Device and method for rapidly measuring porosity and permeability of compact rock

Abstract

The invention relates to the technical field of shale gas development, in particular to a device and method for rapidly measuring the porosity and permeability of compact rock. The problems that devices are complex, powder shale testing cannot be carried out, the testing time is long, the volumes of upstream and downstream chambers are fixed and the like in an experiment for measuring the permeability and the porosity of the low-permeability rock through an existing pulse attenuation method can be solved to a certain extent. The device for rapidly measuring the porosity and permeability of the compact rock comprises a gas source, a gas source conversion device, a gas source valve, a gas inlet valve, a standard cylinder, a six-way valve, a pressure sensor, a pressure increasing valve, a hand-cranking booster pump, a gas outlet valve, a vacuum pump, an injection valve, a suck-back prevention device, a sample cylinder, a constant-temperature oil bath pan, an auxiliary heater and a pipeline.

Description

Technical Field

[0001] The present application relates to the technical field of shale gas development, and in particular to a device and method for rapidly measuring the porosity and permeability of dense rocks. Background Art

[0002] The world's energy development has entered a critical period of transition from fossil energy to new energy. Natural gas, as the cleanest fossil energy, is the "bridge" or the best "partner" for the transition from fossil energy to new energy. The success of the North American "shale gas revolution" has transformed the United States from a major natural gas importer to a major exporter, profoundly changing the world's natural gas supply structure. Driven by the demonstration effect of U.S. shale gas, China has also achieved effective development of shale gas resources, with continued rapid growth in production.

[0003] At present, the United States has commercially exploited shale gas in seven major shale oil and gas producing areas represented by the Marcellus, Permian Basin, Hinesville, Eagle Ford, and Bakken. However, with the deepening of shale oil and gas development, many theoretical and technical difficulties have been encountered. Compared with North America, my country's shale gas reservoirs have strong heterogeneity, large cumulative thickness, small distribution area, relatively low degree of thermal evolution, and diverse organic matter types, which makes the problems encountered in my country's shale development more complicated. Porosity and permeability are the basis for understanding the seepage conditions of shale formations. To solve these problems, the measurement of shale porosity and permeability is particularly critical.

[0004] The diameter of shale pore throats is mostly nanometers, and its permeability measurement is more difficult than that of high-permeability media. The existing methods for measuring shale permeability mainly include steady-state method and non-steady-state method. The steady-state method calculates the permeability by measuring the pressure difference and flow rate when the flow of the tested fluid reaches a stable condition, and uses Darcy's law; the non-steady-state method obtains the permeability based on the pressure decay law at both ends of the sample with time and the corresponding mathematical model, mainly including pulse decay method, oscillation pressure method and GRI method. Among them, the steady-state method and pulse decay method are commonly used methods for indoor measurement of shale permeability.

[0005] However, the steady-state method for measuring shale permeability requires measuring steady-state flow. It takes a long time (several days or even weeks) to establish Darcy steady-state flow, and it is not suitable for ultra-low permeability shales. The pulse decay method was first proposed by Brace (1968) when testing granite permeability. The dimensionless pressure-time response solution is obtained by calculating the material balance in the upstream and downstream chambers and the core to measure the shale permeability. The conventional pulse decay method for measuring shale permeability is very complicated. There are pressure pulses between the upstream and downstream chambers during the experiment, and there is back suction when testing powdered shale. Therefore, there is an urgent need for an experimental device that is simple and can be used for testing powdered shale using the pulse decay method to measure shale permeability and porosity.

[0006] Example: Chinese patent CN107014731B, a low-permeability rock gas-liquid two-drive pressure pulse attenuation permeability test method, uses a low-permeability rock gas-liquid two-drive pressure pulse attenuation permeability test device to measure the permeability and permeability coefficient of low-permeability rocks. Its disadvantages are: more devices, complex installation, cumbersome operation steps, and inability to test powdered shale, resulting in a long test time.

[0007] Furthermore, Lin et al. (1977) analyzed the influence of the upstream and downstream chamber volumes on the experimental results based on Brace's research. For experimental shale cores of different volumes, the optimal ratio of the upstream and downstream chamber volumes of their experimental devices is also different. Conventional pulse attenuation method experimental devices for measuring shale permeability and porosity mostly use cylinders to replace the upstream and downstream chambers, and the upstream and downstream chamber volume ratio is fixed. Therefore, the existing conventional pulse attenuation method for measuring the permeability and porosity of low permeability rocks also urgently needs an experimental device that can adjust the upstream and downstream chamber volume ratio.

[0008] Therefore, the existing pulse attenuation method for measuring the permeability and porosity of low permeability rocks has problems such as complex equipment, inability to perform powdered shale testing, long testing time, and fixed upstream and downstream chamber volumes. Summary of the invention

[0009] In order to solve the problems of complex equipment, inability to perform powdered shale testing, long testing time, and fixed upstream and downstream chamber volumes in the existing pulse attenuation method for measuring the permeability and porosity of low permeability rocks, the present application provides a device and method for quickly measuring the porosity and permeability of dense rocks.

