CN108590630A - A kind of the fracturing fluid leak device and computational methods of multiple-limb seam - Google Patents

Abstract

The invention belongs to the technical field of oil and gas field development, and specifically relates to a fracturing fluid filtration device for multi-branch fractures, including a liquid mixing and feeding device, a stirring device, a filtration device, and a liquid recovery device. The liquid mixing and feeding device includes Liquid distribution tank, feeding tank, electric pump, electronic flowmeter, water pipes, valves, the mixing device includes a mixing tank, a stirring motor, and an agitator, and the filtration device includes a main seam device, a branch seam device, a screw pump, an electronic Flowmeter, pressure gauge, screw pump, electronic flowmeter, pressure gauge are set in series between the filter loss device and the liquid outlet of the mixing tank, the liquid recovery device includes a valve, a drain pipe, and a settling tank. Beneficial effects of the invention: the dynamic process of the mixed liquid of fracturing fluid and proppant being pumped into the formation gradually leaking out in main fractures and branch fractures can be visually observed, and multi-branching of the dynamic laying process of proppant can be realized Fracturing fluid fluid loss device and its calculation method for fractures.

Description

Fracturing fluid filtration device and calculation method for multi-branch fractures

technical field

The invention relates to a fracturing fluid filtration device and a calculation method for multi-branch fractures, belonging to the technical field of oil and gas field development.

Background technique

In the process of hydraulic fracturing, for oil and gas reservoirs with multi-branched fractures due to natural fractures, the leakage of fracturing fluid will be greatly increased due to the existence of natural fractures, which is directly related to the proppant advancing to the depth, so that The fracturing fluid is also affected in terms of sand carrying, sand spreading, and migration, which in turn affects the success or failure of construction. At present, most of the studies on fracturing fluid loss are based on theoretical calculation and software simulation, and the results obtained are relatively ideal, which cannot directly reflect the fluid loss in branch fractures.

The conventional fracturing fluid fluid loss simulation device can only simulate the fluid loss of a single fracture, and the experimental results are relatively single, such as the simulation device mentioned in the Chinese utility model patent application publication specification CN 204086078 U. Moreover, conventional fluid loss simulation devices cannot simulate the continuous and slow dynamic fluid loss process of fracturing fluid in multi-branch fractures and the migration, settlement and laying of proppants in multi-branch fractures during the actual fracturing process. Therefore, it is necessary to design an experimental method for the situation of multi-branch fractures to simulate the fluid loss of fracturing fluids with multi-branch fractures.

Contents of the invention

Aiming at the deficiencies in the prior art, the present invention provides a method that can visually observe the slow continuous fluid loss and proppant in-fracture in main fractures and branch fractures after the mixed liquid of fracturing fluid and proppant is pumped into the formation. The fracturing fluid fluid loss device for the dynamic process of migration, settlement, and laying, and the calculation method for the fluid loss velocity.

Technical scheme of the present invention is as follows:

A fracturing fluid filtration device for multi-branch fractures, characterized in that it includes a liquid distribution and feeding device, a stirring device, a filtration device, and a liquid recovery device, and the liquid distribution and feeding device includes a liquid distribution tank, a feeding tank, and an electric pump , electronic flow meter, water pipe, valve, the water pipe is connected in series with liquid distribution tank, electric pump, electronic flow meter, the port of the water pipe is provided with a valve, the bottom of the charging box is provided with a load cell, and the load cell The lower end is provided with a discharge port, the discharge port is provided with a valve, and the discharge port is connected to the port of the water pipe, and the liquid mixing and feeding device is connected to the upper left of the stirring device;

The stirring device includes a stirring barrel, a stirring motor, and a stirrer, and the stirrer includes a stirring rod and a stirring blade. The stirring motor is arranged at the center position of the upper end of the stirring barrel, and the stirring blades are distributed on the stirring rod in multiple stages. , the bottom of the mixing tank is provided with a liquid outlet, the liquid outlet is provided with a valve, and the liquid outlet is connected to a filtration device;

