Proppant migration process simulation device and migration characteristic test method

Abstract

The invention belongs to the technical field of oil and gas field reservoir fracturing, and particularly relates to a proppant migration process simulation device and a migration characteristic test method. The device comprises a crack simulation part, a simulation shaft and a liquid injection part. The crack simulation part comprises a first glass panel, a second glass panel and a plurality of rubber strips arranged between the first glass panel and the second glass panel, and simulation cracks are formed between the rubber strips. The simulated wellbore penetrates the first glass panel and is configured to communicate with the simulated crack. The liquid injection part comprises a first liquid storage barrel for storing a mixed liquid containing a propping agent and a fracturing liquid, an injection pump connected with the first liquid storage barrel, and a liquid injection pipeline for communicating the first liquid storage barrel with the simulation wellbore. According to the device, the migration process of the propping agent under the actual well condition can be simulated with higher trueness, a good equipment foundation is provided for exploring the migration characteristic of the propping agent in a real crack, and the device has a wide application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of reservoir fracturing in oil and gas fields, and particularly relates to a simulation device for the proppant migration process and a method for testing migration characteristics. Background Art

[0002] In the exploitation of oil and gas reservoirs, low-permeability and extra-low-permeability oil and gas resources are abundant, accounting for more than 70% of the total oil and gas reservoir reserves. However, the reservoirs of such oil and gas reservoirs are extremely dense, and large-scale volume fracturing is often required to improve the seepage channels of oil and gas media in order to release the oil and gas resources in the reservoirs. However, the fractured reservoir often closes rapidly under the action of the overlying rock pressure. Therefore, during on-site construction, a certain proportion of proppants are usually mixed into the fracturing fluid to support the volume fractures opened and extend the stability of the seepage channels. However, it is unknown how the proppants migrate in the complex fracture network under the carrying action of the fracturing fluid, whether they can effectively support the fractures, and whether blockages will form in fractures of different sizes, hindering the subsequent migration of proppants. In addition, in order to prevent filtration loss and affect the reservoir characteristics, the injected fracturing fluid often needs to be flowbacked. However, if a large amount of proppants return together with the fracturing fluid during the flowback process, the supporting effect of the proppants on the fractures will be reduced, and it is easy to accumulate at the bottom of the well, bury the perforations, and reduce the production capacity. Therefore, it is urgent to carry out relevant indoor research to explore how the proppants migrate during the injection process and flowback process of the fracturing fluid, in order to provide a reasonable basis for formulating a reasonable fracturing system and flowback system on site.

[0003] In the related art, a super-large fracture is mainly formed by two vertical glass panels, and a fracturing fluid containing proppants is injected into it to analyze the migration distance of the proppants under the carrying action of the fracturing fluid. However, since this device is different from the complex fracture network formed in the reservoir, the results obtained by this test device and method cannot truly reflect the law of proppant migration, restricting the further development of research and engineering applications. Summary of the Invention

[0004] In view of some or all of the problems existing in the prior art, the present invention provides a simulation device for the proppant migration process and a method for testing migration characteristics.

[0005] According to the first aspect of the present invention, a simulation device for the proppant migration process is provided.

[0006] The simulation device for the proppant migration process includes:

[0007] A fracture simulation part, including a first glass panel with through holes on its surface, a second glass panel arranged below the first glass panel, and a plurality of rubber strips arranged between the first glass panel and the second glass panel, and simulated fractures are formed between the rubber strips;

[0008] A simulated wellbore, configured as a bottomless cylindrical structure with openings at both ends, and its lower end penetrates through the through-hole to communicate with the simulated fracture; and

[0009] A liquid injection part, including a first liquid storage barrel for storing a mixed liquid containing proppant and fracturing fluid, an injection pump connected to the first liquid storage barrel, and a liquid injection pipeline connecting the first liquid storage barrel and the simulated wellbore,

[0010] wherein, the proppant can migrate along with the flow of the fracturing fluid that sequentially flows through the liquid injection pipeline, the simulated wellbore and the simulated fracture in response to the opening of the injection pump, so as to simulate the migration process of the proppant under real well conditions.

