A pore pressure testing device for low-permeability reservoirs

Abstract

This invention discloses a pore pressure testing device for low-permeability reservoirs, comprising: a test chamber with a thermal imaging device on its wall; a fixed frame, comprising two sets respectively disposed at the top and bottom of the test chamber for fixing and assembling samples; and a pore pressure filling device disposed in the middle of the test chamber, with its upper and lower end faces respectively sealing and adhering to one side of the sample above and below.

Description

Technical Field

[0001] This invention relates to the field of petroleum exploration technology, specifically to a pore pressure testing device for low-permeability reservoirs. Background Technology

[0002] The core pore volume compressibility coefficient is an important parameter in hydrocarbon reservoir physics research, and it has significant application value in evaluating the elastic productivity and dynamic geological reserves of oil and gas reservoirs. For low-permeability reservoirs, due to the small pore volume of rock samples, the internal pore pressure is measured before oil and gas extraction to facilitate fracturing and allow oil and gas to escape from the pores. However, excessive fracturing intensity can cause collapse of the low-permeability reservoir, while insufficient fracturing intensity fails to adequately expel oil and gas from the pores. Existing low-permeability reservoir pore pressure testing equipment has low accuracy in measuring pore pressure and pore distribution, thus affecting the required fracturing intensity and fracturing location for low-permeability reservoirs.

[0003] Therefore, those skilled in the art have provided a pore pressure testing device for low-permeability reservoirs to solve the problems mentioned in the background art. Summary of the Invention

[0004] To achieve the above objectives, the present invention provides the following technical solution: a pore pressure testing device for low-permeability reservoirs, comprising:

[0005] The test chamber is equipped with a thermal imaging device on its walls.

[0006] The fixed frame consists of two sets, located at the top and bottom of the test chamber respectively, for securing the assembled sample; and

[0007] A pore filling device is located in the middle of the test chamber, and its upper and lower end faces are respectively sealed and attached to one side of the sample above and below.

[0008] Furthermore, the pore pressurization device includes:

[0009] The pressurizing plate has a pressurizing chamber inside, which is connected to a connecting pipe two. The other end of the connecting pipe two is connected to a fracturing pump truck, and the upper and lower end faces of the pressurizing plate are evenly distributed with guide tubes that are connected to the pressurizing chamber.

[0010] The sealing disc is provided in two sets, which are respectively fixedly sleeved on the outer cylinder opening of the upper and lower guide support cylinders;

[0011] A conductive suspension, introduced into the pressurization chamber via a fracturing pump truck through a connecting pipe 2, is used to fracture the sample; and

[0012] A conductor is inserted into the second connecting tube and connected to the control power supply via a wire.

[0013] Furthermore, it also includes a moisture-absorbing cotton plate that is closely attached to the remaining exposed outer surface of the sample, and humidity sensors are evenly distributed on the moisture-absorbing cotton plate.

[0014] Furthermore, the conductive suspension includes copper powder, an aqueous suspending agent, and a copper sulfate solution.

[0015] Furthermore, the copper powder has a mesh size greater than 5000 mesh.

[0016] Furthermore, a connecting pipe frame is laid in the pressurization chamber, and the connecting pipe frame is connected to a connecting pipe three. The other end of the connecting pipe three is connected to a gas supply device. A partition is fixed inside the cylinder opening on the side of the flow guide cylinder facing the pressurization chamber. A short branch pipe connected to the connecting pipe frame is fixed through the outer diameter side of the partition. A flow guide cylinder connected to the pressurization chamber is fixed through the center of the partition. The flow guide cylinder is covered with a top plate. Sealing piston rings are fixed on the inner and outer annular surfaces of the top plate. The inner and outer sealing piston rings are tightly fitted to the inner wall of the flow guide cylinder and the flow guide cylinder, respectively.

[0017] Furthermore, the side of the sealing disc facing the sample is flush with the outer opening of the guide tube, and a sealing ring gasket is embedded on the outer edge of the side of the sealing disc facing the sample. An overflow groove is formed on the surface of the sealing disc inside the sealing ring gasket.

