阅读说明：本技术 一种二氧化碳压裂液节流系数的测试装置及方法 (Device and method for testing throttling coefficient of carbon dioxide fracturing fluid ) 是由 辛利伟 于 2021-07-20 设计创作，主要内容包括：本发明公开了一种二氧化碳压裂液节流系数的测试装置及方法,其包括液态二氧化碳注入装置、压裂液基液注入装置、支撑剂注入装置、第一模拟测试箱以及混合起泡罐,所述液态二氧化碳注入装置、压裂液基液注入装置、支撑剂注入装置分别通过第一导入管、第二导入管、第三导入管与混合起泡罐相连通,其连通端面均位于混合起泡罐靠上端侧罐壁处,且所述混合起泡罐内部安装有起泡组件,所述第一模拟测试箱中设有模拟井道,呈十字结构,将其内部空间分隔为四组测试室,每组所述测试室内部设有岩层样本,且所述模拟井道内部安装有测试装置,所述测试装置左、右、下侧端分别通过第一回流管、第二回流管、第三回流管与混合起泡罐相连通。(The invention discloses a device and a method for testing the throttling coefficient of a carbon dioxide fracturing fluid, which comprises a liquid carbon dioxide injection device, a fracturing fluid base fluid injection device, a propping agent injection device, a first simulation test box and a mixed foaming tank, wherein the liquid carbon dioxide injection device, the fracturing fluid base fluid injection device and the propping agent injection device are respectively communicated with the mixed foaming tank through a first lead-in pipe, a second lead-in pipe and a third lead-in pipe, the communication end surfaces of the liquid carbon dioxide injection device, the fracturing fluid base fluid injection device and the propping agent injection device are all positioned at the tank wall close to the upper end side of the mixed foaming tank, a foaming component is arranged in the mixed foaming tank, a simulation well way which is in a cross structure is arranged in the first simulation test box, the internal space of the simulation well way is divided into four groups of test chambers, a rock stratum sample is arranged in each group of test chambers, a test device is arranged in the simulation well way, and the left, right and lower side ends of the test devices respectively pass through a first backflow pipe, The second return pipe and the third return pipe are communicated with the mixing foaming tank.)

1. The utility model provides a carbon dioxide fracturing fluid throttling coefficient's testing arrangement, its includes liquid carbon dioxide injection apparatus (1), fracturing fluid base fluid injection apparatus (2), proppant injection apparatus (3), first simulation test case (4) and mix foaming tank (5), its characterized in that: the liquid carbon dioxide injection device (1), the fracturing fluid base liquid injection device (2) and the proppant injection device (3) are respectively communicated with the mixing and foaming tank (5) through a first inlet pipe (101), a second inlet pipe (201) and a third inlet pipe (301), the communication end faces of the mixing and foaming tank (5) are all located at the position close to the tank wall of the upper end side, and a foaming component (6) is arranged in the mixing and foaming tank (5);

a simulation well (404) is arranged in the first simulation test box (4) and is of a cross structure, the internal space of the simulation test box is divided into four groups of test chambers, a rock stratum sample (403) is arranged in each group of test chambers, and a test device is arranged in the simulation well (404);

the left side end, the right side end and the lower side end of the testing device are respectively communicated with the mixing and foaming tank (5) through a first return pipe (103), a second return pipe (203) and a third return pipe (303).

2. The device for testing the throttling coefficient of the carbon dioxide fracturing fluid as claimed in claim 1, wherein: a first metering control valve (105) is installed on the first leading-in pipe (101), and a first metering control valve (102) is installed on the first return pipe (103);

and a first pressure compensating pump (104) is arranged on a first return pipe (103) between the first metering control valve (102) and the mixing and foaming tank (5).

3. The device for testing the throttling coefficient of the carbon dioxide fracturing fluid as claimed in claim 1, wherein: a second metering control valve (205) is arranged on the second leading-in pipe (201), and a second metering control valve (202) is arranged on the second return pipe (203);

and a second pressure compensating pump (204) is arranged on a second return pipe (203) between the second metering control valve (202) and the mixing and foaming tank (5).

