A pressure test ball and a method and application for accurately testing downhole pressure in a light casing fracturing

Abstract

The application provides a pressure test ball and a method for accurately testing downhole pressure in a light casing fracturing and application. The pressure test ball comprises a core and an outer side coated on the core. The core is a hollow spherical body, and a pressure gauge is arranged in the core. The test method comprises the following steps: 1. according to the number of pressure segments of horizontal well fracturing, each segment pressure test ball is marked; 2. the first stage pressure test ball is put into from the wellhead, and the downhole pressure data in the fracturing process is recorded; 3. the remaining segment fracturing and the measurement of downhole pressure data are sequentially completed; 4. the pressure test balls put into the well are sequentially collected on the ground; 5. the pressure gauge data in each segment pressure test ball is read; and 6. the fracturing effect is analyzed and evaluated by using the test data, and the fracturing parameters are further optimized. Through the method that the pressure gauge is arranged in the fracturing ball, the accurate test of key parameters such as downhole pressure and temperature in the horizontal well volume fracturing construction process is realized, and a new way for the volume fracturing test of unconventional oil and gas reservoirs is provided.

Description

Technical Field

[0001] This invention belongs to the field of oil production engineering, specifically relating to a pressure testing ball and a method and application for accurate bottom hole pressure testing in smooth casing fracturing. Background Technology

[0002] Shale oil, tight oil, and other unconventional resource reservoirs are dense and have poor physical properties, making it difficult to achieve economically recoverable production using conventional fracturing techniques. Currently, large-scale volumetric fracturing technology has significantly improved single-well production. This mainly involves inter-section isolation using downhole packing tools (soluble bridge plugs, ball seats, etc.) and high-volume fracturing with bare casing. However, since fracturing is performed without a fracturing string inside the wellbore, the pressure, temperature, and other testing requirements of high-volume volumetric fracturing with bare casing cannot be met during the fracturing process, making it difficult to accurately analyze the fracturing effect. As reservoir conditions deteriorate year by year, it becomes increasingly difficult to further optimize fracturing parameters to improve production.

[0003] Comparison with similar technologies: Technology 1: External Casing Fiber Optic Testing Technology. During the casing installation process after drilling, a permanent fiber optic cable is inserted outside the casing. Ground receiving equipment can be used to test parameters such as bottom hole pressure and temperature during and after fracturing. However, this technology has high requirements for wellbore trajectory and wellbore supporting equipment (the cost of testing a single well is around 10 million RMB). It also requires complex supporting technologies such as azimuth perforation, resulting in high testing costs and making it difficult to apply on a large scale.

[0004] Technology 2: Storage-type electronic devices are incorporated into fracturing tools. For example, Chinese patent application number CN201721768559.4 discloses a downhole storage-type electronic pressure gauge. This invention relates to a downhole pressure gauge, which includes a pressure gauge assembly comprising a battery sleeve, a circuit sleeve, and a sensor mounting body. The battery sleeve is a blind sleeve with a closed upper end, and its lower end is fixedly mounted to the upper end of the circuit sleeve. A four-pin socket is installed inside the circuit sleeve, and a circuit board is inserted into the four-pin socket. A high-temperature battery electrically connected to the upper end of the four-pin socket is located inside the battery sleeve. The lower end of the circuit sleeve is fixedly mounted to the upper end of the sensor mounting body, and an external temperature sensor electrically connected to the four-pin socket is fixedly mounted on the sensor mounting body. This invention has a reasonable and compact structure and is easy to use; it is easy to install and disassemble, and the circuit board is installed through a plug-in connection, making maintenance and replacement easier. By incorporating an external temperature sensor, parameters such as pressure and temperature can be quickly measured. This pressure gauge is connected to the fracturing tubing string and inserted into the well. During fracturing, it can record pressure and temperature parameters. After fracturing operations are completed, the testing tool is retrieved to the surface, where the relevant parameters can be read. However, because fracturing is performed using a fracturing tubing string, the tubing friction is relatively high, making it suitable only for fracturing and stimulation of high-permeability and low-permeability reservoirs. It cannot meet the pressure and temperature testing requirements of high-volume volume fracturing with bare casing.