[0018] Furthermore, the test chamber is also equipped with a connecting pipe, the other end of which is connected to a pressure regulating device.

[0019] Furthermore, the fixing frame covers the edges of the sample.

[0020] Furthermore, the test chamber is also equipped with a humidity control device.

[0021] Compared with the prior art, the present invention provides a pore pressure testing device for low-permeability reservoirs, which has the following advantages:

[0022] In this invention, a conductive suspension is hydraulically fractured into the sample, and then the dense conductor resistance in the conductive suspension is heated by applying electricity. The sample is then scanned by a thermal imaging device to obtain the heat distribution density and heat path diagram inside the sample, thereby obtaining the pore condition inside the sample. The method of supplying liquid and gas for pressure not only makes the operation safer, but also makes the measurement and control of pore pressure more accurate and stable. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the pore pressure testing device of the present invention;

[0024] Figure 2This is a schematic diagram showing the installation setup of the sample of the present invention;

[0025] Figure 3 This is a schematic diagram of the fixed frame of the present invention;

[0026] Figure 4 This is a schematic diagram of the pore pressurization device of the present invention;

[0027] Figure 5 This is a schematic diagram of the pressurization disk structure of the present invention;

[0028] Figure 6 This is a schematic cross-sectional view of the flow guide support structure of the present invention;

[0029] In the diagram: 1. Test chamber; 2. Pore filling device; 3. Sample; 4. Fixing frame; 5. Moisture-absorbing cotton board; 6. Thermal imaging device; 7. Connecting pipe one; 21. Filling plate; 22. Connecting pipe two; 23. Flow guide branch; 24. Sealing plate; 25. Conductor; 26. Connecting pipe rack; 27. Connecting pipe three; 231. Partition plate; 232. Flow guide branch; 233. Top plate; 234. Sealing piston ring; 241. Overflow groove; 242. Sealing rubber ring gasket. Detailed Implementation

[0030] Reference Figure 1-6 The present invention provides a technical solution: a pore pressure testing device for low-permeability reservoirs, comprising:

[0031] Test chamber 1, the walls of which are equipped with thermal imaging devices 6, and the test chamber is provided with transparent windows for observation;

[0032] The fixing frame 4 has two sets, respectively installed at the top and bottom of the test chamber 1, for fixing and assembling the sample 3. During sample preparation, the edges of the sample are cut to form inlay grooves according to the solid structure of the fixing frame, allowing the fixing frame to be fitted into the inlay grooves, thereby improving the sample's fixing stability and sealing performance; and

[0033] The pore filling device 2 is located in the middle of the test chamber 1, and its upper and lower end faces are respectively sealed and attached to one side of the sample 3 above and below.

[0034] In this embodiment, the pore filling device 2 includes:

[0035] The pressurizing plate 21 has a pressurizing chamber inside, and the pressurizing chamber is connected to a connecting pipe 22. The other end of the connecting pipe 22 is connected to a fracturing pump truck. The upper and lower end faces of the pressurizing plate 21 are evenly distributed with guide tubes 23 that are connected to the pressurizing chamber.

[0036] The sealing disc 24 is provided in two sets, which are respectively fixedly sleeved on the outer cylinder opening of the upper and lower guide cylinders 23;

[0037] A conductive suspension, introduced into the pressurization chamber via a fracturing pump truck through connecting pipe 22, is used to fracture the sample; and

[0038] Conductor 25 is inserted into the connecting tube 22 and connected to the control power supply via a wire;

[0039] Specifically, the conductive suspension is first introduced into the pressure chamber through the connecting pipe 22 by the fracturing pump truck. The conductive suspension is then forced to press one side of the sample and enter. After the sample is fracturing, the control power is turned on to connect the conductors and the conductive suspension between them. The conductors in the conductive suspension act as resistors, and the conductors can generate a certain amount of heat. The sample is then scanned by a thermal imaging device to obtain a schematic diagram of the heat distribution in the sample. This allows us to determine the path distribution of the conductive suspension as it is fractured into the sample, thereby determining the porosity distribution in the sample.

