Fracture face roughness and fluid loss consideration proppant placement experimental apparatus and method

Abstract

The application discloses a proppant sanding experiment device and method considering crack surface roughness and filtration, and the experiment device comprises a fracturing fluid supply device and a crack simulation sanding device, the crack simulation sanding device comprises a titanium powder sintered plate, a rotary driving structure and a transparent crack A surface; the crack A surface is sealingly connected with one side of the titanium powder sintered plate, the crack A surface and the titanium powder sintered plate enclose a closed cavity as a visualized simulation crack for sanding experiment, the closed cavity is taken as a simulation crack, the two ends of the closed cavity along the horizontal direction are respectively provided with a liquid inlet and a liquid outlet, the fracturing fluid supply device is connected with the liquid inlet, the liquid inlet and the liquid outlet are both provided with valves, and the surface of the titanium powder sintered plate used for enclosing the closed cavity is arranged as a surface same as the rough surface form and roughness of a real crack. The application can more truly simulate the proppant sanding condition under the condition that the filtration exists in the formation crack.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas development and research technology, and is mainly used to observe the proppant placement morphology in fractures. In particular, it relates to a proppant placement test device and method that takes into account the roughness of the fracture surface and filtration loss. Background Technology

[0002] Hydraulic fracturing technology is currently a key measure for increasing oilfield production. The core principle of this technology is to use a high-pressure pump to inject pre-mixed fracturing fluid into the formation at pressures far exceeding the target reservoir's in-situ stress and rock yield strength. After fracturing, proppant is added, thus creating fractures with a certain conductivity, increasing the permeability of the target reservoir, and changing the oil flow pattern to a bilinear flow—first from the reservoir into the fracture, then from the fracture into the wellbore—thereby achieving increased production. During fracturing operations, the proppant placement pattern within the fracture directly determines the effective height and length of the "fracture channel," and is a crucial factor influencing the fracturing effect. Therefore, exploring the impact of different fracturing parameters on the proppant placement pattern is of great significance for optimizing the design of hydraulic fracturing parameters and thus contributing to increased oilfield production.

[0003] Currently, few commonly used experimental apparatuses for visualizing proppant placement consider the filtration properties of fracture surfaces. Some apparatuses use permeable sponges to simulate filtration, but the experimental results and quality are difficult to guarantee. Other apparatuses simulate filtration by creating openings on one side of the fracture surface, using the concentrated filtration from multiple openings to equate to uniform filtration. However, this leads to abrupt changes in the flow field near the openings and a sharp change in the roughness of the fracture surface. Furthermore, proppant can enter and fill the openings, affecting the filtration effect. Therefore, this method is insufficient to realistically simulate proppant placement under conditions of filtration in formation fractures. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention aims to provide a proppant laying experimental apparatus and method that takes into account the roughness of the fracture surface and filtration loss. The present invention can realistically simulate the proppant laying situation under the condition of filtration loss in formation fractures.

[0005] The technical solution adopted in this invention is as follows:

[0006] A proppant-laying experimental apparatus considering fracture surface roughness and filtration loss includes a fracturing fluid supply device and a fracture simulation proppant-laying device. The fracture simulation proppant-laying device includes a titanium powder sintered plate, a rotary drive structure, and a transparent fracture A-face. The fracture A-face is sealed to one side of the titanium powder sintered plate, and the fracture A-face and the titanium powder sintered plate enclose a sealed cavity that serves as a visual simulated fracture for proppant-laying experiments. The sealed cavity serves as a simulated fracture. The sealed cavity has an inlet and an outlet at both ends along the horizontal direction. The fracturing fluid supply device is connected to the inlet. Both the inlet and outlet are equipped with valves. The surface of the titanium powder sintered plate used to enclose the sealed cavity is set to have the same morphology and roughness as the actual fracture surface.

[0007] The integral structure formed by connecting the crack A surface and the titanium powder sintered plate is connected to the rotation drive structure, which can drive the integral structure formed by connecting the crack A surface and the titanium powder sintered plate to rotate.

[0008] Preferably, the surface of the titanium powder sintered plate used to form the sealed cavity is processed using 3D printing to have the same morphology and roughness as the actual crack rough surface.

[0009] Preferably, the rotary drive structure includes a mounting frame, a rotating wheel, and a rotating wheel drive device. The integral structure formed by connecting the crack A surface with the titanium powder sintered plate is mounted on the mounting frame. Rotating wheels are mounted at both ends of the mounting frame in the horizontal direction. The axis of the rotating wheel is in the horizontal plane. The rotating wheel is connected to the rotating wheel drive device, which can drive the rotating wheel to rotate.

[0010] Preferably, the rotary drive device includes a drive motor and support wheels. Each rotary wheel has symmetrical support wheels arranged on both sides of the vertical plane below it. The rotation axis of the support wheels is parallel to the rotation axis of the rotary wheel. The drive motor is connected to the rotation axis of at least one support wheel. The support wheel serves as the drive wheel, which can drive the rotary wheel to rotate. After the rotary wheel rotates, it can drive the overall structure formed by connecting the crack A surface and the titanium powder sintered plate to rotate around the rotation axis of the rotary wheel, thereby realizing the rotation of the overall structure formed by connecting the crack A surface and the titanium powder sintered plate.