4. The device for testing the throttling coefficient of the carbon dioxide fracturing fluid as claimed in claim 1, wherein: a third metering control valve (305) is arranged on the third leading-in pipe (301), and a third metering control valve (302) is arranged on the third return pipe (303);

and a second pressure compensating pump (304) is arranged on a third return pipe (303) positioned between the third metering control valve (302) and the mixing and foaming tank (5).

5. The device for testing the throttling coefficient of the carbon dioxide fracturing fluid as claimed in claim 1, wherein: the foaming component (6) comprises a first motor (61), the first motor (61) is fixed on the tank wall at the upper end of the mixing foaming tank (5), the output end of the first motor is fixed with a rotating tank (62), and the rotating tank (62) is arranged above the inner part of the mixing foaming tank (5) and is in rotating connection with the tank wall at the inner side of the mixing foaming tank;

a second motor (63) is arranged in the rotating box (62), a plurality of groups are arranged in a circumferential manner, and longitudinal stirring frame pieces (64) are arranged at the output ends of the rotating box;

the lower end of the stirring frame piece positioned in the center is fixedly provided with a conical spiral fan blade (65).

6. The device for testing the throttling coefficient of the carbon dioxide fracturing fluid as claimed in claim 5, wherein: the stirring frame component comprises a stirring support (69), the upper end of the stirring support (69) is fixed with the output end of the motor II (63), and the stirring frame component is structurally a cylindrical stirring support (69) consisting of four groups of support rods which are circumferentially arranged;

the stirring bracket (69) is internally provided with horizontal leakage monitoring plates (67), four groups of the leakage monitoring plates are linearly arranged along the direction from the bottom end to the upper end of the strut rod, a cavity above each group of the leakage monitoring plates (67) is a stirring chamber, the upper end of the stirring chamber at the uppermost layer is a feeding hole, and each group of the leakage monitoring plates is provided with a foam metering element;

from top to bottom layer install forked frame (66), cylindricality frame (68) in the stirring chamber in turn.

7. The device for testing the throttling coefficient of the carbon dioxide fracturing fluid as claimed in claim 1, wherein: the first simulation test box (4) comprises a pressure supplementing element (401), a temperature control element (402) and a flow dividing box (405), the pressure supplementing element (401) is arranged at the box corner end of the first simulation test box (4), and the temperature control element (402) is clamped in the side box wall of the first simulation test box (4);

the flow distribution box (405) is positioned in the center of the first simulation test box (4), the upper end of the flow distribution box is communicated with the mixed foaming tank through a pipeline, the left side end, the right side end and the lower side end of the flow distribution box are respectively provided with a perforation (406) and are connected through pipelines, and the perforations (406) at the left side end, the right side end and the lower side end are respectively communicated with the first return pipe (103), the second return pipe (203) and the third return pipe (303) through pipelines;

and both ends of the perforation (406) are provided with a pressure monitoring element (407) and a temperature monitoring element (408).

8. A method for testing the throttling coefficient of a carbon dioxide fracturing fluid is characterized by comprising the following steps: which comprises the following steps:

s1: taking the same rock stratum block, dividing the rock stratum block into four groups of rock stratum samples with the same size, placing the rock stratum samples into a test chamber in a first simulation test box, regulating and controlling the internal pressure and temperature of the first simulation test box by a pressure supplementing element and a temperature control element to be consistent with the pressure and temperature in the crust where the rock stratum block is located, wherein a first metering control valve, a second metering control valve and a third metering control valve are all in a closed state;

s2: opening a first metering control valve, a second metering control valve and a third metering control valve, respectively injecting certain constant-temperature, constant-pressure and constant-speed liquid carbon dioxide, fracturing fluid base fluid and propping agent into a mixing foaming tank through a liquid carbon dioxide injection device, a fracturing fluid base fluid injection device and a propping agent injection device, starting a motor I and a motor II to run in a matching manner, mixing, stirring and foaming the entering liquid carbon dioxide, fracturing fluid base fluid and propping agent through a foaming component, and introducing the mixture into a flow distribution box through a pressure pump;