The filtration device includes a main seam device, a branch seam device, a screw pump, an electronic flow meter, and a pressure gauge, and a screw pump, an electronic flow meter, and a pressure gauge are arranged in series between the filtration device and the liquid outlet of the mixing tank. The table shows that the main seam device includes a tempered glass plate, a transparent nylon plate, a cavity, a screen surface, a filter screen, and a steel plate frame, and the steel plate frame is arranged around the main seam device, and the cavity includes an upper cavity, The lower cavity, the inner side of the cavity is provided with a screen surface and a filter screen, the cavity is parallel to the upper and lower surfaces of the main seam device, and a tempered glass plate is arranged between the steel plate frame and the upper cavity , the inner side of the tempered glass plate is provided with a transparent nylon plate, a tempered glass plate is provided between the upper cavity and the lower cavity, a transparent nylon plate is provided on the inner side of the tempered glass plate, the steel plate frame and the A toughened glass plate is arranged between the lower chambers, a transparent nylon plate is arranged inside the toughened glass plate, the branch seam device is arranged on both sides of the main seam device, and the branch seam device is connected to the main seam device. The structure of the seam device is the same, the rear end of the main seam device is provided with a main seam liquid outlet, the rear end of the branch seam device is provided with a branch seam liquid outlet, and the outside of the cavity is provided with 4 filtration outlets. A liquid port, an electronic flowmeter, a pressure gauge, and a valve are arranged in series at the fluid loss outlet, and the fluid outlet for fluid loss is connected to the liquid recovery device;

The liquid recovery device includes a valve, a drain pipe, and a settling tank. One end of the drain pipe is connected to the fluid loss outlet, and the other end is connected to the settling tank. The drain pipe is connected to the outlet of the main seam. A pressure gauge, an electronic flowmeter, and a valve are connected in series between the liquid ports, and a pressure gauge, an electronic flowmeter, and a valve are connected in series between the discharge pipe and the liquid outlet of the branch seam.

Further, the included angle between the main seam device and the branch seam device is set to 30°.

Further, the connection between the main seam device and the branch seam device is fixed with steel bars, and a sealing rubber strip is provided.

Further, a sealing ring is provided at the connection between the steel plate frame, the tempered glass plate and the transparent nylon plate.

Further, the distance between the upper cavity and the steel plate frame on the upper surface of the filtration device is equal to the distance between the upper cavity and the lower cavity and is equal to the distance between the lower cavity and the lower surface of the filtration device The distance from the steel border of the surface.

Further, the length of the cavity is 2.5m, the height is 3cm, and the width is 1cm. The outside of the cavity is respectively provided with 4 fluid loss outlets, and each fluid loss outlet is connected to an independent electronic flow rate. gauges, pressure gauges, valves.

Further, the inner surfaces of the nylon plates are rough surfaces, and there is a certain gap between the inner surfaces of the nylon plates, which is used to simulate cracks in rock formations.

Further, the length of the steel plate frame on the upper and lower surfaces of the main seam device is 2.5m, the height is 35cm, and the thickness is 1cm. The tempered glass plate corresponds to its size, and the effective simulated crack surface length is 2.5m, and the height is 30cm. .

Further, the length of the steel plate frame on the upper and lower surfaces of the branch seam device is 1.5m, the height is 35cm, and the thickness is 1cm. The tempered glass plate corresponds to its size, and the effective simulated branch seam surface length is 1.5m, and the height is 30cm .

Further, the calculation method of the fracturing fluid filtration device for multi-branch fractures is characterized in that the steps are as follows:

S1. Experiment preparation, check the integrity of the functions of each component;

S2. According to the on-site construction displacement, sand ratio, and proppant parameters, carry out laboratory preparation according to the same ratio, and calculate the displacement, fracturing fluid volume, and proppant dosage required for the experiment;

S3. Pump the configured fracturing fluid from the liquid distribution tank into the mixing tank, and the proppant enters the mixing tank from the feeding tank, and turn on the stirring motor to fully stir;

