure will rise until it reaches the set pressure differential value. The pressure differential value can be further increased to test the slurry plugging pressure limit.

[0026] After sealing the seam plate group, turn off the electric sealing device, clean the kettle body, and maintain the formation simulation device. After a certain period of time, fill the kettle body with clean water, turn on the electric sealing device, and perform a pressure test on the formation simulation device to test the pressure bearing capacity of the plugging working fluid in different time periods. If the clean water enters the seam plate group from the kettle body under the action of the pressure difference and finally flows into the liquid collecting tank, it indicates that this is the maximum pressure difference that the plugging slurry can withstand.

[0027] Furthermore, the maximum operating temperature of the kettle body is 200° C., the maximum pressure difference is 8 MPa, and the inner diameter of the kettle body is 168.1 mm.

[0028] The beneficial effects of the present invention are as follows: the present invention has a wellbore simulator for simulating wellbore size, temperature, and slurry flow state, a formation simulation device for simulating different fracture widths, fracture heights, and the pressure difference between wellbore pressure and formation pressure, providing electrical energy for the experiment, and a liquid collecting tank system for recording the weight and volume of the leakage amount, which can perform real-time regulation of temperature, pressure, rotation speed and other data, and a control system for automatically collecting data and experimental results generated during the experiment. Through the present invention, the whole process from maintenance to plugging of the plugging working fluid can be simulated, the flow state of the plugging slurry in the wellbore can be simulated under temperature and pressure conditions to simulate the maintenance process, and the fracture plate combination can be used to simulate fractures in formations with variable fracture widths and fracture heights, and the influence of formation fractures with different fracture widths and fracture heights on the plugging performance of the plugging slurry is discussed, so as to optimize the plugging system suitable for different conditions, provide a reference basis for selecting suitable plugging materials on site, and provide targeted construction plans for on-site construction.

[0029] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 A schematic diagram of the structure of a fractured formation plugging experiment simulation evaluation device according to an embodiment of the present invention is shown;

[0032] Figure 2 The external schematic diagram of the fractured formation plugging experiment simulation evaluation device according to the embodiment of the present invention is shown;

[0033] Figure 3It shows a schematic cross-sectional view of a kettle of a fractured formation plugging experiment simulation evaluation device according to an embodiment of the present invention;

[0034] Figure 4 A schematic cross-sectional view of a seam plate according to an embodiment of the present invention is shown;

[0035] Figure 5 Another cross-sectional schematic diagram of a seam plate according to an embodiment of the present invention is shown;

[0036] Figure 6 A top view of a seam plate according to an embodiment of the present invention is shown;

[0037] Figure 7 A schematic cross-sectional view of a seam plate body according to an embodiment of the present invention is shown;

[0038] Figure 8 A top view of a seam plate body according to an embodiment of the present invention is shown;

[0039] Fig. 9 A schematic cross-sectional view of a seam plate assembly according to an embodiment of the present invention is shown.

[0040] In the figure

[0041] 1-nitrogen source, 2-kettle body pressure pump, 3-kettle body pressure relief pump, 4-kettle body, 5-upper kettle cover, 6-kettle body heater, 7-kettle body cooler, 8-kettle body thermocouple, 9-pressure sensor, 10-stirring system, 11-frequency conversion motor, 12-electric gear lever, 13-electric sealing device, 14-lower heater, 15-formation simulation device, 16-temperature sensor, 17-connecting valve, 18-liquid collecting tank, 19- Condenser, 20 - electronic balance, 21 - setting system, 22 - display system, 23 - blade, 24 - pressure cover, 25 - diaphragm, 26 - gasket, 27 - magnetic drive, 28 - sealing disk, 29 - electric push rod, 30 - seam plate assembly, 31 - cylinder body, 32 - seam plate block, 33 - seam plate body, 34 - seam plate group, 35 - seam plate body fixing bolt, 36 - seam plate group fixing bolt, 37 - simulated formation fracture. DETAILED DESCRIPTION

[0042] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0043] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] It should be noted that the terms "first", "second" etc. in the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged in appropriate circumstances, so that the embodiments of the present application described here. In the present application, the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inside", "outside", "middle", "vertical", "horizontal", "lateral", "longitudinal" etc. are based on the orientation or positional relationship shown in the accompanying drawings.

