Spiral sealing sand adding device for carbon dioxide fracturing
By designing a spiral sealing and sand-adding device, the self-sealing conveying and uniform mixing of proppant is achieved by using spiral sand feeding rotor and mechanical and electromagnetic stirring, the problems of existing devices in large sand volume operations, uneven sand mixing and high equipment failure rate are solved, and efficient and uniform mixing of carbon dioxide and proppant are achieved and the reliability of the device is improved.
Patent Information
- Application Number
- CN202510054759.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-14
- Publication Date
- 2025-04-18
AI Technical Summary
The existing carbon dioxide sand fracturing device has problems such as difficulty in operating large amounts of sand, difficulty in achieving high sand ratios, uneven sand mixing, and fast filtration loss. Especially in low-temperature and high-pressure environments, the equipment control is complex, the failure rate is high, the maintenance is inconvenient, and the stirring is not timely and comprehensive, and the proppant settlement is difficult.
A carbon dioxide fracturing spiral sealing and sand-adding device is designed, including a spiral sand-feeding stator, a mechanical stirrer and a built-in electromagnetic stirring block. The spiral sand-feeding rotor is used to achieve self-sealing and transport of proppant, and uniform mixing is achieved through mechanical and electromagnetic stirring. Automatic anti-blocking and anti-blocking methods are used to improve the sealing and stability of the device.
The device realizes efficient mixing of carbon dioxide and proppant, reduces the risk of carbon dioxide leakage, improves the uniformity and efficiency of sand mixing, reduces the failure rate of equipment, and improves the reliability and service life of the device through automatic blocking and anti-blocking methods.
Smart Images
Figure CN119844058A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of oil and gas production increase, and in particular to a carbon dioxide fracturing spiral sealing sand adding device. Background Art
[0002] The research on carbon dioxide sand fracturing and sand mixing equipment started early. The technical difficulties of carbon dioxide sand fracturing operation are mainly reflected in the difficulty of operating with large sand volumes, difficulty in achieving high sand ratios, uneven sand mixing, and fast filtration rate.
[0003] During the liquid carbon dioxide sand mixing process, the temperature of the proppant, equipment, and pipeline must be reduced to about -18°C and the pressure must be increased to 2MPa before the sand mixing operation can be carried out. This method has the problem of water freezing in the proppant, poor fluidity, and even pipeline blockage.
[0004] Traditional sand mixing trucks have shortcomings such as complex equipment control, high failure rate, inconvenient maintenance, large size, and poor adaptability to complex terrain, which directly or indirectly affect the quality of sand fracturing operations. Traditional sand adding technology cannot control the flow rate well. The position design of the pipelines for liquid and proppant in the sand mixing device is unreasonable (especially when there are many interfaces). It relies on liquid flow to impact the proppant to achieve stirring and suspension. There are difficulties such as carbon dioxide leakage, untimely stirring, incomplete stirring, and proppant sedimentation. The carbon dioxide sand mixing truck is a high-pressure and low-temperature equipment. Keeping carbon dioxide in a liquid state during the sand mixing operation requires that the solid-liquid mixing must be carried out under high-pressure conditions. The continuous addition of proppant into the pressurized environment increases the difficulty of the operation. In addition, the low-temperature and high-pressure environment will accelerate the wear of the stirring impeller and will bring severe tests to the dynamic seal of the tank.
[0005] Therefore, in view of the above problems, it is necessary to propose a new carbon dioxide fracturing sand-carrying fluid mixing device, especially a sand mixing device that not only utilizes the impact effect of liquid flow, but also has a simple device, good sealing performance and reasonable design. Summary of the invention
[0006] In order to solve the problems existing in the above-mentioned background technology, the present invention proposes a carbon dioxide fracturing spiral sealing sand adding device, which has the characteristics of simple structure, good sealing performance and reasonable design, and can provide a new sand conveying and mixing method.