S4. Open the bottom valve of the mixing tank, the main seam liquid outlet valve, and the branch seam liquid outlet valve, start the screw pump, pump the mixed fracturing fluid into the main seam device, and open the filter chamber of the filter loss device. The valve at the liquid outlet is lost, and the mixed liquid flows into the settling tank through the drain pipe;

S5 When the main fracture is stable, turn off the screw pump, and use the camera to record the proppant migration, laying process and fracturing fluid filtration process in the fracture; start the electric pump, pump clean water from the liquid distribution tank to clean the device, and record the simulation time and the flowmeter readings in the filtrate area of each fracture, the fluid loss rate is calculated by the following formula:

In the formula: V-filtration volume, m ³ ;

t-filtration time, min;

ω - height of stainless steel flat cavity, m;

l-length of stainless steel flat cavity, m;

ν-filtration rate, m ³ /min.

The beneficial effects of the present invention are:

1. The present invention simulates the main fractures and branch fractures of the formation by setting tempered glass plates, chambers, and transparent nylon plates, which can be visually observed. During the fracturing process of oil and gas fields, when the mixed liquid of fracturing fluid and proppant is pumped into the formation The dynamic process of gradual filter loss in the main fracture and branch fracture, and the dynamic laying process of proppant can be realized.

2. Electronic flowmeters are installed before and after the filtration device of the present invention, and sealing strips are installed at the joints between the steel plate frame and the tempered glass plate and transparent nylon plate, so that the sealing performance is good, the measurement data is more accurate, and the calculation results are closer to the actual formation. Provide a basis for parameter optimization.

3. The cavity of the present invention is equipped with a screen surface and a filter screen, which can effectively isolate the proppant and only allow fluid to pass through, fully reflecting the slow and continuous fluid loss process in the fracturing process.

4. In the present invention, a flow meter and a pressure gauge are installed at the inlet and outlet of the filtration device, which can measure the internal friction of the crack.

5. The invention is easy to install and operate, has the characteristics of large scale and visualization, can observe the experimental process intuitively, analyze the experimental phenomena, and provide a basis for the optimization of fracturing parameters, and the principle of the calculation method is reliable, the model is simple to make, and it is easy to promote.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and therefore do not It should be regarded as a limitation on the scope, and those skilled in the art can also obtain other related drawings based on these drawings without creative work.

Fig. 1 is the structural diagram provided by the present invention;

Fig. 2 is a sectional view of the main seam device and the branch seam device provided by the present invention;

Fig. 3 is a structural diagram of the main seam device and the branch seam device provided by the present invention.

As shown in the figure:

1. Liquid distribution box, 2. Electric pump, 3. Water pipe, 4. Feeding box, 5. Load cell, 6. Stirring motor, 7. Stirring barrel, 8. Stirring rod, 9. Stirring blade, 10, Screw pump , 11. Main seam device, 12. Branch seam device, 13. Tempered glass plate, 14. Transparent nylon plate, 15. Cavity, 16. Steel plate frame, 17. Sealing ring, 18. Drain pipe, 19. Settling tank , 20-27, valve, 28-31, electronic flowmeter, 32-34, pressure gauge;

12-1, A branch seam device, 12-2, B branch seam device, 12-3, C branch seam device;

15-1, sieve surface, 15-2, filter screen, 15-3, filter loss outlet.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

As shown in Figure 1, a fracturing fluid filtration device for multi-branch fractures includes a liquid distribution and feeding device, a stirring device, a filtration device, and a liquid recovery device. The liquid distribution and feeding device includes a liquid distribution tank 1 and a feeding tank 4. Electric pump 2, electronic flow meter 28, water pipe 3, valve, the water pipe is connected in series with the liquid distribution tank 1, electric pump 2, and electronic flow meter 28, the port of the water pipe 3 is provided with a valve 20, and the charging box 4 The bottom of the bottom is provided with a load cell 5, the lower end of the load cell 5 is provided with a discharge port, the discharge port is provided with a valve 21, and the discharge port is connected to the port of the water pipe 3, the liquid feeding The device is connected to the upper left of the stirring device;