s3: injecting the mixture into the formation sample by a perforation, wherein the mixture flows through the perforation, the perforation does not start injection, the pressure monitoring elements at the inflow end and the outflow end of the perforation measure mixture fluid pressures P1 and P2, the temperature monitoring elements measure mixture fluid temperatures T1 and T2, the mixture flows through the perforation, the perforation starts injection, the pressure monitoring elements at the inflow end and the outflow end of the perforation measure mixture fluid pressures P3 and P4, and the temperature monitoring elements measure mixture fluid temperatures T3 and T4, wherein the throttling coefficient CV1 when the perforation does not inject is the difference between T1 and T2 divided by the difference between P1 and P2, and the throttling coefficient when the perforation injects is CV2 is the difference between T3 and T4 divided by the difference between P3 and P4;

s4: opening the first metering control valve, the second metering control valve and the third metering control valve, adjusting and guiding the pressure of the mixture flowing out through the first pressure supplementing pump, the second pressure supplementing pump and the third pressure supplementing pump to be consistent with the pressure flowing through the pressure pump at the same time, forming a circulating flow, and at the moment, repeating the measuring method in S2 by the pressure monitoring element and the temperature monitoring element for measurement again;

s5: thirdly, the first metering control valve, the second metering control valve and the third metering control valve are all in a closed state, the injection amount of the propping agent in the step S2 is increased, meanwhile, the injection amount of the liquid carbon dioxide is correspondingly reduced, the reduction value is equal to the absolute injection amount of the propping agent, the internal phase and the external phase are kept in balance, and the corresponding throttling coefficient is measured and calculated by repeating the measuring method in the step S2 for the fracturing method adopting the constant internal phase construction mode;

s6: the first metering control valve, the second metering control valve, and the third metering control valve are opened again, and the respective throttle coefficients are measured and calculated while the circulation flow is repeated in step S4.

9. The method for testing the throttling coefficient of the carbon dioxide fracturing fluid as claimed in claim 8, wherein the method comprises the following steps: and a foam metering element in the foaming component monitors whether the foam quality in the mixing and foaming tank reaches 60-80%, and the running speed of a first motor and a second motor in the foaming component is increased.

Technical Field

The invention relates to the technical field of unconventional oil and gas exploitation, in particular to a device and a method for testing the throttling coefficient of a carbon dioxide fracturing fluid.

Background

In the field of oil and gas reservoir exploitation, after an oil well is exploited for a certain period, the productivity and permeability of the oil well are reduced, and in order to further improve the productivity, a fracturing technology is adopted. The fracturing method can be divided into hydraulic fracturing and high-energy gas fracturing. Wherein CO is used₂Fracturing method capable of reducing liquid entering hydrocarbon reservoirThe fracturing fluid has the characteristics of high viscosity and good sand carrying performance in the fracturing process, and adopts CO₂The foam fracturing technology has better fracturing effect; however, because of the large differences in the internal formation structure of different hydrocarbon reservoirs, the need for CO is high₂After the fracturing fluid enters the rock stratum through the conduit, the changes of pressure and temperature in the flowing process of the fracturing fluid are tested so as to obtain real and accurate CO₂The throttling coefficient of the fracturing fluid is recorded, so that subsequent CO entering the rock stratum is convenient to carry out₂The dynamics of the fracturing fluid are adjusted to adequately fracture the formation. But now for CO₂Device for testing throttling coefficient of fracturing fluid, obtained throttling coefficient and actual CO in environment where device is tested_2-The throttling coefficient deviation in the flowing process of the fracturing fluid is large, and the CO is only subjected to pressure change₂The throttling coefficient of the fracturing fluid is tested, so that CO is applied to the practical process₂After the fracturing fluid enters the formation, CO is caused₂The pressurization of the fracturing fluid is insufficient, so that the rock stratum cannot be sufficiently fractured, and the subsequent pressurization adjustment process is complicated.

