Sand conveying simulation system

Abstract

The invention relates to a sand conveying simulation system, which comprises a sand mixing tank, a liquid preparation tank and a sand settling tank, and is characterized in that a prepared liquid conveying system is mounted between the sand mixing tank and the liquid preparation tank, and is used for pumping prepared fracturing liquid in the liquid preparation tank into the sand mixing tank; a quantitative sand adding system is mounted at a feeding hole of the sand mixing tank and is used for adding proppant particles into the sand mixing tank; the bottom of the sand mixing tank is connected with a sand mixing liquid pumping system, a shaft is installed on a conveying pipeline of the sand mixing liquid pumping system, and the sand mixing liquid pumping system is used for pumping mixed sand mixing liquid into the shaft; a crack model is arranged at the shaft and connected to a recovery pipeline of the sand setting tank, and an outlet circulating pump is installed between the liquid preparation tank and the sand setting tank and used for pumping liquid at an outlet of the sand setting tank to the liquid preparation tank. The fracturing construction success rate, the sand adding effect and the yield increasing effect can be improved through sand conveying simulation of the cracks, and then efficient development of low-permeability oil and gas reservoirs can be achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas reservoir development research, and in particular relates to a sand transport simulation system. Background Art

[0002] With the advancement of fracturing technology and the development of unconventional and tight oil and gas reservoirs, the traditional single fracture system has gradually developed into a multi-scale fracture well network system. The corresponding fracture creation technology, diversion evaluation and water control proppant research are relatively complete, but the research on effective sand transport in multi-scale fracture systems is still in its infancy.

[0003] At present, preliminary simulation experiments have been carried out at home and abroad. The research results are mostly experimental phenomena and qualitative experimental conclusions. By revealing the transport rules of proppants in large-scale visualized fractures and optimizing parameters such as proppant type, fracturing fluid performance and displacement, it is helpful to overcome the key problems that need to be urgently solved on site, such as the difficulty of sand addition and high construction pressure faced by the development of low-permeability oil and gas reservoirs such as deep shale. However, the existing methods are difficult to conduct effective sand transport simulation experiments, which is not conducive to improving the basic forward-looking research on multi-scale fracture sand addition. Summary of the invention

[0004] In order to solve all or part of the above problems, the purpose of the present invention is to provide a sand transport simulation system, which can improve the success rate of fracturing construction, improve the sand addition effect, and improve the production increase effect through fracture sand transport simulation, thereby realizing the efficient development of low permeability oil and gas reservoirs.

[0005] According to one aspect of the present invention, a sand transport simulation system is provided, comprising a sand mixing tank, a liquid preparation tank and a sand settling tank, wherein a liquid preparation delivery system is installed between the sand mixing tank and the liquid preparation tank, and the liquid preparation delivery system is used to pump the prepared fracturing fluid in the liquid preparation tank into the sand mixing tank;

[0006] A quantitative sand adding system is installed at the feed inlet of the sand mixing tank, and the quantitative sand adding system is used to add proppant particles into the sand mixing tank;

[0007] The bottom of the sand mixing tank is connected to a sand mixing liquid pumping system, a wellbore is installed on the delivery pipeline of the sand mixing liquid pumping system, and the sand mixing liquid pumping system is used to pump the mixed sand mixing liquid into the wellbore;

[0008] A fracture model is provided at the wellbore, and the fracture model is connected to a recovery pipeline of the sand settling tank. An outlet circulation pump is installed between the liquid preparation tank and the sand settling tank, and the outlet circulation pump is used to pump the liquid at the outlet of the sand settling tank to the liquid preparation tank.

[0009] Furthermore, the sand mixing tank is connected to a first liquid additive system, which is used to add medicine to the sand mixing tank; the first liquid additive system includes a feeding tank and a plunger metering pump; a safety valve is provided between the liquid delivery system and the sand mixing tank.

[0010] Furthermore, a quantitative fiber adding system is installed at the feed inlet of the sand mixing tank, and the quantitative fiber adding system is used to transport fiber raw materials into the sand mixing tank;

[0011] The quantitative fiber adding system comprises a storage mechanism for storing fiber raw materials, a feeding mechanism for introducing the fiber raw materials into the sand mixing tank, and a conveying mechanism for conveying the fiber raw materials in the storage mechanism into the sand mixing tank.