[0011] As an extension of the above technical solution, the present invention further includes the following embodiments:

[0012] Including a collection part, the collection part includes a lead-out pipe, a second liquid storage barrel and a liquid discharge pipeline connecting the second liquid storage barrel and the lead-out pipe, which are arranged between the first glass panel and the second glass panel and are configured to enable the mixed liquid in the simulated fracture to flow through itself and discharge from the fracture simulation part.

[0013] Including a liquid pumping part, the liquid pumping part includes a third liquid storage barrel, a liquid pumping pipeline connecting the third liquid storage barrel and the simulated wellbore, and a pumping pump arranged on the liquid pumping pipeline.

[0014] Including a pressure regulating part arranged on the first glass panel, the pressure regulating part includes a pressurizing panel, a support column for supporting the pressurizing panel on the first glass panel, and a pressurizing component with a pressure magnitude regulating function arranged on the pressurizing panel.

[0015] The pressurizing component is a weight set that can be weighted according to actual needs.

[0016] Including a working platform for supporting the fracture simulation part.

[0017] Including an intermediate pipeline assembly connected to the upper end of the simulated wellbore, the intermediate pipeline assembly includes a cover body fixedly connected to the upper end of the simulated wellbore, a manifold pipe, and a distribution pipe connecting the cover body and the manifold pipe. The cover body is configured to enable the liquid in the distribution pipe to enter the simulated wellbore, and both the liquid injection pipeline and the liquid pumping pipeline are configured to be connected to the manifold pipe.

[0018] The simulated fractures include a main simulated fracture and secondary simulated fractures. The main simulated fracture and the secondary simulated fractures are configured such that the quantity, size, placement angle, and tortuosity can all be adjusted according to actual requirements, and the main simulated fracture and the secondary simulated fractures are arranged in an interlaced manner.

[0019] The rubber strip is made of one or more of hydrogenated nitrile rubber, ethylene propylene diene monomer rubber, butyl rubber, and silicone rubber.

[0020] According to a second aspect of the present invention, a method for testing the proppant migration characteristics is provided.

[0021] The method for testing the proppant migration characteristics is carried out using the proppant migration process simulation device as described above, and includes the following steps:

[0022] 1) Inject a mixed liquid containing proppant and fracturing fluid into the first liquid storage barrel;

[0023] 2) Start the injection pump to cause the proppant to perform a simulated migration movement along with the fracturing fluid;

[0024] 3) Observe and measure the migration and retention characteristics of the proppant in the simulated fractures;

[0025] 4) Pour out the mixed liquid in the second liquid storage barrel after the end of step 2), and inject an appropriate amount of the fracturing fluid into the second liquid storage barrel;

[0026] 5) Place the pressure regulating part on the first glass panel and turn on the extraction pump to simulate the backflow process of the proppant;

[0027] 6) During the process of step 5), observe and measure the backflow characteristics of the proppant in the simulated fractures;

[0028] 7) Uncover the first glass panel and calculate and analyze the settlement and plugging characteristics of the proppant.

[0029] The advantages of the present invention compared with the prior art are as follows:

[0030] Through the design of components such as the fracture simulation part, the simulated wellbore, and the liquid injection part, the proppant migration process simulation device according to the present invention realizes the simulation of the proppant migration process in simulated fractures that are closer to the actual downhole conditions, so that the actual migration characteristics of the proppant can be presented more realistically, and thus provides a good equipment foundation for the implementation of the method for testing the proppant migration characteristics according to the present invention.

[0031] The proppant migration characteristic test method according to the present invention is carried out by using the proppant migration process simulation device described above. Thanks to the high-fidelity simulation of the actual well conditions by this device, and by observing the migration and settlement process of the proppant and measuring the retention ratio of the proppant and other means, it can more truly reflect the actual migration characteristics of the proppant, providing a reliable basis for actual engineering applications such as formulating reasonable fracturing and flowback systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 FIG. is a schematic structural diagram of a proppant migration process simulation device according to the present invention.

[0033] All the drawings in the present invention are schematic diagrams for explaining the structure and principle, and are not necessarily drawn according to the actual size and ratio.

