Fracturing fluid viscosity reduction simulation experiment system and experiment method based on ultrasonic cavitation effect

Abstract

The application discloses a fracturing fluid viscosity reduction simulation experiment system based on ultrasonic cavitation effect, which comprises a cavity, an ultrasonic cavitation mechanism, a laser measuring mechanism, an infrared observation mechanism, a loading mechanism and a data acquisition computer, the ultrasonic cavitation mechanism comprises an ultrasonic wave driving controller and an ultrasonic wave transducer, and the laser measuring mechanism comprises a laser driving power supply, a laser emitter and a photosensitive sensor. The application also provides a fracturing fluid viscosity reduction simulation experiment method based on ultrasonic cavitation effect, which comprises the following steps: step S1, establishing the fracturing fluid viscosity reduction simulation experiment system based on ultrasonic cavitation effect, and supplying gas to the cavity to pressurize; step S2, emitting ultrasonic waves, starting the laser measuring mechanism and the infrared observation mechanism, and transmitting data to the data acquisition computer; step S3, data processing; and step S4, setting multiple groups of control experiments, which has the advantages of joint observation, novel conception, ingenious design idea and accurate experimental data.

Description

Technical Field

[0001] This invention belongs to the field of ultrasonic cavitation fracturing fluid viscosity reduction technology, specifically relating to a fracturing fluid viscosity reduction simulation experimental system and experimental method based on ultrasonic cavitation effect. Background Technology

[0002] Coal resources are crucial for my country's industrial development and the livelihood of its people, with high demand across various sectors. However, coal mining presents numerous safety challenges. Due to the dense and hard structure of coal, it generally exhibits low permeability and is prone to coal and gas outbursts. Therefore, improving coal permeability to reduce these risks is urgently needed. To address this, hydraulic fracturing is widely used both domestically and internationally to enhance coal permeability and mitigate coal and gas outburst hazards. However, after hydraulic fracturing, the fluid's viscosity and other characteristics make it prone to becoming trapped within the coal seam fractures. With the recent development of ultrasonic technology in the coal industry, it has been found to significantly reduce the viscosity of fracturing fluids. Utilizing the cavitation effect of ultrasound, effective viscosity reduction of fracturing fluid can be achieved, thereby enhancing its backflow. However, due to the lack of a mature experimental system based on the cavitation effect of ultrasound on fracturing fluid viscosity reduction, the mechanism of action of ultrasound and its energy-based viscosity-reducing effect on fracturing fluid remain incompletely understood. Summary of the Invention

[0003] This invention aims to provide a simulation experimental system and method for reducing the viscosity of fracturing fluid based on ultrasonic cavitation effect, which solves the problem that due to the lack of a mature experimental system for reducing the viscosity of fracturing fluid based on ultrasonic cavitation effect, the mechanism of action of ultrasound and the effect of ultrasonic energy on the viscosity reduction of fracturing fluid are not yet fully understood.

[0004] Therefore, the technical solution adopted in this invention is as follows: a fracturing fluid viscosity reduction simulation experimental system based on ultrasonic cavitation effect, comprising a cavity, an ultrasonic cavitation mechanism, a laser measurement mechanism, an infrared observation mechanism, a loading mechanism, and a data acquisition computer. The ultrasonic cavitation mechanism includes an ultrasonic drive controller and an ultrasonic transducer inserted centrally from above into the cavity. The laser measurement mechanism includes a laser drive power supply, a laser emitter located on one side outside the cavity, and a photosensitive sensor located on the other side outside the cavity and facing the laser emitter. The laser emitters are spaced vertically, and the emitted lasers all pass horizontally through the fracturing fluid located in the front region of the cavity. The uppermost laser emitter emits... The laser can penetrate the fracturing fluid located in the lower front area of ​​the ultrasonic transducer. The infrared observation mechanism includes a heat-conducting plate in the cavity for linear cooling cavitation heating area and a high-speed infrared camera equipped with a macro lens to improve clarity. The loading mechanism includes a fluid delivery pipe, a gas delivery pipe, and a pressure sensor located in the cavity. A liquid outlet pipe is located in the center of the bottom of the cavity. The fluid delivery pipe is equipped with a liquid pump. The gas delivery pipe is used to deliver air that squeezes the fracturing fluid downwards and is equipped with a gas pump. The data acquisition computer is connected to the ultrasonic drive controller, the high-speed infrared camera, the photosensitive sensor, the liquid pump, the gas pump, and the pressure sensor.