Therefore, the person skilled in the art provides a device and a method for testing the throttling coefficient of the carbon dioxide fracturing fluid, so as to solve the problems in the background art.

Disclosure of Invention

In order to achieve the purpose, the invention provides the following technical scheme: a testing device for the throttling coefficient of a carbon dioxide fracturing fluid comprises a liquid carbon dioxide injection device, a fracturing fluid base fluid injection device, a propping agent injection device, a first simulation testing box and a mixed foaming tank, wherein the liquid carbon dioxide injection device, the fracturing fluid base fluid injection device and the propping agent injection device are respectively communicated with the mixed foaming tank through a first lead-in pipe, a second lead-in pipe and a third lead-in pipe, the communication end faces of the two lead-in pipes are all positioned at the tank wall, close to the upper end, of the mixed foaming tank, and a foaming component is arranged in the mixed foaming tank;

the first simulation test box is internally provided with a simulation well which is of a cross structure and divides the internal space of the first simulation test box into four groups of test chambers, a rock stratum sample is arranged in each group of test chambers, and a test device is arranged in the simulation well;

the left, right and lower side ends of the testing device are respectively communicated with the mixing foaming tank through a first return pipe, a second return pipe and a third return pipe.

As a preferred technical solution of the present invention, a first metering control valve is installed on the first introduction pipe, and a first metering control valve is installed on the first return pipe;

and a first pressure compensating pump is arranged on a first return pipe between the first metering control valve and the mixing and foaming tank.

As a preferable technical solution of the present invention, a second metering control valve is installed on the second introduction pipe, and a second metering control valve is installed on the second return pipe;

and a second pressure compensating pump is arranged on a second return pipe between the second metering control valve and the mixing and foaming tank.

As a preferred technical solution of the present invention, a third metering control valve is installed on the third introducing pipe, and a third metering control valve is installed on the third return pipe;

and a second pressure compensating pump is arranged on a third return pipe between the third metering control valve and the mixing and foaming tank.

As a preferred technical scheme of the invention, the foaming component comprises a motor I, the motor I is fixed on the tank wall at the upper end of the mixing foaming tank, the output end of the motor I is fixed with a rotating box, and the rotating box is arranged above the inner part of the mixing foaming tank and is rotationally connected with the tank wall at the inner side of the rotating box;

a second motor is arranged in the rotating box, a plurality of groups of motors are arranged in a circumferential manner, and longitudinal stirring frame pieces are arranged at the output ends of the motors;

the conical spiral fan blade is fixed at the lower end of the stirring frame piece positioned in the center.

As a preferred technical scheme of the invention, one group of the stirring frame components comprises a stirring support, the upper end of the stirring support is fixed with the output end of the second motor, and the structure of the stirring frame is that a cylindrical stirring support consisting of four groups of support rods is circumferentially arranged;

the stirring bracket is internally provided with horizontal leakage monitoring plates, four groups of the leakage monitoring plates are linearly arranged along the direction from the bottom end to the upper end of the strut rod, a cavity above each group of the leakage monitoring plates is a stirring chamber, the upper end of the stirring chamber on the uppermost layer of the leakage monitoring plates is a feeding hole, and each group of the leakage monitoring plates is provided with a foam metering element;

from top to bottom the stirring chamber is middle and upper alternately and is installed forked shape frame, cylindricality frame.

As a preferred technical solution of the present invention, the first simulation test box includes a pressure compensating element, a temperature control element and a flow dividing box, the pressure compensating element is disposed at a corner end of the first simulation test box, and the temperature control element is clamped in a side box wall of the first simulation test box;

the flow distribution box is positioned in the center of the first simulation test box, the upper end of the flow distribution box is communicated with the mixed foaming tank through a pipeline, the left side end, the right side end and the lower side end of the flow distribution box are respectively provided with a perforation and are connected through pipelines, and the perforations at the left side end, the right side end and the lower side end are respectively communicated with the first return pipe, the second return pipe and the third return pipe through pipelines;

and both ends of the perforation are provided with a pressure monitoring element and a temperature monitoring element.