[0045] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0046] like Figure 1 , a fractured formation plugging experiment simulation evaluation device, comprising:

[0047] A kettle body 4, wherein a first space is defined in the kettle body 4, and a stirring system 10 is disposed in the first space and connected to the top of the kettle body 4;

[0048] A formation simulation device 15, the formation simulation device 15 comprises a seam plate assembly 30 and a cylinder body 31, the seam plate assembly 30 is arranged in the cylinder body 31, the seam plate assembly 30 is composed of a seam plate group 34, and simulates leakage channels under different formation conditions;

[0049] The bottom of the kettle body 4 is provided with an electric sealing device 13 , and the bottom of the electric sealing device 13 is connected to the cylinder body 31 .

[0050] like Figure 2 The simulation evaluation device also includes a control system, which includes a setting system 21 and a display system 22. The setting system 21 collects experimental parameters and data and is connected to the display system 22. The display system 22 sets experimental parameters, connects and displays data, and records experimental data in graphic form through computer operation.

[0051] The kettle body 4 is provided with an upper kettle cover 5, a kettle body, and a lower kettle cover. The upper kettle cover 5 is connected to a pressure relief pipeline, a kettle body thermocouple 8, and a stirring system 10. The kettle body 4 is connected to a pressure sensor 9 and a pressure pump. The kettle body heater 6 and a kettle body cooler 7 are wrapped on the outside of the kettle body 4. The pressure sensor 9 and the kettle body thermocouple 8 are inserted into the kettle body 4 to test the pressure and temperature in the kettle. The pressure sensor 9 and the kettle body thermocouple 8 are connected to the control system. The upper kettle cover 5 and the kettle body 4 are connected to the kettle body pressure pump 2 and the kettle body pressure relief pump 3 through the pressure relief pipeline and the pressure pipeline, respectively. The kettle body pressure pump 2 pressurizes the inside of the kettle body 4 through the nitrogen source 1 to simulate the formation pressure difference. The maximum pressure difference can reach 20Mpa. After the experiment, the exhaust is exhausted through the pressure relief pipeline to reduce the pressure inside the kettle body 4. The heating system, cooling system, and pressure control system (pressurization and pressure relief) on the kettle body 4 are connected to the control system through the temperature sensor 16 and the pressure sensor 9 to realize the setting, transmission, and collection of data parameters.

[0052] like Figure 3 The stirring system 10 includes a paddle 23, a magnetic driver 27, and a variable frequency motor 11. The paddle 23 is located inside the kettle body 4. A gasket 26, a diaphragm 25, and a pressure cover 24 are sequentially arranged between the paddle 23 and the magnetic driver 27 to ensure the sealing of the kettle body 4. The magnetic driver 27 is installed on the upper part of the upper kettle cover 5. The magnetic driver 27 is connected to the variable frequency motor 11 through a V-belt to realize the rotation at the same linear speed to provide power for the rotation of the paddle 23.

[0053] The bottom of the cylinder 31 is connected to the liquid collecting tank system, which includes a liquid collecting tank 18, an electronic balance 20, and a condenser 19. The liquid collecting tank 18 is provided with a condenser 19, which is connected to the electronic balance 20, and the electronic balance 20 is connected to the control system. The condenser 19 is used to cool the high-temperature liquid coming out of the kettle 4. When conducting a high-temperature experiment exceeding 100°C, the vaporized liquid can be collected by the condenser 19 to ensure the accuracy of the experiment.

[0054] The electric sealing device 13 includes an electric push rod 29, a stop pin, and a sealing disk 28. The sealing disk 28 is arranged inside the kettle body 4. The electric push rod 29 is arranged below the sealing disk 28. The electric push rod 29 is provided with a stop pin. The kettle body 4 and the formation simulation device 15 are connected or disconnected through the electric sealing device 13. The electric sealing device 13 is switched on and off through the electric push rod 29. When the kettle body 4 and the formation simulation device 15 are connected, the slurry in the kettle body 4 enters the seam plate group 34 under the pressure difference operation, is discharged into the liquid collecting tank 18 through the connecting valve, and enters the beaker of the electronic balance 20 after being collected in the liquid collecting tank 18. The electronic balance 20 is connected to the control system to directly transmit the data to the computer.

[0055] like Figure 4The seam plate group 34 of the formation simulation device 15 is composed of a plurality of seam plate groups 32 with different seam widths and seam heights.

[0056] like Figure 5 , a cross-sectional view of different seam panels 32.

