A device and method for testing the plugging performance of a solid temporary plugging agent for fracturing

Abstract

This invention relates to a device and method for testing the sealing performance of solid temporary plugging agents for fracturing, comprising a pressure cap and a connecting cylinder. By filling the connecting cylinder with different types of solid temporary plugging agents and selecting the corresponding pressure cap for sealing, and using a conventional core displacement experimental device, the sealing effect of the temporary plugging agent on the borehole or fractures of different diameters under the action of a specific fluid can be dynamically tested. This invention can solve the problems of the limited testing types and poor versatility of existing fracturing temporary plugging agent testing devices, and ensure that the evaluation methods and technical indicators during the testing process are consistent, allowing for a reliable assessment of the quality of the temporary plugging agent.

Description

Technical Field

[0001] This invention belongs to the field of temporary plugging agent plugging performance testing technology, and relates to a device and method for testing the plugging performance of solid temporary plugging agents for fracturing. Background Technology

[0002] Temporary plugging fracturing technology is highly adaptable to wellbore trajectories and tubing sizes, and is simple, safe, and efficient to implement, making it the mainstream technology for horizontal well directional fracturing.

[0003] Existing solid plugging agents are mainly available in spherical, granular, and powder forms. Their main performance parameters are: (1) the size of the plugging agent can match the size of artificial fractures and perforations; (2) it can effectively plug perforation clusters and withstand certain pressure; (3) it can dissolve in water within a certain time at reservoir temperature; and (4) the extent of damage to artificial fractures and reservoir permeability after the plugging agent dissolves. To date, there are no unified evaluation indicators and testing procedures for the indoor evaluation of the plugging performance of solid plugging agents, both domestically and internationally. Each company adopts its own product standards, the equipment is not very universal, and the testing items, evaluation methods, and technical indicators of plugging agents are not uniform, making it impossible to reliably judge the quality of the plugging agents.

[0004] Chinese patent document CN112796700A discloses a test method for the sealing performance of a temporary plugging agent for fracturing. The method includes a fracturing simulation device, an electric heating belt, a booster pump, a pressure sensor, a discharge valve, and a flow sensor. After assembling the above structure, the temporary plugging agent whose performance needs to be tested is mixed with fast-dissolving guar gum and filler. After thorough mixing, the mixture is divided into two portions. The discharge valve is closed, and the booster pump is controlled by a background control system to increase the pressure. For every 1 MPa increase in pressure, the displacement of the temporary plugging agent within the fracturing simulation device is recorded. Based on the increased pressure data and the recorded displacement data, the pressure-bearing capacity of the temporary plugging agent is determined. After the pressure test, the first portion of the temporary plugging agent is removed, and the second portion is placed into the fracturing simulation device. An electric heating belt is wrapped around the fracturing simulation device, and the discharge valve is opened through the background control system. The background control system gradually increases the temperature of the electric heating belt, and the flow rate of the liquid flowing from the bottom of the fracturing simulation device is measured using a flow sensor. The heating temperature is monitored in real time by the background control system. However, the testing device described above only tests a single type of temporary plugging agent and cannot select powdered, granular, or spherical temporary plugging agents for testing based on the crack or pore morphology. The device's test results are limited and it lacks versatility.