[0012] Further, the sand mixing tanks are arranged in two groups, and the volumes of the two groups of sand mixing tanks are 500L and 1000L respectively, the two groups of sand mixing tanks are connected by pipelines, the first liquid additive system is connected to the pipeline between the two groups of sand mixing tanks, and valves are arranged on the pipeline between the first liquid additive system and each group of sand mixing tanks;

[0013] Each of the sand mixing tanks is respectively equipped with a mixing motor, each of the mixing motors is respectively connected to a corresponding stirring system, and the stirring speed range of the stirring system is 0-500r / min;

[0014] The sand mixing tank is equipped with a liquid level meter and an observation mirror. The quantitative fiber adding system and the quantitative sand adding system are both installed on the sand mixing tank with a volume of 1000L.

[0015] Furthermore, the liquid preparation tank is connected to a second liquid additive system, which adopts a plunger metering pump. The second liquid additive system is used to add medicine to the liquid preparation tank during liquid preparation; the second liquid additive system consists of a feeding tank, a plunger pump and a pipeline valve.

[0016] Furthermore, the liquid dispensing tanks are arranged in two groups, and the volumes of the two groups of liquid dispensing tanks are both 500L, the two groups of liquid dispensing tanks are connected by pipelines, the second liquid additive system is connected to the pipeline between the two groups of liquid dispensing tanks, and valves are arranged on the pipeline between the second liquid additive system and each group of liquid dispensing tanks;

[0017] A mixing motor is installed on each of the liquid preparation tanks, each of the mixing motors is connected to a mixing and stirring unit, and the liquid preparation tanks are fed with materials using a quantitative powder sprayer.

[0018] Furthermore, the sand settling tanks are arranged in two groups, and the volumes of the two groups of sand settling tanks are both 500L, each of the sand settling tanks is installed with a liquid level gauge, and a large-diameter ball valve is installed at the bottom of each sand settling tank.

[0019] Furthermore, the wellbore comprises an inner tube and an outer tube, the inner tube is provided with a plurality of perforations, the sand mixing liquid pumping system is used to pump the mixed sand mixing liquid into the inner tube, and the fracture model is provided on the outer tube;

[0020] The crack model is a main crack model, and a number of first-level branch crack models and a number of second-level branch crack models equal to the number of the first-level branch crack models are arranged on both sides of the main crack model. The main crack model is connected to each of the first-level branch crack models, and each of the first-level branch crack models is respectively connected to the corresponding second-level branch crack model, and all of the second-level branch crack models are connected to the recovery pipeline of the sand settling tank.

[0021] Furthermore, a first flow meter is installed between each of the secondary branch fracture models and the recovery pipeline of the sand settling tank; the lower end of the main fracture model is connected to the recovery pipeline of the sand settling tank through a connecting pipeline, and a first pressure transmitter is provided on the connecting pipeline;

[0022] The main fracture model has the function of simulating the sand transport conditions of fractures with different roughness and the function of simulating the filtration loss conditions of fractures with different permeabilities.

[0023] Furthermore, a second flow meter and a second pressure transmitter are installed on the delivery pipeline of the sand mixing liquid pumping system; a safety valve is installed between the outlet circulation pump and the liquid distribution tank; and the liquid distribution delivery system and the outlet circulation pump both use direct-connected screw pumps.

[0024] It can be seen from the above technical solution that the sand transport simulation system provided by the present invention has the following beneficial effects:

[0025] The sand transport simulation system of the present invention can be applied to multi-scale visual fracture sand transport simulation dominated by vertical fractures and horizontal fractures. The fracture sand transport simulation can improve the success rate of fracturing construction, improve the sand addition effect, and improve the production increase effect, thereby realizing the efficient development of low permeability oil and gas reservoirs.

[0026] The sand transport simulation system of the present invention can further improve the basic prospective research on multi-scale fracture sand addition, and can provide scientific research and technical support for the development of low permeability oil and gas reservoirs such as shale gas and tight oil. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of a sand transport simulation system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to better understand the purpose, structure and function of the present invention, a sand transport simulation system of the present invention is further described in detail below in conjunction with the accompanying drawings.