[0057] like Figure 6 , a top view of the seam plate 32.

[0058] like Figure 7 The seam plate blocks 32 are spliced ​​into a seam plate body 33 , and a single seam plate body 33 is composed of axially symmetrical seam plate blocks 32 connected and assembled by seam plate body fixing bolts 35 .

[0059] like Figure 8 , the top view of the seam plate body 33, the height of a single seam plate body 33 is 50mm, the seam height after combination is 50-200mm, the width of a single seam plate is 0.5, 1, 2, 3, 4, 5mm, 0.5-1mm variable seam, 1-2mm variable seam, 2-3mm variable seam, 3-4mm variable seam, 4-5mm variable seam, a total of 11 groups of seam plate body 33 specifications.

[0060] like Fig. 9 The formation simulation device 15 simulates formation fractures 37 through the gaps of the seam plate group 34, and the seam plate group 34 is connected by the seam plate group fixing bolts 36. Combining one to four layers of seam plate bodies 33 can simulate different types of formation fractures and evaluate the performance of the plugging working fluid.

[0061] The formation simulation device 15 also includes a lower heater 14 and a sealing valve. The sealing valve is threadedly connected to the bottom of the cylinder 31 to achieve sealing of the cylinder 31. The lower heater 14 is arranged outside the cylinder 31. The lower heater 14 is also connected to a temperature sensor 16 and connected to a control system.

[0062] The simulation evaluation method for plugging fractured formations comprises the following steps: using the simulation evaluation device to simulate the temperature and flow state changes of the plugging working fluid from the maintenance to the plugging process under the full-scale condition of the wellbore:

[0063] Assemble the seam plate group 34 according to the requirements of simulating fracture conditions, fix the seam plate group 34 in the cylinder 31 of the formation simulation device 15, close the connecting valve of the formation simulation device 15, close the electric sealing device 13, and connect the formation simulation device 15 and the electric sealing device 13 through threads;

[0064] Pour the prepared plugging slurry into the kettle body 4, put in the blade 23, install the gasket 26, the diaphragm 25 and the pressure cover 24, connect the upper kettle cover 5 to the variable frequency motor 11, set the blade speed and kettle body temperature in the control system, and allow the plugging slurry to be cured in the kettle body 4;

[0065] After the maintenance is completed, the electric sealing device 13 is opened, the connecting valve 15 of the formation simulation device is opened, and the formation pressure difference is set to allow the plugging slurry to enter the seam plate group 34. As the slurry continues to enter the seam plate group 34, the pressure continues to decrease. At the same time, the lost slurry in the formation simulation device 15 will flow into the liquid collecting tank 18. The volume and weight of the lost slurry are read by the electronic balance 20 and the measuring cylinder, and the kettle body 4 is continuously pressurized by the kettle body pressure pump 2 to maintain the pressure difference;

[0066] If the differential pressure value cannot reach the set value or the slurry is completely lost, the experiment is stopped. If the slurry can withstand a certain pressure in the seam plate group 34 to form an effective plugging, the pressure of the kettle body 4 will rise until it reaches the set pressure differential value. The pressure differential value can be further increased to test the slurry plugging pressure limit.

[0067] After sealing the seam plate group 34, close the electric sealing device 13, clean the kettle body 4, and maintain the formation simulation device 15. After a certain period of time, fill the kettle body 4 with clean water, open the electric sealing device 13, and perform a pressure test on the formation simulation device 15 to test the pressure bearing capacity of the plugging working fluid in different time periods. If the clean water enters the seam plate group 34 from the kettle body 4 under the action of the pressure difference and finally flows into the liquid collecting tank 18, it indicates that this is the maximum pressure difference that the plugging slurry can withstand, which provides a reference basis for the optimization of the performance of the plugging working fluid.

[0068] The kettle 4 has a maximum operating temperature of 200°C, a maximum pressure difference of 8MPa, and an inner diameter of 168.1mm, which can simulate the temperature and flow state changes of the plugging working fluid from maintenance to plugging under full-scale wellbore conditions. Dynamic pressurization of the kettle fluid can simulate the plugging performance of the plugging working fluid under different pressure difference conditions, realize rapid evaluation of the plugging pressure difference capability of the plugging working fluid, reduce experimental sample consumption, and improve the efficiency of experimental evaluation.