[0005] Chinese patent document CN111256961A discloses a device and method for evaluating the performance of a temporary plugging ball. The device includes: a pumping module, a first fluid manifold, a temporary plugging and turning level testing module, a seam opening and turning simulation module, and a data acquisition module. The output end of the pumping module is connected to the temporary plugging and turning level testing module through the first fluid manifold. Multiple holes are provided on the side wall of the temporary plugging and turning level testing module, and the temporary plugging and turning level testing module is connected to an input end of the seam opening and turning simulation module through the multiple holes. The output end of the seam opening and turning simulation module is connected to the data acquisition module, which is used to collect the first flow rate of the fluid output by the seam opening and turning simulation module. Based on the first flow rate, the turning performance of the temporary plugging ball is evaluated. This device can quickly, accurately, and intuitively obtain the sealing ability and turning performance of the temporary plugging ball during the seam opening and turning process. However, this testing device cannot perform targeted testing on temporary plugging agents of different forms such as powder, granules, or balls. The device has poor versatility and its structure is complex and inconvenient to operate. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention discloses a testing device and method for the sealing performance of solid temporary plugging agents for fracturing. The device includes a pressure cap and a connecting cylinder. By filling the connecting cylinder with different types of solid temporary plugging agents and selecting the corresponding pressure cap for sealing, and using a conventional core displacement experimental device, the sealing effect of the temporary plugging agent on boreholes or fractures of different diameters under the action of a specific fluid is dynamically tested. This solves the problems of limited testing types and poor versatility in existing fracturing temporary plugging agent testing devices, ensuring uniformity in evaluation methods and technical indicators during the testing process, and enabling reliable evaluation of the quality of the temporary plugging agent.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a device for testing the sealing performance of a solid temporary plugging agent for fracturing, comprising a first pressure cap, a second pressure cap, a connecting cylinder, and a pad. The connecting cylinder has a through hole at its central axis. The first pressure cap is located at one end of the connecting cylinder, and the second pressure cap is located at the other end of the connecting cylinder. The first pressure cap has a liquid inlet structure at its axial center, and the second pressure cap has a liquid outlet structure at its axial center. The pad is located inside the through hole of the connecting cylinder, and the pad is in close contact with the end face of the first pressure cap. The pad has a liquid guiding through hole at its axial center, and multiple flow channels are concentrically distributed on the end face of the pad. Multiple flow channels are radially arranged on the end face of the pad, and the flow channels connect the liquid guiding through hole and the flow channels. The through hole in the connecting cylinder between the pad and the second pressure cap is filled with a fixed temporary plugging agent.

[0008] Furthermore, the first pressure cap adopts a bolt structure, and the first pressure cap includes a first nut part and a first threaded part, wherein the first threaded part adopts an external thread structure.

[0009] Furthermore, the liquid inlet structure in the first pressure cap adopts a circular liquid guiding through hole, and the liquid outlet structure in the second pressure cap adopts a rectangular liquid guiding through hole.

[0010] As the first type of testing device structure, it can be used for sealing tests of powdered or granular temporary plugging agents within the joint:

[0011] Furthermore, the second pressure cap includes two half bolts, which are spliced ​​together to form a cylindrical bolt structure, and the second pressure cap includes a second nut part and a second threaded part, the second threaded part adopting an external thread structure.

[0012] Furthermore, the connecting cylinder has a straight cylindrical structure, and both ends of the connecting cylinder are provided with internal threaded connecting parts. The first threaded part of the first pressure cap is connected and fixed to the internal threaded connecting part at one end of the connecting cylinder; the second threaded part of the second pressure cap is connected and fixed to the internal threaded connecting part at the other end of the connecting cylinder.

[0013] As a second type of testing device structure, it can be used for pre-sealing tests on powdered or granular temporary plugging agents:

[0014] Furthermore, the second pressure cap adopts a cover structure with a groove, and the second pressure cap is provided with a second threaded part with an internal thread structure.

[0015] Furthermore, the connecting cylinder needle has a stepped cylindrical structure. One end of the connecting cylinder is provided with an internal threaded connection part, and the other end is provided with an external threaded connection part. The first threaded part of the first pressure cap is connected and fixed to the internal threaded connection part at one end of the connecting cylinder; the second threaded part of the second pressure cap is connected and fixed to the external threaded connection part at the other end of the connecting cylinder.

[0016] As a third type of testing device structure, it can be used to perform orifice sealing tests on spherical temporary plugging agents:

[0017] Furthermore, the liquid outlet structure in the second pressure cap adopts a circular liquid guiding through hole, and the second pressure cap and the connecting cylinder are integrally formed. The first threaded part of the first pressure cap is connected and fixed to the end of the connecting cylinder that is away from the second pressure cap.