A method for testing the throttling coefficient of a carbon dioxide fracturing fluid comprises the following steps:

s1: taking the same rock stratum block, dividing the rock stratum block into four groups of rock stratum samples with the same size, placing the rock stratum samples into a test chamber in a first simulation test box, regulating and controlling the internal pressure and temperature of the first simulation test box by a pressure supplementing element and a temperature control element to be consistent with the pressure and temperature in the crust where the rock stratum block is located, wherein a first metering control valve, a second metering control valve and a third metering control valve are all in a closed state;

s2: opening a first metering control valve, a second metering control valve and a third metering control valve, respectively injecting certain constant-temperature, constant-pressure and constant-speed liquid carbon dioxide, fracturing fluid base fluid and propping agent into a mixing foaming tank through a liquid carbon dioxide injection device, a fracturing fluid base fluid injection device and a propping agent injection device, starting a motor I and a motor II to run in a matching manner, mixing, stirring and foaming the entering liquid carbon dioxide, fracturing fluid base fluid and propping agent through a foaming component, and introducing the mixture into a flow distribution box through a pressure pump;

s3: injecting the mixture into the formation sample by a perforation, wherein the mixture flows through the perforation, the perforation does not start injection, the pressure monitoring elements at the inflow end and the outflow end of the perforation measure mixture fluid pressures P1 and P2, the temperature monitoring elements measure mixture fluid temperatures T1 and T2, the mixture flows through the perforation, the perforation starts injection, the pressure monitoring elements at the inflow end and the outflow end of the perforation measure mixture fluid pressures P3 and P4, and the temperature monitoring elements measure mixture fluid temperatures T3 and T4, wherein the throttling coefficient CV1 when the perforation does not inject is the difference between T1 and T2 divided by the difference between P1 and P2, and the throttling coefficient when the perforation injects is CV2 is the difference between T3 and T4 divided by the difference between P3 and P4;

s4: opening the first metering control valve, the second metering control valve and the third metering control valve, adjusting and guiding the pressure of the mixture flowing out through the first pressure supplementing pump, the second pressure supplementing pump and the third pressure supplementing pump to be consistent with the pressure flowing through the pressure pump at the same time, forming a circulating flow, and at the moment, repeating the measuring method in S2 by the pressure monitoring element and the temperature monitoring element for measurement again;

s5: thirdly, the first metering control valve, the second metering control valve and the third metering control valve are all in a closed state, the injection amount of the propping agent in the step S2 is increased, meanwhile, the injection amount of the liquid carbon dioxide is correspondingly reduced, the reduction value is equal to the absolute injection amount of the propping agent, the internal phase and the external phase are kept in balance, and the corresponding throttling coefficient is measured and calculated by repeating the measuring method in the step S2 for the fracturing method adopting the constant internal phase construction mode;

s6: the first metering control valve, the second metering control valve, and the third metering control valve are opened again, and the respective throttle coefficients are measured and calculated while the circulation flow is repeated in step S4.

As a preferable technical scheme of the invention, when the foam metering element in the foaming component monitors whether the foam quality in the mixing and foaming tank reaches 60-80%, the operation speed of the first motor and the second motor in the foaming component is increased.

Compared with the prior art, the invention provides a device and a method for testing the throttling coefficient of a carbon dioxide fracturing fluid, which have the following beneficial effects:

1. the invention can measure the same-layer rock stratum sample and the critical rock stratum sample so as to measure the carbon dioxide fracturing fluid throttling coefficient measurement in different rock stratums, truly simulates the pressure and the temperature of the rock stratum where the rock stratum sample is actually located by regulating and controlling the internal pressure and the temperature of the first simulation test box, so that the measured data is more effective and closer to the actual data, wherein, during the same-layer measurement, the rock stratum sample is divided into four groups, and the position of the carbon dioxide fracturing fluid conveying pipeline is truly reduced by arranging the transverse and longitudinal test devices, compared with the existing test device, the measured value of the throttling coefficient is more accurate, the throttling coefficient corresponding to the measured position is clearly and accurately known, the installation, the setting and the improvement of the subsequent fracturing fluid pipeline are improved, the guarantee is provided, and the testing on the critical surface of the adjacent rock stratum is more convenient by adding the number of the first simulation test box, the testing efficiency is improved.

