Device and method for evaluating temporary plugging performance of temporary plugging agent for oilfield refracturing

Abstract

The invention discloses a temporary plugging performance evaluation device and method of a temporary plugging agent for oilfield refracturing. The evaluation device comprises a flow guide chamber; a flat plate groove is formed in the diversion chamber; a heating module, a pressurizing module and a pressure sensor are arranged on the flow guide chamber; and a temporary plugging agent pumping module is arranged at a liquid inlet of the flow guide chamber. According to the device, the flow guide chamber serves as a core testing module, a flat plate groove is formed in the flow guide chamber, the actual crack state can be simulated, meanwhile, the heating module and the pressurizing module are arranged on the flow guide chamber, the pressure and temperature in an actual stratum can be simulated, and the stratum fracturing process is fully reproduced; meanwhile, the pressure change in a test system is accurately obtained through a pressure sensor on the flow guide chamber, the temporary plugging performance of the temporary plugging agent can be evaluated effectively, and meanwhile, a temporary plugging agent pumping module is arranged at a liquid inlet of the flow guide chamber, so that continuous pumping of the temporary plugging agent is realized. The device fully simulates formation conditions, including formation temperature and formation pressure, and can accurately evaluate the temporary plugging capability of the temporary plugging agent under the formation conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of reservoir stimulation, and relates to a device and a method for evaluating the temporary plugging performance of a temporary plugging agent for repeated fracturing in oilfields. Background Art

[0002] As the reservoir development stage enters the medium and high water cut period, with the increase of the reservoir recovery degree, a large amount of crude oil near the fracture is produced. Horizontally, there is an urgent need to utilize the lateral remaining oil with more complex lateral fractures, and vertically break through the interbedded layers to improve the vertical utilization degree; realize the three-dimensional utilization of the reservoir. Therefore, repeated fracturing of oil wells is carried out. However, the main reason why most repeated fracturing is difficult to obtain high production is that the fractures often open along the old fractures and mostly extend along the old fractures, making it difficult to form new fractures and the ability to utilize the remaining oil is limited. And temporary plugging repeated fracturing is an effective way to generate new fractures. The temporary plugging diversion fracturing technology is to carry the temporary plugging agent into the previously fractured fractures or the perforations connected to the high permeability zone through the working fluid during the fracturing process, form a high-strength filter cake bridge plug, prevent the subsequent fracturing fluid from entering the original fractures and the high permeability zone, force the bottom hole static pressure to rise, and open new fractures in the high stress area. After the operation, the temporary plugging agent is completely dissolved or degraded, so that the fracture restores the conductivity. The temporary plugging agent plays a key role in temporary plugging fracturing. Therefore, the performance of the temporary plugging agent directly affects the success or failure of temporary plugging fracturing.

[0003] There is currently no industry standard for the performance evaluation method of temporary plugging agents. There are mainly three commonly used performance evaluation methods for temporary plugging agents: one is the core displacement method. A certain thickness of temporary plugging agent is filled at the end face of the core, and the pressure-bearing capacity of the filter cake formed by the temporary plugging agent under reservoir temperature conditions is measured. The strength of the temporary plugging agent is evaluated by testing its breakthrough pressure. This method is improved on the basis of the evaluation method of water shutoff and profile control plugging agents and can only evaluate the compressive strength of the temporary plugging agent, not the temporary plugging characteristics of the temporary plugging agent; the second is the physical model test method for temporary plugging in fracturing. This method evaluates the performance of the temporary plugging agent by developing a large-scale rock triaxial mechanical testing system. The principle of this method is that when the particle size of the solid particles of the temporary plugging agent is greater than 1 / 3 to 2 / 3 of the dynamic width of the fracture, a plugging zone is formed. When the net pressure in the fracture reaches the opening pressure of the micro-fracture, new fractures are formed. The temporary plugging agent is more likely to form a temporary plugging zone with a certain effective thickness and length near the fracture opening, increasing the net pressure in the water fracture. At the same time, since the temporary plugging agent cannot be effectively pumped into the fracture during the experiment and there is currently no effective experimental means to place the temporary plugging agent in the fracture, the experiment only simulates the influence of the temporary plugging agent at the fracture opening on the hydraulic fracture, with great limitations; the third is the funnel method. Currently, most of the evaluation methods for temporary plugging agents are based on the funnel method. Different fracture modules can be used according to different particle sizes of the temporary plugging agent, and the sudden change in pressure of the plugging agent in the fracture can be visually observed. However, the conventional method does not consider factors such as formation temperature and formation pressure and does not fully simulate the formation conditions, so the experimental conclusions obtained are not accurate. To accurately evaluate the performance of the temporary plugging agent for plugging external channeling and select a suitable temporary plugging agent for refracturing, it is necessary to carry out innovative research on new methods for evaluating the performance of temporary plugging agents. Summary of the Invention

