Comprehensive experimental evaluation method for in-seam plugging and pressure-bearing effects of temporary plugging agent of mixed proppant

Abstract

The invention relates to a comprehensive experimental evaluation method for the in-crack plugging and pressure-bearing effect of a temporary plugging agent of a mixed proppant. The comprehensive experimental evaluation method comprises the steps that (1) crack parameters are obtained based on target reservoir stratum parameters, and a crack physical model is established; (2) arranging a visual temporary plugging device and a temporary plugging pressure-bearing device, and testing the migration plugging effect of the temporary plugging agent of the mixed proppant in the fracture physical model by using the visual temporary plugging device; and (3) testing the plugging parameters of the temporary plugging agent mixed with the propping agent in the fracture physical model by using a temporary plugging pressure-bearing device, and evaluating the plugging pressure-bearing effect of the temporary plugging agent mixed with the propping agent in the fracture by integrating the migration plugging effect and the plugging parameters. Experimental test parameters are based on field data, a real plugging process is simulated through an indoor experiment, and the plugging pressure-bearing effect of the temporary plugging agent of the mixed proppant in a seam can be accurately evaluated based on the tested temporary plugging parameters.

Description

Technical Field

[0001] The invention relates to the field of oil and gas field production increase and transformation, and in particular to a comprehensive experimental evaluation method for the plugging and pressure-bearing effect of a temporary plugging agent mixed with a proppant. Background Art

[0002] When temporary plugging agents are used for production enhancement, the temporary plugging agents commonly used on site are mainly granular temporary plugging agents and fiber temporary plugging agents. However, due to its own structure, the plugging layer formed by granular temporary plugging agents in the cracks is often not dense enough. The plugging layer formed by fiber temporary plugging agents has insufficient pressure bearing capacity and poor construction operability. Although the composite temporary plugging agent composed of fibers and particles significantly improves the plugging pressure bearing effect, it cannot be used on a large scale due to the high cost of temporary plugging agents. Therefore, it is particularly important to develop more economical and easy-to-construct temporary plugging agents, as well as to optimize the construction process.

[0003] The composite temporary plugging agent formed by combining proppant and temporary plugging agent can not only significantly reduce the overall cost, but also form a more stable and dense temporary plugging zone due to the addition of proppant, thereby improving the plugging and pressure bearing effect. However, existing research lacks an evaluation method for the plugging and pressure bearing effect of temporary plugging agents and proppants in fractures. Summary of the invention

[0004] In view of the above problems, the present invention aims to provide a comprehensive experimental evaluation method for the pressure-bearing effect of temporary plugging agents of mixed proppants in seams.

[0005] To solve the above problems, the technical solution of the present invention is as follows:

[0006] A comprehensive experimental evaluation method for the pressure-bearing effect of a temporary plugging agent mixed with a proppant in a crack, comprising the following steps:

[0007] (1) Obtaining fracture parameters based on target reservoir formation parameters and establishing a fracture physical model;

[0008] (2) Setting up a visual temporary plugging device and a temporary plugging pressure bearing device, and using the visual temporary plugging device to test the migration and plugging effect of the temporary plugging agent of the mixed proppant in the fracture physical model;

[0009] (3) The temporary plugging and pressure-bearing device is used to test the plugging parameters of the temporary plugging agent of the mixed proppant in the fracture physical model, and the plugging and pressure-bearing effect of the temporary plugging agent of the mixed proppant in the fracture is evaluated by comprehensively considering the migration and plugging effect and the plugging parameters.

[0010] Preferably, the crack parameters in step (1) mainly include crack width and crack wall roughness.

[0011] Preferably, the visualized temporary plugging device in step (2) comprises a liquid supply device, a power device, an intermediate container, and a visualized rough fracture plate, wherein the liquid supply device is connected to the intermediate container, the intermediate container is connected to the visualized rough fracture plate, the power device transports the fracturing fluid in the liquid supply device to the intermediate container, and a piston and a stirring device are provided in the intermediate container.