2. The invention is characterized in that three groups of injection devices are arranged, namely a liquid carbon dioxide injection device, a fracturing fluid base fluid injection device and a propping agent injection device, and are injected into a mixed foaming tank to be mixed and foamed in a constant-temperature constant-pressure constant-speed mode, the form of the carbon dioxide fracturing fluid in the actual flowing process is fully reduced, the quality of the mixed foam is measured by a foam measuring element, the mixing condition of the pressure fluid is favorably monitored in real time, the pressure fluid is timely adjusted and introduced into a perforation, the temperature difference and the pressure difference of an inflow end and an outflow end are firstly measured when the perforation is not injected, the temperature difference and the pressure difference of the inflow end and the outflow end are then measured when the perforation is injected, the steps are repeated again under the circulating state for measurement, the flowing process of the carbon dioxide fracturing fluid is truly simulated, and the propping agent injection amount is increased, The injection amount of the carbon dioxide fracturing fluid is reduced, the constant internal phase construction mode in the foam fracturing method in the carbon dioxide fracturing mode can be tested, different mode structures adopted in different methods are further improved, the throttling coefficient of the carbon dioxide fracturing fluid is measured, and the effective authenticity of data is further improved;

3. in the invention, in the circulating measurement process, the mixed liquid directly flows into the mixing foaming tank, so that the measurement efficiency is further accelerated, and the optimal temperature and pressure for injecting the fracturing fluid can be obtained by measuring the respective mass of the final liquid carbon dioxide injection device, the fracturing fluid base fluid injection device and the proppant injection device, comparing the measured mass with the initial mass and observing the fracturing condition of a rock stratum sample.

Drawings

FIG. 1 is a schematic view of a pipe end finisher according to the present invention;

FIG. 2 is an enlarged view of the structure of the conveying mechanism of the present invention;

FIG. 3 is an enlarged view of the cleaning assembly of the present invention;

in the figure: 1. a liquid carbon dioxide injection device; 2. a fracturing fluid base fluid injection device; 3. a proppant injection device; 4. a first simulation test box; 5. a mixing and bubbling tank; 6. a foaming component; 7. a pressure pump; 8. a second simulation test box; 101. a first introduction tube; 102. a first metering control valve; 103. a first return pipe; 104. a first pressure compensating pump; 105. a first metering control valve; 201. a second introduction tube; 202. a second metering control valve; 203. a second return pipe; 204. a second pressure compensating pump; 205. a second metering control valve; 301. a third inlet tube; 302. a third metering control valve; 303. a third return conduit; 304. a third pressure compensating pump; 305. a third metering control valve; 401. a pressure compensating element; 402. a temperature control element; 403. a formation sample; 404. simulating a well; 405. a shunt box; 406. perforating; 407. a pressure monitoring element; 408. a temperature monitoring element; 61. a first motor; 62. a rotary box; 63. a second motor; 64. a stir frame member; 65. a conical helical fan blade; 66. a fork-shaped frame; 67. a leakage monitoring plate; 68. a cylindrical frame; 69. and (4) stirring the bracket.

Detailed Description

Referring to fig. 1-3, the present invention provides a technical solution: a testing device for the throttling coefficient of a carbon dioxide fracturing fluid comprises a liquid carbon dioxide injection device 1, a fracturing fluid base fluid injection device 2, a propping agent injection device 3, a first simulation testing box 4 and a mixed foaming tank 5, wherein the liquid carbon dioxide injection device 1, the fracturing fluid base fluid injection device 2 and the propping agent injection device 3 are respectively communicated with the mixed foaming tank 5 through a first lead-in pipe 101, a second lead-in pipe 201 and a third lead-in pipe 301, the communication end faces of the two pipes are all positioned at the tank wall of the mixed foaming tank 5 close to the upper end side, and a foaming component 6 is arranged in the mixed foaming tank 5;