[0011] Preferably, both the crack A surface and the titanium powder sintered plate are rectangular in shape, and the length direction of both the crack A surface and the titanium powder sintered plate is along the horizontal direction.

[0012] Preferably, the sealed cavity has multiple vertically arranged inlets at one end where the inlets are located, and an outlet is provided at the other end of the sealed cavity directly opposite each inlet. Each inlet and each outlet is equipped with a valve. The fracturing fluid outlet of the fracturing fluid supply device is connected to a first pipeline, and the outlet end of the first pipeline has multiple branch pipes that are respectively connected to each inlet.

[0013] Preferably, a filtrate tank for collecting fracturing fluid flowing out of the titanium powder sintered plate is provided below the titanium powder sintered plate.

[0014] Preferably, the fracturing fluid supply device includes a fracturing fluid tank, an automatic sand-adding device, a mixing tank, a screw pump, a water pump, a hydrocyclone desander, and a proppant collection tank. The inlet of the water pump is connected to the fracturing fluid tank, and the outlet of the water pump is connected to a second pipeline.

[0015] The inlet of the mixing tank is connected to the fracturing fluid tank, the automatic sand adding device is connected to the sand inlet of the mixing tank, the mixing tank is equipped with a stirring device, the outlet of the mixing tank is connected to the inlet of the screw pump, the outlet of the screw pump is connected to a third pipeline, and a valve is installed on the third pipeline;

[0016] The outlets of the second and third pipelines are connected to one end of the fourth pipeline, and the other end of the fourth pipeline is connected to the inlet of the sealed cavity. The outlet of the sealed cavity is connected to the inlet of the hydrocyclone desander through the fifth pipeline. A bypass pipeline connected to the mixing tank is connected to the fifth pipeline. A valve is installed on the bypass pipeline. A valve is installed downstream of the bypass on the fifth pipeline. The sand outlet of the hydrocyclone desander is connected to the proppant collection tank, and the water outlet of the hydrocyclone desander is connected to the fracturing fluid tank.

[0017] Preferably, the titanium powder sintered plate meets the following conditions:

[0018] Titanium powder sintered plates with a filtration accuracy of 0.1–1 μm were used to simulate the filtration loss of ultra-low permeability reservoirs with a permeability of less than 5 mD.

[0019] Titanium powder sintered plates with a filtration accuracy of 1-10 μm were used to simulate the filtration loss of low-permeability reservoirs with a permeability of 5-50 mD.

[0020] Titanium powder sintered plates with a filtration accuracy of 10–50 μm were used to simulate the filtration loss of medium-permeability reservoirs with a permeability of 50–500 mD.

[0021] A titanium powder sintered plate with a filtration accuracy greater than 50 μm was used to simulate the filtration loss of a high-permeability reservoir with a permeability greater than 500 mD.

[0022] The present invention also provides a proppant sand-laying test method that takes into account the roughness of the crack surface and filtration loss. This test method is carried out using the test apparatus described above, and includes the following process:

[0023] A preset amount of fracturing fluid is injected into the sealed cavity of the fracture simulation sand-laying device through the fracturing fluid supply device. After the fracturing fluid injection is completed, the valves of the inlet and outlet are closed. After the proppant in the fracturing fluid has completely settled, the sand dike equilibrium height, sand dike equilibrium time, sand dike leading edge height, and sand dike leading edge distance are obtained.

[0024] The present invention has the following beneficial effects:

[0025] The proppant sand-laying experimental device of this invention, which considers the roughness of the fracture surface and filtration loss, uses titanium powder sintered plates as filtration materials to simulate the uniform filtration loss of various reservoirs. This allows the fracturing fluid to flow smoothly and exit in the form of droplets or mist, avoiding any impact on the flow field and thus interfering with the filtration performance of the titanium powder sintered plates. The surface of the titanium powder sintered plates used to form a closed cavity is designed to have the same morphology and roughness as the actual fracture surface. Compared with the method of simulating filtration loss through openings, this method does not cause abrupt changes in the flow field or the roughness of the fracture surface.

[0026] Furthermore, since current visual proppant-laying experimental devices are generally large in size, practice has shown that after the proppant-laying experiment is completed, a large amount of proppant remains between the crack plates of the device and is difficult to remove, seriously affecting the subsequent experiments. The cleaning problem of conventional crack proppant-laying devices is easily overlooked. The device provided by this invention uses a rotary drive structure to rotate the overall structure formed by the connection between the crack A surface and the titanium powder sintered plate. By using a large-volume flushing method through the liquid inlet of the sealed cavity, the proppant that still remains in the visual simulated crack after the experiment is cleaned. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall structure of the proppant sand-laying experimental device for considering the surface roughness of cracks and filtration loss in an embodiment of the present invention.

[0028] Figure 2 This is a side view of the connection structure between the overall structure formed by connecting the crack A surface and the titanium powder sintered plate in an embodiment of the present invention and the rotation drive structure.

[0029] Figure 3 for Figure 2 The left view.