[0012] Preferably, the test steps of the visualized temporary plugging device in step (2) include: based on the liquid volume required for the experiment, weighing the temporary plugging agent of the mixed proppant according to the selected mass concentration; preparing the fracturing fluid and adding it to the intermediate container, turning on the stirring device, and adding the weighed temporary plugging agent to the intermediate container, so that the temporary plugging agent and the fracturing fluid are fully and evenly mixed while preventing the temporary plugging agent from settling at the bottom of the intermediate container; setting the displacement in the pumping system, opening the pipeline valve, and recording the migration and plugging process of the temporary plugging agent in the crack by a camera. When the height of the plugging layer formed by the temporary plugging agent in the crack reaches the height of the crack, it is considered that the plugging is formed in the crack.

[0013] Preferably, the displacement acquisition method of the experimental test is:

[0014]

[0015] Where: Q 1 is the displacement of a single seam on site, m 3 / min; W 1 is the actual crack width, m; H 1 is the actual crack height, m; W 2 is the experimental crack width, m; H 2 is the experimental crack height, m; Q 2 is the injection displacement in the experiment, L / min.

[0016] Preferably, the temporary plugging pressure-bearing device in step (2) includes a liquid supply device, a power device, an intermediate container, and a rough rock plate, wherein the liquid supply device is connected to the intermediate container, the intermediate container is connected to the rough rock plate, the power device transports the fracturing fluid in the liquid supply device to the intermediate container, and a piston and a stirring device are provided in the intermediate container.

[0017] Preferably, the test step of the temporary plugging pressure-bearing device in step (2) includes: based on the liquid volume required for the experiment, weighing the temporary plugging agent of the mixed proppant according to the selected mass concentration; preparing the fracturing fluid and adding it to the intermediate container, turning on the stirring device, and adding the weighed temporary plugging agent to the intermediate container, so that the temporary plugging agent and the fracturing fluid are fully and evenly mixed while preventing the temporary plugging agent from settling at the bottom of the intermediate container; setting the displacement in the pumping system, opening the pipeline valve, recording the pressure change during the experiment through the data acquisition system, and determining the plugging parameters through the pressure change.

[0018] Preferably, the plugging parameters in step (2) include stable plugging pressure peak value, pressure onset rate per unit time and unit plugging pressure gradient.

[0019] Preferably, the method for obtaining the pressure starting speed per unit time is:

[0020]

[0021] Where: a is the pressure-increasing speed per unit time, MPa / s; P is the stable plugging pressure peak, MPa; T is the time required from the start of plugging to reaching the stable plugging pressure peak, s.

[0022] Preferably, the method for obtaining the unit plugging pressure gradient is:

[0023]

[0024] Where: B is the unit plugging pressure gradient, MPa / cm; P is the stable plugging pressure peak, MPa; L is the plugging layer length, cm.

[0025] Preferably, step (2) further comprises: testing the migration and plugging effect of a single temporary plugging agent in a fracture physical model under the same conditions.

[0026] Preferably, in step (3), when the height of the plugging layer formed by the temporary plugging agent in the visualized temporary plugging device reaches the height of the fracture; in the temporary plugging pressure-bearing device, the stable plugging pressure peak value, the pressure-initiating speed per unit time and the unit plugging pressure gradient of the plugging layer formed by the temporary plugging agent in the fracture meet the on-site requirements, it indicates that the temporary plugging agent has a good plugging pressure-bearing effect in the fractures in the required plugging area of ​​the target reservoir.

[0027] The beneficial effects of the present invention are as follows: the present invention designs the fracture parameters, temporary plugging agent concentration, pumping displacement and other parameters required for the experiment based on the actual on-site engineering data, simulates and restores the actual temporary plugging process through indoor physical experiments, and accurately evaluates the plugging and pressure-bearing effect of the temporary plugging agent of the mixed proppant in the fracture through the measured temporary plugging parameters, thus filling the gap in the current lack of an evaluation method for the sealing and pressure-bearing effect of the temporary plugging agent of the mixed proppant in the fracture. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present invention, but are not intended to limit the present invention.