[0007] The technical solution of the present invention to solve the above problems is:
[0008] A spiral sealing sand adding device for carbon dioxide fracturing, which is special in that:
[0009] The invention comprises a base and a spiral sand-feeding stator. A sealed proppant ascending storage chamber is arranged in the base. A sealed sand-mixing container inner chamber is arranged on the upper part of the base. The spiral sand-feeding stator is vertically arranged in the base and the inner chamber of the sand-mixing container. A sand-feeding sealing joint is arranged on the top of the spiral sand-feeding stator. A spiral sand-feeding rotor is arranged in the spiral sand-feeding stator. The lower end of the spiral sand-feeding rotor passes through the inner chamber of the sand-mixing container and the base. The upper end of the spiral sand-feeding rotor passes through the sand-feeding sealing joint and is connected to a mechanical agitator. A sand-feeding outlet is arranged on the upper part of the spiral sand-feeding stator. There is a built-in electromagnetic stirring block, and an inclined bottom plate of the sand mixing container is arranged in the inner cavity of the sand mixing container. The center of the inclined bottom plate of the sand mixing container is connected to the outer wall of the spiral sand feeding stator, and the periphery of the inclined bottom plate of the sand mixing container is connected to the inner wall of the inner cavity of the sand mixing container. The inclined bottom plate of the sand mixing container divides the inner cavity of the sand mixing container into two upper and lower sealed cavities, and an electromagnetic stirrer is arranged in the lower sealed cavity; the proppant rising storage cavity is connected to the proppant input pipeline, and the air inlet pipeline is connected from the top of the inner cavity of the sand mixing container, and the outside of the inner cavity of the sand mixing container is connected to the temperature control device; the bottom of the upper sealed cavity of the inner cavity of the sand mixing container is connected to the sand mixing outlet pipeline.
[0010] The proppant enters the proppant rising storage chamber from the proppant input pipe, and the motor drives the spiral sand delivery rotor to rotate, moving the proppant to the sand delivery outlet. After being mixed with carbon dioxide in the inner cavity of the sand mixing container, the proppant leaves the sand mixing container through the sand mixing outlet pipe at the inclined bottom plate position. The built-in electromagnetic stirring block and electromagnetic stirrer are respectively located at the upper and lower parts of the inclined bottom plate of the sand mixing container; the proppant rising storage chamber, the spiral sand delivery stator and the proppant rising storage chamber are all supported by the base.
[0011] Furthermore, a motor is fixed on the base, and the motor directly drives the spiral sand feeding rotor to rotate or drives the spiral sand feeding rotor to rotate through a reduction device.
[0012] Furthermore, a carbon dioxide sealing joint is installed on the top of the inner cavity of the sand mixing container, and an air intake pipeline is connected to the carbon dioxide sealing joint to prevent carbon dioxide leakage.
[0013] Furthermore, a temperature and pressure sensor is installed on the top of the inner cavity of the sand mixing container; and the inclined bottom plate of the sand mixing container is inclined downward from the inside to the outside.
[0014] Furthermore, the outer side of the inner cavity of the sand mixing container is wrapped with a jacket, the jacket is a closed shell, a refrigerant is built into the jacket, and a temperature control device controls the refrigerant to control the temperature of the inner cavity of the sand mixing container.
[0015] Furthermore, the above-mentioned carbon dioxide fracturing spiral sealing sand adding device also includes a carbon dioxide tank, the inlet end of the air intake pipeline is connected to the carbon dioxide tank, and a carbon dioxide flow meter is installed on the air intake pipeline.
[0016] Furthermore, the above-mentioned carbon dioxide fracturing spiral sealing sand adding device also includes a proppant tank, the inlet end of the proppant input pipeline is connected to the proppant tank, and the proppant input pipeline is equipped with a proppant flow meter.
[0017] Furthermore, a buffer device is provided on the sand mixing outlet pipeline, the buffer device is provided with a discharge valve, and the sand mixing outlet pipeline is connected to the booster pump.
[0018] Furthermore, the spiral sand conveying rotor is a composite structure having a circular thread section screw, a rectangular thread section screw, a turbine form, or other structures having an upward conveying function.
[0019] Furthermore, the inner cavity of the sand mixing container, the sand delivery sealing joint, the built-in electromagnetic stirring block, and the inclined bottom plate of the sand mixing container are all made of steel resistant to carbon dioxide corrosion.