[0005] Technique 3: This technique calculates bottomhole pressure by recording the surface wellhead pressure during fracturing. The formula is: Bottomhole pressure = Wellhead pressure + Wellbore fluid column pressure - Fluid friction. However, due to factors such as uneven fracturing fluid concentration, changes in flow rate, and the roughness of the casing inner wall during fracturing, the calculated friction and fluid column pressure have significant errors, resulting in a large error in the calculated bottomhole pressure. Furthermore, it cannot measure bottomhole temperature data, limiting its application. In short, this technique is rarely used in practice. Summary of the Invention

[0006] The purpose of this invention is to provide a pressure testing ball and a method for accurately testing bottom hole pressure in fracturing with a smooth casing, and its application, in order to overcome the above-mentioned technical defects.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for accurately testing bottom hole pressure during smooth casing fracturing includes the following steps: (1) Prepare a corresponding number of pressure test balls according to the number of horizontal well fracturing sections, and mark the pressure test balls for each section; (2) The first-stage pressure test ball is dropped from the wellhead to perform volumetric fracturing. The pressure gauge inside the pressure test ball starts working simultaneously to record the bottom hole pressure data during the fracturing process. (3) Complete the measurement of the remaining fracturing section and bottom hole pressure data in sequence; (4) After the fracturing is completed, the surface is vented and the pressure test ball returns to the surface under the action of formation pressure. The pressure test balls that were put into the well are collected in sequence on the surface. (5) Open each pressure test ball in sequence and read the pressure value recorded by the pressure gauge inside each pressure test ball; (6) Analyze and evaluate the fracturing effect using the test data collected by the pressure gauge, and further optimize the fracturing parameters.

[0008] Furthermore, the pressure test ball contains a pressure gauge with a length of 60-65 mm.

[0009] Further, in step (6), the specific method for analyzing and evaluating the fracturing effect using the test data recorded by the pressure gauge is as follows: the bottom hole pressure data recorded during each fracturing process is plotted as a pressure curve of pressure versus time, which can intuitively determine the effectiveness of pressure distribution in each stage of multi-stage fracturing in a horizontal well.

[0010] Furthermore, the specific method for judging the effectiveness of each segment's pressure distribution is as follows: if there is a sudden pressure change in other segments at the same time during the fracturing of a certain segment, it can be judged that the fracturing of this segment is connected with other segments, and the pressure distribution is ineffective; otherwise, if there is no connection, the pressure distribution is effective.

[0011] Further, in step (6), the specific method for optimizing fracturing parameters using the test data recorded by the pressure gauge is as follows: import the recorded bottom hole pressure data of a certain section using the FracproPT fracturing software, and use its pressure analysis function to determine the fracture extension pressure, micro-fracture opening time, and fracture length parameters. Based on the analysis results, the displacement, fracturing fluid volume, and sand addition volume of the block well fracturing operation can be optimized.

[0012] A pressure testing sphere includes a core and a shell, the shell covering the outside of the core. The core is a hollow sphere, and a pressure gauge is built into the hollow sphere. The pressure gauge is preferably a storage-type electronic pressure gauge, which has a wide pressure and temperature range, compact structure, stable performance, and advantages such as high precision, high resolution, ease of use, and low testing cost.

[0013] Preferably, the core comprises an upper hemisphere and a lower hemisphere, which are detachably connected.

[0014] Preferably, the hollow sphere is filled with reinforcing fibers or ceramic particles.

[0015] Preferably, the outer shell is made of elastic rubber or elastic resin, and the core is made of any one of soluble magnesium-aluminum alloy, biodegradable nanomaterials, or biodegradable resin.