[0029] like Figure 1 As shown, it shows a sand transport simulation system of an embodiment of the present invention, including a sand mixing tank 1, a liquid preparation tank 2 and a sand settling tank 3, wherein a liquid preparation and delivery system 10 is installed between the sand mixing tank 1 and the liquid preparation tank 2, and the liquid preparation and delivery system 10 is used to pump the prepared fracturing fluid in the liquid preparation tank 2 into the sand mixing tank 1; a quantitative sand adding system 9 is installed at the feed inlet of the sand mixing tank 1, and the quantitative sand adding system 9 is used to add proppant particles into the sand mixing tank 1; a sand mixing liquid pumping system 12 is connected to the bottom of the sand mixing tank 1, and a wellbore 14 is installed on the delivery pipeline of the sand mixing liquid pumping system 12, and the sand mixing liquid pumping system 12 is used to pump the mixed liquid into the wellbore 14; a fracture model is provided at the wellbore 14, and the fracture model is connected to the recovery pipeline of the sand settling tank 3, and an outlet circulation pump 11 is installed between the liquid preparation tank 2 and the sand settling tank 3, and the outlet circulation pump 11 is used to pump the sand mixing liquid at the outlet of the sand settling tank 3 to the liquid preparation tank 2.

[0030] Specifically, the liquid preparation tank 2 is used to prepare fracturing fluid, and the fracturing fluid prepared in the liquid preparation tank 2 is pumped into the sand mixing tank 1 through the liquid preparation and delivery system 10. A quantitative sand adding system 9 is installed at the feed port of the sand mixing tank. The quantitative sand adding system 9 is used to add proppant particles into the sand mixing tank 1. The added proppant particles and fracturing fluid are mixed in the sand mixing tank 1, and the mixed sand is pumped into the wellbore 14 through the mixed sand pumping system 12. A fracture model is provided at the wellbore 14. After passing through the fracture model, the mixed sand enters the sand settling tank 3 through the recovery pipeline of the sand settling tank 3. The liquid in the mixed sand (mainly fracturing fluid) is pumped to the liquid preparation tank 2 through the outlet circulation pump 11 for reuse.

[0031] The quantitative sand adding system 9 adds proppant particles into the sand mixing tank 1 in a uniform and quantitative manner, and controls the amount of proppant added by different adding times. Adding different amounts of proppant can meet the simulation requirements under different sand ratios.

[0032] The sand transport simulation system of the embodiment of the present invention can be applied to multi-scale visual fracture sand transport simulation dominated by vertical and horizontal fractures. The sand transport simulation of fractures can improve the success rate of fracturing construction, improve the sand addition effect, and improve the production increase effect, thereby realizing the efficient development of low-permeability oil and gas reservoirs. The sand transport simulation system of the embodiment of the present invention can further improve the basic prospective research of multi-scale fracture sand addition, and can provide scientific research and technical support for the development of low-permeability oil and gas reservoirs such as shale gas and tight oil.

[0033] The sand mixing tank 1 is connected to a first liquid additive system 6 for adding reagents to the sand mixing tank 1 ; the first liquid additive system 6 comprises a feeding tank and a plunger metering pump; a safety valve is provided between the liquid delivery system 10 and the sand mixing tank 1 .

[0034] The first liquid additive system 6 of this embodiment is used to add medicine to the sand mixing tank 1. The feeding tank is used to store the medicine to be added, and the feeding tank and the sand mixing tank 1 are connected by a pipeline. A valve is provided on the pipeline to control the conduction or cutoff of the pipeline. The plunger metering pump is provided on the pipeline between the feeding tank and the sand mixing tank 1, and the plunger metering pump is used to pump the medicine in the feeding tank to the sand mixing tank 1. The safety valve of this embodiment is used to play a protective role in abnormal situations.

[0035] The sand mixing tank 1 is connected to a quantitative fiber adding system 8, which is used to convey fiber raw materials into the sand mixing tank 1. Specifically, the quantitative fiber adding system 8 includes a storage mechanism for storing fiber raw materials, a feeding mechanism for feeding fiber raw materials into the sand mixing tank 1, and a conveying mechanism for conveying the fiber raw materials in the storage mechanism into the sand mixing tank 1.

[0036] Among them, the sand mixing tanks 1 are set into two groups, and the volumes of the two groups of sand mixing tanks 1 are 500L and 1000L respectively. The two groups of sand mixing tanks 1 are connected by pipelines, and the first liquid additive system 6 is connected to the pipeline between the two groups of sand mixing tanks 1. Valves are provided on the first liquid additive system 6 and the pipelines between the two groups of sand mixing tanks 1. When necessary, the connection between the two sand mixing tanks 1 can be achieved by opening the valve on the pipeline between the two groups of sand mixing tanks 1.