[0020] Advantages of the present invention:
[0021] 1) The present invention proposes a spiral sealed sand-adding device for carbon dioxide fracturing, which reduces the number of holes opened on the top or side of the inner cavity of the sand mixing container as much as possible to prevent carbon dioxide leakage caused by the holes on the top or side; the motor is connected to a power supply to provide power, and the motor is installed at the lower part of the inner cavity of the sand mixing container; the self-sealing of the proppant entry process is achieved by utilizing the matching relationship between the spiral sand-feeding rotor and the spiral sand-feeding stator;
[0022] 2) The sand delivery sealing joint divides the spiral sand delivery stator into two parts. The upper part of the spiral sand delivery stator can carry a mechanical stirrer for rotation and stirring, and the lower part of the spiral sand delivery stator can realize the upward movement of the proppant;
[0023] 3) The device uses two methods for stirring and mixing (first starting the mechanical stirrer and then starting the built-in electromagnetic stirrer), using the gravity of the proppant and the impact force of the carbon dioxide fluid;
[0024] 4) The device has three means of controlling the proppant flow, namely, proppant tank outlet valve adjustment, motor speed adjustment, and sand delivery outlet size adjustment;
[0025] 5) The device adopts automatic anti-blocking and anti-stuck means, which are respectively reflected in the continuous entry of the screw, anti-blocking of the inclined surface, anti-blocking of the discharge channel of the buffer device, and anti-blocking of the two stirring and mixing methods. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 This is a schematic diagram of the composition of a spiral closed sand adding device for carbon dioxide fracturing;
[0027] Figure 2 It is a schematic diagram of the layout of the spiral sand conveying rotor, spiral sand conveying stator and sand conveying outlet.
[0028] Description of reference numerals:
[0029] 1-proppant input pipeline; 2-proppant rising storage chamber; 3-spiral sand delivery rotor; 4-spiral sand delivery stator; 5-sand delivery outlet; 6-inner cavity of sand mixing container; 7-sand delivery sealing joint; 8-built-in electromagnetic stirring block; 9-sand mixing container inclined bottom plate; 10-electromagnetic stirrer; 11-mechanical stirrer; 12-temperature and pressure sensor; 13-carbon dioxide sealing joint; 14-base; 15-motor; 16-temperature control device; 17-sand mixing outlet pipeline; 18-buffer device; 19-leakage valve; 20-carbon dioxide flowmeter; 21-carbon dioxide tank; 22-proppant flowmeter; 23-proppant tank; 24-boosting pump; 25-air inlet pipeline. DETAILED DESCRIPTION
[0030] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention.
[0031] See also Figure 1 The present invention proposes a carbon dioxide fracturing spiral sealed sand adding device, comprising a proppant input pipeline 1, a proppant rising storage chamber 2, a spiral sand feeding rotor 3, a spiral sand feeding stator 4, a sand feeding outlet 5, a sand mixing container inner cavity 6, a sand feeding sealing joint 7, a built-in electromagnetic stirring block 8, an inclined bottom plate 9 of the sand mixing container, an electromagnetic stirrer 10, a mechanical stirrer 11, a temperature and pressure sensor 12, a carbon dioxide sealing joint 13, a base 14, a motor 15, a temperature control device 16 and a sand mixing outlet pipeline 17.
[0032] The sealed proppant ascending storage chamber 2 is arranged in the base 14, the sealed sand mixing container inner chamber 6 is arranged on the upper part of the base 14, the spiral sand delivery stator 4 is vertically arranged in the base 14 and the sand mixing container inner chamber 6, and the top of the spiral sand delivery stator 4 is provided with a sand delivery sealing joint 7. The spiral sand delivery stator 4 cooperates with the spiral sand delivery rotor 3, the lower end of the spiral sand delivery rotor 3 passes through the sand mixing container inner chamber 6 and the base 14, and the upper end of the spiral sand delivery rotor 3 passes through the sand delivery sealing joint 7 and is connected to the mechanical stirrer 11. Figure 2The spiral sand delivery stator 4 has a sand delivery outlet 5 at the top, and the sand mixing container inner cavity 6 is provided with a sand mixing container inclined bottom plate 9. The center of the sand mixing container inclined bottom plate 9 is connected to the outer wall of the spiral sand delivery stator 4, and the periphery of the sand mixing container inclined bottom plate 9 is connected to the inner wall of the sand mixing container inner cavity 6. The sand mixing container inclined bottom plate 9 divides the sand mixing container inner cavity 6 into two upper and lower sealed cavities. The outside of the spiral sand delivery stator 4 is connected to a built-in electromagnetic stirring block 8 and an electromagnetic stirrer 10. The built-in electromagnetic stirring block 8 and the electromagnetic stirrer 10 are respectively in the upper and lower sealed cavities of the sand mixing container inclined bottom plate 9. The proppant rising storage cavity 2 is connected to the proppant input pipeline 1, and the air inlet pipeline 25 is connected from the top of the sand mixing container inner cavity 6. The outside of the sand mixing container inner cavity 6 is connected to the temperature control device 16; the bottom of the upper sealed cavity of the sand mixing container inner cavity 6 is connected to the sand mixing outlet pipeline 17.
