A high reynolds number slick water fracturing fluid drag reduction mechanism testing device and method

Abstract

The application discloses a high Reynolds number slick water fracturing fluid drag reduction mechanism testing device and method, the testing device comprises sand storage tanks, input pump one, sand mixing tank, input pump two, venturi, test tube, solid-liquid separator, input pump three which are sequentially connected, the test tube is a transparent glass tube, a flow meter one is arranged between the test tube and the solid-liquid separator; both ends of the test tube are provided with pressure sensors, the top of the test tube is provided with a PIV testing system, the front or back of the test tube is provided with a CCD camera; the output end of the input pump three is connected with the sand mixing tank and the liquid storage tank respectively, and the output end of the liquid storage tank is connected with the negative pressure taking port of the venturi. The application can simulate the high Reynolds number flow sand carrying process of the slick water fracturing fluid in the pipeline, can realize visual observation of the flow process, can quantitatively obtain the size of the friction of the fracturing fluid, can accurately capture the pipe flow field information and can reveal the drag reduction mechanism of the slick water fracturing fluid.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field development technology, and in particular to a testing device and method for the drag reduction mechanism of high Reynolds number slickwater fracturing fluid. Background Technology

[0002] With the continuous exploration and development of oil and gas resources, unconventional oil and gas resources such as shale gas have become a major challenge in oil and gas extraction. Hydraulic fracturing is a key technology for improving oil and gas production capacity. It involves injecting a certain volume of fracturing fluid into the formation to create artificial fractures. Subsequently, a proppant of a certain strength is injected and placed within the fractures to prevent complete closure and create highly conductive oil and gas flow channels. For unconventional oil and gas reservoirs such as shale, large-scale, high-volume injection of slickwater is generally used to create complex fracture networks. However, this high-volume injection method inevitably generates significant frictional resistance along the pipeline, increasing the load on the pump truck, the risk of construction, and reducing the lifespan of the pump truck. Therefore, drag-reducing agents are often added to the slickwater to reduce frictional losses, ensuring safe construction and improving economic efficiency. Thus, the drag-reducing properties of slickwater are of great significance for the economical and efficient development of oil and gas reservoirs.

[0003] In hydraulic fracturing, the frictional resistance of the fracturing fluid is mainly affected by factors such as the pumping rate, temperature, pressure, and type of drag-reducing agent. Current experimental setups for laboratory research on the drag-reducing performance of fracturing fluids have two limitations: firstly, they struggle to achieve tests under high Reynolds number flow conditions, resulting in significant discrepancies between test results and those obtained in actual field operations; secondly, they cannot analyze the drag-reducing mechanism of slickwater, failing to reveal the true reasons behind the varying drag-reducing performance of slickwater fracturing fluids. Therefore, it is essential to develop a device and method capable of testing the drag-reducing characteristics and mechanisms of slickwater flow at high Reynolds number levels. Summary of the Invention

[0004] To address the aforementioned problems, this invention aims to provide a testing device and method for the drag reduction mechanism of high Reynolds number slickwater fracturing fluid.

[0005] The technical solution of the present invention is as follows:

[0006] On one hand, a testing device for the drag reduction mechanism of high Reynolds number slickwater fracturing fluid is provided, comprising a sand storage tank, an input pump one, a sand mixing tank, an input pump two, a venturi tube, a test tube, a solid-liquid separator, and an input pump three connected in sequence. The input pump one enables the sand in the sand storage tank to enter the sand mixing tank at a uniform speed. The sand mixing tank is equipped with a stirring device. A valve one is installed on the pipeline between the sand mixing tank and the input pump two. The test tube is made of transparent glass. A flow meter one is installed between the test tube and the solid-liquid separator.

[0007] The test tube has a pressure sensor at its input end and a pressure sensor at its output end. The top of the test tube is equipped with a PIV test system, and the front or back of the test tube is equipped with a CCD camera.

[0008] The output end of the input pump three is connected to one input end of the tee via a pipeline; one output end of the tee is connected to the sand mixing tank via a pipeline, and valve two and flow meter two are sequentially installed on the connected pipeline; the other output end of the tee is connected to the storage tank via a pipeline, and valve three is installed on the connected pipeline; the output end of the storage tank is connected to the negative pressure tap of the venturi tube via a pipeline, and valve four is installed on the connected pipeline.

[0009] Preferably, the input pump is a screw pump.

[0010] Preferably, the second input pump includes two centrifugal pumps connected in parallel, and the third input pump is a centrifugal pump.

[0011] Preferably, the test tube is placed in a constant temperature water bath, which is made of transparent glass.