[0018] Furthermore, the liquid inlet structure of the first pressure cap adopts a conical liquid guide hole, with the side of the conical liquid guide hole with the larger opening facing into the connecting cylinder.

[0019] Furthermore, based on the aforementioned testing apparatus, this invention also discloses a method for testing the plugging performance of a solid temporary plugging agent for fracturing, which includes the following steps:

[0020] Test device assembly and sample loading: Select the components of the test device according to the test requirements and assemble them. After assembly, weigh a certain amount of test fixing agent and fill it into the connecting cylinder, and put in the pad. Use a torque wrench to apply a predetermined torque to tighten the first pressure cap.

[0021] Test device installation: Insert the assembled test device and a 2-3cm long hollow steel cylinder into the rubber sleeve of the core holder. The hollow steel cylinder is used to receive the outflowing temporary plugging agent.

[0022] Test: Connect the core holder to the equipment, set the confining pressure to be 2 MPa greater than the injection pressure, set the maximum displacement pressure, set the flow medium velocity to 4 mL / min, and keep the flow medium injected at a constant pressure. When the core holder reaches the maximum displacement pressure, switch to constant pressure injection. When the liquid outlet velocity of the liquid outlet structure in the test device is greater than or equal to the flow medium injection velocity, or when the displacement pressure drops sharply, the experiment is stopped.

[0023] Results analysis: The highest displacement pressure value measured during the test is the current sealing strength of the temporary fixation agent, in MPa; the time from the start of the displacement pressure increase to the end of the pressure drop is the effective sealing time of the current temporary fixation agent, in H.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] 1) The testing device in this invention adopts a structure of connecting cylinder, pressure cap and pad, etc. The device is simple to assemble and easy to disassemble. It can make full use of conventional core displacement test equipment to test the sealing performance of solid temporary plugging agents. In addition, different pressure cap structures are set for different types of temporary plugging agents, which can realize the simulation of the sealing process in three ways: before the fracture, inside the fracture and the pore, covering all evaluation types of solid temporary plugging agents, and the device has better versatility.

[0026] 2) The test device in this invention has a hexagonal structure in the outer layer of the pressure cap at both ends. This device can accurately control the compaction degree of the temporary plugging agent by adding pad blocks and using a torque wrench to precisely adjust the torque of the pressure cap. This is more conducive to the standardization of the test method and can improve the accuracy of the test results.

[0027] 3) The testing device in this invention is for testing the sealing performance of the joint. The pressure cap is spliced ​​with two half bolts, which is more conducive to disassembly and cleaning after sealing. The pressure cap and the connecting cylinder are connected by threads, which is more convenient for disassembly and cleaning after testing. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of a solid temporary plugging agent for fracturing performance testing device in Embodiment 1;

[0029] Figure 2 This is a schematic diagram of the internal structure of the solid temporary plugging agent sealing performance testing device for fracturing in Example 1 of this embodiment;

[0030] Figure 3 This is a schematic diagram of the structure of the second pressure cap in Embodiment 1;

[0031] Figure 4 This is a schematic diagram of the structure of a solid temporary plugging agent for fracturing performance testing device in Embodiment 2;

[0032] Figure 5 This is a schematic diagram of the internal structure of the solid temporary plugging agent sealing performance testing device for fracturing in Embodiment 2;

[0033] Figure 6 This is a schematic diagram of the structure of a solid temporary plugging agent for fracturing performance testing device in Embodiment 3;

[0034] Figure 7 This is a schematic diagram of the internal structure of the solid temporary plugging agent sealing performance testing device for fracturing in Embodiment 3;

[0035] Figure 8 This is a schematic diagram of the installation of the solid temporary plugging agent sealing performance testing device for fracturing in Example 4. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0038] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0039] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0040] Example 1:

[0041] like Figure 1-3 As shown in the figure, this embodiment 1 discloses a device for testing the sealing performance of solid temporary plugging agent for fracturing. The device can be used to test the sealing performance of powdered or granular temporary plugging agent in the fracture. Specifically, the device includes a first pressure cap 2, a second pressure cap 3, a connecting cylinder 1, and a pad block 4.