[0033] The proppant enters the proppant rising storage chamber 2 from the proppant input pipe 1, and the motor 15 drives the spiral sand feeding rotor 3 to rotate, moving the proppant to the sand feeding outlet 17, and after being mixed with carbon dioxide in the inner cavity 6 of the sand mixing container, it leaves the proppant through the sand mixing outlet pipe 17 at the inclined bottom plate position of the sand mixing container; the proppant rising storage chamber 2, the spiral sand feeding stator 4, and the proppant rising storage chamber 2 are all supported by the base 14.
[0034] Specifically, in some embodiments provided by the present invention, the inner cavity 6 of the sand mixing container, the sand delivery sealing joint 7, the built-in electromagnetic stirring block 8, and the inclined bottom plate 9 of the sand mixing container are all made of carbon dioxide corrosion resistant steel. Figure 1 The sand mixing container inclined bottom plate 9 has a certain inclination angle and is inclined downward from the inside to the outside. The sand mixing outlet pipe 17 is located above the edge of the sand mixing container inclined bottom plate 9, which can effectively prevent blockage.
[0035] Specifically, in some embodiments provided by the present invention, see Figure 1 The inner cavity 6 of the sand mixing container is connected to the buffer device 18 via the sand mixing outlet pipe 17, and the buffer device 18 is provided with a discharge valve 19; the sand mixing outlet pipe 17 is connected to the booster pump 24, and a valve is provided on the sand mixing outlet pipe 17 between the buffer device 18 and the inner cavity 6 of the sand mixing container.
[0036] Specifically, in some embodiments of the present invention, the carbon dioxide sealing joint 13 is connected to the carbon dioxide tank 21 via an air intake pipeline 25, a valve is provided at the outlet of the carbon dioxide tank 21, and a carbon dioxide flowmeter 20 is installed on the air intake pipeline 25 for monitoring the flow rate of carbon dioxide.
[0037] Specifically, in some embodiments provided by the present invention, the inlet of the proppant input pipeline 1 is connected to the proppant tank 23, a valve is provided on the proppant input pipeline 1, and the proppant input pipeline 1 is also equipped with a proppant flow meter 22.
[0038] Specifically, in some embodiments provided by the present invention, in order to achieve better sealing of the inner cavity 6 of the sand mixing container, the top or side openings of the inner cavity 6 of the sand mixing container should be reduced as much as possible to prevent the top or side openings from causing carbon dioxide leakage. The self-sealing of the proppant entry process is achieved by utilizing the matching relationship between the spiral sand delivery rotor 3 and the spiral sand delivery stator 4. The spiral sand delivery rotor 3 can also be replaced by a circular thread section screw, a rectangular thread section screw, a turbine form, or other composite structures with an upward conveying function. In this embodiment, the working cross-section of the spiral sand delivery rotor 3 is rectangular, forming a series of cavities, which can be used as a temporary storage and ascending space for the proppant. The motor 15 is connected to a power supply to provide power. The motor is installed at the lower part of the base 14, and the motor directly drives or drives the spiral sand delivery rotor to rotate through a reduction device.