[0029] Figure 1 It is a schematic diagram of the process of the present invention;

[0030] Figure 2 This is a schematic diagram of a visualized temporary blocking device in an embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of a temporary plugging pressure-bearing device in an embodiment of the present invention;

[0032] Figure 4 This is a diagram showing the final plugging effect of the temporary plugging agent in the crack under different parameter combinations in the embodiment of the present invention;

[0033] Figure 5 This is a diagram showing the pressure bearing capacity of the plugging layer formed by the temporary plugging agent in the crack under different parameter combinations when the experimental displacement is 0.29 L / min in the embodiment of the present invention;

[0034] Figure 6 This is a diagram showing the pressure bearing capacity of the plugging layer formed by the temporary plugging agent in the crack under different parameter combinations when the experimental displacement is 0.44 L / min in the embodiment of the present invention;

[0035] Figure 7 Graph showing the pressure-increasing speed per unit time of the plugging layer formed by the temporary plugging agent in the fracture under different parameter combinations in the embodiment of the present invention;

[0036] Figure 8 This is a unit plugging pressure gradient diagram of the plugging layer formed by the temporary plugging agent in the fracture under different parameter combinations in the embodiment of the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure shall have the usual meanings understood by persons with ordinary skills in the field to which the present disclosure belongs. The words "include" or "comprise" and the like used in the present disclosure mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, but do not exclude other elements or objects.

[0039] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. Figure 1 As shown, the present invention provides a comprehensive experimental evaluation method for the pressure-bearing effect of temporary plugging agent in cracks of mixed proppant, comprising the following steps:

[0040] (1) Obtaining fracture parameters based on target reservoir formation parameters and establishing a fracture physical model;

[0041] In a specific embodiment, those skilled in the art can obtain crack parameters through field testing, indoor experiments or numerical simulation, and the crack parameters mainly include crack width and crack wall roughness. The crack width and crack wall roughness can be obtained by using existing technologies. After obtaining the above parameters, a visualized rough crack plate and rough rock plate can be prepared by common technologies.

[0042] (2) Setting up a visual temporary plugging device and a temporary plugging pressure bearing device, and using the visual temporary plugging device to test the migration and plugging effect of the temporary plugging agent of the mixed proppant in the fracture physical model;

[0043] Optionally, in order to conduct comparative analysis, the migration and plugging effect of a single temporary plugging agent in the fracture physical model under the same conditions can also be tested.

[0044] In a specific embodiment, Figure 2 As shown, the visualized temporary plugging device includes a liquid supply device 1, a power device, an intermediate container 7, and a visualized rough crack plate 14 (A), wherein the liquid supply device 1 is connected to the intermediate container 7, the intermediate container 7 is connected to the visualized rough crack plate 14 (A), the power device transports the fracturing fluid in the liquid supply device 1 to the intermediate container 7, the intermediate container 7 is provided with an intermediate piston 6 and a stirring device, and the stirring device is configured as a stirring blade 8.