[0005] As a preferred embodiment of the above scheme, four laser emitters are arranged vertically and horizontally. The heat-conducting plate is positioned below the ultrasonic transducer and in the fracturing fluid area at the rear of the cavity. This avoids interference between the laser emitters and the laser attenuation data, thus preventing interference. Furthermore, since cavitation reactions cause the temperature inside the cavity to rise, especially in areas where cavitation is concentrated, the heat-conducting plate is needed to dissipate the heat. Since the ultrasonic transducer is not located in an area where cavitation is concentrated, the heat-conducting plate is positioned below the ultrasonic transducer, saving materials and resulting in a reasonable design.

[0006] A further preferred embodiment is that the top of the cavity is provided with a gas delivery interface and three liquid delivery interfaces are provided around the perimeter. The liquid delivery interfaces are connected to the three branch pipes at the end of the liquid delivery pipe, and the gas delivery interface is connected to the gas delivery pipe. The reasonable design of circumferential liquid injection can ensure that the fracturing fluid is quickly and evenly distributed throughout the cavity.

[0007] A further preferred embodiment is that the bottom of the cavity is provided with circumferential support legs, which provides strong stability.

[0008] More preferably, the pressure sensor is placed at the bottom of the cavity to facilitate accurate transmission of pressure within the cavity.

[0009] This invention also provides a simulation experiment method for reducing the viscosity of fracturing fluid based on ultrasonic cavitation effect, comprising the following steps:

[0010] Step S1: Build the above-mentioned simulation experimental system for reducing the viscosity of fracturing fluid based on ultrasonic cavitation effect. First, check the airtightness of each interface of the cavity. After the airtightness is qualified, inject fracturing fluid into the equipment cavity. Then, pressurize the cavity by supplying air through the gas pipe until the pressure sensor reaches the pressure design value.

[0011] Step S2: The ultrasonic transducer is activated by the ultrasonic drive controller to emit ultrasonic waves into the fracturing fluid, thereby generating a cavitation effect at the end of the ultrasonic transducer. The cavitation effect is more obvious the closer to the end. At the same time, the laser measurement mechanism and the infrared observation mechanism are activated. The photosensitive sensor receives the laser emitted from the laser emitter that penetrates the fracturing fluid and transmits the attenuation data of the laser penetrating the fracturing fluid to the data acquisition computer. The high-speed infrared camera observes the development process of the cavitation effect in each region of the fracturing fluid in the cavity in real time and transmits the data to the data acquisition computer.

[0012] Step S3: After opening the outlet pipe to drain the fracturing fluid from the cavity, clean the cavity. Use a data acquisition computer to process the collected data and plot the laser intensity curve of the laser emitted from the laser emitter from the top down at the corresponding position of the photosensitive sensor. At the same time, couple the cavitation development process observed at different times with it to obtain a graph that can intuitively represent the relationship between cavitation intensity and the viscosity reduction effect of fracturing fluid.

[0013] Step S4: Set up multiple control experiments based on different ultrasonic power and frequency. Repeat steps S1-S3 for each group of experiments to obtain the effect of ultrasonic energy on the viscosity reduction effect of fracturing fluid.

[0014] As a preferred embodiment of the above scheme, in step S2, the attenuation data of the laser penetrating the fracturing fluid is calculated according to the attenuation formula, which is: I = I0·e (-αx) Where I0 is the initial intensity of the laser, I is the intensity after propagation distance x, α is the attenuation coefficient, and e is the base of the natural logarithm. The formula is reasonable.