[0012] Preferably, a one-way valve is provided between the valve four and the venturi tube, allowing flow in the direction of the venturi tube.

[0013] Preferably, valve one is a ball valve, and valves two, three, and four are electric regulating valves.

[0014] Preferably, both the first flow meter and the second flow meter are turbine flow meters.

[0015] Preferably, the test tube has an inner diameter of 8 mm and a length of 3 m.

[0016] Preferably, the pressure sensor 1, pressure sensor 2, flow meter 1, flow meter 2, PIV testing system, and CCD camera are all connected to a computer.

[0017] On the other hand, a method for testing the drag reduction mechanism of high Reynolds number slickwater fracturing fluid is also provided, which uses the high Reynolds number slickwater fracturing fluid drag reduction mechanism testing device described in any one of the above-mentioned methods, and includes the following steps:

[0018] S1: Turn on the stirring device and prepare slickwater fracturing fluid containing tracer in the sand mixing tank;

[0019] S2: Open valve one, input pump two, input pump three, valve two, valve three, and valve four to circulate the fracturing fluid. During the circulation process, control valve two and valve three to keep the liquid level in the storage tank constant.

[0020] S3: Turn on the PIV test system and CCD camera, and adjust their positions relative to the test tube to ensure that the captured flow field information is clear and stable;

[0021] S4: Turn on input pump one to make the sand evenly enter the sand mixing tank and conduct a high Reynolds number slickwater sand-carrying friction test.

[0022] S5: The pressure difference between the two ends of the test tube is obtained through pressure sensor one and pressure sensor two, thereby obtaining the friction magnitude of the slickwater fracturing fluid;

[0023] By obtaining flow field information through PIV testing, the turbulence intensity, turbulence dissipation rate, and vortex intensity inside the test tube can be obtained, thereby revealing the drag reduction mechanism of slickwater fracturing fluid.

[0024] The beneficial effects of this invention are:

[0025] By incorporating a storage tank and a Venturi tube, this invention can simulate the high Reynolds number flow and proppant carrying process of slickwater fracturing fluid in a pipeline. By using a transparent glass test tube, pressure sensors at both ends of the test tube, a PIV testing system, and a CCD camera, this invention can not only visualize the flow process but also quantitatively obtain the magnitude of the fracturing fluid's friction and accurately capture the flow field information inside the tube, thereby revealing the drag reduction mechanism of slickwater fracturing fluid. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of the high Reynolds number slickwater fracturing fluid drag reduction mechanism testing device of the present invention.

[0028] Numbered in the diagram: 1-Sand storage tank, 2-Input pump one, 3-Sand mixing tank, 4-Input pump two, 5-Venturi tube, 6-Test tube, 7-Solid-liquid separator, 8-Input pump three, 9-Stirring device, 10-Valve one, 11-Flow meter one, 12-Pressure sensor one, 13-Pressure sensor two, 14-PIV testing system, 15-CCD camera, 16-Valve two, 17-Flow meter two, 18-Storage tank, 19-Valve three, 20-Valve four, 21-Constant temperature water bath, 22-Check valve. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and technical features described in this application can be combined with each other. It should also be pointed out that, unless otherwise indicated, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terms "comprising" or "including" and similar words used in this invention refer to elements or objects preceding the word that encompass the elements or objects listed following the word and their equivalents, without excluding other elements or objects.

[0030] In this invention, unless otherwise stated, the terms "first," "second," etc., are used to distinguish similar objects, not to describe a specific order or sequence. It should be understood that the terms used in this way generally refer to the direction shown in the accompanying drawings, or to the vertical, perpendicular, or gravitational direction of the component itself; similarly, for ease of understanding and description, "inner," "outer," etc., refer to the inner or outer contours relative to the component itself. However, the above directional terms are not intended to limit the invention.

[0031] On the one hand, such as Figure 1 As shown, this invention provides a testing device for the drag reduction mechanism of high Reynolds number slickwater fracturing fluid, comprising a sand storage tank 1, an input pump 2, a mixing tank 3, an input pump 4, a venturi tube 5, a test tube 6, a solid-liquid separator 7, and an input pump 8 connected in sequence. The input end of the input pump 8 is connected to the liquid output end of the solid-liquid separator 7. The input pump 2 enables the sand in the sand storage tank 1 to enter the mixing tank 3 at a uniform speed. The mixing tank 3 is equipped with a stirring device 9. A valve 10 is provided on the pipeline between the mixing tank 3 and the input pump 4. The test tube 6 is made of transparent glass, and a flow meter 11 is provided between the test tube 6 and the solid-liquid separator 7.