[0045] In a specific embodiment, the visualization temporary plugging device includes a liquid supply device 1, a manifold 2, a power pump 3, a valve 4, an infusion nozzle 5, an intermediate piston 6, an intermediate container 7, a stirring fan 8, a motor 9, a stirring controller 10, a pressure sensor 11, a valve 12, a data acquisition system 13, a visualization rough crack plate 14 (A), a high-definition camera 15 (A), a valve 16, and a fracturing fluid recovery barrel 17. Among them, the power pump 3 is connected to the liquid supply device 1 through the manifold 2, and the fracturing liquid is pumped into the upper part of the intermediate piston 6 in the intermediate container 7 through the infusion nozzle 5 connected to the manifold 2; by changing the displacement setting of the power pump 3, the pumping rate of the liquid by the infusion nozzle 5 can be changed, and the pumping displacement of the fracturing liquid in the intermediate container 6 can be changed; the stirring blades 8 inside the intermediate container 6 are connected to the motor 9, and the motor 9 is equipped with a stirring regulator 10, which can adjust the speed at any time; the visual rough crack plate 14 (A) is fixed by an external metal frame, and the inflow manifold is connected to a pressure sensor 11, which can read the pressure change in real time through the data acquisition system 13, and the positive direction of the crack device is also equipped with a high-definition camera 15 (A), which can record the migration and plugging process of the temporary plugging agent in the crack, and the output manifold of the crack device is connected to a fracturing fluid recovery barrel 17.

[0046] In a specific embodiment, the experimental steps are: based on the liquid volume required for the experiment, weigh the same mass of the temporary plugging agent of the mixed proppant and the single temporary plugging agent according to the selected same mass concentration; prepare the fracturing fluid and add it into the intermediate container, start the stirring device, and add the weighed temporary plugging agent into the intermediate container, wherein the purpose of stirring is to make the temporary plugging agent and the fracturing fluid fully and evenly mixed while preventing the temporary plugging agent from settling at the bottom of the intermediate container, so as to ensure that the temporary plugging agent smoothly enters the fracture device through the transport pipeline; set the displacement in the pumping system, open the pipeline valve, and record the migration and plugging process of the temporary plugging agent in the fracture through a camera, wherein when the height of the plugging layer formed by the temporary plugging agent in the fracture reaches the height of the fracture device, it is considered that the plugging is formed in the fracture.

[0047] In the above test, the mass solubility of the temporary plugging agent should be selected according to the commonly used mass concentration on site corresponding to the selected fracture width. The configuration of the fracturing fluid is mainly based on the commonly used viscosity of the fracturing fluid on site.

[0048] The setting of the pumping displacement during the experiment is mainly based on the on-site construction displacement, the number of effective open clusters, the actual fracture parameters and the fracture device parameters in the experiment, and is calculated according to the flow velocity similarity criterion.

[0049]

[0050] Where: Q 1 is the displacement of a single seam on site, m 3 / min; W 1 is the actual crack width, m; H 1 is the actual crack height, m; W 2 is the crack width of the experimental device, m; H 2 is the crack height of the experimental device, m; Q 2 is the injection displacement in the experiment, L / min.

[0051] In a specific example, the temporary plugging pressure-bearing device includes a fluid supply device, a power device, an intermediate container, and a rough rock plate, wherein the fluid supply device is connected to the intermediate container, the intermediate container is connected to the rough rock plate, the power device transports the fracturing fluid in the fluid supply device to the intermediate container, and an intermediate piston and a stirring device are provided in the intermediate container.

[0052] like Figure 3 As shown, a temporary plugging and pressure-bearing device is constructed, which includes a liquid supply barrel 1, a manifold 2, a power pump 3, a valve 4, an infusion nozzle 5, an intermediate piston 6, an intermediate container 7, a stirring fan 8, a motor 9, a stirring controller 10, a pressure sensor 11, a valve 12, a data acquisition system 13, a rough rock plate 14 (B), a clamp 15 (B), a valve 16, and a fracturing fluid recovery barrel 17.

[0053] In a specific embodiment, the experimental steps are: based on the liquid volume required for the experiment, weigh the temporary plugging agent of the mixed proppant and the single temporary plugging agent of the same mass according to the same mass concentration; prepare the fracturing fluid and add it into the intermediate container, start the stirring device, and add the weighed temporary plugging agent into the intermediate container; set the displacement in the pumping system, open the pipeline valve, and record the pressure changes during the experiment through the data acquisition system, obtain the stable plugging pressure peak, and record the time used, and calculate the pressure rise rate per unit time based on the following formula.