[0030] Among them, 1-fracturing fluid tank, 2-automatic sand adding device, 3-mixing tank, 4-stirring rod, 5-weighbridge, 6-screw pump, 7-fracture simulation sand spreading device, 8-water pump, 9-cyclone desander, 10-proppant collection tank, 11-first valve, 12-first inlet valve, 13-second inlet valve, 14-third inlet valve, 15-filtrate tank, 16-first outlet valve, 17-second outlet valve, 18-third outlet valve, 1 9-Second valve, 20-Third valve, 21-Operating panel, 22-Digital camera, 23-Computer, 701-Hex bolt for fastening, 702-Washer, 703-Nut, 704-A-side frame, 705-Crack A-side, 706-Simulated perforation eye, 707-Titanium powder sintered plate, 708-B-side frame, 709-Rotator, 710-Circular arc rack, 711-Gear motor, 712-Base, 713-Fixed support rod. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0032] See Figures 1-3 This invention relates to a proppant-laying experimental apparatus considering the roughness of the fracture surface and filtration loss. The apparatus includes a fracturing fluid supply device and a fracture simulation proppant-laying device 7. The fracture simulation proppant-laying device 7 includes a titanium powder sintered plate 707, a rotary drive structure, and a transparent fracture A-face 705. The fracture A-face 705 is sealed to one side of the titanium powder sintered plate 707. The fracture A-face 705 and the titanium powder sintered plate 707 enclose a sealed cavity serving as a visual simulated fracture for proppant-laying experiments. The sealed cavity is used as a simulated fracture. An inlet and an outlet are respectively provided at both ends of the sealed cavity in the horizontal direction. The fracturing fluid supply device is connected to the inlet. Both the inlet and outlet are equipped with valves. The surface of the titanium powder sintered plate 707 used to enclose the sealed cavity is set to have the same morphology and roughness as the actual fracture surface.

[0033] The process of conducting a proppant sand-laying experiment considering crack surface roughness and filtration loss using the experimental apparatus described in this invention includes:

[0034] A preset amount of fracturing fluid is injected into the sealed cavity of the fracture simulation sand-laying device 7 through the fracturing fluid supply device. After the fracturing fluid injection is completed, the valves of the inlet and outlet are closed. After the proppant in the fracturing fluid has completely settled, the sand dike equilibrium height, sand dike equilibrium time, sand dike leading edge height and sand dike leading edge distance are obtained.

[0035] This invention takes into account the effects of uniform filtration of the crack surface and the roughness of the crack wall on the experiment during the sand laying process. The surface of the titanium powder sintered plate 707 can be processed by 3D printing to produce a surface with the same shape and roughness as the real crack surface. Therefore, this invention can more realistically simulate the laying pattern of the proppant in the crack during the construction process.

[0036] To address the problem of a large amount of proppant remaining between the crack plates in the device after the experiment and being difficult to drain, severely affecting subsequent experiments, this invention incorporates a rotary drive structure. Specifically, the integral structure formed by connecting crack A-side 705 and the titanium powder sintered plate 707 is connected to the rotary drive structure, which drives the integral structure formed by crack A-side 705 and the titanium powder sintered plate 707 to rotate. After the experiment, a high-volume flushing method is used through the liquid inlet of the sealed cavity to clean the proppant remaining in the visualized simulated crack. During the cleaning process, continuous rotation ensures that the proppant in the simulated crack mixes with the cleaning water and is discharged from the liquid outlet along with the cleaning water.

[0037] As one possible solution of the present invention, see Figure 2 and Figure 3 The rotary drive structure includes a mounting frame, a rotating wheel 709, and a rotating wheel drive device. The integral structure formed by connecting the crack A surface 705 and the titanium powder sintered plate 707 is mounted on the mounting frame. Rotating wheels 709 are mounted at both ends of the mounting frame in the horizontal direction. The axis of the rotating wheel 709 is in the horizontal plane. The rotating wheel 709 is connected to the rotating wheel drive device, which can drive the rotating wheel 709 to rotate.

[0038] As one possible solution of the present invention, see Figure 2 and Figure 3 The rotating drive device includes a drive motor and support wheels. Each rotating wheel 709 has support wheels symmetrically arranged on both sides of its vertical plane below it. The axis of rotation of the support wheels is parallel to the axis of rotation of the rotating wheel 709. At least one support wheel's axis is connected to the drive motor, which serves as the drive wheel. The other support wheels serve as driven wheels. The specific number of driven wheels can be determined by those skilled in the art based on the size of the entire device. If the overall structure formed by connecting the crack A surface 705 and the titanium powder sintered plate 707 is large, several support wheels can be used as drive wheels. If the overall structure is small, only one drive wheel is needed. The specific form is not required in this invention. In this invention, the drive wheel can drive the rotating wheel 709 to rotate. After the rotating wheel 709 rotates, it can drive the overall structure formed by connecting the crack A surface 705 and the titanium powder sintered plate 707 to rotate around the axis of rotation of the rotating wheel 709, thus realizing the rotation of the overall structure formed by connecting the crack A surface 705 and the titanium powder sintered plate 707.