[0034] The specific meanings of the reference numerals in the drawings are as follows:

[0035] 1, fracture simulation part; 11, first glass panel; 12, second glass panel; 13, rubber strip; 14, simulated fracture; 2, simulated wellbore; 3, liquid injection part; 31, first liquid storage barrel; 32, injection pump; 33, liquid injection pipeline; 4, proppant; 5, fracturing fluid; 6, collection part; 61, outlet pipe; 62, second liquid storage barrel; 7, liquid pumping part; 71, third liquid storage barrel; 72, liquid pumping pipeline; 73, extraction pump; 8, pressure adjustment part; 81, pressurized panel; 82, support column; 821, suction cup; 83, weight set; 9, working platform; 10, intermediate pipeline assembly; 101, cover body; 102, collecting pipe; 103, distribution pipe; 100, proppant migration process simulation device. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] The embodiments of the present invention will be described in more detail below with reference to the drawings.

[0037] According to the first aspect of the present invention, a proppant migration process simulation device 100 (hereinafter referred to as "device 100") is provided.

[0038] Figure 1Schematic structural diagram of device 100 according to the present invention. As shown in the figure, device 100 includes a fracture simulation part 1, a simulated wellbore 2, and an injection part 3. The fracture simulation part 1 includes a first glass panel 11 with a plurality of through holes (not shown, the same below) formed on its surface, a second glass panel 12 arranged opposite to the first glass panel 11 and located below the first glass panel 11, and a plurality of rubber strips 13 disposed between the first glass panel 11 and the second glass panel 12. By adjusting the quantity, attitude, and placement position of the rubber strips 13, a plurality of simulated fractures 14 with different characteristics such as size, placement angle, tortuosity, etc. are formed between the rubber strips 13 to simulate real fractures (not shown, the same below) under actual well conditions. The quantity of the simulated wellbores 2 corresponds to the quantity of the through holes formed on the first glass panel 11, and its structure is a bottomless cylindrical structure with openings at both ends. And the lower end of each simulated wellbore 2 penetrates through a through hole and is connected to the simulated fracture 14. The injection part includes a first liquid storage barrel 31, an injection pump 32 connected to the first liquid storage barrel 31, and an injection pipeline 33 connecting the first liquid storage barrel 31 and the simulated wellbore 2. The first liquid storage barrel 31 is used to store a mixed liquid containing a proppant 4 and a fracturing fluid 5. In addition, it should be noted that both the first glass panel 11 and the second glass panel 12 have relatively high transparency, so that the staff can observe the migration condition of the proppant 4 in the simulated fracture 14 through the first glass panel 11 and the second glass panel 12.

[0039] During specific operation, the staff first injects an appropriate amount of the mixed liquid containing the proppant 4 and the fracturing fluid 5 into the first liquid storage barrel 31, and then turns on the injection pump 32. The fracturing fluid 5 drives the proppant 4 to flow through the injection pipeline 33, the simulated wellbore 2, and the simulated fracture 14 in sequence under the push of the injection pump 32, and flows out from the simulated fracture 14. During this process, the proppant 4 moving simultaneously with the fracturing fluid 5 realizes migration in the simulated fracture 14, thereby simulating the migration process of the proppant 4 under real well conditions.

[0040] Through this design, the fracture simulation part 1 is used to simulate and generate a plurality of simulated fractures 14 highly similar to real fractures. Then, with the pushing action of the injection part 3, the proppant 4 can realize migration in the simulated fracture 14 to simulate the migration process of the proppant 4 under real well conditions. Due to the high similarity between the simulated wellbore 2 and the simulated fracture 14 and the actual well conditions, the device 100 can be used to achieve a high-fidelity simulation of the migration process of the proppant 4 in real fractures, providing a good equipment basis for subsequent exploration of the actual migration characteristics of the proppant 4.

[0041] Such as Figure 1As shown, in an embodiment of the present invention, the device 100 includes a collection part 6. The collection part 6 includes a discharge pipe 61, a second liquid storage barrel 62, and a drainage pipeline (not shown, the same below). The discharge pipe 61 is arranged between the first glass panel 11 and the second glass panel 12, and several discharge pipes 61 can be arranged according to actual needs. The discharge pipe 61 is configured to enable the mixed liquid containing the proppant 4 and the fracturing fluid 5 in the simulated crack 14 to flow through itself and discharge from the crack simulation part 1. The second liquid storage barrel 62 is configured as a barrel-shaped structure for collecting the mixed liquid flowing out of the simulated crack 14. The drainage pipeline is a conventional pipeline applicable in the art and is configured to connect the discharge pipe 61 and the second liquid storage barrel 62, so as to facilitate the introduction of the mixed liquid flowing out of the simulated crack 14 into the second liquid storage barrel 62. Through this design, on the one hand, the mixed liquid flowing out of the simulated crack 14 can be collected, so that the mixed liquid can be reused, avoiding the waste of experimental materials. On the other hand, since the second liquid storage barrel 62 can be used to store the mixed liquid, and the second liquid storage barrel 62 is connected to the crack simulation part 1 through the drainage pipeline, it provides a necessary structural basis for the subsequent simulation of the backflow process of the proppant 4.