[0004] Aiming at the problems existing in the prior art, the present invention provides a device and method for evaluating the temporary plugging performance of a temporary plugging agent for repeated fracturing in oilfields, thereby solving the technical problem that the performance of the temporary plugging agent cannot be accurately evaluated in the prior art.

[0005] The present invention is realized through the following technical solutions:

[0006] A device for evaluating the temporary plugging performance of a temporary plugging agent for repeated fracturing in oilfields includes a diversion chamber;

[0007] A flat plate groove is arranged inside the diversion chamber; a heating module, a pressurizing module and a pressure sensor are arranged on the diversion chamber;

[0008] A temporary plugging agent pumping and injection module is arranged at the liquid inlet of the diversion chamber.

[0009] Preferably, the flat plate groove is a wedge-shaped groove.

[0010] Preferably, the height adjustment range at both ends of the wedge-shaped groove is 2 - 23 mm.

[0011] Preferably, the temporary plugging agent pumping and injection module includes a liquid pump;

[0012] One end of the liquid pump is connected with a piston, and the other end is communicated with a water tank.

[0013] A method for evaluating the temporary plugging performance of a temporary plugging agent for repeated fracturing in oilfields is carried out by the above evaluation device and includes the following steps:

[0014] Use the heating module and the pressurizing module to control the temperature and pressure of the diversion chamber, and use the temporary plugging agent injection module to continuously inject the uniformly mixed guar gum base fluid and the temporary plugging agent to be evaluated into the diversion chamber, and observe the change of the pressure sensor to complete the evaluation of the temporary plugging performance of the temporary plugging agent for repeated fracturing in oilfields.

[0015] Preferably, during the process of observing the change of the pressure sensor, if the pressure increase value is greater than 4 MPa, the temporary plugging agent to be evaluated meets the usage requirements; otherwise, increase the concentration of the temporary plugging agent to be evaluated and repeat the evaluation process until the pressure increase value is greater than 4 MPa.

[0016] Preferably, if the pressure increase value is greater than 5 MPa, reduce the concentration of the temporary plugging agent to be evaluated and repeat the evaluation process until the pressure increase value is greater than 4 MPa and less than 5 MPa.

[0017] Preferably, the concentration of the guar gum base fluid is 2 - 3 kg / m 3 .

[0018] Preferably, the mass concentration of the temporary plugging agent to be evaluated is 4% - 10%.

[0019] Preferably, control the temperature of the diversion chamber to be 0°C - 90°C, and control the pressure of the diversion chamber to be 0 - 50 MPa.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects:

[0021] The present invention discloses an evaluation device for the temporary plugging performance of a temporary plugging agent for repeated fracturing in oilfields, including a diversion chamber; a flat plate groove is arranged inside the diversion chamber; a heating module, a pressurizing module and a pressure sensor are arranged on the diversion chamber; a temporary plugging agent injection module is arranged at the liquid inlet of the diversion chamber. In this device, the diversion chamber serves as the core test module, with a flat plate groove inside, which can simulate the actual fracture state. At the same time, a heating module and a pressurizing module are arranged on the diversion chamber, which can simulate the pressure and temperature in the actual formation, fully reproduce the formation fracturing process, and at the same time accurately obtain the pressure change in the test system through the pressure sensor on the diversion chamber, and can effectively evaluate the temporary plugging performance of the temporary plugging agent. At the same time, a temporary plugging agent injection module is arranged at the liquid inlet of the diversion chamber, realizing the continuous injection of the temporary plugging agent. This device fully simulates the formation conditions, including formation temperature and formation pressure, and can accurately evaluate the temporary plugging ability of the temporary plugging agent under formation conditions.