[0040] In this embodiment, a moisture-absorbing cotton plate 5 is attached to the remaining exposed outer surface of the sample, and humidity sensors are evenly distributed on the moisture-absorbing cotton plate 5. By monitoring the humidity concentration and humidity distribution of the moisture-absorbing cotton plate through the humidity sensors, the time when the sample is completely crushed and the magnitude of the crushing supply pressure can be obtained.

[0041] In this embodiment, the conductive suspension includes copper powder, an aqueous suspending agent, and a copper sulfate solution. The copper powder acts as a conductor and a resistor. The aqueous suspending agent ensures that the copper powder is evenly and densely suspended. The copper sulfate solution is added to improve the conductivity of the conductive suspension. The particle size of the conductive suspension is 1 to 3 μm.

[0042] In this embodiment, the copper powder has a mesh size greater than 5000 mesh.

[0043] In this embodiment, a connecting pipe rack 26 is laid in the pressurization chamber, and a connecting pipe 27 is connected to the connecting pipe rack 26. The other end of the connecting pipe 27 is connected to a gas supply device. A partition 231 is fixed inside the cylinder opening on the side of the flow guide cylinder 23 facing the pressurization chamber. A short branch pipe connected to the connecting pipe rack 26 is fixed through the outer diameter side of the partition 231. A flow guide branch pipe 232 connected to the pressurization chamber is fixed through the axis of the partition 231. A top plate 233 is sleeved on the flow guide branch pipe 232. Sealing piston rings 234 are fixed on the inner and outer annular surfaces of the top plate 233, respectively. The inner and outer sealing piston rings are tightly fitted to the inner wall of the flow guide branch pipe 232 and the inner wall of the flow guide cylinder 23, respectively.

[0044] Specifically, when the humidity sensor reading changes, the fracturing pump truck stops operating and disconnects from the connecting pipe 2. At this time, the air supply device continuously pressurizes and pushes the top plate to fracture the conductive suspension. This ensures the safety of the control power supply when it starts up, and improves the ease of control when the sample is about to be fracturing, as well as the accuracy of control when stopping fracturing after the sample is fracturing is complete.

[0045] In this embodiment, the sealing disc 241 is flush with the outer opening of the guide tube 23 on the side facing the sample, and a sealing ring gasket 242 is embedded on the outer edge of the sealing disc 241 facing the sample. An overflow groove 241 is provided on the surface of the sealing disc 242. The overflow groove is used to store the liquid that has a backflow path during the fracturing process and to compensate the sample surface in the area where the guide tube is not in use.

[0046] In this embodiment, the test chamber 1 is also provided with a connecting pipe 7, and the other end of the connecting pipe 7 is connected to a pressure regulating device so as to regulate the pressure environment at the stratum where the sample is located.

[0047] In this embodiment, the fixing frame 4 covers the edges of the sample.

[0048] In this embodiment, the test chamber 1 is also equipped with a humidity control device to adjust the humidity environment at the stratum where the sample is located.

[0049] In practice, two sets of samples are prepared, and the edges of the samples are cut to form cutting grooves. The fixing frame is then embedded in the cutting grooves and fixed to the top and bottom of the test chamber, and pressed against the pore pressure device. The pressure and humidity values ​​inside the test chamber are adjusted, and a conductive suspension with a diameter of 1 to 3 μm is prepared. After completion, the conductive suspension is injected through the connecting pipe 2 by a fracturing pump truck. When the humidity sensor reading changes, the fracturing pump truck stops running and disconnects from the connecting pipe 2. At this time, the air supply device continuously pressurizes and pushes the top plate to fracture the conductive suspension. The temperature sensor continues to monitor the temperature, and the air supply device is stopped according to the area of ​​change in the humidity sensor reading. The pressure value is recorded, and then the control power supply and thermal imaging device are started to observe the heat distribution diagram, thus obtaining the pore pressure and distribution of the sample.