[0042] The connecting cylinder 1 has a through hole at its central axis, the first pressure cap 2 is located at one end of the connecting cylinder 1, and the second pressure cap 3 is located at the other end of the connecting cylinder 1. The first pressure cap 2 has a liquid inlet structure 201 at its axial center, and the second pressure cap 3 has a liquid outlet structure 301 at its axial center. The pad 4 is located inside the through hole of the connecting cylinder 1 and is in close contact with the end face of the first pressure cap 2. The pad 4 has a liquid guiding through hole at its axial center, and multiple flow guide grooves are concentrically distributed on the end face of the pad 4. Multiple flow guide channels are radially arranged on the end face of the pad 4, and the flow guide channels connect the liquid guiding through hole and the flow guide grooves. The through hole in the connecting cylinder 1 between the pad 4 and the second pressure cap 3 is filled with a temporary sealing agent.

[0043] More specifically, the first pressure cap 2 adopts a bolt structure, and includes a first nut portion and a first threaded portion, the first threaded portion being an external thread structure. The second pressure cap 3 includes two half-bolts, which are spliced ​​together to form a cylindrical bolt structure, and includes a second nut portion and a second threaded portion, the second threaded portion being an external thread structure. The above-mentioned pressure caps adopt a threaded connection method, which makes installation and disassembly more convenient. Furthermore, the pressure cap can be spliced ​​from two half-bolts, and during testing, it can be spliced ​​together to form a complete pressure cap structure for sealing. After testing, the pressure cap can be disassembled and separated into two parts for easy cleaning.

[0044] More specifically, the liquid inlet structure 201 in the first pressure cap 2 adopts a circular liquid guiding through hole, and the liquid outlet structure 301 in the second pressure cap 3 adopts a rectangular liquid guiding through hole.

[0045] In this embodiment 1, the connecting cylinder 1 has a straight cylindrical structure, and both ends of the connecting cylinder 1 are provided with internal threaded connecting parts. The first threaded part of the first pressure cap 2 is connected and fixed to the internal threaded connecting part at one end of the connecting cylinder 1; the second threaded part of the second pressure cap 3 is connected and fixed to the internal threaded connecting part at the other end of the connecting cylinder 1.

[0046] Example 2:

[0047] like Figure 4-5 As shown in the figure, this embodiment 2 discloses a device for testing the sealing performance of solid temporary plugging agent for fracturing. The device can be used to perform pre-fracturing sealing tests on powdered or granular temporary plugging agents. Specifically, the device includes a first pressure cap 2, a second pressure cap 3, a connecting cylinder 1, and a pad block 4.

[0048] The connecting cylinder 1 has a through hole at its central axis, the first pressure cap 2 is located at one end of the connecting cylinder 1, and the second pressure cap 3 is located at the other end of the connecting cylinder 1. The first pressure cap 2 has a liquid inlet structure 201 at its axial center, and the second pressure cap 3 has a liquid outlet structure 301 at its axial center. The pad 4 is located inside the through hole of the connecting cylinder 1 and is in close contact with the end face of the first pressure cap 2. The pad 4 has a liquid guiding through hole at its axial center, and multiple flow guide grooves are concentrically distributed on the end face of the pad 4. Multiple flow guide channels are radially arranged on the end face of the pad 4, and the flow guide channels connect the liquid guiding through hole and the flow guide grooves. The through hole in the connecting cylinder 1 between the pad 4 and the second pressure cap 3 is filled with a temporary sealing agent.

