Rock hydraulic fracturing device under acid-base action

Abstract

The utility model discloses a kind of rock hydraulic fracturing devices under acid-base action, including the pressure-receiving platform for installing the rock sample to be measured, the confining pressure mechanism for embedding the rock sample to be measured and the pressure transmission mechanism being set above the confining pressure mechanism and being inserted into the rock sample to be measured;The pressure transmission mechanism includes the hole packer being inserted into the rock sample to be measured and the pressure transmission rod seal being inserted into the hole packer;The confining pressure mechanism includes the water injection internal pressure film being sleeved outside the rock sample to be measured, one side of the water injection internal pressure film is provided with liquid injection pipe, the other side of the water injection internal pressure film is provided with liquid discharge pipe.The utility model is simple in structure, reasonable in design, after applying acid-base corrosion environment to the rock sample to be measured, and the hole packer and the pressure transmission rod seal are sealed to the rock sample to be measured for sealing loading to be fractured, to adapt to the rock hydraulic fracturing demand under acid-base action, adapt to the mechanical research of coal rock mass under complex geological environment.

Description

Technical Field

[0001] This utility model belongs to the field of hydraulic fracturing technology, and in particular relates to a device for hydraulic fracturing rocks under acid and alkali conditions. Background Technology

[0002] With the development of coal mining, accurately assessing the mechanical characteristics of coal and rock masses in complex geological environments is crucial. Due to long-term exposure to acidic and alkaline chemical corrosion environments, the internal pore structure and mechanical properties of coal and rock masses are significantly deteriorated by environmental influences. Although traditional rock mechanics testing devices can simulate pressure conditions, they have the following limitations: First, they cannot apply acidic or alkaline corrosive environments, making it difficult for test results to reflect true geological conditions; second, insufficient sealing leads to easy leakage of acidic and alkaline media, affecting data accuracy and posing safety hazards.

[0003] Therefore, there is an urgent need for a simple and reasonably designed rock hydraulic fracturing device under acid and alkali conditions. After applying an acid or alkali corrosive environment to the rock sample, the sample is sealed and fracturing is performed through a sealing device and a pressure transmission rod seal, so as to meet the requirements of rock hydraulic fracturing under acid and alkali conditions. Utility Model Content

[0004] The technical problem to be solved by this utility model is to provide a rock hydraulic fracturing device under acid and alkali action, which addresses the shortcomings of the prior art. The device has a simple structure and reasonable design. After applying an acid and alkali corrosive environment to the rock sample to be tested, the rock sample is sealed and fracturing is performed by sealing the sample through a sealing device and a pressure transmission rod seal. This device is suitable for the requirements of rock hydraulic fracturing under acid and alkali action and for mechanical research of coal and rock masses in complex geological environments.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is: a rock hydraulic fracturing device under acid and alkali action, characterized in that: it includes a pressure bearing platform for mounting the rock sample to be tested, a confining pressure mechanism for embedding the rock sample to be tested, and a pressure transmitting mechanism disposed above the confining pressure mechanism and extending into the rock sample to be tested, wherein an inner cylindrical hole is provided at the center of the rock sample to be tested.

[0006] The pressure transmission mechanism includes a sealing device that extends into the inner cylindrical hole and a pressure transmission rod seal that extends into the sealing device.

[0007] The confining pressure mechanism includes a water-injected inner pressure membrane sleeved outside the rock sample to be tested. A liquid injection pipe is provided on one side of the water-injected inner pressure membrane, and a liquid discharge pipe is provided on the other side of the water-injected inner pressure membrane.

[0008] The above-mentioned rock hydraulic fracturing device under acid and alkali action is characterized in that: the pressure transmission rod sealing element includes a pressure block, a pressure rod and a pressure head arranged sequentially from top to bottom, the pressure rod is a threaded rod, the top of the pressure rod is threadedly connected to the bottom of the pressure block, the bottom of the pressure rod is fixedly connected to the pressure head, and the pressure head extends into the sealing device.