[0016] An application of a method for accurate bottom-hole pressure testing in smooth casing fracturing is described below: S1. Based on the number of fracturing stages in the horizontal well, prepare the corresponding number of pressure test balls and label each stage's pressure test balls as N1, N2, N3...N n ; S2, fracturing begins. The first stage fracturing soluble bridge plug or soluble ball seat is lowered into the well and set. Then the bridge-jetting tool string is pulled out. Next, the first stage fracturing test ball is dropped from the wellhead to perform volume fracturing. The pressure gauge inside the fracturing test ball starts working simultaneously and records the bottom hole pressure data P1 during the fracturing process. S3, sequentially complete the fracturing of stages 2 to N, and collect pressure data P2, P3...P for each stage. n Measurement; S4, the soluble bridge plug or soluble ball seat dissolves, and the surface venting occurs after fracturing. Pressure test balls N, which were sequentially collected from the well, are then collected at the surface. n N n-1 N n-2 ...N1; S5, open each pressure test ball in sequence and read the pressure value recorded by the pressure gauge inside each pressure test ball; S6. Analyze and evaluate the fracturing effect using the test data obtained in step S5, and further optimize the fracturing parameters.

[0017] principle: The pressure test ball used for volumetric fracturing has a built-in pressure gauge that can read parameters such as bottom hole pressure and temperature at different times during the fracturing process. In the process of multi-stage fracturing of unconventional reservoirs with bare casing, multiple pressure test balls of this type are deployed. After the fracturing is completed, the pressure test ball returns to the surface, and the data of its built-in pressure gauge is read to provide basic data for fracturing effect analysis and design optimization.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention utilizes pressure testing spheres for volumetric fracturing, which incorporate pressure gauges capable of reading downhole pressure, temperature, and other parameters at different times during the fracturing process. Multiple such pressure testing spheres are deployed during multi-stage, multi-layer fracturing of unconventional reservoirs using a bare casing system. After fracturing, the spheres return to the surface, and the data from their internal pressure gauges is read. This enables precise testing of key downhole parameters such as pressure and temperature during horizontal well volumetric fracturing operations, providing a new approach for testing volumetric fracturing in unconventional oil and gas reservoirs and offering an important method for optimizing fracturing process parameters and increasing single-well production.

[0019] 2. This invention measures the bottom hole pressure and temperature using a storage-type electronic pressure gauge built into the pressure testing ball. This allows for a direct assessment of the effectiveness of pressure distribution in each stage of multi-stage fracturing in horizontal wells and provides key test data support for optimizing volumetric fracturing process parameters.

[0020] 3. Compared with the existing technology, the present invention has technical advantages such as accurate test data and simple operation procedures, while the operation cost is low and the cost advantage is obvious.

[0021] 4. The core of the pressure test ball is formed by the upper and lower hemispheres connecting to form a hollow sphere. During assembly, the pressure gauge and filling material are placed in the hemisphere first, and then tightened by hand. The pressure test ball prepared by this method has adjustable density, high strength, good pressure bearing capacity, and is easy to process and simple in process, making it suitable for various downhole working conditions.

[0022] 5. The outer shell of the pressure test ball is made of elastic rubber or elastic resin. Elastic rubber has excellent cushioning and wear resistance, and is not easily bumped or worn. When it reaches the bridge plug seat, due to the good elasticity of the elastic rubber, it can deform to a greater extent under external force, thus making it fit more tightly with the bridge plug seat and sealing more firmly.

[0023] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other design solutions and drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 Flowchart for downhole pressure testing and analysis; Figure 2 This is a schematic diagram of the pressure testing ball.

[0026] Explanation of reference numerals in the attached figures: 1. Outer shell; 2. Core; 3. Pressure gauge.

[0027] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Detailed Implementation

[0028] The following will clearly and completely describe the concept, specific structure, and technical effects of the present invention in conjunction with embodiments and accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. In the description of the present invention, it should be understood that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0029] Example 1 This embodiment relates to a method for accurately testing bottom hole pressure during smooth casing fracturing, including the following steps: (1) Prepare a corresponding number of pressure test balls according to the number of horizontal well fracturing sections, and mark the pressure test balls for each section; (2) The first-stage pressure test ball is dropped from the wellhead to perform volumetric fracturing. The pressure gauge inside the pressure test ball starts working simultaneously to record the bottom hole pressure data during the fracturing process. (3) Complete the measurement of the remaining fracturing section and bottom hole pressure data in sequence; (4) After the fracturing is completed, the surface is vented and the pressure test ball returns to the surface under the action of formation pressure. The pressure test balls that were put into the well are collected in sequence on the surface. (5) Open each pressure test ball in sequence and read the pressure value data recorded by the pressure gauge inside each pressure test ball; (6) Analyze and evaluate the fracturing effect using the test data collected by the pressure gauge, and further optimize the fracturing parameters.