a simulation well 404 is arranged in the first simulation test box 4, the simulation well is of a cross structure, the internal space of the simulation test box is divided into four groups of test chambers, a rock stratum sample 403 is arranged in each group of test chambers, and a test device is arranged in the simulation well 404;

the left, right and lower side ends of the testing device are respectively communicated with the mixing foaming tank 5 through a first return pipe 103, a second return pipe 203 and a third return pipe 303;

as a preferred embodiment, in the present apparatus, by increasing the number of the first simulation test boxes, if a set of test boxes is additionally installed on the right side of the first simulation test box as the second simulation test box, the throttling coefficient of the carbon dioxide fracturing fluid is measured when the rock stratum sample at the critical surface is fractured, wherein the left side pipeline is communicated with the right side pipeline of the first simulation test box, the right, lower and upper side pipelines thereof are all merged into a set of pipelines and communicated with the mixing bubbling tank, and when the first simulation test box and the second simulation test box operate together, the second metering control valve 202 is closed, so as to further measure more data measured by the throttling coefficient of the carbon dioxide fracturing fluid in different rock strata, thereby improving the accuracy of the measured data.

In this embodiment, the first introducing pipe 101 is provided with a first metering control valve 105, and the first return pipe 103 is provided with a first metering control valve 102;

and a first return pipe 103 between the first metering control valve 102 and the mixing and frothing tank 5 is provided with a first pressure compensating pump 104.

In this embodiment, a second metering control valve 205 is installed on the second introduction pipe 201, and a second metering control valve 202 is installed on the second return pipe 203;

and a second pressure compensating pump 204 is mounted on the second return line 203 between said second metering control valve 202 and the mixing and frothing tank 5.

In this embodiment, a third metering control valve 305 is installed on the third introducing pipe 301, and a third metering control valve 302 is installed on the third return pipe 303;

and a second pressure supplementing pump 304 is mounted on a third return pipe 303 between said third metering control valve 302 and the mixing and frothing tank 5.

In this embodiment, the frothing assembly 6 comprises a first motor 61, the first motor 61 is fixed on the tank wall at the upper end of the mixing frothing tank 5, the output end of the first motor is fixed with a rotating box 62, and the rotating box 62 is arranged above the inside of the mixing frothing tank 5 and is rotatably connected with the tank wall at the inner side thereof;

a second motor 63 is arranged in the rotating box 62, a plurality of groups are arranged in a circumferential manner, and longitudinal stirring frame pieces 64 are arranged at the output ends of the rotating box;

the conical spiral fan blade 65 is fixed at the lower end of the stirring frame piece positioned in the center;

the outflow of mixture can be accelerated through the rotation of spiral flabellum, and is the vortex formula and flows, improves the smoothness nature that the mixture flows out.

In this embodiment, one group of the stirring frame members includes a stirring support 69, the upper end of the stirring support 69 is fixed to the output end of the second motor 63, and the structure of the stirring support is that four groups of column rods are circumferentially arranged to form a cylindrical stirring support 69;

the stirring bracket 69 is internally provided with horizontal leakage monitoring plates 67, four groups of the leakage monitoring plates are linearly arranged along the direction from the bottom end to the upper end of the strut rod, a cavity above each group of the leakage monitoring plates 67 is a stirring chamber, the upper end of the stirring chamber at the uppermost layer is a feeding hole, and each group of the leakage monitoring plates is provided with a foam metering element;

fork-shaped frames 66 and cylindrical frames 68 are alternately arranged in the stirring chamber from top to bottom;

as the best embodiment, the stirring of the forked frame is matched with the self-rotating stirring, and when the mixture is transferred from the upper layer to the lower layer, the mixture is stirred and drained alternately for one time, so that the foaming efficiency of the mixture is improved.