[0022] Furthermore, the flat groove is a wedge-shaped groove, which makes the shape of the crack closer to the actual formation crack and obtains a more accurate simulation result.

[0023] Furthermore, the height adjustment range at both ends of the wedge-shaped groove is 2 - 23 mm, which can simulate different crack widths.

[0024] Furthermore, the temporary plugging agent injection module includes a liquid pump; one end of the liquid pump is connected with a piston, and the other end is communicated with a water tank. Since the temporary plugging agent contains solid particles, water in the water tank is pumped by the liquid pump, and then the pumped water pushes the piston to move. The piston pushes the temporary plugging agent into the diversion chamber for testing. The combination of the liquid pump and the piston is used to realize the injection of the temporary plugging agent, effectively avoiding the damage to the liquid pump when directly using the liquid pump to inject the temporary plugging agent.

[0025] The present invention also discloses a method for evaluating the temporary plugging performance of a temporary plugging agent for oilfield refracturing. Using the evaluation device in the present invention, directly mix the temporary plugging agent to be evaluated with the guar gum-based fluid, then use the temporary plugging agent injection module to pump the mixed liquid into the diversion chamber, and use the heating module and the pressurization module to control the temperature and pressure of the diversion chamber to simulate the formation conditions. During the test, observe the change of the pressure sensor to realize the evaluation of the temporary plugging performance of the temporary plugging agent for oilfield refracturing. This method is simple to operate, the process is controllable, and the accuracy is high, effectively realizing the full and accurate evaluation of the temporary plugging performance of the temporary plugging agent.

[0026] Furthermore, during the process of observing the change of the pressure sensor, if the pressure increase value is greater than 4 MPa, the temporary plugging agent to be evaluated meets the usage requirements. Otherwise, increase the concentration of the temporary plugging agent to be evaluated and repeat the evaluation process until the pressure increase value is greater than 4 MPa. Setting the pressure threshold to 4 MPa during the evaluation process can effectively realize the evaluation of the temporary plugging performance of the temporary plugging agent.

[0027] Furthermore, if the pressure increase value is greater than 5 MPa, reduce the concentration of the temporary plugging agent to be evaluated and repeat the evaluation process until the pressure increase value is greater than 4 MPa and less than 5 MPa. This can ensure the temporary plugging performance of the temporary plugging agent while determining the minimum usage concentration of the temporary plugging agent and effectively controlling the dosage of the temporary plugging agent.

[0028] Furthermore, the concentration of the guar gum-based fluid is 2 - 3 kg / m 3 , which can effectively realize the carrying of the temporary plugging agent.

[0029] Furthermore, the mass concentration of the temporary plugging agent to be evaluated is 4% - 10%, which can enable the temporary plugging agent to form a bridging temporary plug in the wedge-shaped groove of the diversion chamber.

[0030] Further, controlling the temperature of the diversion chamber to be 0-90°C and the pressure of the diversion chamber to be 0-50 MPa can fully realize the reproduction simulation of formation conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use 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 should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0032] Figure 1 It is a schematic structural diagram of a temporary plugging performance evaluation device for a temporary plugging agent used in repeated fracturing of oilfields in the present invention;

[0033] Wherein: 1, pressure sensor; 2, piston; 3, diversion chamber; 4, heating module; 5, liquid pump; 6, water tank; 7, pressurization module. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0035] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0036] It should be noted that similar reference numerals and letters indicate similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0037] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "horizontal", "inner", etc. are used to indicate the orientation or positional relationship, it is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the invention product is usually placed during use. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, terms such as "first", "second", etc. are only used for distinguishing descriptions and cannot be construed as indicating or implying relative importance.

[0038] In addition, if the term "horizontal" appears, it does not mean that the component is required to be absolutely horizontal, but it can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but it can be slightly inclined.