[0009] The above-mentioned rock hydraulic fracturing device under acid and alkali action is characterized in that: a sealing ring and an upper limit ring are sleeved on the pressure rod, the lower end of the sealing ring is attached to the pressure head, the upper end of the sealing ring is attached to the upper limit ring, and the inner wall of the upper limit ring is threadedly connected to the pressure rod.

[0010] The outer diameter of the pressure head, the outer diameter of the sealing ring, and the outer diameter of the upper limit ring are the same. The outer diameter of the pressure head and the inner diameter of the sealing device are the same, so that the pressure head can extend into the sealing device.

[0011] The above-mentioned rock hydraulic fracturing device under acid and alkali action is characterized in that: the sealing device includes a sealing hollow rod extending into an inner cylindrical hole and a sealing ring integrally sleeved outside the sealing hollow rod; a gap is provided between the bottom of the sealing hollow rod and the bottom of the inner cylindrical hole of the rock sample to be tested; the sealing ring fits against the top of the rock sample to be tested; the outer diameter of the sealing ring is larger than the diameter of the inner cylindrical hole; and the connection between the sealing ring and the top of the inner cylindrical hole of the rock sample to be tested is sealed with acrylic structural adhesive.

[0012] The pressure head extends into the top of the sealing hollow rod.

[0013] The above-mentioned rock hydraulic fracturing device under acid and alkali action is characterized in that: the injection pipe is equipped with an injection valve and a pressure gauge, and the discharge pipe is equipped with a discharge valve.

[0014] The above-mentioned rock hydraulic fracturing device under acid and alkali action is characterized in that: the bottom of the rock sample to be tested is fixed to the pressure platform by acrylic structural adhesive.

[0015] The above-mentioned rock hydraulic fracturing device under acid and alkali action is characterized in that: two locking nuts are sleeved on the top of the pressure rod, and the locking nuts abut against the bottom of the pressure block.

[0016] This utility model has the following advantages compared with the prior art:

[0017] 1. This utility model has a simple structure and is easy to operate. It overcomes the limitations of traditional methods that lack acid and alkali corrosion conditions, and is compatible with compressive strength testing machines, which significantly reduces the complexity and cost of the equipment.

[0018] 2. The rock sample to be tested in this utility model has an inner cylindrical hole at the center position. This is to inject acid and alkali solutions into the inner cylindrical hole to fully simulate the chemical corrosion environment of the mineral layer, thereby achieving the application of an acid and alkali environment to the rock sample to be tested.

[0019] 3. This utility model is designed so that the sealing device extends into the inner cylindrical hole of the rock sample to be tested, and the pressure transmission rod seal extends into the sealing device until the bottom of the pressure transmission rod seal is in contact with the inner cylindrical hole of the rock sample to be tested. In this way, the sealing device and the pressure transmission rod seal interact to seal the rock sample to be tested, thereby preventing the solution from leaking after the rock sample is subjected to the environment.

[0020] 4. The confining pressure mechanism in this utility model is designed to simulate a water pressure environment and adapt to the geological environment requirements of different coal and rock masses.

[0021] 5. The cost of this new rock hydraulic fracturing device under acid and alkali corrosion is much lower than that of traditional large-scale rock mechanical strength testing machinery, enabling its widespread application and promotion in engineering.

[0022] In summary, this utility model has a simple structure and reasonable design. After applying an acid-alkali corrosion environment to the rock sample to be tested, the rock sample is sealed and cracked by a sealing device and a pressure transmission rod seal to meet the requirements of water pressure cracking of rocks under acid and alkali action, and to meet the mechanical research of coal and rock masses in complex geological environments.

[0023] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of this utility model.

[0025] Figure 2 This is a schematic diagram of the rock sample to be tested and the sealing device of this utility model.

[0026] Figure 3 This is a schematic diagram of the structure of the pressure transmission rod seal of this utility model.