[0015] More preferably, in step S4, the following experimental groups are set: 100W power, 20kHz frequency ultrasound as the first experimental group; 100W power, 27kHz frequency ultrasound as the second experimental group; 100W power, 35kHz frequency ultrasound as the third experimental group; 150W power, 40kHz frequency ultrasound as the fourth experimental group; 150W power, 20kHz frequency ultrasound as the fifth experimental group; 150W power, 27kHz frequency ultrasound as the sixth experimental group; 150W power, 35kHz frequency ultrasound as the seventh experimental group; and 150W power, 40kHz frequency ultrasound as the eighth experimental group. Steps S1-S3 are repeated for each experimental group to obtain a graph showing the relationship between cavitation intensity and the viscosity reduction effect of fracturing fluid. This allows for a deeper study of the influence of ultrasonic energy on the viscosity reduction effect of fracturing fluid.

[0016] The beneficial effects of this invention are:

[0017] (1) Compared to the current lack of mature experimental systems for reducing the viscosity of fracturing fluid based on the ultrasonic cavitation effect, and the insufficient understanding of the mechanism of ultrasonic action and the effect of ultrasonic energy on reducing the viscosity of fracturing fluid, this scheme utilizes an ultrasonic cavitation mechanism and a loading mechanism to study the effect of ultrasonic cavitation on reducing the viscosity of fracturing fluid in the laboratory. The loading mechanism simulates the pressure environment of fracturing fluid in the actual environment, and the ultrasonic cavitation mechanism generates a cavitation effect in the fracturing fluid. The infrared observation mechanism and the laser measurement mechanism can observe and measure the development process of the cavitation effect in the fracturing fluid in the cavity and the viscosity reduction effect of the cavitation effect. The high-speed infrared camera can observe the development and rupture process of cavitation bubbles, and thus observe the cavitation development process. The laser measurement system measures the attenuation of the laser light passing through the fracturing fluid medium, thereby measuring the viscosity of the liquid in different regions from top to bottom in the cavity. The components work in an interconnected manner, and the laser measurement mechanism and the infrared observation mechanism are combined to jointly explore the influence of different cavitation intensities at different locations on the viscosity reduction effect of fracturing fluid. The concept is novel.

[0018] (2) The laser emitters are arranged at intervals, and the emitted lasers all pass horizontally through the fracturing fluid in the front area of ​​the cavity. The laser emitted by the uppermost laser emitter can pass through the fracturing fluid in the front area of ​​the lower part of the ultrasonic transducer. Since the cavitation effect in the lower part of the ultrasonic transducer extends into the cavity is the weakest, close to no cavitation effect, the laser emitted by the laser emitter at this location can be used as a reference group without the influence of ultrasonic cavitation. Moreover, since the cavitation effect is more obvious the closer to the ultrasonic transducer's ultrasonic oscillator end, the laser emitters are arranged at intervals, so that the degree of cavitation effect in different affected areas can be observed. The design idea is ingenious and the experimental data is accurate.

[0019] In summary, this method has advantages such as joint observation by laser measurement and infrared observation mechanisms, novel concept, ingenious design, and accurate experimental data. Attached Figure Description

[0020] Figure 1 A front view of a fracturing fluid viscosity reduction simulation experimental system based on ultrasonic cavitation effect (high-speed infrared camera not shown).

[0021] Figure 2 This is a side sectional view of the cavity. Detailed Implementation

[0022] The present invention will be further described below with reference to the embodiments and accompanying drawings:

[0023] Such as combination Figure 1 — Figure 2 As shown, a fracturing fluid viscosity reduction simulation experimental system based on ultrasonic cavitation effect consists of a cavity 1, an ultrasonic cavitation mechanism 2, a laser measurement mechanism 3, an infrared observation mechanism 4, a loading mechanism 5, and a data acquisition computer 6.