Described stirring device comprises mixing tank 7, stirring motor 6, stirrer, and described stirrer comprises stirring bar 8, stirring blade 9, and described stirring motor 6 is arranged on the upper end center position of described mixing tank 7, and described stirring blade 9 multi-stage distribution on the stirring rod 8, the bottom of the mixing tank 7 is provided with a liquid outlet, the liquid outlet is provided with a valve 22, and the liquid outlet is connected to a filtration device;

As shown in Figures 2 to 3, the fluid loss device includes a main slot device 11, a branch slot device 12, a screw pump 10, an electronic flow meter, a pressure gauge, and the fluid outlet of the fluid loss device and the mixing tank 7 A screw pump 10, an electronic flowmeter 29, and a pressure gauge 32 are arranged in series, and the main seam device 11 includes a tempered glass plate 13, a transparent nylon plate 14, a cavity 15, a screen surface 15-1, a filter screen 15-2, Steel plate frame 16, the steel plate frame 16 is arranged around the main seam device 11, the cavity 15 includes an upper cavity and a lower cavity, and the inside of the cavity 15 is provided with a screen surface 15-1, a filter 15-2, the length of the cavity 15 is 2.5m, the height is 3cm, and the width is 1cm, the cavity 15 is parallel to the upper and lower surfaces of the main seam device 11, and the steel plate frame 16 is connected to the upper cavity Tempered glass plate 13 is arranged between, described tempered glass plate 13 inner side is provided with transparent nylon plate 14, the inner surface of described nylon plate 14 is rough surface, and there is certain gap between the inner surface of described nylon plate 14, For simulating cracks in rock formations, a tempered glass plate 13 is provided between the upper chamber and the lower chamber, a transparent nylon plate 14 is provided on the inner side of the tempered glass plate 13, and the steel plate frame 16 and the tempered glass Plate 13, the joint of the transparent nylon plate 14 is provided with a sealing ring 17, a tempered glass plate 13 is provided between the steel plate frame 16 and the lower cavity, and a transparent nylon plate is provided inside the tempered glass plate 13 14. The distance between the upper cavity and the steel plate frame 16 on the upper surface of the filtration device is equal to the distance between the upper cavity and the lower cavity and the distance between the lower cavity and the lower surface of the filtration device. The distance between the steel plate frame 16 on the surface, the branch seam device 12 is arranged on both sides of the main seam device 11, and the structure of the branch seam device 12 is consistent with the main seam device 11, and the main seam device 11 and The included angle of the branch seam device 12 is set to 30°, the connection between the main seam device 11 and the branch seam device 12 is fixed with steel bars, and a sealing strip is provided, the rear end of the main seam device 11 There is a main seam liquid outlet, the rear end of the branch seam device 12 is provided with a branch seam liquid outlet, and the outside of the cavity 15 is provided with four fluid loss outlets 15-3, and the fluid loss outlet The liquid port 15-3 is connected in series with an electronic flowmeter 30, a pressure gauge 33, and a valve 23. The fluid loss outlet 15-3 is connected to the liquid recovery device, and the steel plate frame 16 on the upper and lower surfaces of the main seam device 11 The length is 2.5m, the height is 35cm, and the thickness is 1cm. The tempered glass plate 13 corresponds to its size. The effective simulated crack surface length is 2.5m, and the height is 30cm. The steel plate frame on the upper and lower surfaces of the branch seam device 12 16 has a length of 1.5m, a height of 35cm, and a thickness of 1cm. The tempered glass plate 12 corresponds to its size, and the length of the effectively simulated branch seam is 1.5m, and the height is 30cm;

The liquid recovery device includes a valve, a drain pipe 18, and a settling tank 19. One end of the drain pipe 18 is connected to the fluid loss outlet 15-3, and the other end is connected to the settling tank 19. A pressure gauge, an electronic flow meter, and a valve are arranged in series between the pipe 18 and the liquid outlet of the main seam, and a pressure gauge 34, an electronic flowmeter, and a pressure gauge 34 are arranged in series between the discharge pipe 18 and the outlet of the branch seam. Flow meter 31, valve 25.