[0030] Furthermore, the specific method for analyzing and evaluating the fracturing effect using test data recorded by pressure gauges is as follows: plot the bottom hole pressure data recorded during each fracturing process into a pressure-time curve, which can intuitively determine the effectiveness of pressure distribution in each stage of multi-stage fracturing in horizontal wells.

[0031] Furthermore, the specific method for judging the effectiveness of pressure distribution in each segment is as follows: if there is a sudden pressure change in other segments at the same time during the fracturing of a certain segment, it can be judged that the fracturing of this segment is connected with other segments and the pressure distribution is ineffective; otherwise, if there is no connection, the pressure distribution is effective.

[0032] Furthermore, the specific method for optimizing fracturing parameters using data recorded by the pressure gauge is as follows: import the recorded bottom hole pressure data of a certain section using the FracproPT fracturing software, and use its pressure analysis function to determine the fracture extension pressure, microfracture opening time, and fracture length parameters. Based on the analysis results, the displacement, fracturing fluid volume, and sand addition volume of the block well fracturing operation can be optimized.

[0033] This invention utilizes pressure testing spheres for volumetric fracturing, which incorporate pressure gauges capable of reading downhole pressure, temperature, and other parameters at different times during the fracturing process. Multiple such pressure testing spheres are deployed during multi-stage, multi-layer fracturing of unconventional reservoirs using a bare casing system. After fracturing, the spheres return to the surface, and the data from their internal pressure gauges is read. This enables precise testing of key downhole parameters such as pressure and temperature during horizontal well volumetric fracturing operations, providing a new approach for testing volumetric fracturing in unconventional oil and gas reservoirs and offering an important method for optimizing fracturing process parameters and increasing single-well production.

[0034] Example 2 This embodiment provides a pressure testing sphere, including a core 2 and a shell 1. The shell 1 covers the outside of the core 2. The core 2 is a hollow sphere, and a pressure gauge 3 is built into the hollow sphere. The pressure gauge 3 is preferably a storage-type electronic pressure gauge with a length of 50~65mm, preferably 60~65mm. The storage-type electronic pressure gauge used in this embodiment has a wide pressure and temperature range, a compact structure, stable performance, and advantages such as high precision, high resolution, ease of use, and low testing cost.

[0035] Furthermore, the core 2 includes an upper hemisphere and a lower hemisphere, which are detachably connected to form a hollow sphere, preferably by a threaded connection. Specifically, the upper hemisphere has an annular threaded groove, and the lower hemisphere has a threaded boss that mates with the threaded groove on the upper hemisphere. Alternatively, the upper hemisphere may have an annular threaded boss, and the lower hemisphere may have an annular threaded groove. It should be noted that the depth of the threaded groove should be greater than the height of the threaded boss. This ensures a smaller connection gap and a tighter fit when the upper and lower hemispheres are connected. The threaded connection between the upper and lower hemispheres eliminates the need for other components, facilitating disassembly and assembly, and simplifying the overall structure. Preferably, the inner wall of the upper hemisphere is provided with blind holes for fixing the storage-type electronic pressure gauge, and the inner wall of the lower hemisphere is provided with blind holes for fixing the storage-type electronic pressure gauge. During assembly, one end of the storage-type electronic pressure gauge is first placed in the blind hole on the inner wall of the upper or lower hemisphere, and then it is tightened by hand. The pressure test ball prepared by this method has adjustable density, high strength, good pressure bearing capacity, and is easy to process and simple in process, and can be used in various fracturing fluid environments.

[0036] Furthermore, the hollow sphere is filled with reinforcing fibers or ceramic particles. Polylactic acid (PLA) is a preferred but not limited to fiber reinforcement material. PLA is a high-performance, inexpensive biodegradable plastic that can undergo hydrolysis under certain environmental conditions to produce lactic acid. Lactic acid can react with magnesium alloys, magnesium hydroxide, etc., to form corresponding water-soluble lactate salts.