[0039] Specifically, see Figure 1The sand delivery sealing joint 7 divides the spiral sand delivery rotor 3 into two parts. The upper part of the spiral sand delivery rotor 3 can carry the mechanical stirrer 11 for rotation and stirring, and the lower part of the spiral sand delivery rotor 3 can realize the upward movement of the proppant. Each thread has a conveying effect on the proppant, and compared with the traditional conveying and mixing method, it has a better sand mixing effect. The device uses two methods for stirring and mixing (first start the mechanical stirrer 11, and then start the built-in electromagnetic stirrer 10), using the gravity of the proppant and the impact force of the carbon dioxide fluid. After the proppant is transported into the inner cavity 6 of the sand mixing container from the sand delivery outlet 17, it enters the carbon dioxide fluid by its own gravity to enhance the mixing effect; the carbon dioxide entering from the carbon dioxide sealing joint 13 has a certain speed and kinetic energy, and its downward impact can also enhance the mixing effect. The built-in electromagnetic stirring block 8 and the electromagnetic stirrer 10 realize electromagnetic stirring, and the mechanical stirrer 11 realizes traditional mechanical stirring. Both methods of mixing and stirring are inside the equipment; the mechanical stirrer is started first, and then the built-in electromagnetic stirrer is started; the two methods of mixing and stirring reduce the cost of sand mixing equipment and the problem of uneven mixing. The device has three means of controlling the flow of proppant, namely, the outlet valve adjustment of the proppant tank 23, the motor speed adjustment, and the sand delivery outlet size adjustment. The two flow meters can well observe the flow rate of carbon dioxide and proppant, and better adjust the content ratio of carbon dioxide and proppant through the temperature and pressure control system to make the sand mixing fracturing effect better. The jacket is wrapped around the inner cavity 6 of the sand mixing container and the outside of the feed pipe. The jacket is a closed shell. The temperature of the refrigerant in the jacket is controlled within the range of 6 to 8°C through the refrigerant circulation pipeline and refrigeration unit of the temperature control device. The booster pump 24 mainly controls the degree of pressurization of the output sand-carrying liquid. When the booster pump is partially opened in the bypass pipeline, it can indirectly increase the pressure of the inner cavity 6 of the sand mixing container. Within this pressure and temperature range, the carbon dioxide in the booster pump is in liquid or supercritical form, and the water contained in the proppant will not freeze, ensuring the continuous operation of the carbon dioxide closed sand mixing-boosting. The device adopts automatic anti-blocking and anti-stuck means, which are respectively reflected in the continuous entry of the screw, the anti-blocking of the inclined surface of the inclined bottom plate 9 of the sand mixing container, the anti-blocking of the discharge channel of the buffer device, and the anti-blocking of the two stirring and mixing methods.
[0040] Specifically, in some embodiments provided by the present invention, the positions of the top of the proppant rising storage chamber 2 and the bottom of the sand mixing container inner chamber 6 can be adjusted. For example, the bottom of the sand mixing container inner chamber 6 can be directly placed on the top of the proppant rising storage chamber 2 to achieve the compactness of the overall device of the carbon dioxide fracturing spiral sealing sand adding device; according to the actual size of the electromagnetic agitator 10, the position of the inclined bottom plate 9 of the sand mixing container can be adjusted downward longitudinally, or the bottom position of the sand mixing container inner chamber 6 can be adjusted upward to further achieve the compactness of the sand mixing container inner chamber 6, but it is not recommended to adjust the inclined bottom plate 9 of the sand mixing container too downward to avoid excessive concentration of the proppant at the bottom, which is not conducive to discharge.
[0041] Specifically, in some embodiments provided by the present invention, when the mechanical agitator 11 is too close to the top of the inner cavity 6 of the sand mixing container, or the stirring effect of the mechanical agitator 11 is not ideal, the spiral sand feeding rotor 3 can be manually adjusted downward when the device stops running; when the spiral sand feeding rotor 3 is transporting the proppant, there is a certain blockage or poor matching with the spiral sand feeding stator 4, etc., the spiral sand feeding rotor 3 can be manually adjusted upward or downward when the device stops running to eliminate the blockage problem.
[0042] Matters not covered by the present invention are known technologies.
[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art can still adjust the technical solutions described in the above embodiments or replace some of the technical features by equivalents. Therefore, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.