[0024] The bottom of cavity 1 is provided with a support leg 13 in a circumferential direction.

[0025] A liquid outlet pipe 11 is located at the center of the bottom of cavity 1.

[0026] The ultrasonic cavitation mechanism 2 consists of an ultrasonic drive controller 21 and an ultrasonic transducer 22 that is placed centrally above the cavity 1.

[0027] The laser measurement mechanism 3 consists of a laser driving power supply 33, a laser emitter 31 located on one side outside the cavity 1, and a photosensitive sensor 32 located on the other side outside the cavity 1 and facing the laser emitter 31.

[0028] The laser emitters 31 are arranged vertically at intervals, and the emitted lasers all pass horizontally through the fracturing fluid located in the front area of ​​the cavity 1.

[0029] The laser emitter 31 preferably consists of four lasers spaced vertically apart.

[0030] The laser emitted by the uppermost laser emitter 31 can penetrate the fracturing fluid located in the lower front area of ​​the ultrasonic transducer 22.

[0031] The infrared observation mechanism 4 consists of a heat-conducting plate 41 located inside the cavity 1 for the linear cooling cavitation heating area and a high-speed infrared camera 42 equipped with a macro lens to improve clarity.

[0032] The heat-conducting plate 41 is positioned below the ultrasonic transducer 22 and is located in the fracturing fluid area on the rear side of the cavity 1.

[0033] The loading mechanism 5 consists of a fluid delivery pipe 51 for conveying fracturing fluid, a gas delivery pipe 52, and a pressure sensor 53 located inside the cavity 1.

[0034] The infusion tube 51 is equipped with a liquid pump 511.

[0035] The gas supply pipe 52 is used to supply air for downward compression of fracturing fluid, and the gas supply pipe 52 is equipped with a pneumatic pump 521.

[0036] The data acquisition computer 6 is connected to the ultrasonic drive controller 21, the photosensitive sensor 32, the high-speed infrared camera 42, the liquid pump 511, the air pressure pump 521, and the pressure sensor 53.

[0037] The top of the cavity 1 is provided with a gas supply interface and three liquid supply interfaces 12 are provided around the perimeter. The liquid supply interfaces 12 are connected to the three branch pipes at the end of the liquid supply tube 51, and the gas supply interface is connected to the gas supply tube 52.

[0038] Pressure sensor 53 is installed at the bottom of cavity 1.

[0039] A simulation experiment method for reducing the viscosity of fracturing fluid based on ultrasonic cavitation effect, the specific implementation steps of which are as follows:

[0040] Step S1: Build the above-mentioned simulation experimental system for reducing the viscosity of fracturing fluid based on ultrasonic cavitation effect. First, check the airtightness of each interface of the cavity 1. After the airtightness is qualified, inject fracturing fluid into the equipment cavity. Then, pressurize the cavity 1 by supplying air through the gas pipe 52 until the pressure sensor 53 reaches the pressure design value.

[0041] Step S2: The ultrasonic transducer 22 is activated by the ultrasonic drive controller 21 to emit ultrasonic waves into the fracturing fluid, thereby generating a cavitation effect at the end of the ultrasonic transducer. The cavitation effect is more obvious the lower part is closer to the end. At the same time, the laser measurement mechanism 3 and the infrared observation mechanism 4 are activated. The photosensitive sensor 32 receives the laser emitted by the laser emitter 31 that penetrates the fracturing fluid and transmits the attenuation data of the laser penetrating the fracturing fluid to the data acquisition computer 6. The high-speed infrared camera 42 observes the development process of the cavitation effect in each region of the fracturing fluid in the cavity 1 in real time and transmits the data to the data acquisition computer 6.

[0042] In step S2, the attenuation data of the laser penetrating the fracturing fluid is calculated according to the attenuation formula, which is: I = I0·e (-αx) Where I0 is the initial intensity of the laser, I is the intensity after propagation distance x, α is the attenuation coefficient, and e is the base of the natural logarithm.