[0054]

[0055] Where: a is the pressure-increasing speed per unit time, MPa / s; P is the stable plugging pressure peak, MPa; T is the time required from the start of plugging to reaching the stable plugging pressure peak, s.

[0056] After the experiment, the fracture device was opened to measure the length of the plugging layer, and the unit plugging pressure gradient was calculated based on the following formula;

[0057]

[0058] Where: B is the unit plugging pressure gradient, MPa / cm; P is the stable plugging pressure peak, MPa; L is the plugging layer length, cm.

[0059] (3) The temporary plugging and pressure-bearing device is used to test the plugging parameters of the temporary plugging agent of the mixed proppant in the fracture physical model, and the plugging and pressure-bearing effect of the temporary plugging agent of the mixed proppant in the fracture is evaluated by comprehensively considering the migration and plugging effect and the plugging parameters.

[0060] In a specific embodiment, when the height of the plugging layer formed by the temporary plugging agent in the visualization experiment reaches the height of the fracture; in the pressure bearing capacity experiment, the stable plugging pressure peak, the pressure-initiating speed per unit time and the unit plugging pressure gradient of the plugging layer formed by the temporary plugging agent in the fracture meet the on-site requirements, then the temporary plugging agent has a better plugging pressure-bearing effect in the fractures in the required plugging area of ​​the target reservoir.

[0061] Application Examples

[0062] In order to facilitate the understanding and application of the technical solution of the present invention by those skilled in the art, the present invention is explained below through specific embodiments. In a specific embodiment, a comprehensive experimental evaluation method for the pressure-bearing effect of a temporary plugging agent of a mixed proppant in a crack specifically comprises the following steps:

[0063] (1) Obtain fracture parameters based on the target reservoir formation parameters and establish a fracture physical model.

[0064] Taking the field data of a certain reservoir as an example, the crack width of the target plugging area can be obtained based on the common process, which is about 3mm. The visualized rough plate simulates a crack with a length of 30cm, a height of 10cm, and a width of 3mm. The rough rock plate simulates a crack with a length of 17.8cm, a height of 3.8cm, and a width of 3cm. The roughness of the above crack plates can be obtained based on the common process, and the fracture physical device required for the experiment is established by combining the above parameters.

[0065] (2) Setting up a visual temporary plugging device and a temporary plugging pressure bearing device, and using the visual temporary plugging device to test the migration and plugging effect of the temporary plugging agent of the mixed proppant in the fracture physical model.

[0066] like Figure 2 The visual temporary plugging device is shown in the figure. During on-site construction, the displacement of a single section is usually 4 to 6 m 3 / min, assuming that there are 4 clusters of cracks opened in one section, the liquid flow rate of a single crack is 0.50~0.75m 3 The actual reservoir fracture height is 30m, the fracture entrance width is 6.5mm, and the fracture height of the experimental device is 0.1m. Therefore, based on the velocity similarity criterion, the simulated field single fracture fluid inflow is 0.50m 3 / min, 0.75m 3 / min, the experimental displacements corresponding to 3.0mm cracks are 0.77L / min and 1.15L / min respectively; based on field experience, the mass concentration of temporary plugging agent is usually 1.5%, and the viscosity of fracturing fluid is usually 3-5mPa·s. Since the effects of displacement and viscosity on the migration and plugging of temporary plugging agent in fractures are similar, the mass concentration of temporary plugging agent in this scheme is designed to be 1.5%, and the viscosity of fracturing fluid is designed to be 4mPa·s. The detailed experimental scheme is shown in Table 1.