[0042] Preferably, in an embodiment of the present invention, the discharge pipe 61 is made of hydrogenated nitrile rubber. Through this design, the characteristics of hydrogenated nitrile rubber, such as high temperature resistance, corrosion resistance, and good elastoplasticity, are utilized, so that the discharge pipe 61 is difficult to be damaged due to the corrosion of the fracturing fluid and the extrusion of the first glass panel 11 and the second glass panel 12, thereby improving the service life of the discharge pipe 61.

[0043] Preferably, the discharge pipe 61 is seamlessly connected to the outlet end of the simulated crack 14 using an adhesive sealant to form a discharge channel for the fracturing fluid 5.

[0044] In an embodiment of the present invention, for the purpose of enabling the mixed liquid to be discharged from the simulated crack 15 more smoothly, the discharge pipes 61 are distributed around the first glass panel 11 and the second glass panel 12.

[0045] Such as Figure 1As shown, in an embodiment of the present invention, the device 100 includes a liquid pumping part 7. The liquid pumping part 7 includes a third liquid storage barrel 71, a liquid pumping pipeline 72 connecting the third liquid storage barrel 71 with the simulated wellbore 2, and a pumping pump 73 arranged on the liquid pumping pipeline 72. Through this design, after the device 100 completes the simulation of the migration process of the proppant 4 during the fracturing process, the staff can use the liquid pumping part 7 to simulate the backflow process of the proppant 4. That is, the proppant 4 can be pumped back from the second liquid storage barrel 62 under the action of the liquid pumping part 7, passing through the liquid drainage pipeline, the outlet pipe 61, the simulated fracture 14, the simulated wellbore 2, the liquid pumping pipeline 72 in sequence, and finally flowing into the third liquid storage barrel 71 to simulate the backflow process of the proppant 4, thereby providing a necessary equipment basis for subsequent exploration of the backflow migration characteristics of the proppant 4.

[0046] In an embodiment of the present invention, a control valve (not shown, the same below) is arranged on the liquid injection pipeline 33. Through this design, when using the device 100 to simulate the migration process of the proppant 4 during the fracturing process, the control valve is in the open state so that the mixed liquid can enter the fracture simulation part 1. When it is necessary to use the device 100 to simulate the backflow process of the proppant 4, the control valve is closed, so that the reversely moving mixed liquid can all enter the third liquid storage barrel 71 without entering the first liquid storage barrel 31, to avoid the adverse effects on the simulation and test results caused by the mixed liquid flowing into the first liquid storage barrel 31.

[0047] As Figure 1 As shown, in an embodiment of the present invention, the device 100 includes a pressure regulating part 8. The pressure regulating part 8 is arranged on the first glass panel 11, and the pressure regulating part 8 includes a pressurizing panel 81, a support column 82 supporting the pressurizing panel 81 above the first glass panel 11, and a pressurizing component with a pressure size adjustment function arranged on the pressurizing panel 81. During the backflow process of the proppant 4 under actual working conditions, the fluid pressure in the real fracture is lower than the overburden pressure of the reservoir, which is the main reason for some of the proppant 4 to be retained in the real fracture. Through the design of this embodiment, when the staff uses the device 100 to simulate the backflow process of the proppant 4, they can apply pressure to the first glass panel 11 through the pressure regulating part 8, so as to achieve the purpose of applying pressure to the simulated fracture 4, and further can more realistically simulate the pressure environment when the proppant 4 is backflowing, and finally make the simulation process more similar to the actual working conditions, ensuring the authenticity and reliability of the migration characteristics of the proppant 4 tested subsequently.

[0048] Further, in an embodiment of the present invention, the pressurizing assembly 83 adopts a weight set 83 that can be weighted according to actual requirements. With this design, the staff can control the pressure applied to the first glass panel 11 by increasing or decreasing the number of weights in the weight set 83 or replacing the weights in the weight set 83, enhancing the convenience of operating the device 100.