[0037] Furthermore, the outer shell 1 is made of elastic rubber or elastic resin, and the thickness of the outer shell 1 is preferably 3-6mm. Elastic rubber has good cushioning and wear resistance, and is not easy to bump or wear. When it reaches the bridge plug ball seat position, due to the good elasticity of the elastic rubber, it can deform to a large extent under the action of external force. Therefore, it can fit more tightly with the bridge plug ball seat, and the seal is more secure, which is suitable for various downhole working conditions.

[0038] Core 2 is made of any one of soluble magnesium-aluminum alloy, biodegradable nanomaterials, or biodegradable resin. Soluble magnesium alloy is preferred, as it has higher specific strength and specific stiffness than most structural materials, is environmentally friendly, and can be rapidly dissolved in aqueous solutions of co-solvents (solid potassium chloride, solid sodium chloride, or solid acid).

[0039] Furthermore, various processes can be used to prepare the pressure test ball of the present invention. For example, the outer layer 1 can be formed by injection molding, and the core 2 is made by loading soluble magnesium-aluminum alloy, biodegradable nanomaterials or biodegradable resin into a spherical shell mold of different sizes and cold pressing it at room temperature to form a hemispherical shell. The preparation of the core 2 is not limited to this process.

[0040] The pressure testing ball of this invention has technical advantages such as being simple and effective, easy to install, and easy to disassemble.

[0041] Example 3 The difference from Embodiment 2 is that the core 2 of the pressure test ball provided in this embodiment is a hollow sphere formed by the upper and lower hemispheres connected together. The hollow sphere contains a storage-type electronic pressure gauge and a downhole electronic tag. Specifically, the inner wall of the upper hemisphere shell is provided with a first blind hole and a second blind hole for fixing the storage-type electronic pressure gauge and the downhole electronic tag, respectively, and the inner wall of the lower hemisphere shell is provided with a third blind hole and a fourth blind hole for fixing the storage-type downhole electronic pressure gauge and the electronic tag, respectively.

[0042] The downhole electronic tag can receive and transmit radio frequency signals. It uses high-frequency wireless communication technology to connect with a storage electronic pressure gauge and wirelessly connects with a surface reader to wirelessly transmit bottom hole pressure data to the surface reader.

[0043] It should be further explained that, to ensure that the electronic tag can receive and transmit radio frequency signals using radio frequency identification technology, a ceramic layer is preferably set on the outer surface of the upper and lower hemispheres. The ceramic layer can be formed by chemical plating or chemical vapor deposition processes, but is not limited to these. Setting a ceramic layer on the outer surface of the core 2 can not only ensure the smooth passage of signals, but also protect the electronic tag in a high-pressure and humid environment, enabling it to withstand the harsh working environment downhole.

[0044] Example 4 This embodiment provides an application of a method for accurately testing bottom hole pressure in smooth casing fracturing. The specific application process is as follows: S1. Based on the number of fracturing stages in the horizontal well, prepare the corresponding number of pressure test balls and label each stage's pressure test balls as N1, N2, N3...N n ; S2, fracturing begins. The first stage fracturing soluble bridge plug or soluble ball seat is lowered into the well and set. Then the bridge-jetting tool string is pulled out. Next, the first stage fracturing test ball is dropped from the wellhead to perform volume fracturing. The pressure gauge inside the fracturing test ball starts working simultaneously and records the bottom hole pressure data P1 during the fracturing process. S3, sequentially complete the fracturing of stages 2 to N, and collect pressure data P2, P3...P for each stage. n Measurement; S4, the soluble bridge plug or soluble ball seat dissolves, and the surface venting occurs after fracturing. Pressure test balls N, which were sequentially collected from the well, are then collected at the surface. n N n-1 N n-2 ...N1; S5, open each pressure test ball in sequence and read the pressure value data recorded by the pressure gauge inside each pressure test ball; S6. Analyze and evaluate the fracturing effect using the test data obtained in step S5, and further optimize the fracturing parameters. Specifically, this includes: ① plotting the bottom hole pressure data recorded during each fracturing stage into a pressure-time curve. If there is a sudden pressure change in other stages at the same time during the fracturing of a certain stage, it can be determined that the fracturing of this stage is connected with other stages and the pressure distribution is ineffective; otherwise, there is no connection and the pressure distribution is effective. The effectiveness of the pressure distribution in each stage during multi-stage fracturing of a horizontal well can be intuitively judged. ② Import the recorded bottom hole pressure data of a certain section using the FracproPT fracturing software. Its pressure analysis function can be used to determine parameters such as fracture extension pressure, microfracture opening time, and fracture length. Based on the analysis results, parameters such as displacement, fracturing fluid volume, and sand addition volume for subsequent fracturing operations in the same block can be optimized.