[0067] Table 1 Visual temporary plugging experimental scheme

[0068] Serial number 6mm fiber concentration 2mm particle concentration 70 / 140 mesh proppant concentration Viscosity (mPa·s) Displacement (L / min) 1 1.5％ 0 0 4 0.77 2 0 1.5％ 0 4 0.77 3 1％ 0 0.5％ 4 0.77 4 0 1％ 0.5％ 4 0.77 5 1.5％ 0 0 4 1.15 6 0 1.5％ 0 4 1.15 7 1％ 0 0.5％ 4 1.15 8 0 1％ 0.5％ 4 1.15

[0069] The experimental liquid volume was set to 4L, and the temporary plugging agent of the mixed proppant and the single temporary plugging agent of the same mass were weighed according to the mass concentration of 1.5%; the prepared fracturing fluid was added into the intermediate container, the stirring device was turned on, and the weighed temporary plugging agent was added into the intermediate container, wherein the purpose of stirring was to make the temporary plugging agent and the fracturing fluid fully and evenly mixed while preventing the temporary plugging agent from settling at the bottom of the intermediate container, so as to ensure that the temporary plugging agent could smoothly enter the fracture device through the transport pipeline; according to different parameter combinations, the corresponding displacement was set in the pumping system, the pipeline valve was opened, and the migration and plugging process of the temporary plugging agent in the fracture was recorded by the camera, wherein when the height of the plugging layer formed by the temporary plugging agent in the fracture reached the height of the fracture device, it was considered that the plugging layer was formed in the fracture.

[0070] The final plugging effect of the temporary plugging agent in the crack under different parameters based on the visualization temporary plugging device is as follows Figure 4 shown.

[0071] It can be seen from the results that the final plugging effects of the temporary plugging agents in the above-mentioned different parameters in the fracture all meet the optimization requirements. Based on these parameters, the corresponding displacement is changed according to the specific parameters of the corresponding fracture device to carry out pressure bearing capacity test experiments in order to evaluate the better plugging pressure bearing effect.

[0072] like Figure 3 The temporary plugging pressure-bearing device is shown in the figure. During on-site construction, the displacement of a single section is usually 4 to 6m 3 / min, assuming that there are 4 clusters of cracks opened in one section, the liquid flow rate of a single crack is 0.50~0.75m 3 The actual reservoir fracture height is 30m, the fracture entrance width is 6.5mm, and the fracture height of the experimental device is 0.038m. Therefore, based on the velocity similarity criterion, the simulated field single fracture fluid inflow is 0.50m 3 / min, 0.75m 3 / min, the experimental displacements corresponding to 3.0mm cracks are 0.29L / min and 0.44L / min respectively; based on field experience, the mass concentration of temporary plugging agent is usually 1.5%, and the viscosity of fracturing fluid is usually 3-5mPa·s. Since the effects of displacement and viscosity on the migration and plugging of temporary plugging agent in fractures are similar, the mass concentration of temporary plugging agent in this scheme is designed to be 1.5%, and the viscosity of fracturing fluid is designed to be 4mPa·s. The detailed experimental scheme is shown in Table 2.

[0073] Table 2 Temporary plugging and pressure test plan

[0074] Serial number 6mm fiber concentration 2mm particle concentration 70 / 140 mesh proppant concentration Viscosity (mPa·s) Displacement (L / min) 1 1.5％ 0 0 4 0.29 2 0 1.5％ 0 4 0.29 3 1％ 0 0.5％ 4 0.29 4 0 1％ 0.5％ 4 0.29 5 1.5％ 0 0 4 0.44 6 0 1.5％ 0 4 0.44 7 1％ 0 0.5％ 4 0.44 8 0 1％ 0.5％ 4 0.44

[0075] The experimental liquid volume was set to 2L, and the temporary plugging agent of the mixed proppant and the single temporary plugging agent of the same mass were weighed according to the mass concentration of 1.5%; the prepared fracturing fluid was added into the intermediate container, the stirring device was turned on, and the weighed temporary plugging agent was added into the intermediate container; the corresponding displacement was set in the pumping system according to different parameter combinations, the pipeline valve was opened, and the pressure changes during the experiment were recorded through the data acquisition system. When the data was stable, it was considered that the plugging pressure of the plugging layer formed by the temporary plugging agent in the fracture reached a stable peak, and the time used was recorded, and the pressure starting speed per unit time and the unit plugging pressure gradient were calculated.