[0039] See Figure 2 and Figure 3 The rotor 709 can be fitted onto the outside of the mounting frame, thus preventing interference between the rotor 709 and the inlet and outlet pipes at both ends of the integral structure formed by connecting the crack A surface 705 and the titanium powder sintered plate 707. This also shortens the... Figure 3 The dimensions shown are in the left-right direction. Furthermore, the rotating wheel 709, fitted outside the mounting frame, reduces the force required for rotation, lowering the power requirements of the motor and saving costs. For this type of rotating wheel 709, the support wheel and drive wheel contact the rotating wheel 709 via friction pairs. In this case, rubber rings are placed around the outer circumference of the support wheel, drive wheel, and rotating wheel 709 to achieve effective rotation of the rotating wheel 709. Alternatively, the support wheel, drive wheel, and rotating wheel 709 can also employ a gear structure.

[0040] See Figures 1-3 As an optional embodiment of the present invention, both the crack A-face 705 and the titanium powder sintered plate 707 are rectangular in shape, and the length directions of the crack A-face 705 and the titanium powder sintered plate 707 are along the horizontal direction.

[0041] See Figures 1-3 This invention provides a sealed cavity with multiple vertically arranged inlets at one end and outlets at the other end, each corresponding to an inlet. Each inlet and outlet is equipped with a valve. The fracturing fluid outlet of the fracturing fluid supply device is connected to a first pipeline, with multiple branch pipes at the outlet end of the first pipeline connected to each inlet. Because of the height difference between the different inlets and outlets, the proppant deposition morphology obtained in experiments with different combinations of inlets and outlets will vary. Therefore, this invention can provide more simulation scenarios.

[0042] See Figure 1 The present invention can also provide a filtrate tank 15 for collecting fracturing fluid flowing out of the titanium powder sintering plate 707 below the titanium powder sintering plate 707. The fracturing fluid can be recovered by using the filtrate tank 15, saving experimental costs.

[0043] See Figure 1The fracturing fluid supply device of the present invention can adopt the following structure: the fracturing fluid supply device includes a fracturing fluid tank 1, an automatic sand-adding device 2, a mixing tank 3, a screw pump 6, a water pump 8, a hydrocyclone desander 9, and a proppant collection tank 10. The inlet of the water pump 8 is connected to the fracturing fluid tank 1, and the outlet of the water pump 8 is connected to a second pipeline. The water pump 8 can provide cleaning water to the simulated fracture of the fracture simulation sand-laying device 7 to clean the proppant retained in the visualized simulated fracture. The inlet of the mixing tank 3 is connected to the fracturing fluid tank 1, and the automatic sand-adding device 2 is connected to the sand inlet of the mixing tank 3. The mixing tank 3 is equipped with a stirring device, which can be a stirring rod 4. The outlet of the mixing tank 3 is connected to the inlet of the screw pump 6, and the outlet of the screw pump 6 is connected to a third pipeline with a valve. In the mixing tank 3, the fracturing fluid provided in the fracturing fluid tank and the sand added by the automatic sand-adding device 2 can be mixed evenly, and then the screw pump 6 can be used to collect the proppant. Pump 6 delivers the fracturing fluid. The outlets of the second and third pipelines are connected to one end of the fourth pipeline, and the other end of the fourth pipeline is connected to the inlet of the sealed cavity. The fourth pipeline can inject the mixed flow delivered by the screw pump 6 into the simulated fracture for fracturing simulation. The outlet of the sealed cavity is connected to the inlet of the hydrocyclone desander 9 through the fifth pipeline. The fifth pipeline is connected to a bypass pipeline connected to the mixing tank 3. A valve is installed on the bypass pipeline. A valve is installed downstream of the bypass on the fifth pipeline. The mixed flow discharged from the outlet can be sent to the hydrocyclone desander 9 for separation of fracturing fluid and sand. Alternatively, the mixed flow can be directly sent to the mixing tank 3 through the bypass pipeline for reuse. The sand outlet of the hydrocyclone desander 9 is connected to the proppant collection tank 10, and the water outlet of the hydrocyclone desander 9 is connected to the fracturing fluid tank 1. The fracturing fluid separated in the hydrocyclone desander 9 can be recycled to the fracturing fluid tank 1, and the separated sand can be collected by the proppant collection tank 10. Therefore, this invention minimizes material waste, achieving near-zero waste, whether for simulating cracks or for cleaning, thus reducing experimental costs. Furthermore, the overall operation requires minimal manpower, reducing the physical exertion of the experimenter and ensuring their safety. This invention can also incorporate a weighbridge 5, on which the mixing tank 3 is placed, allowing for real-time measurement of the material's mass in the mixing tank 3.

[0044] The titanium powder sintered plate 707 of this invention is used to achieve uniform filtration loss. Its porosity and pore size can be artificially controlled. Titanium powder sintered plates with different porosity and permeability conditions are selected according to experimental design requirements to simulate the real filtration loss of various reservoirs.

[0045] Titanium powder sintered plate 707 with a filtration accuracy of 0.1-1μm was used to simulate the filtration loss of ultra-low permeability reservoirs with a permeability of less than 5mD.