[0039] In the description of the embodiments of the present invention, it should also be noted that unless otherwise clearly specified and limited, if terms such as "set", "installed", "connected", "connected" are used, they should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0040] The following further describes the present invention in detail with reference to the drawings:

[0041] Embodiment 1

[0042] As Figure 1 shown, the present invention discloses a temporary plugging performance evaluation device for a temporary plugging agent used in repeated fracturing of oilfields, including a diversion chamber 3; a flat plate groove is provided inside the diversion chamber 3; a heating module 4, a pressurization module 7 and a pressure sensor are provided on the diversion chamber 3; a temporary plugging agent pump injection module is provided at the liquid inlet of the diversion chamber 3. Among them, the heating module 4 can be a heating rod.

[0043] In a preferred embodiment of the present invention, the flat plate groove is a wedge-shaped groove. The wedge-shaped groove makes the shape of the fracture closer to the actual formation fracture, obtaining a more accurate simulation result. At the same time, the height adjustment range at both ends of the wedge-shaped groove is 2-23 mm, and the simulation of different fracture widths can be realized.

[0044] Meanwhile, the temporary plugging agent pumping module includes a liquid pump 5; one end of the liquid pump 5 is connected to a piston 2, and the other end is communicated with a water tank 6. Since the temporary plugging agent contains solid particles, the water in the water tank 6 is pumped by the liquid pump 5, and then the pumped water pushes the piston to move. The piston pushes the temporary plugging agent into the diversion chamber for testing. The combination of the liquid pump 5 and the piston 2 is used to realize the pumping of the temporary plugging agent, effectively avoiding the damage to the liquid pump 5 when directly using the liquid pump 5 to pump the temporary plugging agent. Therefore, the device in the present invention has a good simulation evaluation effect on temporary plugging agents such as particulate and fibrous types that are difficult to simulate and inject in the diversion chamber.

[0045] In this device, the diversion chamber is the core test module, with a flat plate groove inside, which can simulate the actual fracture state. At the same time, the diversion chamber 3 is provided with a heating module and a pressurization module, which can simulate the pressure and temperature in the actual formation, fully reproduce the formation fracturing process, and accurately obtain the pressure change in the test system through the pressure sensor on the diversion chamber, and can evaluate the temporary plugging performance of the effective temporary plugging agent. At the same time, a temporary plugging agent pumping module is provided at the liquid inlet of the diversion chamber 3 to realize the continuous pumping of the temporary plugging agent. This device fully simulates the formation conditions, including formation temperature and formation pressure, and can accurately evaluate the temporary plugging ability of the temporary plugging agent under formation conditions.

[0046] Example 2

[0047] In addition, another inventive point of the present invention lies in disclosing a method for evaluating the temporary plugging performance of a temporary plugging agent for repeated fracturing in oilfields. This evaluation method is carried out through the above-mentioned evaluation device and includes the following steps:

[0048] Use the heating module 4 and the pressurization module 7 to control the temperature and pressure of the diversion chamber 3, and use the temporary plugging agent pumping module to continuously inject the uniformly mixed guar gum base fluid and the temporary plugging agent to be evaluated into the diversion chamber 3, and observe the change of the pressure sensor to complete the evaluation of the temporary plugging performance of the temporary plugging agent for repeated fracturing in oilfields. During the process of observing the change of the pressure sensor, if the pressure increase value is greater than 4 MPa, the temporary plugging agent to be evaluated meets the usage requirements. Otherwise, increase the concentration of the temporary plugging agent to be evaluated and repeat the evaluation process until the pressure increase value is greater than 4 MPa. In addition, if the pressure increase value is greater than 5 MPa, reduce the concentration of the temporary plugging agent to be evaluated and repeat the evaluation process until the pressure increase value is greater than 4 MPa and less than 5 MPa, which can ensure the temporary plugging performance of the temporary plugging agent while clarifying the minimum usage concentration of the temporary plugging agent and effectively controlling the dosage of the temporary plugging agent.

[0049] Among them, the concentration of the guar gum base fluid is 2 - 3 kg / m 3 , which can effectively realize the carrying of the temporary plugging agent.