[0076] The stable plugging pressure peak test results under different temporary plugging parameters based on the temporary plugging pressure bearing device are as follows: Figure 5 , Figure 6 As shown in the figure, the unit time pressure starting speed and unit plugging pressure gradient diagram of the plugging layer formed by the temporary plugging agent in the fracture under different parameter combinations are shown in Figure 7, Figure 8 shown.

[0077] (3) The temporary plugging and pressure-bearing device is used to test the plugging parameters of the temporary plugging agent of the mixed proppant in the fracture physical model, and the plugging and pressure-bearing effect of the temporary plugging agent of the mixed proppant in the fracture is evaluated by comprehensively considering the migration and plugging effect and the plugging parameters.

[0078] according to Figure 4 It can be seen that under the above parameter conditions, the height of the plugging layer formed by the temporary plugging agent in the fracture reaches the height of the fracture plate, which can be regarded as a plugging in the fracture. The required plugging pressure on site is usually 3-4MPa, and the pressure-initiating speed per unit time is greater than 0.04MPa / s and the unit plugging pressure gradient is greater than 0.3MPa / cm. Therefore, 3.5MPa is used as the target plugging pressure, 0.04MPa / s and 0.3MPa / cm are the target pressure-initiating speed per unit time and then the target unit plugging pressure gradient. Figure 5 , Figure 6 As a result, under the same conditions, the peak value of the stable plugging pressure formed by the temporary plugging agent mixed with proppant in the fracture is larger, indicating that the mechanical strength of the plugging layer formed by the temporary plugging agent mixed with proppant is better. Figure 7 and Figure 8 The results show that under the same conditions, the temporary plugging agent of the mixed proppant has a greater pressure-initiating speed per unit time and a unit plugging pressure gradient in the fracture, indicating that the temporary plugging agent of the mixed proppant has a better plugging efficiency in the fracture and the compactness of the formed plugging layer. Therefore, the temporary plugging agent of the mixed proppant has a better plugging pressure-bearing effect in the fracture. Combined with the migration and plugging results of the temporary plugging agent in the fracture, the peak value of the stable plugging pressure of the plugging layer, the pressure-initiating speed per unit time and the unit plugging pressure gradient, the appropriate construction parameters can be further optimized. Therefore, in this embodiment, the parameter combinations of sequence numbers 3, 6, 7, and 8 have a better pressure-bearing effect on the plugging of the target reservoir fractures.

[0079] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A comprehensive experimental evaluation method for the pressure-bearing effect of a temporary plugging agent mixed with a proppant, comprising the following steps: (1) Obtaining fracture parameters based on target reservoir formation parameters and establishing a fracture physical model; (2) Setting up a visual temporary plugging device and a temporary plugging pressure bearing device, and using the visual temporary plugging device to test the migration and plugging effect of the temporary plugging agent of the mixed proppant in the fracture physical model; (3) The temporary plugging and pressure-bearing device is used to test the plugging parameters of the temporary plugging agent of the mixed proppant in the fracture physical model, and the plugging and pressure-bearing effect of the temporary plugging agent of the mixed proppant in the fracture is evaluated by comprehensively considering the migration and plugging effect and the plugging parameters.

2. According to the comprehensive experimental evaluation method for the pressure-bearing effect of the temporary plugging agent of the mixed proppant in the crack according to claim 1, the crack parameters in step (1) mainly include crack width and crack wall roughness.

3. According to the comprehensive experimental evaluation method for the pressure-bearing effect of the temporary plugging agent of the mixed proppant in the crack, the visual temporary plugging device in step (2) includes a liquid supply device, a power device, an intermediate container, and a visual rough crack plate, wherein the liquid supply device is connected to the intermediate container, the intermediate container is connected to the visual rough crack plate, the power device transports the fracturing fluid in the liquid supply device to the intermediate container, and the intermediate container is provided with an intermediate piston and a stirring device.