[0049] As Figure 1 shown, in an embodiment of the present invention, in order to maintain the structural stability of the pressure regulating part 8, no less than six support columns 82 are arranged below the pressurizing panel 81.

[0050] As Figure 1 shown, in an embodiment of the present invention, in order to stably arrange the pressure regulating part 8 on the first glass panel 11 and reduce the conditions that are not conducive to the smooth operation of the device 100, such as sliding and shaking of the pressure regulating part 8, a suction cup 821 is arranged at the lower end of each support column 82, and the support column 82 is adsorbed on the first glass panel 11 through the suction cup 821.

[0051] As Figure 1 shown, in an embodiment of the present invention, the device 100 includes a working platform 9 arranged below the crack simulation part 1 for supporting the crack simulation part 1. With this design, the crack simulation part 1 can be stably supported on the ground or the working panel through the working platform 9, thus providing a solid structural foundation for the crack simulation part 1 and other components of the device 100 to play their roles safely and stably.

[0052] As Figure 1 shown, in an embodiment of the present invention, the device 100 includes an intermediate pipeline assembly 10. The intermediate pipeline assembly 10 is configured to be connected to the upper end of the simulation wellbore 2, and it includes a cover body 101 fixedly connected to the upper end of the simulation wellbore 2, a manifold 102, and a distribution pipe 103 connected between the cover body 101 and the manifold 102. The cover body 101 is configured to enable the liquid in the distribution pipe 103 to enter the simulation wellbore 2, and both the liquid injection pipeline 33 and the liquid extraction pipeline 72 are configured to be connected to the manifold 102. Obviously, the number of the cover body 101 and the distribution pipe 103 should be equal to the number of the simulation wellbores 2, and the number of the manifold 102 is one. With this design, on the one hand, when the number of the simulation wellbores 2 is relatively large, through the design of the manifold 102 and the distribution pipe 103, the connection relationship between the liquid injection pipeline 33 and the liquid extraction pipeline 72 and the simulation wellbore 2 can be simplified, and the distribution pipe 103 plays the role of multi-purpose use. On the other hand, through the setting of the cover body 101, when the pressure in the liquid injection pipeline 33 and the liquid extraction pipeline 72 is relatively large, the mixed liquid will not overflow from the simulation wellbore 2, thus ensuring the smooth progress of the simulation operation of the device 100.

[0053] Preferably, the cover body 101 and the simulated wellbore 2 are configured to be fixedly connected together by a threaded connection.

[0054] In an embodiment of the present invention, the simulated fracture 14 includes a main simulated fracture with a crack size between 1 and 10 mm (including the boundary values) and a secondary simulated fracture with a crack size less than 1 mm. The main simulated fracture and the secondary simulated fracture are configured such that the quantity, size, placement angle, tortuosity, etc. can all be adjusted according to actual requirements, and the main simulated fracture and the secondary simulated fracture are arranged in a staggered manner. Through this design, the simulated fracture 14 forms a complex fracture network, and its constituent form can be adjusted according to actual requirements. Thus, on the one hand, the similarity between the simulated fracture 14 and the real fracture is greatly improved, providing an important structural basis for the device 100 to highly realistically simulate the migration process of the proppant 4 in the real fracture, making the subsequent detection results of the migration characteristics of the proppant 4 more credible. On the other hand, the shape adjustability of the simulated fracture 14 enables the staff to use the device 100 to simulate various types of real fractures, thereby expanding the applicable range of the device 100.

[0055] In an embodiment of the present invention, the rubber strip 13 is made of one or more of hydrogenated nitrile rubber, ethylene propylene diene monomer rubber, butyl rubber, and silicone rubber. These rubbers all have certain elastoplasticity, can better simulate real fractures, and are not easily damaged due to compression. In addition, using these rubbers to make the rubber strip 13 can also conveniently achieve the purpose of adapting to different simulation requirements through attitude adjustment.

[0056] In a preferred embodiment of the present invention, the rubber strip 13 is made of hydrogenated nitrile rubber. Due to the good elastoplasticity and pressure and corrosion resistance of hydrogenated nitrile rubber, through this design, the rubber strip 13 can well cope with the pressure exerted by the surrounding environment and the corrosion of the fracturing fluid 5, thereby increasing the service life of the rubber strip 13.