[0050] The mass concentration of the temporary plugging agent to be evaluated is 4% - 10%, which enables the temporary plugging agent to form a bridging temporary plug in the wedge-shaped groove of the diversion chamber.

[0051] Control the temperature of the diversion chamber 3 to be 0°C - 90°C, and control the pressure of the diversion chamber 3 to be 0 - 50 MPa, which can fully realize the reproduction simulation of formation conditions.

[0052] In the evaluation method of the present invention, by using the evaluation device of the present invention, directly mix the temporary plugging agent to be evaluated with the guar gum base fluid, then use the temporary plugging agent pumping module to pump the mixed liquid into the diversion chamber, and use the heating module 4 and the pressurizing module 7 to control the temperature and pressure of the diversion chamber 3 to simulate formation conditions. During the test, observe the change of the pressure sensor to realize the evaluation of the temporary plugging performance of the temporary plugging agent for oilfield refracturing. This method is simple to operate, the process is controllable, and the accuracy is high, effectively realizing the full and accurate evaluation of the temporary plugging performance of the temporary plugging agent.

[0053] Example 3

[0054] To fully explain the technical solution of the present invention, it is illustrated by the following examples.

[0055] A method for evaluating the temporary plugging performance of a temporary plugging agent for oilfield refracturing includes the following steps:

[0056] Step 1: Prepare 2000 - 2500 mL of guar gum base fluid with a concentration of 2 - 3 kg / m 3 ;

[0057] Step 2: Use high-pressure air to push the piston to the bottom of the container, then relieve the pressure of the container, and disassemble the pressure cap and plug of the container; the volume of the piston container of this piston is 10 L;

[0058] Step 3: Pour the prepared guar gum base fluid into the container, and add a temporary plugging agent with a mass concentration of 4% - 10% to the container. After mixing evenly, install and restore the pressure cap and plug of the container, and connect the pipeline of the connecting device.

[0059] Step 4: Install the upper and lower plugs of the diversion chamber in place. After installing the inlet and outlet joints of the diversion chamber to the diversion chamber, install the diversion chamber on the pressure testing machine and connect the inlet and outlet interfaces of the diversion chamber;

[0060] Step 5: According to the cross-sectional area of the piston of the diversion chamber and the cross-sectional area of the piston of the upper loading hydraulic cylinder, convert the pressurizing pressure of the hydraulic cylinder, and turn on the hydraulic tracking for pressure loading to simulate the formation pressure;

[0061] Step 6: Insert the heating rod around the diversion chamber, and set it according to the formation temperature of the block where the test well is located to simulate the formation temperature;

[0062] Step 7: Input experimental parameters including test flow rate, pressure-bearing time, etc. into the computer; turn on the power supplies of the peristaltic pump, displacement meter, balance, compensation pump, and start the constant flow pump, and record the pressure through the pressure sensor on the connecting pipeline.

[0063] Step 8: Judge the plugging performance of the temporary plugging agent according to the pressure increase situation, and observe whether the temporary plugging agent can form a temporary plug in the diversion chamber and whether there is a pressure increase phenomenon. If the pressure increases by more than 4 MPa, it indicates that the plugging performance of the temporary plugging agent meets the requirements at this mass concentration. Then, within the mass concentration range of the temporary plugging agent, adjust the mass concentration of the temporary plugging agent in Step 3 to be smaller until the pressure increase is greater than 4 MPa and less than 5 MPa, and obtain the minimum mass concentration of the temporary plugging agent that meets the plugging performance. If the pressure increase is less than 4 MPa, increase the mass concentration of the temporary plugging agent in Step 3 and conduct the experiment again.

[0064] In a preferred embodiment of the present invention, the guar gum base fluid is a hydroxypropyl guar gum base fluid, a carboxymethyl guar gum base fluid, or a carboxymethyl hydroxypropyl guar gum base fluid.