[0069] It can effectively simulate underground temperature (maximum operating temperature 200℃), bottom hole pressure difference (maximum pressure difference 20MPa) and flow state of plugging working fluid under different displacement conditions in the wellbore, and simulate the curing process of plugging working fluid, especially cement slurry, in the flow of the wellbore; the simulation of formation fractures has been innovatively designed compared with the previous one, adopting modular seam plate form, using seam plate blocks to combine into seam plate parts, and seam plate parts to combine into seam plate groups, realizing the simulation of various seam widths, seam heights, equal width seams and variable width seams, with convenient processing, fast assembly and freedom It has the characteristics of easy assembly and disassembly, easy cleaning, etc.; according to the performance requirements of the plugging working fluid of "being able to enter, stop, hold firmly and block tightly", two sets of temperature and pressure control systems are actually implemented, which are respectively used to simulate the "enter and stop" ability of the plugging working fluid, that is, to test the slurry sealing pressure limit and the "hold firmly and block tightly" ability, that is, the pressure limit of the plugging working fluid, and the performance of the plugging working fluid is evaluated in stages; the control system in the invention can set experimental parameters, connect and display data, record experimental data, and realize efficient analysis of experimental data. A modular seam plate form is adopted, seam plates are combined into seam plate parts, and seam plate parts are combined into seam plate groups, thus realizing the simulation of various seam widths, seam heights, equal-width seams and variable-width seams, and having the characteristics of convenient processing, quick assembly, free combination, easy disassembly and easy cleaning. The kettle body and the formation simulation device adopt a split design, with two sets of temperature and pressure control systems, which are used to simulate the "entry and stop" and "firm and tight blocking" capabilities of the plugging working fluid respectively, which is convenient for design and cleaning, simplifies the experimental process, and significantly reduces the economic cost of the experimental device.

[0070] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fractured formation plugging test simulation evaluation device, characterized in that: include: A kettle body (4), wherein a first space is defined in the kettle body (4), and a stirring system (10) is arranged in the first space and connected to the top of the kettle body (4); A formation simulation device (15), the formation simulation device (15) comprising a seam plate assembly (30) and a cylinder (31), the seam plate assembly (30) being arranged in the cylinder (31), the seam plate assembly (30) being composed of a seam plate group (34) to simulate leakage channels under different formation conditions; Wherein, an electric sealing device (13) is provided at the bottom of the kettle body (4), and the bottom of the electric sealing device (13) is connected to the cylinder body (31).

2. The fractured formation plugging test simulation evaluation device according to claim 1, characterized in that: The simulation evaluation device also includes a control system, which includes a setting system (21) and a display system (22). The setting system (21) collects experimental parameters and data and is connected to the display system (22). The display system (22) sets experimental parameters, connects and displays data, and records experimental data through computer operation and displays them in graphic form.

3. The fractured formation plugging test simulation evaluation device according to claim 2, characterized in that: The kettle body (4) is provided with an upper kettle cover (5) and a lower kettle cover. The upper kettle cover (5) is connected to a pressure relief pipeline, a kettle body thermocouple (8), and a stirring system (10). The kettle body (4) is connected to a pressure sensor (9) and a pressure pump. The kettle body heater (6) and a kettle body cooler (7) are wrapped on the outside of the kettle body (4). The pressure sensor (9) and the kettle body thermocouple (8) are inserted into the kettle body (4) for testing the pressure and temperature inside the kettle. The pressure sensor (9) and the kettle body thermocouple (8) are connected to a control system. The upper kettle cover (5) and the kettle body (4) are connected to a kettle body pressure pump (2) and a kettle body pressure relief pump (3) through a pressure relief pipeline and a pressure pipeline, respectively. The kettle body pressure pump (2) pressurizes the inside of the kettle body (4) through a nitrogen source (1).

4. The fractured formation plugging test simulation evaluation device according to claim 3, characterized in that: The stirring system (10) comprises a paddle (23), a magnetic driver (27), and a variable frequency motor (11); the paddle (23) is located inside a kettle body (4); a gasket (26), a diaphragm (25), and a pressure cover (24) are sequentially arranged between the paddle (23) and the magnetic driver (27) to ensure the sealing of the kettle body (4); the magnetic driver (27) is arranged on the upper part of the upper kettle cover (5); the magnetic driver (27) is connected to the variable frequency motor (11) through a V-belt to realize rotation at the same linear speed to provide power for the rotation of the paddle (23).