[0057] In an embodiment of the present invention, adhesive sealant is applied to the upper and lower sides of the rubber strip 13 for bonding with the first glass panel 11 and the second glass panel 12. Through this design, the firm setting of the rubber strip 13 is achieved, so that the simulated fracture 14 can maintain a stable state during the operation of the device 100, avoiding adverse effects on the simulation process and test results due to deformation of the simulated fracture 14 during the simulation test.

[0058] In an embodiment of the present invention, according to the actual needs of simulation and testing, the number of simulated wellbores 2 is three.

[0059] In one embodiment of the present invention, the first glass panel 11 is made of ultra-high pressure-resistant glass. Through this design, the first glass panel 11 has better pressure-resistant performance, which helps to maintain the good working state of the device 100 and improve its service life.

[0060] In one embodiment of the present invention, the second glass panel 12 is made of ultra-high pressure-resistant glass. Through this design, the second glass panel 12 has better pressure-resistant performance, which helps to maintain the good working state of the device 100 and improve its service life.

[0061] According to the device 100 of the present invention, through the design of components such as the crack simulation part 1, the simulated wellbore 2, and the liquid injection part 3, the migration process of the proppant 4 is simulated in a simulated crack closer to the actual downhole conditions, so that the actual migration characteristics of the proppant 4 can be presented more realistically. Furthermore, the exploration and measurement results of the migration characteristics of the proppant 4 based on the device 100 are more reliable. In addition, through the design of the liquid extraction part 7 and the pressure regulation part 8, the device 100 can also be used to highly realistically simulate the flowback process of the proppant 4, providing a reliable structural basis for more comprehensively detecting the migration characteristics of the proppant 4.

[0062] According to the second aspect of the present invention, a method for testing the migration characteristics of a proppant is provided.

[0063] This method is carried out by using the device 100 as described above and includes the following steps:

[0064] 1) Inject a mixed liquid containing the proppant 4 and the fracturing fluid 5 into the first liquid storage barrel 31;

[0065] 2) Open the control valve on the liquid injection pipeline 33 and start the injection pump 32 to make the proppant 4 perform a simulated migration movement along with the fracturing fluid 5;

[0066] 3) During the process of step 2), observe and measure the migration and retention of the proppant 4 in the simulated crack 14 to obtain the migration characteristics of the proppant 4;

[0067] 4) Pour out the mixed liquid in the second liquid storage barrel 62 after the end of step 2), and inject an appropriate amount of fracturing fluid 5 into the second liquid storage barrel 62;

[0068] 5) Place the pressure regulation part 8 on the first glass panel 11, close the control valve on the liquid injection pipeline 33, and turn on the extraction pump 73 to simulate the flowback process of the proppant 4;

[0069] 6) During the process of step 5), observe and measure the flowback characteristics of the proppant 4 in the simulated crack 14;

[0070] 7) Uncover the first glass panel 11 to calculate and analyze the settlement and plugging characteristics of the proppant 4.

[0071] In one embodiment of the present invention, the same type of proppant 4 is dyed the same color, and different types of proppants 4 are dyed different colors.

[0072] In a specific embodiment of the present invention, the proppant migration characteristic test method is carried out according to the following steps:

[0073] 1) Inject a mixed liquid containing the proppant 4 and the fracturing fluid 5 into the first liquid storage barrel 31.

[0074] Dye different types of proppants 4. For example, dye the 40 / 70 mesh ceramic particles red and the 70 / 100 mesh quartz sand black. Then weigh and proportion different types of proppants 4 according to the experimental requirements, and place the proppant 4 in a shaker (not shown, the same below) to mix evenly. After that, uniformly mix the proppant 4 and the fracturing fluid 5 under the action of a stirrer (not shown, the same below), pour them into the first liquid storage barrel 31, and continuously stir with an electromagnetic stirrer (not shown, the same below) to ensure that the proppant 4 and the fracturing fluid 5 are always in a uniformly mixed state.

[0075] 2) Turn on the injection pump 32 to make the proppant 4 perform a simulated migration movement with the fracturing fluid 5.