[0043] Step S3: After opening the outlet pipe 11 to drain the fracturing fluid from the cavity 1, clean the cavity 1. Use the data acquisition computer 6 to process the collected data and plot the laser intensity curve of the laser emitted from the laser emitter 31 from top to bottom at the corresponding position received by the photosensitive sensor 32. At the same time, couple the cavitation development process observed at different times with it to obtain a graph that can intuitively represent the relationship between cavitation intensity and fracturing fluid viscosity reduction effect.

[0044] Step S4: Set up multiple control experiments based on different ultrasonic power and frequency. Repeat steps S1-S3 for each group of experiments to obtain the effect of ultrasonic energy on the viscosity reduction effect of fracturing fluid.

[0045] In step S4, the following experimental groups were set up: 100W power, 20kHz frequency ultrasound as the first experimental group; 100W power, 27kHz frequency ultrasound as the second experimental group; 100W power, 35kHz frequency ultrasound as the third experimental group; 150W power, 40kHz frequency ultrasound as the fourth experimental group; 150W power, 20kHz frequency ultrasound as the fifth experimental group; 150W power, 27kHz frequency ultrasound as the sixth experimental group; 150W power, 35kHz frequency ultrasound as the seventh experimental group; and 150W power, 40kHz frequency ultrasound as the eighth experimental group. Steps S1-S3 were repeated for each experimental group to obtain the relationship between cavitation intensity and fracturing fluid viscosity reduction effect.

Claims

1. A fracturing fluid viscosity reduction simulation experimental system based on ultrasonic cavitation effect, characterized in that: The system includes a cavity (1), an ultrasonic cavitation mechanism (2), a laser measurement mechanism (3), an infrared observation mechanism (4), a loading mechanism (5), and a data acquisition computer (6). The ultrasonic cavitation mechanism (2) includes an ultrasonic drive controller (21) and an ultrasonic transducer (22) inserted into the cavity (1) from above. The laser measurement mechanism (3) includes a laser drive power supply (33), a laser emitter (31) located on one side outside the cavity (1), and a photosensitive sensor (32) located on the other side outside the cavity (1) and facing the laser emitter (31). The laser emitters (31) are spaced vertically, and the emitted lasers all pass horizontally through the fracturing fluid located in the front area of ​​the cavity (1). The laser emitted by the uppermost laser emitter (31) can pass through the fracturing fluid located in the front area below the ultrasonic transducer (22). The infrared observation mechanism (4) The linear observation mechanism (4) includes a heat-conducting plate (41) located in the cavity (1) for the linear cooling cavitation heating area and a high-speed infrared camera (42) equipped with a macro lens to improve clarity. The loading mechanism (5) includes a fluid delivery pipe (51) for conveying fracturing fluid, a gas delivery pipe (52) and a pressure sensor (53) located in the cavity (1). The cavity (1) has a liquid outlet pipe (11) at the bottom center. The fluid delivery pipe (51) is equipped with a liquid pump (511). The gas delivery pipe (52) is used to deliver air that squeezes the fracturing fluid downward. The gas delivery pipe (52) is equipped with a pneumatic pump (521). The data acquisition computer (6) is connected to the ultrasonic drive controller (21), the photosensitive sensor (32), the high-speed infrared camera (42), the liquid pump (511), the pneumatic pump (521) and the pressure sensor (53).

2. The fracturing fluid viscosity reduction simulation experimental system based on ultrasonic cavitation effect according to claim 1, characterized in that: The laser emitter (31) consists of four lasers spaced vertically apart. The heat-conducting plate (41) is positioned below the ultrasonic transducer (22) and is located in the fracturing fluid area on the rear side of the cavity (1).