[0046] Titanium powder sintered plate 707 with a filtration accuracy of 1-10 μm is used to simulate the filtration loss of low-permeability reservoirs with permeability of 5-50 mD.

[0047] Titanium powder sintered plate 707 with a filtration accuracy of 10-50 μm was used to simulate the filtration loss of medium-permeability reservoirs with a permeability of 50-500 mD.

[0048] A titanium powder sintered plate 707 with a filtration accuracy greater than 50 μm was used to simulate the filtration loss of a high-permeability reservoir with a permeability greater than 500 mD.

[0049] The above-described solution of the present invention can also include a control processing module, which includes an operating console 21, a digital camera 22, and a computer 23. The digital camera 22 is used to photograph and record the sand-laying morphology of the simulated cracks; the computer 23 is used to process the data of the sand embankment morphology in the images captured by the digital camera 22. The operating console 21 is connected to the automatic sand-adding device 2, the hydrocyclone desander 9, the water pump 8, the screw pump 6, and the agitator 4. The operating console 21 is used to control the operation of the automatic sand-adding device 2, the hydrocyclone desander 9, the water pump 8, the screw pump 6, and the agitator 4.

[0050] Example 1

[0051] like Figures 1-3 As shown, the proppant sand-laying experimental device considering the roughness of the fracture surface and filtration loss in this embodiment includes an experimental module and a control and processing module. The experimental module includes: fracturing fluid tank 1, automatic sand-adding device 2, mixing tank 3, stirring rod 4, weighbridge 5, screw pump 6, fracture simulation sand-laying device 7, water pump 8, cyclone desander 9, proppant collection tank 10, first valve 11, first inlet valve 12, second inlet valve 13, third inlet valve 14, filtrate tank 15, first outlet valve 16, second outlet valve 17, third outlet valve 18, second valve 19, third valve 20, operating table 21, digital camera 22, and computer 23.

[0052] The fracturing fluid tank 1 has a capacity of 1m³. 3 The automatic sand adding device 2 uses a YE2-225S-8 motor with a sand adding speed of 0.1 kg / min to 10 kg / min; the mixing tank 3 has a capacity of 1.5 m³. 3 The stirring rod 4 is 1.5m long and rotates at a speed of 5–300 r / min; the weighbridge 5 measures from 20 to 20,000 pounds with an error of 0.1%; the screw pump 6 is a G85-2 single screw pump with a maximum displacement of 30m³. 3 / h, motor power ≤11.5KW; water pump model 8 is WXZ50-32, maximum displacement is 50m³ / h. 3 / h, motor power ≤7.5KW; cyclone separator 9, model TSXL-100, filtration accuracy 5mm; proppant collection tank 10, capacity 0.2m³. 3 The filtrate tank 15 has a capacity of 0.1 m³. 3The digital camera model 22 is a Canon EOS 90D with an effective pixel count of 32.64 million pixels.

[0053] The hydrocyclone separator 9 is used to separate the sand-liquid mixture; the control panel 21 is used to control and adjust the operation of the automatic sand adding device 2, the stirring rod 4, the screw pump 6 and the water pump 8; the digital camera 22 is used to photograph and record the sand-laying pattern of the cracks; the computer 23 is used to process the data of the sand embankment pattern in the photos taken by the digital camera 22.

[0054] The crack simulation sand-laying device 7 includes a fastening hexagonal bolt 701, a washer 702, a nut 703, an A-side frame 704, a crack A-side 705, a simulated perforation hole 706, a titanium powder sintered plate 707, a B-side frame 708, a rotating wheel 709, a circular arc rack 710, a gear motor 711, a base 712, and a fixed support rod 713. The crack A-side 705 is made of transparent acrylic glass; the A-side frame 704, B-side frame 708, rotating wheel 709, base 712, and fixed support rod 713 are all made of solid steel. The A-side frame 704, B-side frame 708, and fixed support rod 713 together constitute the basic structure of the mounting frame. In this embodiment, the titanium powder sintered plate 707 adopts a cuboid structure, with a length of 3000mm, a height of 500mm, and a width of 200mm. The horizontal permeability of the titanium powder sintered plate 707 is more than ten times that of the vertical permeability, which is consistent with the actual reservoir properties. The fracturing fluid flows stably under the action of the titanium powder sintered plate and flows out in the form of water droplets or water mist on the side of the titanium powder sintered plate near the B-side frame 708. Compared with open-pore filtration, it avoids the flow field changes that would affect the filtration properties of the titanium powder sintered plate. The outflowing fracturing fluid is collected in the filtrate tank 15.

[0055] The closed cavity formed between crack A-side 705 and the titanium powder sintered plate 707 is a visual simulation crack for the sand-laying experiment. The closed cavity is a rectangular space with a length of 3000 mm, a height of 500 mm, and a width of 10 mm. On one side of the visual simulation crack ( Figure 2 The front side shown Figure 3 The opening on the right side (as shown) has three simulated perforation holes 706, which serve as fracturing fluid inlets. This visualizes the other side of the simulated fracture. Figure 2 The rear side (not shown) is shown. Figure 3 As shown on the left, three outlets are also provided at the opening. The three inlets and three outlets are directly opposite each other, and the horizontal height of each pair of inlets and outlets is the same. Due to the height difference between different inlets and outlets, the proppant sand laying morphology obtained in experiments with different combinations of inlets and outlets will be different.