[0037] A mixing motor 4 is installed on each mixing tank 1, and each mixing motor 4 is connected to a corresponding stirring system. The mixing motor 4 of this embodiment is used to drive the stirring system to rotate. The stirring system is located in the mixing tank 1. The rotation of the stirring system can make the proppant particles, fracturing fluid, reagents and fiber raw materials in the mixing tank mix faster, thereby shortening the mixing time. The stirring speed range of the stirring system is 0-500r / min.

[0038] The sand mixing tank 1 is equipped with a level meter and an observation mirror. The level meter is used to visually read the liquid level of the liquid in the sand mixing tank 1, and the observation mirror is used to conveniently observe the situation in the sand mixing tank 1. In specific implementation, the observation mirror is, for example, an anti-fog observation mirror with light.

[0039] Among them, the quantitative fiber adding system 8 and the quantitative sand adding system 9 are both installed on the sand mixing tank 1 with a volume of 1000L. When necessary, the valve between the two groups of sand mixing tanks 1 can be opened to allow the fiber raw materials and / or proppant particles in the sand mixing tank 1 with a volume of 1000L to flow into the sand mixing tank 1 with a volume of 500L.

[0040] The liquid preparation tank 2 is connected to a second liquid additive system 7, and the second liquid additive system 7 is used to add medicine to the liquid preparation tank 2 during liquid preparation; the second liquid additive system 7 includes a feeding tank and a plunger metering pump.

[0041] The second liquid additive system 7 of this embodiment is used to add medicine to the liquid preparation tank 2 during liquid preparation. The feed tank is used to store the medicine to be added, and the feed tank and the liquid preparation tank 2 are connected by a pipeline. A valve is provided on the pipeline to control the conduction or cutoff of the pipeline. The plunger metering pump is provided on the pipeline between the feed tank and the liquid preparation tank 2, and the plunger metering pump is used to pump the medicine in the feed tank to the liquid preparation tank 2.

[0042] Among them, the liquid preparation tank 2 is set into two groups, and the volume of the two groups of liquid preparation tanks 2 is 500L. The two groups of liquid preparation tanks 2 are connected by pipelines. The second liquid additive system 7 is connected to the pipeline between the two groups of liquid preparation tanks 2, and valves are provided on the pipeline between the second liquid additive system 7 and each group of liquid preparation tanks 2. When used, opening the corresponding valve can achieve the purpose of adding medicine to the corresponding liquid preparation tank 2 through the second liquid additive system 7.

[0043] Each liquid preparation tank 2 is equipped with a mixing motor 5, each mixing motor 5 is connected to a mixing and stirring unit, the mixing motor 5 is used to drive the mixing and stirring unit to rotate to achieve a stirring effect, the mixing and stirring unit is arranged in each liquid preparation tank 2, and the mixing and stirring unit rotates to accelerate the mixing of the liquid and powder therein. The liquid preparation tank 2 uses a quantitative powder sprayer for feeding.

[0044] Among them, the sand settling tank 3 is set in two groups, and the volume of the two groups of sand settling tanks 3 is 500L. The two groups of sand settling tanks 3 are connected to the outlet circulation pump 11. The mixed sand liquid entering the sand settling tank 3 through the fracture model will be separated into the lower layer of sediment and the upper liquid. The outlet circulation pump 11 is used to pump the upper liquid of the sand settling tank 3 to the liquid distribution tank 2 again. A large-diameter ball valve is installed at the bottom of each sand settling tank 3, and the lower layer of sediment in the sand settling tank 3 is discharged through the large-diameter ball valve. Among them, a liquid level gauge is installed on each sand settling tank 3, and the liquid level gauge is used to intuitively read the liquid level of the liquid in the sand settling tank 3.

[0045] The wellbore includes an inner tube and an outer tube, the outer tube is sleeved on the outside of the inner tube, a plurality of perforations are arranged on the inner tube, and the sand mixing liquid pumping system 12 is used to pump the mixed sand mixing liquid into the inner tube, and the fracture model is arranged on the outer tube. After the sand mixing liquid pumping system 12 pumps the mixed sand mixing liquid into the inner tube, the mixed sand mixing liquid flows into the outer tube through the perforations of the inner tube, and then enters the fracture model on the outer tube, and finally the sand mixing liquid entering the fracture model flows into the sand settling tank 3.