[0027] Figure 4 This is a schematic diagram of the rock sample to be tested and the water-injected internal pressure membrane of this utility model.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1—Pressure block; 2—Upper limit ring; 3—Pressure rod;

[0030] 3-1—Locking nut; 4—Sealing ring; 5—Pressure head;

[0031] 6—Sealing device; 6-1—Sealing hollow rod; 6-2—Sealing ring;

[0032] 7—Rock sample to be tested; 7-1—Inner cylindrical hole; 8—Water injection inner pressure membrane;

[0033] 9—liquid injection pipe; 10—liquid drain pipe; 11—liquid injection valve;

[0034] 12—Pressure platform; 13—Drain valve; 14—Pressure gauge. Detailed Implementation

[0035] like Figures 1 to 4 As shown, the present invention includes a pressure-bearing platform 12 for mounting a rock sample 7 to be tested, a confining pressure mechanism for embedding the rock sample 7 to be tested, and a pressure-transmitting mechanism disposed above the confining pressure mechanism and extending into the rock sample 7 to be tested. An inner cylindrical hole 7-1 is provided at the center of the rock sample 7 to be tested.

[0036] The pressure transmission mechanism includes a sealing device 6 extending into the inner cylindrical hole 7-1 and a pressure transmission rod seal extending into the sealing device 6.

[0037] The confining pressure mechanism includes a water-injected inner pressure membrane 8 sleeved on the outside of the rock sample 7 to be tested. A liquid injection pipe 9 is provided on one side of the water-injected inner pressure membrane 8, and a liquid discharge pipe 10 is provided on the other side of the water-injected inner pressure membrane 8.

[0038] In this embodiment, the pressure rod seal includes a pressure block 1, a pressure rod 3, and a pressure head 5 arranged sequentially from top to bottom. The pressure rod 3 is a threaded rod, the top of the pressure rod 3 is threadedly connected to the bottom of the pressure block 1, the bottom of the pressure rod 3 is fixedly connected to the pressure head 5, and the pressure head 5 extends into the sealing device 6.

[0039] In this embodiment, a sealing ring 4 and an upper limit ring 2 are fitted on the pressure rod 3. The lower end of the sealing ring 4 is attached to the pressure head 5, and the upper end of the sealing ring 4 is attached to the upper limit ring 2. The inner wall of the upper limit ring 2 is threadedly connected to the pressure rod 3.

[0040] The outer diameter of the pressure head 5, the outer diameter of the sealing ring 4, and the outer diameter of the upper limit ring 2 are the same. The outer diameter of the pressure head 5 and the inner diameter of the sealing device 6 are the same, so that the pressure head 5 can extend into the sealing device 6.

[0041] In this embodiment, the sealing device 6 includes a sealing hollow rod 6-1 extending into the inner cylindrical hole 7-1 and a sealing ring 6-2 integrally sleeved outside the sealing hollow rod 6-1. A gap is provided between the bottom of the sealing hollow rod 6-1 and the bottom of the inner cylindrical hole 7-1 of the rock sample 7 to be tested. The sealing ring 6-2 fits against the top of the rock sample 7 to be tested. The outer diameter of the sealing ring 6-2 is larger than the diameter of the inner cylindrical hole 7-1. The connection between the sealing ring 6-2 and the top of the inner cylindrical hole 7-1 of the rock sample 7 to be tested is sealed with acrylic structural adhesive.

[0042] The pressure head 5 extends into the top of the sealing hollow rod 6-1.

[0043] In this embodiment, the injection pipe 9 is equipped with an injection valve 11 and a pressure gauge 14, and the drainage pipe 10 is equipped with a drainage valve 13.

[0044] In this embodiment, the bottom of the rock sample 7 to be tested is fixed to the pressure platform 12 by acrylic structural adhesive.