[0076] Select the constant speed mode to turn on the injection pump 32, and uniformly inject the mixed liquid of the fracturing fluid 5 containing the proppant 4 into the simulated wellbore 2, so that the proppant 4 flows through the simulated fracture 14 (including the main simulated fracture and the secondary simulated fracture, the same below), and is finally collected in the second liquid storage barrel 62.

[0077] 3) Observe and measure the migration and retention of the proppant 4 in the simulated fracture 14 to obtain the migration characteristics of the proppant 4.

[0078] During the process of step 2), by observing and calculating the movement trajectories, migration distances, and discharge rates (the ratio of the mass of various proppants 4 finally discharged into the second liquid storage barrel 62 to the original mass of various proppants 4 in step 1), etc., of different color proppants 4 in simulated fractures 14 of different sizes and angles, analyze the migration laws of different types of proppants 4.

[0079] 4) Re-inject the fracturing fluid 5 into the second liquid storage barrel 62.

[0080] After step 2) is completed, pour out the mixed liquid in the second liquid storage barrel 62, and inject an appropriate amount of fracturing fluid 5 into the second liquid storage barrel 62.

[0081] 5) Place the pressure regulating part 8, and turn on the extraction pump 73 to simulate the backflow process of the proppant 4.

[0082] Place the pressure regulating part 8 on the first glass panel 11, place a certain mass of weight set 83 according to the experimental requirements, close the control valve on the liquid injection pipeline 33, turn on the extraction pump 73, extract the fracturing fluid 5 from the second liquid storage bucket 62 at a certain flow rate, make the fracturing fluid 5 flow through the outlet pipe 61 and the simulated fracture 14, enter the simulated wellbore 2, and finally flow through the extraction pump 73 and be collected in the third liquid storage bucket 71.

[0083] 6) Observe the backflow characteristics of the proppant 4.

[0084] During the process of step 5), by observing the movement trajectories and migration distances of proppants 4 of different colors, analyze the backflow characteristics of different types of proppants 4 in simulated fractures 14 of different sizes and different angles.

[0085] 7) Uncover the first glass panel 11 to analyze the settlement and plugging characteristics of the proppant 4.

[0086] After step 6) is completed, uncover the first glass panel 11. After the fracturing fluid 5 is completely air-dried, take out the proppants 4 settled in the simulated fractures 14 of different sizes and different angles, weigh the masses of various proppants 4, and calculate the ratio of the mass of each proppant 4 at this time to the original mass of each proppant 4 in step 1) (the settlement rate during the backflow process), and analyze to obtain the settlement and plugging laws of the proppant 4.

[0087] The data reflecting the settlement and plugging characteristics of different types of proppants 4 in the simulated fracture 14 during the backflow process obtained in this embodiment are shown in Table 1:

[0088] Table 1 Data table of settlement rate of different types of proppants during backflow process in simulated fracture

[0089]

[0090] Note: The higher the settlement rate of the proppant 4 after backflow, the more it meets the engineering requirements. Because if the settlement rate of the proppant 4 is higher, the real fracture is less likely to close, which is more beneficial to the oil and gas production operation.

[0091] According to the proppant migration characteristic testing method of the present invention, the device 100 is used. Benefiting from the high-fidelity simulation of the actual well conditions by this device, and by observing the migration and settlement processes of the proppant 4 and measuring the retention ratio of the proppant 4 and other means, it more truly reflects the characteristics of the proppant 4 migration in the actual situation, and provides a reliable basis for actual engineering applications such as formulating reasonable fracturing and backflow systems.

[0092] In the present invention, "a plurality of" refers to natural numbers not less than 1.

[0093] In the present invention, the specific meanings of "upper", "lower", "left", "right", "inner", "outer", "middle", "edge", etc. when expressing orientation terms are based on Figure 1 the drawing state of the device 100 in [reference].