[0046] Among them, the crack model is a main crack model 15, and a number of first-level branch crack models 17 and second-level branch crack models 16 equal in number to the first-level branch crack models 17 are arranged on both sides of the main crack model 15. The main crack model 15 is connected to each first-level branch crack model 17, and each first-level branch crack model 17 is respectively connected to the corresponding second-level branch crack model 16, and all the second-level branch crack models 16 are connected to the recovery pipeline of the sand settling tank 3.

[0047] The fracture model of this embodiment includes a main fracture model 15, a plurality of primary branch fracture models 17 and secondary branch fracture models 16 equal in number to the primary branch fracture models 17, wherein the main fracture model 15 is arranged on the outer cylinder, the sand mixing liquid first flows into the main fracture model 15, then flows into the primary branch fracture model 17 connected thereto through the main fracture model 15, then flows into the secondary branch fracture model 16, finally flows into the recovery pipeline of the sand settling tank 3 through the secondary branch fracture model 16, and finally the sand mixing liquid enters the sand settling tank 3.

[0048] Among them, the main crack model 15, several first-level branch crack models 17 and several second-level branch crack models 16 are all constructed by rock plates arranged in the outer tube. Two rock plates can build a crack, and the mixed sand liquid flows through the crack between the two rock plates on the outer tube to realize the simulation of the crack sand transportation situation.

[0049] Among them, a horizontal dip angled crack model 18 is installed on each secondary branch crack model 16, the dimensions of the main crack model 15, the primary branch crack model 17 and the secondary branch crack model 16 are all 1000 mm long × 600 mm high, the crack width range of the main crack model 15 is 0-20 mm, the dimensions of the horizontal dip angled crack model 18 are 800 mm long × 600 mm high, and the crack width range of the horizontal dip angled crack model 18 is 0-20 mm.

[0050] Among them, a first flow meter 19 is installed between each secondary branch fracture model 16 and the recovery pipeline of the sand settling tank 3; the lower end of the main fracture model 15 is connected to the recovery pipeline of the sand settling tank 3 through a connecting pipeline, and a first pressure transmitter 20 is provided on the connecting pipeline. The first flow meter 19 of this embodiment is used to monitor the change of flow rate, and the first pressure transmitter 20 is used to convert the corresponding pressure signal into an electrical signal.

[0051] Among them, the main fracture model 15 has the function of simulating the sand transport conditions of fractures with different roughness and the function of simulating the filtration loss conditions with different permeabilities.

[0052] To simulate the sand transport of cracks with different roughness, the corresponding main fracture model can be built using rock plates with different roughness. To simulate the filtration loss with different permeabilities, small holes are distributed on the rock plate, and a back plate is set on the side of the rock plate with small holes away from the other rock plate. The filtration loss through the small holes is the filtration loss with different permeabilities. The filtration loss through the small holes can be fed back by the weight of the collected filtration loss. After the filtration loss passes through the small holes, it is blocked by the back plate in the outer cylinder. Therefore, the setting of the back plate can facilitate the collection of the filtration loss through the small holes. The aperture of the small holes is set to 1.4 cm, for example.

[0053] Among them, the conveying pipeline of the sand mixing liquid pumping system 12 is installed with a second flow meter 13 and a second pressure transmitter 21; a safety valve is installed between the outlet circulation pump 11 and the liquid distribution tank 2; the liquid distribution delivery system 10 and the outlet circulation pump 11 both use direct-connected screw pumps. The second flow meter 13 of this embodiment is used to monitor the change of flow rate, and the second pressure transmitter 21 is used to convert the corresponding pressure signal into an electrical signal.

[0054] The embodiment of the present invention adopts 3D printing technology to obtain a simulated rock plate that simulates real rock plates with different permeabilities. The aforementioned main crack model 15, several first-level branch crack models 17 and several second-level branch crack models 16 are all built by the simulated rock plate. 3D printing performs numerical reconstruction through "reverse engineering" according to the numerical reconstruction method. The reconstructed model surface has the same parameters as the real rough surface and filtration loss surface, which is used as the basis for PC plate engraving, and is equipped with numerical reconstruction software and a core fracture surface scanner (scanning area ≥178*38mm), so as to realize the role of introducing roughness variables or fixing rough surface features in experimental research, thereby realizing the function of simulating the sand transport conditions of cracks with different roughness, and the function of simulating filtration loss conditions with different permeabilities.