3. The fracturing fluid viscosity reduction simulation experimental system based on ultrasonic cavitation effect according to claim 1, characterized in that: The cavity (1) has a gas delivery interface on the top side and three liquid delivery interfaces (12) around the perimeter. The liquid delivery interface (12) is connected to the three branch pipes at the end of the liquid delivery tube (51), and the gas delivery interface is connected to the gas delivery tube (52).

4. The fracturing fluid viscosity reduction simulation experimental system based on ultrasonic cavitation effect according to claim 1, characterized in that: The cavity (1) is provided with a support leg (13) circumferentially at the bottom.

5. The fracturing fluid viscosity reduction simulation experimental system based on ultrasonic cavitation effect according to claim 1, characterized in that: The pressure sensor (53) is located at the bottom of the cavity (1).

6. A simulation experiment method for reducing the viscosity of fracturing fluid based on ultrasonic cavitation effect, characterized in that, Includes the following steps: Step S1: Build a fracturing fluid viscosity reduction simulation experimental system based on ultrasonic cavitation effect as described in any one of claims 1-3. First, check the air tightness of each interface of the cavity (1). After the air tightness is qualified, inject fracturing fluid into the equipment cavity. Then, pressurize the cavity (1) by supplying air through the gas pipe (52) until the pressure sensor (53) reaches the pressure design value. Step S2: The ultrasonic transducer (22) is activated by the ultrasonic drive controller (21) to emit ultrasonic waves into the fracturing fluid, thereby generating a cavitation effect at the end of the ultrasonic transducer. The cavitation effect is more obvious the lower part is closer to the end. At the same time, the laser measurement mechanism (3) and the infrared observation mechanism (4) are activated. The photosensitive sensor (32) receives the laser emitted from the laser emitter (31) that penetrates the fracturing fluid and transmits the attenuation data of the laser penetrating the fracturing fluid to the data acquisition computer (6). The high-speed infrared camera (42) observes the development process of the cavitation effect in each region of the fracturing fluid in the cavity (1) in real time and transmits the data to the data acquisition computer (6). Step S3: After opening the outlet pipe (11) to drain the fracturing fluid from the cavity (1), clean the cavity (1), process the collected data using the data acquisition computer (6), and plot the laser intensity curve of the laser emitted from the laser emitter (31) from the top down at the corresponding position received by the photosensitive sensor (32). At the same time, couple the cavitation development process observed at different times with it to obtain a graph that can intuitively represent the relationship between cavitation intensity and the viscosity reduction effect of fracturing fluid. Step S4: Set up multiple control experiments based on different ultrasonic power and frequency. Repeat steps S1-S3 for each group of experiments to obtain the effect of ultrasonic energy on the viscosity reduction effect of fracturing fluid.

7. The experimental method for simulating viscosity reduction of fracturing fluid based on ultrasonic cavitation effect according to claim 6, characterized in that: In step S2, the attenuation data of laser penetration into the fracturing fluid is calculated according to the attenuation formula, which is: I = I0·e (-αx) Where I0 is the initial intensity of the laser, I is the intensity after propagation distance x, α is the attenuation coefficient, and e is the base of the natural logarithm.

8. The experimental method for simulating viscosity reduction of fracturing fluid based on ultrasonic cavitation effect according to claim 6, characterized in that: In step S4, the following experimental groups are set up: 100W power, 20kHz frequency ultrasound as the first experimental group; 100W power, 27kHz frequency ultrasound as the second experimental group; 100W power, 35kHz frequency ultrasound as the third experimental group; 150W power, 40kHz frequency ultrasound as the fourth experimental group; 150W power, 20kHz frequency ultrasound as the fifth experimental group; 150W power, 27kHz frequency ultrasound as the sixth experimental group; 150W power, 35kHz frequency ultrasound as the seventh experimental group; and 150W power, 40kHz frequency ultrasound as the eighth experimental group. Steps S1-S3 are repeated for each experimental group to obtain the relationship between cavitation intensity and fracturing fluid viscosity reduction effect.

Images