A calculation method of a fracturing fluid filtration device for multi-branch fractures, the steps are as follows:

S1. Experiment preparation, check the integrity of the functions of each component;

S2. According to the on-site construction displacement, sand ratio, and proppant parameters, carry out laboratory preparation according to the same ratio, and calculate the displacement, fracturing fluid volume, and proppant dosage required for the experiment;

S3. Pump the configured fracturing fluid from the liquid distribution tank 1 into the mixing tank 7, the proppant enters the mixing tank 7 from the feeding tank 4, and turn on the stirring motor 6 to fully stir;

S4. Open the bottom valve 22 of the mixing tank 7, the valve 24 at the liquid outlet of the main seam, and the valves 25-27 at the liquid outlet of the branch seam, start the screw pump 10, and pump the mixed fracturing fluid into the main seam device 11 , open the valve 23 at the fluid outlet outlet 15-3 of the cavity 15 of the fluid loss device, and the mixed liquid flows into the settling tank 19 through the drain pipe 18;

S5 When the main fracture is stable, turn off the screw pump 10, and use the camera to record the proppant migration, laying process and fracturing fluid filtration process in the fracture; start the electric pump 2, pump clean water from the liquid distribution tank 1 to clean the device, Record the simulation time and the readings of the flowmeters in the filtrate area of each fracture, and calculate the filtration rate by the following formula:

In the formula: V-filtration volume, m ³ ; t-filtration time, min; ω-stainless steel flat chamber height, m; l-stainless steel flat chamber length, m; ν-filtration speed, m ³ /min.

Example:

(1) Experiment preparation, check the integrity of the functions of each component, and the valve is closed.

(2) According to the on-site construction displacement, sand ratio, and proppant parameters, the laboratory preparation was carried out in the same proportion. The experimental assumptions were: in the process of fracturing construction, clean water fracturing fluid was used, 30/50 mesh proppant was used, and the apparent density It is 1.76g/cm3, the pump injection displacement is 10m3/min, and the simulated sand ratio is 6%. The artificial fractures formed are 50m high and 8mm wide.

Combined with the experimental parameters, it is calculated according to the need for 10 minutes to stabilize the sand embankment:

The velocity of the mixed fluid in the real formation fracture is:

Simulated mixed fluid flow rate in the main fracture: ν'=25m/min×0.35m×0.008m=0.07m ³ /min

That is to say, during the experiment, the pumping rate of 0.07m ³ /min was used to pump the mixed solution with a sand ratio of 6%.

10min simulated seam mixture total flow:

Amount of fracturing fluid base fluid: 3.3m ³ ×0.94＝3.10m ³

Proppant dosage: 3m ³ ×0.06＝0.20m ³

0.20m ³ ×1.76×10 ³ Kg/m ³ =0.352Kg

The calculated displacement required for the experiment is 0.07m ³ /min, the volume of fracturing fluid base fluid is 3.10m ³ , the amount of proppant is 0.20m ³ , and the fracturing fluid is clear water fracturing fluid.

(3) Open the valve 20 and valve 21, pump the prepared fracturing fluid from the liquid distribution tank 1 into the mixing tank 7, the dosage is controlled by the electronic flowmeter 24, and the proppant enters the mixing tank 7 from the feeding tank 4, and the dosage is determined by the scale The heavy sensor 5 controls and turns on the stirring motor 6 for sufficient stirring.

(4) Open valve 22, valve 23, valve 24, valve 25, valve 26, valve 27 and the fluid loss outlet 15-3 valve 23 of the cavity 15 of main seam device 11 and branch seam device 12, start the screw pump 10. Pump the mixed fracturing fluid into the main fracture, and the mixed fluid flows into the settling tank 19 through the drain pipe 18; the device simulates the continuous and slow filtration process of the fracturing fluid in the formation, as well as the dynamic migration and sanding process