[0055] The 3D printing method of the simulated rock slab simulating the real rock slab with different permeability comprises the following steps:

[0056] Rough surface data acquisition: Scanning technology is used to measure the size and shape of real rock slabs, which is applied to reverse engineering. It is responsible for surface data copying and three-dimensional measurement of workpieces. For existing three-dimensional objects without technical documents, the contour data of the object can be quickly measured, and then constructed, edited, and modified to generate a digital model of the surface in a universal output format. The use of three-dimensional laser scanning can fully collect the digital terrain information of the rough fracture surface of shale and digitally replicate the rough fracture surface of shale.

[0057] Rough fracture surface reconstruction: Open the natural fractures in shale to obtain the rough fracture surface of shale, and use a laser scanner to collect data. After the data is collected, the software is used to remove invalid noise data and organize the data. The rough fracture surface morphology of shale obtained by the laser scanner will produce some noise points during the actual scanning process. When performing single rough surface analysis, a noise reduction process is performed.

[0058] Data collation: Use a laser scanner to scan in the XY plane, and present the scanned single rough surface data in the form of regular square grid data.

[0059] Analysis of the surface characteristics of rough fractures in shale: Analyze the rough fracture surface of shale, study the elevation distribution and fractal dimension of the rough surface. To facilitate data comparison, take the lowest point of each rough fracture surface as the starting reference plane with coordinate 0, calculate the normal distribution characteristics of the elevation difference of the rock rough surface, and then use the box covering method to calculate the fractal dimension of the surface roughness. The box covering method is to cover the rough surface with cubic boxes of different sizes. The relationship between the number of box covers and the box size represents the size of the fractal dimension. The calculation formula of the box covering method is as follows:

[0060]

[0061] In the formula, D represents the fractal dimension; N represents the number of covered boxes; ε represents the size of the covered box. According to the above formula, the fractal dimension of the rough fracture surface of shale is between 2.467 and 2.879.

[0062] Printing: The formed shale rough surface model is replicated on the material surface to realize the materialization of the numerical model and perform 3D printing to obtain a simulated rock plate.

[0063] The sand transport simulation system of the embodiment of the present invention can be applied to a multi-scale visual fracture sand transport simulation experimental device dominated by vertical fractures and horizontal fractures; the embodiment of the present invention can further improve the basic forward-looking research on multi-scale fracture sand addition; the embodiment of the present invention can continuously provide scientific research and technical support for the development of low permeability oil and gas reservoirs such as shale gas and tight oil, and then promote the research results to the development of tight and low permeability oil and gas reservoirs; the embodiment of the present invention improves the success rate of fracturing construction, improves the sand addition effect, improves the production increase effect, and realizes the efficient development of low permeability oil and gas reservoirs.

[0064] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0065] In addition, the terms "one", "two", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. In the description of the present invention, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0066] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; 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 replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A sand transport simulation system, characterized in that: The invention comprises a sand mixing tank (1), a liquid preparation tank (2) and a sand settling tank (3), wherein a liquid preparation and delivery system (10) is installed between the sand mixing tank (1) and the liquid preparation tank (2), and the liquid preparation and delivery system (10) is used to pump the prepared fracturing fluid in the liquid preparation tank (2) into the sand mixing tank (1); A quantitative sand adding system (9) is installed at the feed inlet of the sand mixing tank (1), and the quantitative sand adding system (9) is used to add proppant particles into the sand mixing tank (1); The bottom of the sand mixing tank (1) is connected to a sand mixing liquid pumping system (12), a wellbore (14) is installed on the delivery pipeline of the sand mixing liquid pumping system (12), and the sand mixing liquid pumping system (12) is used to pump the mixed sand mixing liquid into the wellbore (14); A fracture model is provided at the wellbore (14), and the fracture model is connected to the recovery pipeline of the sand settling tank (3). An outlet circulation pump (11) is installed between the liquid preparation tank (2) and the sand settling tank (3), and the outlet circulation pump (11) is used to pump the liquid at the outlet of the sand settling tank (3) to the liquid preparation tank (2).

2. The sand transport simulation system according to claim 1, characterized in that: The sand mixing tank (1) is connected to a first liquid additive system (6), and the first liquid additive system (6) is used to add medicine to the sand mixing tank (1); the first liquid additive system (6) comprises a feeding tank and a plunger metering pump; and a safety valve is provided between the liquid mixing and conveying system (10) and the sand mixing tank (1).