[0032] The test tube 6 has a pressure sensor 12 at its input end and a pressure sensor 13 at its output end. The test tube 6 has a PIV test system 14 at its top and a CCD camera 15 at its front or back.

[0033] The output end of the input pump 3 8 is connected to one input end of the tee via a pipeline; one output end of the tee is connected to the sand mixing tank 3 via a pipeline, and valve 2 16 and flow meter 2 17 are sequentially installed on the connected pipeline; the other output end of the tee is connected to the liquid storage tank 18 via a pipeline, and valve 3 19 is installed on the connected pipeline; the output end of the liquid storage tank 18 is connected to the negative pressure tap of the venturi tube 5 via a pipeline, and valve 4 20 is installed on the connected pipeline.

[0034] In the above embodiment, a CCD camera 15 is used to photograph the test tube 6, which can achieve a five-fold magnification ratio to obtain a larger and sharper image result.

[0035] For high-volume, high-Reynolds-number pumping methods in the field, this invention utilizes the Reynolds-number similarity criterion to increase the intake volume (i.e., increase the experimental displacement) by adding a Venturi tube 5, thereby achieving high Reynolds-number flow in the test tube 6. In another embodiment, this invention further achieves high Reynolds-number flow by reducing the diameter of the test tube 6; specifically, the test tube 6 is a straight tube with an inner diameter of 8 mm and a length of 3 m. In a specific embodiment, the test tube 6 is composed of multiple detachably connected sub-test tubes, thus making the size of the test tube 6 adjustable.

[0036] In one specific embodiment, input pump 2 is a screw pump, input pump 4 includes two centrifugal pumps connected in parallel; input pump 8 is a centrifugal pump; valve 10 is a ball valve; valves 16, 19, and 20 are electrically adjustable valves; flow meters 11 and 17 are both turbine flow meters. In this embodiment, the use of electrically adjustable valves facilitates long-term effective valve closure and ease of operation.

[0037] In one specific embodiment, the test tube 6 is placed in a constant temperature water bath 21, which is made of transparent glass. The constant temperature water bath 21 can simulate the formation temperature and prevent heat loss, and can also prevent inaccurate PIV process tests caused by reflections from directly photographing the test tube 6.

[0038] In one specific embodiment, a one-way valve 22 is provided between the valve 20 and the venturi tube 5, allowing flow in the direction of the venturi tube 5.

[0039] In one specific embodiment, the pressure sensor 12, pressure sensor 13, flow meter 11, flow meter 17, PIV testing system 14, and CCD camera 15 are respectively connected to a computer.

[0040] On the other hand, the present invention also provides a method for testing the drag reduction mechanism of high Reynolds number slickwater fracturing fluid, which uses the high Reynolds number slickwater fracturing fluid drag reduction mechanism testing device described in any one of the above-mentioned methods, and includes the following steps:

[0041] S1: Turn on the stirring device 9 and prepare the slickwater fracturing fluid containing the tracer in the sand mixing tank 3;

[0042] S2: Open valve 10, input pump 2 4, input pump 3 8, valve 2 16, valve 3 19, and valve 4 20 to circulate the fracturing fluid. During the circulation process, control valve 2 16 and valve 3 19 to keep the liquid level in the storage tank 18 constant.

[0043] S3: Turn on the PIV test system 14 and CCD camera 15, and adjust their positions relative to the test tube 6 to ensure that the captured flow field information is clear and stable.

[0044] S4: Turn on input pump 2 to make the sand evenly enter the sand mixing tank 3 and conduct a high Reynolds number slickwater sand-carrying friction test.

[0045] S5: The pressure difference between the two ends of the test tube 6 is obtained through pressure sensor 12 and pressure sensor 23, thereby obtaining the friction magnitude of the slickwater fracturing fluid.

[0046] By obtaining flow field information (fluid velocity) through PIV testing, the turbulence intensity, turbulence dissipation rate, and vortex intensity inside the test tube can be obtained, thereby revealing the drag reduction mechanism of slickwater fracturing fluid.

[0047] The turbulence intensity is calculated using the following formula:

[0048]

[0049]

[0050] In the formula: I is the turbulence intensity, which is dimensionless; R e ρ is the Reynolds number, dimensionless; ρ is the fluid density, kg / m³. 3 ν is the fluid velocity, m / s; d is the diameter of the test tube, m; μ is the viscosity, Pa·s.

[0051] The turbulence dissipation rate is calculated using the following formula:

[0052]

[0053] In the formula: ε is the turbulent dissipation rate, m 2 / s 3 C μ Typically taken as 0.09; k is turbulent kinetic energy, m 2 / s 2 ; l is the turbulence scale, m.