(5) After the main fracture is stabilized, turn off the screw pump, stop pumping the sand-carrying fracturing fluid, use the camera to record the proppant migration, laying process and fracturing fluid filtration process in the fracture, and record the main fracture of the parallel plate for 10 minutes The total fluid loss is 2.25×10 ^-4 m ³ , the total fluid loss of parallel plate branch seam A is 6.75×10 ^-5 m ³ , the total fluid loss of parallel plate branch seam C is 6×10 ^-5 m ³ , and the The total filtration loss of plate branch joint B is 9×10 ^-5 m ³ , start the electric pump, and pump clean water from the liquid distribution tank to clean the device;

Substituting the above experimental data into formula (1), the following results are obtained:

Parallel plate main seam filtration rate:

Parallel plate branch seam A filtration rate:

Parallel plate branch seam B filtration rate:

Parallel plate branch seam C filtration rate:

During the above experiment,

The beneficial effects of the fracturing fluid fluid loss device and calculation method for multi-branch fractures provided by the present invention are: the mixed liquid of fracturing fluid and proppant can be visually observed when the mixed liquid of fracturing fluid and proppant is pumped into the formation, gradually The dynamic process of fluid loss can be realized, and the dynamic laying process of proppant can be realized. The calculated fluid loss velocity can provide a basis for the optimization of fracturing parameters.

The above description does not limit the present invention in any form. Although the present invention has been disclosed above through the embodiments, it is not used to limit the present invention. When the technical content disclosed above can be used to make some changes or be modified into equivalent embodiments with equivalent changes, any simple modifications made to the above embodiments according to the technical essence of the present invention, Equivalent changes and modifications still fall within the scope of the technical solution of the present invention.

Claims (10)