[0050] The above description is merely a preferred embodiment of the invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A pore pressure testing device for low-permeability reservoirs, characterized in that, It includes: The test chamber (1) has a thermal imaging device (6) installed on its walls; The fixed frame (4) has two sets, respectively set at the top and bottom of the test box (1). The interior of the fixed frame (4) is used to fix the assembly sample (3); and A pore filling device (2) is set in the middle of the test box (1), and its upper and lower end faces are respectively sealed and attached to one side of the sample (3) above and below; The pore pressurization device (2) includes: The pressurizing plate (21) has a pressurizing chamber inside, and the pressurizing chamber is connected to a connecting pipe two (22). The other end of the connecting pipe two (22) is connected to a fracturing pump truck, and the upper and lower end faces of the pressurizing plate (21) are evenly distributed with guide tubes (23) that are connected to the pressurizing chamber. The sealing block (24) is provided in two sets, which are respectively fixedly sleeved on the outer cylinder opening of the upper and lower guide cylinders (23); A conductive suspension, which is introduced into the pressurization chamber via a fracturing pump truck through connecting pipe two (22), is used to fracture the sample; and Conductor (25) is inserted into the connecting tube (22) and connected to the control power supply through a wire; The pressurization chamber is provided with a connecting pipe rack (26), which is connected to a connecting pipe three (27). The other end of the connecting pipe three (27) is connected to a gas supply device. A septum (231) is fixed inside the cylinder opening on the side of the flow guide cylinder (23) facing the pressurization chamber. A short branch pipe connected to the connecting pipe rack (26) is fixed through the outer diameter side of the septum (231). A flow guide branch pipe (232) connected to the pressurization chamber is fixed through the axis of the septum (231). The flow guide branch pipe (232) is covered with a top plate (233). The top plate (233) is located on top of the septum (231). The gas supply device can continuously pressurize and push the top plate (233) to pressurize the conductive suspension inside the sample and crush the sample.

2. The pore pressure testing device for low-permeability reservoirs according to claim 1, characterized in that, The testing device also includes a moisture-absorbing cotton plate (5) that is closely attached to the remaining exposed outer surface of the sample, and humidity sensors are evenly distributed on the moisture-absorbing cotton plate (5).

3. The pore pressure testing device for low-permeability reservoirs according to claim 1, characterized in that, The conductive suspension includes copper powder, an aqueous suspending agent, and a copper sulfate solution.

4. The pore pressure testing device for low-permeability reservoirs according to claim 3, characterized in that, The copper powder has a mesh size greater than 5000 mesh.

5. The pore pressure testing device for low-permeability reservoirs according to claim 1, characterized in that, The top plate (233) is fixed with sealing piston rings on its inner and outer ring surfaces respectively. The sealing piston rings on the inner and outer ring surfaces are tightly fitted to the outer wall of the guide branch pipe (232) and the inner wall of the guide branch cylinder (23) respectively.

6. The pore pressure testing device for low-permeability reservoirs according to claim 1, characterized in that, The sealing disc (24) is flush with the outer opening of the guide tube (23) on the side facing the sample, and a sealing ring gasket (242) is embedded on the outer edge of the sealing disc (24) facing the sample. An overflow groove (241) is provided on the surface of the sealing disc in the sealing ring gasket (242).

7. The pore pressure testing device for low-permeability reservoirs according to claim 1, characterized in that, The test box (1) is also equipped with a connecting pipe (7), and the other end of the connecting pipe (7) is connected to a pressure regulating device.

8. The pore pressure testing device for low-permeability reservoirs according to claim 1, characterized in that, The fixed frame (4) covers the edges of the sample.

9. The pore pressure testing device for low-permeability reservoirs according to claim 1, characterized in that, The test chamber (1) is also equipped with a humidity control device.

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