[0045] In this embodiment, two locking nuts 3-1 are sleeved on the top of the pressure rod 3, and the locking nuts 3-1 abut against the bottom of the pressure block 1.

[0046] In this embodiment, during actual use, the pressure block 1 is a cuboid measuring 20mm × 20mm × 10mm, with a threaded hole at the center of its bottom. The pressure rod 3 is a solid cylinder with a diameter of 3.8mm and a height of 83mm. The top of the pressure rod 3 extends into the threaded hole, allowing the top of the pressure rod 3 to be threadedly connected to the bottom of the pressure block 1. The bottom of the pressure rod 3 is welded and fixedly connected to the pressure head 5.

[0047] In this embodiment, in actual use, the pressure head 5 is a solid cylinder with a diameter of 5.8 mm and a height of 4 mm.

[0048] In this embodiment, in actual use, the sealing ring 4 is a hollow cylinder with an outer diameter of 5.8 mm and an inner diameter of 3.8 mm. The sealing ring 4 is a polytetrafluoroethylene resin ring that can slide along the hollow rod 6-1 of the sealing hole while maintaining a seal.

[0049] The sealing ring 4 is fitted onto the pressure rod 3 and contacts the pressure head 5. An upper limit ring 2 is provided on the upper part of the sealing ring 4. The upper limit ring 2 is threaded onto the pressure rod 3 and abuts against the upper end of the sealing ring 4 to interlock the pressure block 1 and the sealing ring 4 and prevent loosening during the test.

[0050] In this embodiment, the sealing ring 4 is set in order to prevent acid and alkali solutions from seeping out through the gap between the indenter 5 and the sealing hollow rod 6-1 when the indenter 5 is pressed into the rock sample 7 to be tested, thereby improving the sealing performance.

[0051] In this embodiment, initially, the pressure head 5 enters the top of the sealing hollow rod 6-1 from above the sealing device 6. The sealing ring 4 has high friction with the inner wall of the top of the sealing hollow rod 6-1, thus restricting the pressure transmission mechanism from falling directly into the cylindrical hole 7-1. Subsequently, when the pressure block 1 is loaded with a compressive strength machine, the pressure rod 3 pushes the sealing ring 4 and the pressure head 5 down along the sealing hollow rod 6-1, providing vertical pressure to the rock sample 7 to be tested until the rock sample 7 breaks and then stops extending, or when the maximum depth at the bottom of the sealing hollow rod 6-1 is reached, the pressure is continuously increased until the rock sample 7 to be tested breaks.

[0052] In this embodiment, during actual use, the rock sample 7 to be tested is manually placed inside the water-injected inner pressure membrane 8, and the inner wall of the water-injected inner pressure membrane 8 is tightly attached to the outer wall of the rock sample 7 to achieve a sealed fit. The bottom of the rock sample 7 to be tested is then fixed to the pressure platform 12 with sealant.

[0053] In this embodiment, during actual use, the water injection internal pressure membrane 8 is a hollow polyurethane cylindrical sleeve, which is wear-resistant, tear-resistant, and highly resistant to chemical corrosion. Furthermore, the connection between the injection pipe 9 and the drain pipe 10 is sealed. The thickness of the water injection internal pressure membrane 8 is 2mm.

[0054] It should be noted that the water pressure range that the water-injected inner pressure membrane 8 can withstand depends on the thickness of the polyurethane. A 1mm thick polyurethane can usually withstand 5 to 10 MPa. The confining pressure of a general test is controlled at 1 to 5 MPa. Therefore, the inner pressure membrane of this polyurethane will not expand away from the outer wall of the rock sample 7 under test, thus meeting the confining pressure sealing loading requirements.

[0055] In this embodiment, in actual use, the sealing hollow rod 6-1 is a cylinder with an outer diameter of 7.8 mm and an inner diameter of 5.8 mm, and the sealing ring 6-2 has an outer diameter of 12.8 mm.