In this embodiment, the first simulation test box 4 includes a voltage compensation element 401, a temperature control element 402, and a flow dividing box 405, the voltage compensation element 401 is disposed at a corner end of the first simulation test box 4, and the temperature control element 402 is clamped in a side box wall of the first simulation test box 4;

the flow distribution box 405 is positioned in the center of the first simulation test box 4, the upper end of the flow distribution box is communicated with the mixed foaming tank through a pipeline, the left side end, the right side end and the lower side end of the flow distribution box are respectively provided with a perforation 406 and are connected through a pipeline, and the perforation 406 at the left side end, the right side end and the lower side end are respectively communicated with the first return pipe 103, the second return pipe 203 and the third return pipe 303 through pipelines;

both ends of the perforation 406 are provided with a pressure monitoring element 407 and a temperature monitoring element 408.

A method for testing the throttling coefficient of a carbon dioxide fracturing fluid comprises the following steps:

s1: taking the same rock stratum block, dividing the rock stratum block into four groups of rock stratum samples with the same size, placing the rock stratum samples into a test chamber in a first simulation test box, regulating and controlling the internal pressure and temperature of the first simulation test box by a pressure supplementing element and a temperature control element to be consistent with the pressure and temperature in the crust where the rock stratum block is located, wherein a first metering control valve, a second metering control valve and a third metering control valve are all in a closed state;

s2: opening a first metering control valve, a second metering control valve and a third metering control valve, respectively injecting certain constant-temperature, constant-pressure and constant-speed liquid carbon dioxide, fracturing fluid base fluid and propping agent into a mixing foaming tank through a liquid carbon dioxide injection device, a fracturing fluid base fluid injection device and a propping agent injection device, starting a motor I and a motor II to run in a matching manner, mixing, stirring and foaming the entering liquid carbon dioxide, fracturing fluid base fluid and propping agent through a foaming component, and introducing the mixture into a flow distribution box through a pressure pump;

s3: injecting the mixture into the formation sample by a perforation, wherein the mixture flows through the perforation, the perforation does not start injection, the pressure monitoring elements at the inflow end and the outflow end of the perforation measure mixture fluid pressures P1 and P2, the temperature monitoring elements measure mixture fluid temperatures T1 and T2, the mixture flows through the perforation, the perforation starts injection, the pressure monitoring elements at the inflow end and the outflow end of the perforation measure mixture fluid pressures P3 and P4, and the temperature monitoring elements measure mixture fluid temperatures T3 and T4, wherein the throttling coefficient CV1 when the perforation does not inject is the difference between T1 and T2 divided by the difference between P1 and P2, and the throttling coefficient when the perforation injects is CV2 is the difference between T3 and T4 divided by the difference between P3 and P4;

s4: opening the first metering control valve, the second metering control valve and the third metering control valve, adjusting and guiding the pressure of the mixture flowing out through the first pressure supplementing pump, the second pressure supplementing pump and the third pressure supplementing pump to be consistent with the pressure flowing through the pressure pump at the same time, forming a circulating flow, and at the moment, repeating the measuring method in S2 by the pressure monitoring element and the temperature monitoring element for measurement again;

s5: thirdly, the first metering control valve, the second metering control valve and the third metering control valve are all in a closed state, the injection amount of the propping agent in the step S2 is increased, meanwhile, the injection amount of the liquid carbon dioxide is correspondingly reduced, the reduction value is equal to the absolute injection amount of the propping agent, the internal phase and the external phase are kept in balance, and the corresponding throttling coefficient is measured and calculated by repeating the measuring method in the step S2 for the fracturing method adopting the constant internal phase construction mode;

s6: the first metering control valve, the second metering control valve, and the third metering control valve are opened again, and the respective throttle coefficients are measured and calculated while the circulation flow is repeated in step S4.

In this embodiment, the foam metering element in the foaming assembly monitors whether the foam quality inside the mixing and foaming tank reaches 60% to 80%, and increases the operation rate of the first motor and the second motor in the foaming assembly.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can substitute or change the technical solution of the present invention and the inventive concept within the technical scope of the present invention, and the technical solution and the inventive concept thereof should be covered by the scope of the present invention.