5. The fractured formation plugging test simulation evaluation device according to claim 2, characterized in that: The bottom of the cylinder (31) is connected to a liquid collecting tank system, which includes a liquid collecting tank (18), an electronic balance (20), and a condenser (19). The liquid collecting tank (18) is provided with a condenser (19), the condenser (19) is connected to the electronic balance (20), and the electronic balance (20) is connected to a control system.

6. The fractured formation plugging test simulation evaluation device according to claim 1, characterized in that: The electric sealing device (13) comprises an electric push rod (29), a stop pin, and a sealing disk (28). The sealing disk (28) is arranged inside the kettle body (4). The electric push rod (29) is located below the sealing disk (28). The electric push rod (29) is arranged outside the kettle body (4). The stop pin is arranged on the electric push rod (29). The kettle body (4) and the formation simulation device (15) are connected or disconnected through the electric sealing device (13). The electric sealing device (13) is switched on and off through the electric push rod (29).

7. The fractured formation plugging test simulation evaluation device according to claim 1, characterized in that: The seam plate group (34) of the formation simulation device (15) is composed of a plurality of seam plates (32) with different seam widths and seam heights. The formation simulation device (15) simulates formation fractures (37) through the gaps of the seam plate group (34). The seam plate group (34) is connected through seam plate group fixing bolts (36) to form a combination of one to four layers of seam plate bodies (33). A single seam plate body (33) is composed of axially symmetrical seam plates (32) connected and combined through seam plate body fixing bolts (35).

8. The fractured formation plugging test simulation evaluation device according to claim 1, characterized in that: The formation simulation device (15) further comprises a lower heater (14), wherein the lower heater (14) is arranged outside the cylinder (31), and the lower heater (14) is also connected to a temperature sensor (16) and to a control system.

9. A simulation evaluation method for plugging leakage in fractured formations, characterized by: The simulation evaluation device according to any one of claims 1 to 8 is used to simulate and evaluate the changes in temperature and flow state of the wellbore plugging working fluid during the plugging process, comprising the following steps: Assembling the seam plate group (34) according to the requirements of simulating fracture conditions, fixing the seam plate group (34) in the cylinder body (31) of the formation simulation device (15), closing the connection valve of the formation simulation device (15), closing the electric sealing device (13), and connecting the formation simulation device (15) and the electric sealing device (13) by threading; Pour the prepared plugging slurry into the kettle body (4), put in the impeller (23), install the gasket (26), the diaphragm (25) and the gland (24), connect the kettle cover (5) to the variable frequency motor (11), set the impeller speed and kettle body temperature in the control system, and allow the plugging slurry to be cured in the kettle body (4); After the maintenance is completed, the electric sealing device (13) is opened, the connecting valve (15) of the formation simulation device is opened, and the formation pressure difference is set to allow the plugging slurry to enter the seam plate group (34). As the slurry continues to enter the seam plate group (34), the pressure continues to decrease. At the same time, the lost slurry in the formation simulation device (15) will flow into the liquid collecting tank (18). The volume and weight of the lost slurry are read by the electronic balance (20) and the measuring cylinder, and the kettle body (4) is continuously pressurized by the kettle body pressure pump (2) to maintain the pressure difference; If the differential pressure value cannot reach the set value or the slurry is completely lost, the experiment is stopped. If the slurry can withstand a certain pressure in the seam plate group (34) to form an effective plugging, the pressure of the kettle body (4) will rise until it reaches the set pressure differential value. The pressure differential value can be further increased to test the slurry plugging pressure limit. After sealing the seam plate group (34), the electric sealing device (13) is turned off, the kettle body (4) is cleaned, and the formation simulation device (15) is maintained. After a certain period of time, the kettle body (4) is filled with clean water, the electric sealing device (13) is turned on, and the formation simulation device (15) is pressure tested to test the pressure bearing capacity of the plugging working fluid in different time periods. If the clean water enters the seam plate group (34) from the kettle body (4) under the action of the pressure difference and finally flows into the liquid collecting tank (18), it indicates that this is the maximum pressure difference that the plugging slurry can withstand.

10. The fractured formation plugging experiment simulation evaluation method according to claim 9, characterized in that: The maximum operating temperature of the kettle body (4) is 200°C, the maximum pressure difference is 8 MPa, and the inner diameter of the kettle body (4) is 168.1 mm.

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