[0056] The connection between the sealing ring 6-2 and the top of the inner cylindrical hole 7-1 of the rock sample 7 is sealed with acrylic structural adhesive to prevent leakage of acid and alkali solutions during the test.

[0057] It should be noted that current methods require multiple soaking-drying cycles to simulate long-term corrosion environments. However, this soaking only corrodes the surface or shallow pores of the rock sample and cannot quickly penetrate to the interior. Therefore, multiple cycles are needed to compensate for the inadequacy of a single corrosion test. In reality, corrosion in underground mineral formations is long-term and continuous, and the intermittent nature of wet-dry cycles cannot accurately simulate this process. The corrosion effect needs to be "accumulated" through repeated cycles. Therefore, in this application, an inner cylindrical hole 7-1 is set at the center of the rock sample 7, and an acid or alkali solution is injected to 1 / 3 of the height of the inner cylindrical hole 7-1. The acid or alkali solution diffuses from the inside out through capillary action and pore penetration, more closely resembling the long-term corrosion mechanism of underground mineral formations. A 72-hour standing period ensures that the solution fully penetrates the entire rock sample, achieving a uniform corrosion effect without the need for further cycles. This single corrosion loading test improves experimental efficiency. Furthermore, when coal and rock masses are exposed to acidic or alkaline environments in underground mineral formations for extended periods, corrosion typically occurs in localized areas of pores or fissures, rather than complete immersion. Injecting 1 / 3 of the solution can simulate this localized corrosion condition, which is closer to the actual geological situation.

[0058] In this embodiment, in actual use, the rock sample 7 to be tested is a cylinder with a diameter of 50 mm and a height of 100 mm, and the inner cylindrical hole 7-1 is a circular hole with a diameter of 8 mm and a depth of 65 mm.

[0059] In specific use of this utility model, a rock sample 7 to be tested is selected. An acid or alkali solution is injected into the inner cylindrical hole 7-1 of the rock sample 7 to 1 / 3 of the height of the inner cylindrical hole 7-1. A polyethylene sealing film is wrapped around the rock sample 7 and sealed by heating and shrinking with a hot air gun to ensure that the acid or alkali solution will not leak or evaporate during the static corrosion period, and at the same time to prevent external environmental interference. After that, it is left to stand for at least 72 hours to fully simulate the chemical corrosion environment of the underground mineral layer.

[0060] Next, the wrapped polyethylene sealing film is removed and installed into the water-injected inner pressure membrane 8. Acid and alkali solutions are then added to the inner cylindrical hole 7-1 of the rock sample 7 to be tested, until the solution reaches 2 / 3 of the height of the inner cylindrical hole 7-1. The sealing hollow rod 6-1 of the sealing device 6 is inserted into the inner cylindrical hole 7-1, with the bottom of the sealing hollow rod 6-1 extending into the acid and alkali solution to realize the subsequent rock hydraulic fracturing device under acid and alkali action. The connection between the sealing ring 6-2 and the top of the inner cylindrical hole 7-1 of the rock sample 7 is sealed with acrylic structural adhesive. The pressure head 5 is placed in the sealing hollow rod 6-1 of the sealing device 6.

[0061] The rock sample 7 to be tested is placed on the pressure platform 12 and fixed on the pressure platform 12 with acrylic structural adhesive.

[0062] Close the drain valve 13 and open the injection valve 11. Connect the water pump to the inlet of the injection pipe 9 and inject water into the water-injection inner pressure diaphragm 8 through the water pump and the injection pipe 9. Observe the value of the pressure gauge 14. Stop injecting water when the required confining pressure is reached and close the injection valve 11.

[0063] The entire sample is placed on the compressive strength tester, the tester is started, and the test block 1 is used to load the sample to obtain the compressive strength of the rock sample 7, which facilitates the analysis of the bearing capacity of the rock sample 7.