1. A fracturing fluid filtration device for multi-branch fractures, characterized in that it comprises a liquid distribution feeding device, a stirring device, a filtration device, a liquid recovery device, and the liquid distribution feeding device includes a liquid distribution tank, a feeding tank, Electric pump, electronic flow meter, water pipe, valve, the water pipe is connected in series with the liquid distribution box, electric pump, and electronic flow meter, the port of the water pipe is provided with a valve, the bottom of the charging box is provided with a weighing sensor, and the weighing The lower end of the heavy sensor is provided with a discharge port, the discharge port is provided with a valve, and the discharge port is connected to the port of the water pipe, and the liquid mixing and feeding device is connected to the upper left of the stirring device; The stirring device includes a stirring barrel, a stirring motor, and a stirrer, the stirring motor is arranged at the center position of the upper end of the stirring barrel, the stirrer includes a stirring rod, and stirring blades, and the stirring blades are distributed on the stirring rod in multiple stages , the bottom of the mixing tank is provided with a liquid outlet, the liquid outlet is provided with a valve, and the liquid outlet is connected to a filtration device; The filtration device includes a main seam device, a branch seam device, a screw pump, an electronic flow meter, and a pressure gauge, and a screw pump, an electronic flow meter, and a pressure gauge are arranged in series between the filtration device and the liquid outlet of the mixing tank. The table shows that the main seam device includes a tempered glass plate, a transparent nylon plate, a cavity, a screen surface, a filter screen, and a steel plate frame, and the steel plate frame is arranged around the main seam device, and the cavity includes an upper cavity, The lower cavity, the inner side of the cavity is provided with a screen surface and a filter screen, the cavity is parallel to the upper and lower surfaces of the main seam device, and a tempered glass plate is arranged between the steel plate frame and the upper cavity , the inner side of the tempered glass plate is provided with a transparent nylon plate, a tempered glass plate is provided between the upper cavity and the lower cavity, a transparent nylon plate is provided on the inner side of the tempered glass plate, the steel plate frame and the A toughened glass plate is arranged between the lower chambers, a transparent nylon plate is arranged inside the toughened glass plate, the branch seam device is arranged on both sides of the main seam device, and the branch seam device is connected to the main seam device. The structure of the seam device is the same, the rear end of the main seam device is provided with a main seam liquid outlet, the rear end of the branch seam device is provided with a branch seam liquid outlet, and the outside of the cavity is provided with 4 filtration outlets. A liquid port, an electronic flowmeter, a pressure gauge, and a valve are arranged in series at the fluid loss outlet, and the fluid outlet for fluid loss is connected to the liquid recovery device; The liquid recovery device includes a valve, a drain pipe, and a settling tank. One end of the drain pipe is connected to the fluid loss outlet, and the other end is connected to the settling tank. The drain pipe is connected to the outlet of the main seam. A pressure gauge, an electronic flowmeter, and a valve are connected in series between the liquid ports, and a pressure gauge, an electronic flowmeter, and a valve are connected in series between the discharge pipe and the liquid outlet of the branch seam. 2 . The fracturing fluid fluid loss device for multi-branch fractures according to claim 1 , wherein the included angle between the main fracture device and the branch fracture device is set to 30°. 3. The fracturing fluid filtration device for multi-branched fractures according to claim 1, characterized in that the connection between the main fracture device and the branched fracture device is fixed with a steel bar, and a sealing strip is provided . 4 . The fracturing fluid filtration device for multi-branch fractures according to claim 1 , wherein a sealing ring is provided at the junction of the steel plate frame, the tempered glass plate, and the transparent nylon plate. 5. The fracturing fluid filtration device for multi-branch fractures according to claim 1, wherein the distance between the upper cavity and the steel plate frame on the upper surface of the filtration device is equal to that of the upper cavity The distance between the body and the lower cavity is equal to the distance between the lower cavity and the steel plate frame on the lower surface of the filtration device. 6. the fracturing fluid filtration device of a kind of multi-branch fracture according to claim 1, is characterized in that, described cavity length is 2.5m, and height is 3cm, and width is 1cm, and the outside of described cavity respectively There are 4 fluid loss outlets, and each fluid loss outlet is connected to an independent electronic flowmeter, pressure gauge, and valve. 7. The fracturing fluid filtration device for multi-branch fractures according to claim 1, wherein the inner surface of the nylon plate is a rough surface, and there is a certain gap between the inner surfaces of the nylon plate , used to simulate rock formation fractures. 8. The fracturing fluid filtration device for a multi-branch fracture according to claim 1, wherein the length of the steel plate frames on the upper and lower surfaces of the main fracture device is 2.5m, the height is 35cm, and the thickness is 1cm , the tempered glass plate corresponds to its size, the effective simulated crack surface length is 2.5m, and the height is 30cm. 9. the fracturing fluid filtration device of a kind of multi-branch fracture according to claim 1, is characterized in that, the length of the steel plate frame of the upper and lower surfaces of the branch fracture device is 1.5m, height is 35cm, and thickness is 1cm, The tempered glass plate corresponds to its size, and the effective simulated branch seam length is 1.5m, and the height is 30cm. 10. A calculation method of a fracturing fluid filtration device for multi-branch fractures as described in any one of claims 1-9, wherein the steps are as follows: S1. Experiment preparation, check the integrity of the functions of each component; S2. According to the on-site construction displacement, sand ratio, and proppant parameters, carry out laboratory preparation according to the same ratio, and calculate the displacement, fracturing fluid volume, and proppant dosage required for the experiment; S3. Pump the configured fracturing fluid from the liquid distribution tank into the mixing tank, and the proppant enters the mixing tank from the feeding tank, and turn on the stirring motor to fully stir; S4. Open the bottom valve of the mixing tank, the main seam liquid outlet valve, and the branch seam liquid outlet valve, start the screw pump, pump the mixed fracturing fluid into the main seam device, and open the filter chamber of the filter loss device. The valve at the liquid outlet is lost, and the mixed liquid flows into the settling tank through the drain pipe; S5 When the main fracture is stable, turn off the screw pump, and use the camera to record the proppant migration, laying process and fracturing fluid filtration process in the fracture; start the electric pump, pump clean water from the liquid distribution tank to clean the device, and record the simulation time and the flowmeter readings in the filtrate area of each fracture, the fluid loss rate is calculated by the following formula: In the formula: V-filtration volume, m ³ ; t-filtration time, min; ω-stainless steel flat chamber height, m; l-stainless steel flat chamber length, m; ν-filtration speed, m ³ /min.