3. The sand transport simulation system according to claim 2, characterized in that: A quantitative fiber adding system (8) is installed at the feed inlet of the sand mixing tank (1), and the quantitative fiber adding system (8) is used to transport fiber raw materials into the sand mixing tank (1); The quantitative fiber adding system (8) comprises a storage mechanism for storing fiber raw materials, a feeding mechanism for introducing the fiber raw materials into the sand mixing tank (1), and a conveying mechanism for conveying the fiber raw materials in the storage mechanism into the sand mixing tank (1).

4. The sand transport simulation system according to claim 3, characterized in that: The sand mixing tanks (1) are arranged in two groups, and the volumes of the two groups of sand mixing tanks (1) are 500L and 1000L respectively. The two groups of sand mixing tanks (1) are connected via pipelines. The first liquid additive system (6) is connected to the pipeline between the two groups of sand mixing tanks (1), and valves are arranged on the pipeline between the first liquid additive system (6) and each group of sand mixing tanks (1); Each of the sand mixing tanks (1) is respectively equipped with a mixing motor (4), and each of the mixing motors (4) is respectively connected to a corresponding stirring system, and the stirring speed range of the stirring system is 0-500r / min; The sand mixing tank (1) is equipped with a liquid level meter and an observation mirror. The quantitative fiber adding system (8) and the quantitative sand adding system (9) are both installed on the sand mixing tank (1) with a volume of 1000L.

5. The sand transport simulation system according to claim 1, characterized in that: The liquid preparation tank (2) is connected to a second liquid additive system (7), the second liquid additive system (7) adopts a plunger metering pump, and the second liquid additive system (7) is used to add medicine to the liquid preparation tank (2) during liquid preparation; the second liquid additive system (7) is composed of a feeding tank, a plunger pump and a pipeline valve.

6. The sand transport simulation system according to claim 5, characterized in that: The liquid dispensing tanks (2) are arranged in two groups, and the volumes of the two groups of liquid dispensing tanks (2) are both 500 L. The two groups of liquid dispensing tanks (2) are connected via pipelines, the second liquid additive system (7) is connected to the pipeline between the two groups of liquid dispensing tanks (2), and valves are arranged on the pipeline between the second liquid additive system (7) and each group of liquid dispensing tanks (2); A mixing motor (5) is installed on each of the liquid preparation tanks (2), and each of the mixing motors (5) is connected to a mixing and stirring unit. The liquid preparation tanks (2) are fed with materials using a quantitative powder spraying machine.

7. The sand transport simulation system according to claim 1, characterized in that: The sand settling tanks (3) are arranged in two groups, and the volumes of the two groups of sand settling tanks (3) are both 500L. A liquid level gauge is installed on each of the sand settling tanks (3), and a large-diameter ball valve is installed at the bottom of each of the sand settling tanks (3).

8. The sand transport simulation system according to claim 1, characterized in that: The wellbore comprises an inner tube and an outer tube, the inner tube is provided with a plurality of perforations, the sand mixing liquid pumping system (12) is used to pump the mixed sand mixing liquid into the inner tube, and the fracture model is provided on the outer tube; The crack model is a main crack model (15), and a plurality of first-level branch crack models (17) and a number of second-level branch crack models (16) equal to the number of the first-level branch crack models (17) are arranged on both sides of the main crack model (15); the main crack model (15) is connected to each of the first-level branch crack models (17), and each of the first-level branch crack models (17) is respectively connected to a corresponding second-level branch crack model (16), and all of the second-level branch crack models (16) are connected to a recovery pipeline of the sand settling tank (3).

9. The sand transport simulation system according to claim 8, characterized in that: A first flow meter (19) is installed between each of the secondary branch fracture models (16) and the recovery pipeline of the sand settling tank (3); the lower end of the main fracture model (15) is connected to the recovery pipeline of the sand settling tank (3) through a connecting pipeline, and a first pressure transmitter (20) is provided on the connecting pipeline; The main fracture model (15) has the function of simulating the sand transport conditions of fractures with different roughness, and the function of simulating the filtration loss conditions of fractures with different permeabilities.

10. The sand transport simulation system according to claim 1, characterized in that: A second flow meter (13) and a second pressure transmitter (21) are installed on the delivery pipeline of the sand mixing liquid pumping system (12); a safety valve is installed between the outlet circulation pump (11) and the liquid preparation tank (2); and the liquid preparation delivery system (10) and the outlet circulation pump (11) both adopt direct-connected screw pumps.

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