Claims
1. A spiral sealing sand adding device for carbon dioxide fracturing, which is special in that: The invention comprises a base (14) and a spiral sand-feeding stator (4), wherein a sealed proppant ascending storage chamber (2) is provided in the base (14), a sealed sand-mixing container inner chamber (6) is provided on the upper part of the base (14), the spiral sand-feeding stator (4) is vertically arranged in the base (14) and the sand-mixing container inner chamber (6), and a sand-feeding sealing joint (7) is provided on the top of the spiral sand-feeding stator (4); The spiral sand delivery stator (4) is provided with a spiral sand delivery rotor (3), the lower end of the spiral sand delivery rotor (3) passes through the inner cavity (6) of the sand mixing container and the base (14), the upper end of the spiral sand delivery rotor (3) passes through the sand delivery sealing joint (7) and is connected to the mechanical stirrer (11), the upper part of the spiral sand delivery stator (4) is provided with a sand delivery outlet (5), the outer side of the upper part of the spiral sand delivery stator (4) is provided with a built-in electromagnetic stirring block (8), the inner cavity (6) of the sand mixing container is provided with a slanted bottom plate (9), the center of the slanted bottom plate (9) of the sand mixing container is connected to the outer wall of the spiral sand delivery stator (4), the outer periphery of the slanted bottom plate (9) of the sand mixing container is connected to the inner wall of the inner cavity (6) of the sand mixing container, the slanted bottom plate (9) of the sand mixing container divides the inner cavity (6) of the sand mixing container into two upper and lower sealed cavities, and the lower sealed cavity is provided with an electromagnetic stirrer (10); The proppant rising storage chamber (2) is connected to the proppant input pipeline (1), and the air inlet pipeline (25) is connected from the top of the sand mixing container inner chamber (6). The outside of the sand mixing container inner chamber (6) is connected to the temperature control device (16); the bottom of the upper sealed cavity of the sand mixing container inner chamber (6) is connected to the sand mixing outlet pipeline (17).
2. The spiral sealing sand adding device for carbon dioxide fracturing according to claim 1 is characterized in that: The spiral sand-feeding rotor (3) is driven to rotate by a motor (15), and the motor (15) is fixed on a base (14).
3. The spiral sealing and sand adding device for carbon dioxide fracturing according to claim 2 is characterized in that: A carbon dioxide sealing joint (13) is installed on the top of the inner cavity (6) of the sand mixing container, and an air intake pipeline (25) is connected to the carbon dioxide sealing joint (13).
4. The spiral sealing and sand adding device for carbon dioxide fracturing according to any one of claims 1 to 3 is characterized in that: A temperature and pressure sensor (12) is installed on the top of the inner cavity (6) of the sand mixing container; and the inclined bottom plate (9) of the sand mixing container is inclined downward from the inside to the outside.
5. The spiral sealing sand adding device for carbon dioxide fracturing according to claim 4 is characterized in that: The outer side of the inner cavity (6) of the sand mixing container is wrapped with a jacket, which is a closed shell and has a refrigerant built in the jacket for controlling the temperature of the inner cavity (6) of the sand mixing container.
6. The carbon dioxide fracturing spiral sealing sand adding device according to claim 5 is characterized in that: It also comprises a carbon dioxide tank (21), the inlet end of the air intake pipeline (25) is connected to the carbon dioxide tank (21), and a carbon dioxide flow meter (20) is installed on the air intake pipeline (25).
7. The carbon dioxide fracturing spiral sealing sand adding device according to claim 6 is characterized in that: It also comprises a proppant tank (23), the inlet end of the proppant input pipeline (1) is connected to the proppant tank (23), and a proppant flow meter (22) is installed on the proppant input pipeline (1).
8. The carbon dioxide fracturing spiral sealing and sand adding device according to claim 7 is characterized in that: The sand mixing outlet pipeline (17) is provided with a buffer device (18), the buffer device (18) is provided with a discharge valve (19), and the sand mixing outlet pipeline (17) is connected to a booster pump (24).
9. The spiral sealing and sand adding device for carbon dioxide fracturing according to any one of claims 1 to 3 is characterized in that: The spiral sand-feeding rotor (3) is a screw with a circular thread section or a screw with a rectangular thread section.
10. The spiral sealing and sand adding device for carbon dioxide fracturing according to any one of claims 1 to 3 is characterized in that: The inner cavity (6) of the sand mixing container, the sand delivery sealing joint (7), the built-in electromagnetic stirring block (8), and the inclined bottom plate (9) of the sand mixing container are all made of steel resistant to carbon dioxide corrosion.