[0056] The crack A-side 705 is externally formed by an A-side frame 704; the titanium powder sintered plate 707 is externally formed by a B-side frame 708. The A-side frame 704 is welded to the rotating wheel 709, and the B-side frame 708 is in contact with the rotating wheel 9. The A-side frame 704 and the B-side frame 708 are fixed to the overall structure formed by the crack A-side 705 and the titanium powder sintered plate 707 using a combination of fastening hexagonal bolts 701, washers 702, and nuts 703, thereby fixing the visualized simulated crack. Several fixed support rods 713 are provided in the middle of the A-side frame 704 and the B-side frame 708. The fixed support rods 713 are used to laterally (…) the crack A-side 705 and the titanium powder sintered plate 707. Figure 2 The left and right directions shown Figure 3 The front and rear directions are used to limit and support the flow, so as to prevent deformation of the crack A surface 705 and the titanium powder sintered plate 707 due to the internal pressure of the simulated crack during the experiment. This would lead to poor sealing between the crack A surface 705 and the titanium powder sintered plate 707, resulting in leakage and affecting the accuracy of the experimental results.

[0057] The lower half of the rotating wheel 709 has an arc-shaped rack 710 on its outer edge, such as... Figure 2 As shown, two gear motors 711 are symmetrically arranged on both sides of the vertical plane below each rotating wheel 709. The arc rack 710 meshes with the gears on the gear motors 711. The meshing parameters are as follows: gear module - 1; pressure angle - 20°; addendum coefficient - 0.3; dedendum coefficient - 1.6; synchronization ratio - 30.

[0058] The gear motor 711, model KA57 / 2, has a power of ≤7.5KW. The gears on the gear motor mesh with the arc rack 710 for transmission. When cleaning the visualized simulated crack, the gear motor drives the visualized simulated crack to rotate 45° to the left and right, coordinating with the water pump 8 to inject water and complete the cleaning process. The gear motor 711 is mounted on the base 712.

[0059] The method for conducting experiments using the proppant sand-laying experimental apparatus that considers crack surface roughness and filtration loss in this embodiment includes the following steps:

[0060] S1. Select a titanium powder sintering plate that meets the experimental design requirements.

[0061] S2. Prepare the required fracturing fluid (slightly excess) according to the experimental design, and pump the fracturing fluid into the fracture simulation proppant device until it is full. S2 specifically includes the following steps: Calculate the volume of the visualized simulated fracture to be 0.015 m³. 3Based on the fracturing fluid volume required by the experimental design, prepare an additional volume of fracturing fluid to simulate the volume of the visual fracture. Add the prepared fracturing fluid from fracturing fluid tank 1 to mixing tank 3. Open the first valve 11, the device inlet valve, the device outlet valve, and the second valve 19. Control the screw pump 6 from the operating panel 21 to pump the fracturing fluid into the visual simulated fracture. Observe the value on the weighbridge 5. Once the visual simulated fracture is filled with fracturing fluid, the fracturing fluid in the visual simulated fracture is equivalent to the pre-fracturing fluid. Close the screw pump 6 and all valves.

[0062] S3. According to the experimental design, add the required proppant to the fracturing fluid and stir to ensure uniform distribution. The specific process of S3 includes: determining the amount of proppant required by the experimental design, adding proppant to the mixing tank 3 using the automatic sand adding device 2, adjusting the sand adding speed to ensure a stable sand ratio, and simultaneously starting the stirring rod 4 to ensure that the fracturing fluid and proppant in the mixing tank 3 are mixed evenly.

[0063] The amount of proppant used needs to be calculated based on the sand ratio required by the experimental design. The calculation process is as follows:

[0064] m 砂 =V 压 ×S×ρ 砂

[0065] m 砂 —Propionage mass, in kg

[0066] S—Experimental sand ratio, %

[0067] V 压 —Fracturing fluid volume, in m³ 3

[0068] ρ 砂 —Prop density, in kg / m³ 3 .

[0069] S4. Pump the mixed sand solution into the simulated sand-laying device in the crack and record the entire experimental process. The specific steps of S4 include: turning on the digital camera 22 to record the sand-laying morphology in the simulated crack; opening the first valve 11 and the third valve 20; opening the device's inlet and outlet valves; setting the appropriate pump displacement on the control panel 21 and starting the screw pump 6; starting the timer when the proppant enters the simulated crack; observing the value on the weighbridge 5; when the value is 0, it indicates that the mixed sand solution pumping is complete; closing the screw pump 6, the stirring rod 4, and all valves; and ending the experiment after the proppant has completely settled in the simulated crack. Using the computer 23, data acquisition and processing are performed to obtain the sand embankment equilibrium height, sand embankment equilibrium time, sand embankment leading edge height, and sand embankment leading edge distance for this experiment.