[0094] Finally, it should be noted that although the present invention has been described in detail with reference to the preferred embodiments, various improvements can be made to it and components therein can be replaced with equivalents without departing from the scope of the present invention. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A simulation device for the proppant migration process, comprising: A fracture simulation part (1), including a first glass panel (11) with through holes on its surface, a second glass panel (12) arranged below the first glass panel (11), and several rubber strips (13) arranged between the first glass panel (11) and the second glass panel (12), and a simulated fracture (14) is formed between the rubber strips (13); A simulated wellbore (2), constructed as a bottomless cylindrical structure with both ends open, and its lower end penetrates through the through hole to communicate with the simulated fracture (14); and A liquid injection part (3), including a first liquid storage bucket (31) for storing a mixed liquid containing proppant (4) and fracturing fluid (5), an injection pump (32) connected to the first liquid storage bucket (31), and a liquid injection pipeline (33) connecting the first liquid storage bucket (31) and the simulated wellbore (2), wherein the proppant (4) can migrate along with the flow of the fracturing fluid (5) that successively flows through the liquid injection pipeline (33), the simulated wellbore (2), and the simulated fracture (14) in response to the opening of the injection pump (32), so as to simulate the migration process of the proppant (4) under actual well conditions.

2. The proppant migration process simulation device according to claim 1, wherein: It includes a collection part (6), and the collection part (6) includes a derivation pipe (61) arranged between the first glass panel (11) and the second glass panel (12) and configured to enable the mixed liquid in the simulated fracture (14) to flow through itself and discharge from the fracture simulation part (1), a second liquid storage bucket (62), and a liquid discharge pipeline connecting the second liquid storage bucket (62) and the derivation pipe (61).

3. The proppant migration process simulation device according to claim 2, characterized in that: It includes a liquid extraction part (7), and the liquid extraction part (7) includes a third liquid storage bucket (71), a liquid extraction pipeline (72) connecting the third liquid storage bucket (71) and the simulated wellbore (2), and an extraction pump (73) arranged on the liquid extraction pipeline (72).

4. The proppant migration process simulation device according to claim 3, wherein: It includes a pressure adjustment part (8) arranged on the first glass panel (11), and the pressure adjustment part (8) includes a pressurized panel (81), a support column (82) supporting the pressurized panel (81) on the first glass panel (11), and a pressurization component with a pressure magnitude adjustment function arranged on the pressurized panel (81).

5. The proppant migration process simulation device according to claim 4, wherein: The pressurization component is a weight set (83) that can be weighted according to actual needs.

6. The proppant migration process simulation device according to claim 4, wherein: It includes a working platform (9) for supporting the fracture simulation part (1).

7. The proppant migration process simulation device according to claim 6, characterized in that: It includes an intermediate pipe assembly (10) connected to the upper end of the simulated wellbore (2). The intermediate pipe assembly (10) includes a cover body (101) fixedly connected to the upper end of the simulated wellbore (2), a manifold pipe (102), and a distribution pipe (103) connected between the cover body (101) and the manifold pipe (102). The cover body (101) is configured to enable the liquid in the distribution pipe (103) to enter the simulated wellbore (2). Both the liquid injection pipe (33) and the liquid extraction pipe (72) are configured to communicate with the manifold pipe (102).

8. The proppant migration process simulation device according to any one of claims 4 to 7, characterized in that: The simulated fracture (14) includes a main simulated fracture and a secondary simulated fracture. The main simulated fracture and the secondary simulated fracture are configured such that the quantity, size, placement angle, and tortuosity can all be adjusted according to actual needs, and the main simulated fracture and the secondary simulated fracture are arranged in an interlaced manner.

9. The proppant migration process simulation device according to claim 8, characterized in that: The rubber strip (13) is made of one or more of hydrogenated nitrile rubber, ethylene propylene diene monomer rubber, butyl rubber, and silicone rubber.

10. A method for testing the migration characteristics of proppants, which is carried out by using the proppant migration process simulation device according to any one of claims 4 to 9, and includes the following steps: 1) Inject a mixed liquid containing proppants (4) and fracturing fluid (5) into the first liquid storage barrel (31); 2) Start the injection pump (32) to enable the proppants (4) to perform simulated migration movement along with the fracturing fluid (5); 3) During the process of step 2), observe and measure the migration and retention characteristics of the proppants (4) in the simulated fracture (14); 4) Pour out the mixed liquid in the second liquid storage barrel (62) after the end of step 2), and inject an appropriate amount of the fracturing fluid (5) into the second liquid storage barrel (62); 5) Place the pressure regulating part (8) on the first glass panel (11), and turn on the extraction pump (73) to simulate the backflow process of the proppants (4); 6) During the process of step 5), observe and measure the backflow characteristics of the proppants (4) in the simulated fracture (14); 7) Uncover the first glass panel (11), and calculate and analyze the settlement and plugging characteristics of the proppants (4).

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