[0045] This invention measures bottom hole pressure and temperature using a built-in storage electronic pressure gauge in a pressure testing ball, which can intuitively determine the effectiveness of pressure distribution in each stage of multi-stage fracturing in horizontal wells and provide key test data support for optimizing volumetric fracturing process parameters.

[0046] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for accurately testing bottom hole pressure during smooth casing fracturing, characterized in that, Includes the following steps: (1) Prepare a corresponding number of pressure test balls according to the number of pressure-dividing sections of the horizontal well fracturing, and mark each pressure test ball; the pressure test ball is equipped with a pressure gauge, and the length of the pressure gauge is 60~65mm; (2) The first-stage pressure test ball is dropped from the wellhead to perform volumetric fracturing. The pressure gauge inside the pressure test ball starts working simultaneously to record the bottom hole pressure data during the fracturing process. (3) Complete the measurement of the remaining fracturing sections and bottom hole pressure data in sequence; (4) After fracturing is completed, the surface is vented. Under the action of formation pressure, the pressure test ball returns to the surface and is collected in sequence on the surface. (5) Open each pressure test ball in sequence and read the pressure value recorded by the pressure gauge inside each pressure test ball; (6) Analyze and evaluate the fracturing effect using test data recorded by pressure gauges, and further optimize fracturing parameters. The specific method for analyzing and evaluating the fracturing effect using test data recorded by pressure gauges is as follows: plot the bottom hole pressure data recorded during each fracturing process into a pressure-time curve. This allows for a direct assessment of the effectiveness of pressure distribution in each segment during multi-segment fracturing of a horizontal well. The specific method for assessing the effectiveness of pressure distribution in each segment is as follows: if there is a sudden pressure change in other segments at the same time during fracturing of a certain segment, it can be determined that the segment is connected to other segments during fracturing and the pressure distribution is ineffective; otherwise, if there is no connection, the pressure distribution is effective. The test data recorded by the pressure gauge can be used to optimize fracturing parameters. Specifically, the bottom hole pressure data of a certain section can be imported into the FracproPT fracturing software. Its pressure analysis function can be used to determine the fracture extension pressure, microfracture opening time, and fracture length parameters. Based on the analysis results, the displacement, fracturing fluid volume, and sand addition volume of the block well fracturing operation can be optimized.

2. The method for accurately testing bottom hole pressure during smooth casing fracturing according to claim 1, characterized in that, In step (1), each pressure test ball is labeled as N1, N2, N3...N n ; In step (2), before the first-stage pressure test ball is deployed, a soluble bridge plug or soluble ball seat for first-stage fracturing is first deployed into the well and set. Then, the bridge-jetting tool string is retrieved, and the first-stage fracturing test ball is deployed from the wellhead for volume fracturing. The pressure gauge inside the fracturing test ball starts working simultaneously and records the bottom hole pressure data P1 during the fracturing process. In step (3), the fracturing of segments 2 to N is completed sequentially, and the pressure data P2, P3...P of each segment are collected. n Measurement; In step (4), the soluble bridge plug or soluble ball seat dissolves, and after fracturing, the surface is vented. Pressure test balls N, which were sequentially collected from the well, are then collected on the surface. n N n-1 N n-2 ...N1.

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