[0070] S5. Clean the simulated fracture proppant device and dry the flushed proppant for the next experiment. The specific process of S5 includes: adding clean water to the fracturing fluid tank 1, opening the device's inlet valve, outlet valve, and third valve 20, setting the required water pump frequency on the operating platform 21, starting the water pump to pump clean water into the simulated fracture, and simultaneously turning on the gear motor 711. The gear meshes with the arc rack 710, causing the simulated fracture to rotate 45° to the left and right to clean it. The flushed proppant-fluid mixture enters the hydrocyclone desander 9, which separates the liquid and discharges the separated proppant into the fracturing fluid tank and the proppant into the proppant collection tank 10. The proppant is then dried in preparation for the next experiment.

[0071] Example 2

[0072] This embodiment uses the experimental setup of Embodiment 1, and the specific experimental method includes the following steps:

[0073] (1) A post-pressure proppant sand-laying experiment was conducted on the Chang 6 reservoir in the Wuqi area of ​​the Ordos Basin. The average porosity of the study area was 8.97%, and the average reservoir permeability was 0.32 mD. A titanium powder sintered plate with a filtration accuracy of 0.5 μm was selected to simulate the filtration loss of the reservoir.

[0074] (2) According to the experimental requirements, a total density of 1.05 g / cm³ was prepared. 3 0.8m of slickwater fracturing fluid 3 The prepared fracturing fluid is added from fracturing fluid tank 1 to mixing tank 3. The first valve 11, device inlet valve 12, device outlet valve 16, and second valve 19 are opened. The pump discharge rate on the control panel 21 is set to 1m³ / min. 3 / h and control the start of screw pump 6 to pump fracturing fluid into the visualized simulated fracture. Observe the value on weighbridge 5. When the value drops to 824 kg, the visualized simulated fracture is filled with fracturing fluid. At this time, the fracturing fluid in the visualized simulated fracture is equivalent to the pre-fracturing fluid. Close screw pump 6 and all valves.

[0075] (3) Select 30 / 50 mesh (average particle size 0.45 mm) ceramsite proppant with a bulk density of 1450 kg / m³. 3 The experimental sand ratio is 2%. Determine the required proppant dosage m for the experimental design. 砂 =V 压 ×S×ρ 砂 =0.8×0.02×1450=23.2kg, use automatic sand adding device 2 to add proppant to mixing tank 3, adjust the sand adding speed to 5kg / min to ensure a stable sand ratio, at the same time start the stirring rod 4 and set the speed to 60r / min, so that the fracturing fluid and proppant in mixing tank 3 are mixed evenly.

[0076] (4) Turn on the digital camera 22 to record the sand-laying morphology in the visualized simulated crack, open the first valve 11 and the third valve 20, open the device inlet valve 13 and the device outlet valve 17, and set the pump displacement on the control panel 21 to 4m³ / h. 3 Start the screw pump 6 and begin timing when the proppant enters the simulated crack. Observe the value on the weighbridge 5. When the value is 0, it indicates that the sand mixing liquid has been pumped out. Close the screw pump 6, agitator 4, and all valves. The experiment ends after the proppant in the simulated crack has completely settled. Use computer 23 for data acquisition and processing, obtaining the following results: sand embankment equilibrium height 395 mm, sand embankment equilibrium time 7.8 min, sand embankment leading edge height 90 mm, and sand embankment leading edge distance 450 mm.

[0077] (5) Add clean water to fracturing fluid tank 1, open the inlet valve 14, outlet valve 18 and third valve 20, and set the pump displacement on the control panel 21 to 6m³ / h. 3 At / h, the water pump is started to pump clean water into the visualized simulated fracture. At the same time, the gear motor 711 is turned on, and the gear meshes with the arc rack 710, driving the visualized simulated fracture to rotate at a speed of 10 r / min with a maximum left and right amplitude of 45° to clean the visualized simulated fracture. The flushed sand-liquid mixture enters the hydrocyclone desander 9, which discharges the separated liquid to the fracturing fluid tank 1 and the separated proppant to the proppant collection tank 10. The proppant is dried to prepare for the next experiment.