[0049] More specifically, the first pressure cap 2 adopts a bolt structure, and the first pressure cap 2 includes a first nut portion and a first threaded portion, the first threaded portion adopting an external thread structure. The second pressure cap 3 adopts a cover structure with a groove, and the second pressure cap 3 has a second threaded portion with an internal thread structure.

[0050] More specifically, the liquid inlet structure 201 in the first pressure cap 2 adopts a circular liquid guiding through hole, and the liquid outlet structure 301 in the second pressure cap 3 adopts a rectangular liquid guiding through hole.

[0051] In this embodiment 2, the connecting cylinder 1 has a stepped cylindrical structure. One end of the connecting cylinder 1 is provided with an internal thread connection part, and the other end is provided with an external thread connection part. The first thread part of the first pressure cap 2 is connected and fixed to the internal thread connection part at one end of the connecting cylinder 1; the second thread part of the second pressure cap 3 is connected and fixed to the external thread connection part at the other end of the connecting cylinder 1.

[0052] Example 3:

[0053] like Figure 6-7As shown in the figure, this embodiment 3 discloses a device for testing the sealing performance of solid temporary plugging agent for fracturing. The device can be used to test the pore sealing of spherical temporary plugging agent. Specifically, the device includes a first pressure cap 2, a second pressure cap 3, a connecting cylinder 1, and a pad block 4.

[0054] The connecting cylinder 1 has a through hole at its central axis, the first pressure cap 2 is located at one end of the connecting cylinder 1, and the second pressure cap 3 is located at the other end of the connecting cylinder 1. The first pressure cap 2 has a liquid inlet structure 201 at its axial center, and the second pressure cap 3 has a liquid outlet structure 301 at its axial center. The pad 4 is located inside the through hole of the connecting cylinder 1 and is in close contact with the end face of the first pressure cap 2. The pad 4 has a liquid guiding through hole at its axial center, and multiple flow guide grooves are concentrically distributed on the end face of the pad 4. Multiple flow guide channels are radially arranged on the end face of the pad 4, and the flow guide channels connect the liquid guiding through hole and the flow guide grooves. The through hole in the connecting cylinder 1 between the pad 4 and the second pressure cap 3 is filled with a temporary sealing agent.

[0055] More specifically, the first pressure cap 2 adopts a bolt structure, and the first pressure cap 2 includes a first nut part and a first threaded part, the first threaded part adopting an external thread structure. The liquid outlet structure 301 in the second pressure cap 3 adopts a circular liquid guiding through hole, and the second pressure cap 3 is integrally formed with the connecting cylinder 1. The first threaded part of the first pressure cap 2 is connected and fixed to the end of the connecting cylinder 1 opposite to the second pressure cap 3.

[0056] More specifically, the liquid inlet structure 201 of the first pressure cap 2 adopts a conical liquid guide hole, with the side of the conical liquid guide hole with a larger opening facing the inside of the connecting cylinder 1. During the test, a spherical temporary plugging agent can be placed into the conical liquid guide hole, and then the first pressure cap 2 can be screwed onto the connecting cylinder 1 using a torque wrench. This ensures that the spherical temporary plugging agent fully adheres to the conical surface of the conical liquid guide hole. To prevent the temporary plugging ball from loosening, a pad block 4 of a certain thickness can be further added.

[0057] Example 4:

[0058] Combination Figure 8 As shown, based on the testing apparatus in Examples 1-3 above, Example 4 discloses a method for testing the plugging performance of a solid temporary plugging agent for fracturing, which includes the following steps:

[0059] Test device assembly and sample loading: According to the test requirements, select the components of the test device and assemble them. After assembly, weigh a certain amount of test fixing agent and fill it into the connecting cylinder 1, and put in the pad 4. Use a torque wrench to apply a predetermined torque to tighten the first pressure cap 2.

[0060] Test device installation: Insert the assembled test device and a 2-3cm long hollow steel cylinder 5 into the rubber sleeve 6 of the core holder. The hollow steel cylinder 5 is used to receive the outflowing temporary plugging agent.