[0065] An evaluation device for the temporary plugging performance of a temporary plugging agent for oilfield refracturing includes a diversion chamber 3, a piston 2, a pressure sensor 1, a liquid pump 5, a water tank 6, a heating module 4, and a pressurizing module 7; the inside of the diversion chamber 3 is a flat wedge-shaped groove, and the heights of both ends of the wedge-shaped groove can be adjusted to simulate fractures of different scales. One end of the liquid pump 5 is connected to the upper end of the piston container 2 through a connecting pipeline, and the other end is communicated with the water tank 6; the pressurizing module 7 can act on the diversion chamber 3 to apply confining pressure to the diversion chamber; a branch is provided on the connecting pipeline; the pressure sensor 1 is arranged on the branch, and another pressure sensor 1 is arranged on the connecting pipelines on both sides of the diversion chamber. Here, the liquid pump 5 can be a constant speed pump.

[0066] Compared with the conventional methods of establishing a mathematical model to evaluate the performance of the temporary plugging agent and using a core displacement device to test the performance of the temporary plugging agent, the present invention can accurately evaluate the performance of the temporary plugging agent by setting formation conditions to simulate the real injection process of the temporary plugging agent, and provide a basis for selecting the optimal temporary plugging agent for refracturing.

[0067] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A temporary plugging performance evaluation device for temporary plugging agents used in repeated fracturing of oilfields, Characterized in that, It includes a diversion chamber (3); A flat groove is provided inside the diversion chamber (3); a heating module (4), a pressurization module and a pressure sensor are provided on the diversion chamber (3); A temporary plugging agent pumping module is provided at the liquid inlet of the diversion chamber (3).

2. The temporary plugging performance evaluation device for temporary plugging agents used in repeated fracturing of oilfields according to claim 1, Characterized in that, The flat groove is a wedge-shaped groove.

3. The temporary plugging performance evaluation device for temporary plugging agents used in repeated fracturing of oilfields according to claim 2, Characterized in that, The height adjustment range at both ends of the wedge-shaped groove is 2 - 23 mm.

4. The temporary plugging performance evaluation device for temporary plugging agents used in repeated fracturing of oilfields according to claim 1, Characterized in that, The temporary plugging agent pumping module includes a liquid pump (5); One end of the liquid pump (5) is connected to a piston (2), and the other end is communicated with a water tank (6).

5. A temporary plugging performance evaluation method for temporary plugging agents used in repeated fracturing of oilfields, Characterized in that, It is carried out by using the evaluation device described in any one of claims 1 - 4, and includes the following steps: Using the heating module (4) and the pressurization module to control the temperature and pressure of the diversion chamber (3), and using the temporary plugging agent pumping module to continuously inject the uniformly mixed guar gum base fluid and the temporary plugging agent to be evaluated into the diversion chamber (3), observing the change of the pressure sensor, and completing the evaluation of the temporary plugging performance of the temporary plugging agent for repeated fracturing of oilfields.

6. The temporary plugging performance evaluation method for temporary plugging agents used in repeated fracturing of oilfields according to claim 5, Characterized in that, During the process of observing the change of the pressure sensor, if the pressure increase value is greater than 4 MPa, the temporary plugging agent to be evaluated meets the usage requirements; otherwise, increase the concentration of the temporary plugging agent to be evaluated, and repeat the evaluation process until the pressure increase value is greater than 4 MPa.

7. The temporary plugging performance evaluation method for temporary plugging agents used in repeated fracturing of oilfields according to claim 6, Characterized in that, If the pressure increase value is greater than 5 MPa, reduce the concentration of the temporary plugging agent to be evaluated, and repeat the evaluation process until the pressure increase value is greater than 4 MPa and less than 5 MPa.

8. The temporary plugging performance evaluation method for temporary plugging agents used in repeated fracturing of oilfields according to claim 5, Characterized in that, The concentration of the guar gum-based fluid is 2 to 3 kg / m 3 .

9. The temporary plugging performance evaluation method for temporary plugging agents used in repeated fracturing of oilfields according to claim 5, Characterized in that, The mass concentration of the temporary plugging agent to be evaluated is 4% - 10%.

10. The temporary plugging performance evaluation method for temporary plugging agents used in repeated fracturing of oilfields according to claim 5, Characterized in that, Control the temperature of the diversion chamber (3) to be 0°C - 90°C, and control the pressure of the diversion chamber (3) to be 0 - 50 MPa.

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