4. According to the comprehensive experimental evaluation method for the pressure-bearing effect of the temporary plugging agent of the mixed proppant in the crack according to claim 3, the test step of the visual temporary plugging device in step (2) comprises: Based on the liquid volume required for the experiment, weigh the temporary plugging agent of the mixed proppant according to the selected mass concentration; prepare the fracturing fluid and add it into the intermediate container, turn on the stirring device, and add the weighed temporary plugging agent into the intermediate container, so that the temporary plugging agent and the fracturing fluid are fully and evenly mixed while preventing the temporary plugging agent from settling at the bottom of the intermediate container; set the displacement in the pumping system, open the pipeline valve, and record the migration and plugging process of the temporary plugging agent in the crack through a camera. When the height of the plugging layer formed by the temporary plugging agent in the crack reaches the height of the crack, it is considered that a plugging is formed in the crack.

5. According to the comprehensive experimental evaluation method of the pressure-bearing effect of the temporary plugging agent of the mixed proppant in the crack according to claim 4, the displacement acquisition method of the experimental test is: Where: Q1 is the displacement of a single seam on site, m 3 / min; W1 is the actual crack width, m; H1 is the actual crack height, m; W2 is the experimental crack width, m; H2 is the experimental crack height, m; Q2 is the injection displacement in the experiment, L / min.

6. According to the comprehensive experimental evaluation method of the temporary plugging and pressure-bearing effect of the mixed proppant in the seam, the temporary plugging and pressure-bearing device in step (2) includes a liquid supply device, a power device, an intermediate container, and a rough rock plate, wherein the liquid supply device is connected to the intermediate container, the intermediate container is connected to the rough rock plate, the power device transports the fracturing fluid in the liquid supply device to the intermediate container, and a piston and a stirring device are provided in the intermediate container.

7. According to the comprehensive experimental evaluation method for the sealing and pressure-bearing effect of the temporary plugging agent of the mixed proppant in claim 6, the testing step of the temporary plugging and pressure-bearing device in step (2) comprises: Based on the liquid volume required for the experiment, weigh the temporary plugging agent of the mixed proppant according to the selected mass concentration; prepare the fracturing fluid and add it to the intermediate container, turn on the stirring device, and add the weighed temporary plugging agent to the intermediate container, so that the temporary plugging agent and the fracturing fluid are fully and evenly mixed while preventing the temporary plugging agent from settling at the bottom of the intermediate container; set the displacement in the pumping system, open the pipeline valve, record the pressure changes during the experiment through the data acquisition system, and determine the plugging parameters through the pressure changes.

8. According to the comprehensive experimental evaluation method for the pressure-bearing effect of the temporary plugging agent of the mixed proppant in the crack according to claim 7, the plugging parameters in step (3) include the stable plugging pressure peak, the pressure starting speed per unit time and the unit plugging pressure gradient.

9. According to the comprehensive experimental evaluation method for the pressure-bearing effect of the temporary plugging agent of the mixed proppant in the crack according to claim 8, the method for obtaining the pressure-initiating speed per unit time is: Where: a is the pressure-increasing speed per unit time, MPa / s; P is the stable plugging pressure peak, MPa; T is the time required from the start of plugging to reaching the stable plugging pressure peak, s; The method for obtaining the unit plugging pressure gradient is: Where: B is the unit plugging pressure gradient, MPa / cm; P is the stable plugging pressure peak, MPa; L is the plugging layer length, cm.

10. The comprehensive experimental evaluation method for the sealing and pressure-bearing effect of a temporary plugging agent of a mixed proppant in a fracture according to claim 1, further comprising the step of testing the migration and sealing effect of a single temporary plugging agent in a fracture physical model under the same conditions.

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