Claims

1. A proppant-laying sand experimental apparatus considering the roughness of crack surfaces and filtration loss, characterized in that, The device includes a fracturing fluid supply device and a fracture simulation sand-laying device (7). The fracture simulation sand-laying device (7) includes a titanium powder sintered plate (707), a rotary drive structure, and a transparent fracture A-face (705). The fracture A-face (705) is sealed to one side of the titanium powder sintered plate (707). The fracture A-face (705) and the titanium powder sintered plate (707) form a closed cavity that serves as a visual simulation fracture for sand-laying experiments. The closed cavity serves as a simulation fracture. The two ends of the closed cavity along the horizontal direction are respectively provided with an inlet and an outlet. The fracturing fluid supply device is connected to the inlet. Both the inlet and outlet are provided with valves. The surface on the titanium powder sintered plate (707) used to form the closed cavity is set to be the same as the surface roughness and roughness of the real fracture roughness surface. The titanium powder sintered plate (707) meets the following conditions: Titanium powder sintered plates (707) with a filtration accuracy of 0.1~1μm were used to simulate the filtration loss of ultra-low permeability reservoirs with a permeability of less than 5mD. Titanium powder sintered plates (707) with a filtration accuracy of 1~10μm were used to simulate the filtration loss of low-permeability reservoirs with permeability of 5~50mD. Titanium powder sintered plates (707) with a filtration accuracy of 10~50μm were used to simulate the filtration loss of medium-permeability reservoirs with a permeability of 50~500mD. A titanium powder sintered plate (707) with a filtration accuracy greater than 50 μm was used to simulate the filtration loss of a high-permeability reservoir with a permeability greater than 500 mD. The integral structure formed by connecting the crack A surface (705) and the titanium powder sintered plate (707) is connected to the rotation drive structure, which can drive the integral structure formed by connecting the crack A surface (705) and the titanium powder sintered plate (707) to rotate. The rotary drive structure includes a mounting frame, a rotating wheel (709), and a rotating wheel drive device. The integral structure formed by connecting the crack A surface (705) and the titanium powder sintered plate (707) is mounted on the mounting frame. Rotating wheels (709) are mounted on both ends of the mounting frame in the horizontal direction. The axis of the rotating wheel (709) is in the horizontal plane. The rotating wheel (709) is connected to the rotating wheel drive device, which can drive the rotating wheel (709) to rotate.

2. The proppant sand-laying experimental apparatus considering crack surface roughness and filtration loss according to claim 1, characterized in that, The rotating drive device includes a drive motor and support wheels. Each rotating wheel (709) has support wheels symmetrically arranged on both sides of the vertical plane below it. The rotation axis of the support wheel is parallel to the rotation axis of the rotating wheel (709). The drive motor is connected to the rotation axis of at least one support wheel. The support wheel serves as the drive wheel and can drive the rotating wheel (709) to rotate. After the rotating wheel (709) rotates, it can drive the overall structure formed by connecting the crack A surface (705) and the titanium powder sintered plate (707) to rotate around the rotation axis of the rotating wheel (709), thereby realizing the rotation of the overall structure formed by connecting the crack A surface (705) and the titanium powder sintered plate (707).

3. The proppant sand-laying experimental apparatus considering crack surface roughness and filtration loss according to claim 1, characterized in that, Both the crack A surface (705) and the titanium powder sintered plate (707) are rectangular in shape, and the length direction of the crack A surface (705) and the titanium powder sintered plate (707) is along the horizontal direction.

4. The proppant sand-laying experimental apparatus considering crack surface roughness and filtration loss according to claim 1, characterized in that, The sealed cavity has multiple vertical inlets at one end where the inlets are located, and an outlet at the other end where the outlets are located, positioned directly opposite each inlet. Each inlet and outlet is equipped with a valve. The fracturing fluid outlet of the fracturing fluid supply device is connected to a first pipeline, and the outlet end of the first pipeline has multiple branch pipes that are connected to each inlet respectively.

5. The proppant sand-laying experimental apparatus considering crack surface roughness and filtration loss according to claim 1, characterized in that, Below the titanium powder sintered plate (707) is a filtrate tank (15) for collecting the fracturing fluid flowing out from the titanium powder sintered plate (707).

6. The proppant sand-laying experimental apparatus considering crack surface roughness and filtration loss according to claim 1, characterized in that, The fracturing fluid supply device includes a fracturing fluid tank (1), an automatic sand adding device (2), a mixing tank (3), a screw pump (6), a water pump (8), a cyclone desander (9), and a proppant collection tank (10). The inlet of the water pump (8) is connected to the fracturing fluid tank (1), and the outlet of the water pump (8) is connected to a second pipeline. The inlet of the mixing tank (3) is connected to the fracturing fluid tank (1), the automatic sand adding device (2) is connected to the sand inlet of the mixing tank (3), the mixing tank (3) is equipped with a stirring device, the outlet of the mixing tank (3) is connected to the inlet of the screw pump (6), the outlet of the screw pump (6) is connected to a third pipeline, and a valve is provided on the third pipeline; The outlets of the second and third pipelines are connected to one end of the fourth pipeline. The other end of the fourth pipeline is connected to the inlet of the sealed cavity. The outlet of the sealed cavity is connected to the inlet of the cyclone desander (9) through the fifth pipeline. A bypass pipeline connected to the mixing tank (3) is connected to the fifth pipeline. A valve is installed on the bypass pipeline. A valve is installed downstream of the bypass on the fifth pipeline. The sand outlet of the cyclone desander (9) is connected to the proppant collection tank (10). The water outlet of the cyclone desander (9) is connected to the fracturing fluid tank (1).

7. A proppant sand-laying test method considering crack surface roughness and filtration loss, characterized in that, The experimental method is performed using the experimental apparatus described in any one of claims 1-6, and includes the following process: A preset amount of fracturing fluid is injected into the sealed cavity of the fracture simulation sand-laying device (7) through the fracturing fluid supply device. After the fracturing fluid injection is completed, the valves of the inlet and outlet are closed. After the proppant in the fracturing fluid has completely settled, the sand dam equilibrium height, sand dam equilibrium time, sand dam leading edge height and sand dam leading edge distance are obtained.

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