[0064] In summary, this utility model has a simple structure and reasonable design. After applying an acid-alkali corrosion environment to the rock sample to be tested, the rock sample is sealed and cracked by a sealing device and a pressure transmission rod seal to meet the requirements of water pressure cracking of rocks under acid and alkali action, and to meet the mechanical research of coal and rock masses in complex geological environments.

[0065] The above description is merely a preferred embodiment of the present utility model and does not constitute any limitation on the present utility model. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present utility model shall still fall within the protection scope of the present utility model.

Claims

1. A device for hydrostatic fracturing of rocks under acid and alkali conditions, characterized in that: It includes a pressure-bearing platform (12) for mounting the rock sample (7) to be tested, a confining pressure mechanism for embedding the rock sample (7) to be tested, and a pressure transmission mechanism set above the confining pressure mechanism and extending into the rock sample (7) to be tested. The rock sample (7) to be tested has an inner cylindrical hole (7-1) at its center. The pressure transmission mechanism includes a sealing device (6) extending into the inner cylindrical hole (7-1) and a pressure transmission rod seal extending into the sealing device (6); The confining pressure mechanism includes a water-injected inner pressure membrane (8) sleeved outside the rock sample (7) to be tested. A liquid injection pipe (9) is provided on one side of the water-injected inner pressure membrane (8), and a liquid discharge pipe (10) is provided on the other side of the water-injected inner pressure membrane (8).

2. The rock hydraulic fracturing device under acid-base action according to claim 1, characterized in that: The pressure rod seal includes a pressure block (1), a pressure rod (3) and a pressure head (5) arranged sequentially from top to bottom. The pressure rod (3) is a threaded rod. The top of the pressure rod (3) is threaded to the bottom of the pressure block (1). The bottom of the pressure rod (3) is fixed to the pressure head (5). The pressure head (5) extends into the sealing device (6).

3. The rock hydraulic fracturing device under acid-base action according to claim 2, characterized in that: The pressure rod (3) is fitted with a sealing ring (4) and an upper limit ring (2). The lower end of the sealing ring (4) is attached to the pressure head (5), and the upper end of the sealing ring (4) is attached to the upper limit ring (2). The inner wall of the upper limit ring (2) is threadedly connected to the pressure rod (3). The outer diameter of the pressure head (5), the outer diameter of the sealing ring (4), and the outer diameter of the upper limit ring (2) are the same. The outer diameter of the pressure head (5) and the inner diameter of the sealing device (6) are the same, so that the pressure head (5) can extend into the sealing device (6).

4. A rock hydraulic fracturing device under acid-base action according to claim 3, characterized in that: The sealing device (6) includes a sealing hollow rod (6-1) extending into the inner cylindrical hole (7-1) and a sealing ring (6-2) integrally sleeved on the outside of the sealing hollow rod (6-1). A gap is provided between the bottom of the sealing hollow rod (6-1) and the bottom of the inner cylindrical hole (7-1) of the rock sample (7) to be tested. The sealing ring (6-2) fits against the top of the rock sample (7) to be tested. The outer diameter of the sealing ring (6-2) is larger than the diameter of the inner cylindrical hole (7-1). The connection between the sealing ring (6-2) and the top of the inner cylindrical hole (7-1) of the rock sample (7) to be tested is sealed with acrylic structural adhesive. The pressure head (5) extends into the top of the sealing hollow rod (6-1).

5. A rock hydraulic fracturing device under acid-base action according to claim 1, characterized in that: The injection pipe (9) is equipped with an injection valve (11) and a pressure gauge (14), and the drain pipe (10) is equipped with a drain valve (13).

6. A rock hydraulic fracturing device under acid-base action according to claim 1, characterized in that: The bottom of the rock sample (7) to be tested is fixed to the pressure platform (12) by acrylic structural adhesive.

7. A rock hydraulic fracturing device under acid-base action according to claim 2, characterized in that: Two locking nuts (3-1) are fitted on the top of the pressure rod (3), and the locking nuts (3-1) abut against the bottom of the pressure block (1).

Images