[0061] Test procedure: Connect the core holder to the equipment, set the confining pressure to be 2 MPa greater than the injection pressure, set the maximum displacement pressure, set the flow medium velocity to 4 mL / min, and maintain a constant flow medium injection. When the core holder reaches the maximum displacement pressure, switch to constant pressure injection. When the liquid outlet velocity of the liquid outlet structure 301 in the test device is greater than or equal to the flow medium injection velocity, or when the displacement pressure drops sharply, the experiment is stopped.

[0062] Results analysis: The highest displacement pressure value measured during the test is the current sealing strength of the temporary fixation agent, in MPa; the time from the start of the displacement pressure increase to the end of the pressure drop is the effective sealing time of the current temporary fixation agent, in H.

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A device for testing the plugging performance of a solid temporary plugging agent for fracturing, characterized in that, The device includes a first pressure cap, a second pressure cap, a connecting cylinder, and a pad. The connecting cylinder has a through hole at its central axis. The first pressure cap is located at one end of the connecting cylinder, and the second pressure cap is located at the other end. The first pressure cap has a liquid inlet structure at its axial center, and the second pressure cap has a liquid outlet structure at its axial center. The pad is located inside the through hole of the connecting cylinder and is in close contact with the end face of the first pressure cap. The pad has a liquid guiding through hole at its axial center, and multiple flow channels are concentrically distributed on its end face. Multiple flow channels are radially arranged on the end face of the pad, and the flow channels connect the liquid guiding through hole and the flow channels. The through hole in the connecting cylinder between the pad and the second pressure cap is filled with a temporary sealing agent. The first pressure cap adopts a bolt structure, and the first pressure cap includes a first nut part and a first threaded part, wherein the first threaded part adopts an external thread structure; The liquid inlet structure in the first pressure cap adopts a circular liquid guiding through hole, and the liquid outlet structure in the second pressure cap adopts a rectangular liquid guiding through hole; The second pressure cap includes two half bolts, which are spliced ​​together to form a cylindrical bolt structure. The second pressure cap includes a second nut part and a second threaded part, and the second threaded part adopts an external thread structure.

2. The device for testing the plugging performance of solid temporary plugging agent for fracturing according to claim 1, characterized in that, The connecting cylinder has a straight cylindrical structure, and both ends of the connecting cylinder are provided with internal threaded connecting parts. The first threaded part of the first pressure cap is connected and fixed to the internal threaded connecting part at one end of the connecting cylinder; the second threaded part of the second pressure cap is connected and fixed to the internal threaded connecting part at the other end of the connecting cylinder.

3. A method for testing the plugging performance of a solid temporary plugging agent for fracturing using the testing device for plugging performance of a solid temporary plugging agent for fracturing as described in any one of claims 1-2, characterized in that, Includes the following steps: Test device assembly and sample loading: Select the components of the test device according to the test requirements and assemble them. After assembly, weigh a certain amount of test fixing agent and fill it into the connecting cylinder, and put in the pad. Use a torque wrench to apply a predetermined torque to tighten the first pressure cap. Test device installation: Insert the assembled test device and a 2-3cm long hollow steel cylinder into the rubber sleeve of the core holder. The hollow steel cylinder is used to receive the outflowing temporary plugging agent. Test: Connect the core holder to the equipment, set the confining pressure to be 2 MPa greater than the injection pressure, set the maximum displacement pressure, set the flow medium velocity to 4 mL / min, and keep the flow medium injected at a constant pressure. When the core holder reaches the maximum displacement pressure, switch to constant pressure injection. When the liquid outlet velocity of the liquid outlet structure in the test device is greater than or equal to the flow medium injection velocity, or when the displacement pressure drops sharply, the experiment is stopped. Results analysis: The highest displacement pressure value measured during the test is the current sealing strength of the temporary fixation agent, in MPa; the time from the start of the displacement pressure increase to the end of the pressure drop is the effective sealing time of the current temporary fixation agent, in H.

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