[0054] The vortex intensity is analyzed using vorticity, which is calculated using the following formula:

[0055]

[0056] In the formula: |Ω| is the vorticity, s -1 μx μ y μ z These represent the magnitudes of the velocities in the x, y, and z directions, respectively, in m / s.

[0057] When using the testing method of the present invention, different drag-reducing agents can be added in step S1 to qualitatively and quantitatively analyze the friction magnitude and drag-reducing mechanism of the corresponding high Reynolds number flowing slickwater fracturing fluid, which is a significant improvement compared with the prior art.

[0058] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A high Reynolds number slick water fracturing fluid drag reduction mechanism testing device, characterized in that, The device comprises a sand storage tank, an input pump one, a sand mixing tank, an input pump two, a Venturi tube, a test tube, a solid-liquid separator, and an input pump three connected in sequence. The input end of the test tube is provided with a pressure sensor one, the output end of the test tube is provided with a pressure sensor two, the top of the test tube is provided with a PIV test system, and the front or back of the test tube is provided with a CCD camera. The output end of the input pump three is connected with one input end of a three-way pipe through a pipeline, one output end of the three-way pipe is connected with the sand mixing tank through a pipeline, and valve two and flow meter two are arranged on the pipeline in sequence, the other output end of the three-way pipe is connected with a liquid storage tank through a pipeline, and valve three is arranged on the pipeline, and the output end of the liquid storage tank is connected with the negative pressure taking port of the Venturi tube through a pipeline, and valve four is arranged on the pipeline.

2. The drag reduction mechanism testing device for slick water fracturing fluid with high Reynolds number according to claim 1, characterized in that, The input pump one is a screw pump.

3. The drag reduction mechanism testing device for slick water fracturing fluid with high Reynolds number according to claim 1, characterized in that, The input pump two comprises two centrifugal pumps arranged in parallel, and the input pump three is a centrifugal pump.

4. The drag reduction mechanism testing device for slick water fracturing fluid with high Reynolds number according to claim 1, characterized in that, The test tube is arranged in a constant-temperature sink, and the constant-temperature sink is made of transparent glass.

5. The drag reduction mechanism testing device for slick water fracturing fluid with high Reynolds number according to claim 1, characterized in that, A one-way valve for flowing to the Venturi tube is arranged between the valve four and the Venturi tube.

6. The drag reduction mechanism testing device for slick water fracturing fluid with high Reynolds number according to claim 1, characterized in that, The valve one is a spherical valve, and the valve two, the valve three, and the valve four are electrically controlled valves.

7. The drag reduction mechanism testing device for slick water fracturing fluid with high Reynolds number according to claim 1, characterized in that, The flow meter one and the flow meter two are turbine flow meters.

8. The drag reduction mechanism testing device for slick water fracturing fluid with high Reynolds number according to claim 1, characterized in that, The inner diameter of the test tube is 8 mm, and the length is 3 m.

9. The drag reduction mechanism testing device for slick water fracturing fluid with high Reynolds number according to any one of claims 1-8, characterized in that, The pressure sensor one, the pressure sensor two, the flow meter one, the flow meter two, the PIV test system, and the CCD camera are connected with a computer respectively.

10. A method for testing the drag reduction mechanism of a slick water fracturing fluid at high Reynolds number, characterized in that, The high Reynolds number slick water fracturing fluid drag reduction mechanism test device is used for detection, and comprises the following steps: S1: opening the stirring device, and configuring the slick water fracturing fluid containing a tracer in the sand mixing tank; S2: opening the valve one, the input pump two, the input pump three, the valve two, the valve three, and the valve four, so that the fracturing fluid circulates, and the liquid level in the liquid storage tank is kept constant by controlling the valve two and the valve three; S3: opening the PIV test system and the CCD camera, and adjusting the positions of the PIV test system and the CCD camera and the test tube, so that the flow field information obtained by shooting is clear and stable; S4: opening the input pump one, so that the sand uniformly enters the sand mixing tank, and the high Reynolds number slick water sand carrying drag test is performed; S5: obtaining the pressure difference between the two ends of the test tube through the pressure sensor one and the pressure sensor two, so as to obtain the drag of the slick water fracturing fluid; The flow field information obtained by the PIV test is used to obtain the turbulent intensity, the turbulent dissipation rate, and the vortex intensity in the test tube, so as to obtain the drag reduction mechanism of the slick water fracturing fluid. The flow field information obtained by the PIV test is used to obtain the turbulent intensity, the turbulent dissipation rate, and the vortex intensity in the test tube, so as to obtain the drag reduction mechanism of the slick water fracturing fluid.

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