[0010] The embodiment of the present application is implemented as follows:

[0011] In a first aspect, the present application provides a device for rapidly measuring the porosity and permeability of dense rocks, including a gas source, a gas source conversion device, a gas source valve, an air inlet valve, a standard cylinder, a six-way valve, a pressure sensor, a booster valve, a hand-cranked booster pump, an air outlet valve, a vacuum pump, an injection valve, an anti-backflow device, a sample cylinder, a constant temperature oil bath, an auxiliary heater and pipelines;

[0012] The gas source is connected to the gas source conversion device, the gas source conversion device is connected to the standard cylinder through a pipeline, the gas source valve is located between the gas source conversion device and the pipeline, the air inlet valve is located between the standard cylinder and the pipeline connected to the gas source, the standard cylinder is connected to the six-way valve through a pipeline, the detection end of the pressure sensor is connected to the six-way valve through bolts, the booster pump is connected to the six-way valve through a pipeline, the booster valve is located between the booster pump and the pipeline, the vacuum pump is connected to the six-way valve through a pipeline, the air outlet valve is located between the vacuum pump and the pipeline, the anti-backflow device is located inside the sample cylinder, and is connected to the air inlet of the sample cylinder, the standard cylinder and the sample cylinder are placed in the constant temperature oil bath, and the auxiliary heater is wrapped around the outside of the pipeline.

[0013] In a possible implementation, the six-way valve includes a first valve connected to the standard cylinder, a second valve connected to the sample cylinder, a third valve connected to the vacuum pump, a fourth valve connected to the booster pump, and fifth and sixth valves that are always kept closed.

[0014] In a possible implementation, the detection end of the pressure sensor converts the collected millivolt signal into a digital communication signal RS232, and then connects to a computer via USB. The computer collects real-time data of pipeline pressure to facilitate adjustment of the pressure in the standard cylinder.

[0015] In a second aspect, the present application provides a method for rapidly measuring the porosity and permeability of dense rocks, comprising:

[0016] A shale powder sample from a deep layer in the Sichuan Basin was dried at 105°C for 50 hours, the mass of the shale sample (powder sample or plunger) was measured, and the volume of the shale sample to be tested was obtained based on its density;

[0017] Fill the sample cylinder with a known volume of shale sample. At the same time, adjust the mechanical locking mechanism to make the sample cylinder and the shale sample in close contact, ensuring that the volume in the cylinder other than the apparent volume is minimized.

[0018] Open the vacuum valve and use the vacuum pump to evacuate the experimental device for 600 s;

[0019] Close the vacuum valve and the third valve of the six-way valve, open the air inlet valve, injection valve, and the first, second, and fourth valves on the six-way valve, then open the gas source valve, inflate the device to the preset pressure P0 (5Mpa, 7Mpa, 9Mpa), and proceed to the next step of the experiment;

[0020] Close the gas source valve, gas injection valve and air intake valve, open the booster valve and the third valve on the six-way valve, then use a hand-cranked booster pump to increase the pressure in the standard cylinder by 0.5 MPa, so that there is a pressure pulse of 0.5 MPa in the sample cylinder and the standard cylinder, record the pressure P1, and proceed to the next step of the experiment;

[0021] Close the intake valve, boost valve and the third valve on the six-way valve, open the gas injection valve at a speed of 1 / 4 turn per second, and record the elapsed time and pressure until the pressure change is less than 200Pa for 1,200 consecutive seconds (the final pressure is called P2), and the test is completed;

[0022] The test data are processed to obtain the shale porosity and permeability.

[0023] In a possible implementation, when the step of opening the vacuum valve and evacuating the experimental device for 600 seconds using a vacuum pump is performed, it is also necessary to ensure that the pressure measured by the sensor in the device does not fluctuate by more than 200 Pa within 120 seconds.

[0024] In one possible implementation, when closing the vacuum valve and the third valve of the six-way valve, opening the air intake valve, the injection valve and the first, second and fourth valves on the six-way valve, and then opening the air source valve to inflate the device to a preset pressure P0 (5Mpa, 7Mpa, 9Mpa), it is necessary to control the pressure measured by the sensor in the device to not fluctuate by more than 200Pa within 120s.

[0025] In one possible implementation, after closing the gas source valve, the gas injection valve and the air intake valve, the boost valve and the third valve on the six-way valve are opened, and then a hand-cranked boost pump is used to increase the pressure in the standard cylinder by 0.5 MPa, so that there is a pressure pulse of 0.5 MPa in the sample cylinder and the standard cylinder. When recording the pressure P1 step, it is necessary to control the pressure measured by the sensor in the device to not fluctuate by more than 200 Pa within 120 seconds.

[0026] In a possible implementation, the processing of the test data to obtain the shale porosity and permeability further includes:

[0027] By formula Calculate the pore volume of shale powder;

[0028] The porosity calculation formula is:

[0029] The volume fraction FR(t) is calculated using the following formula:

[0030]

[0031] Where 1-FR(t) represents the fraction of the amount of gas entering the powdered shale particles from the starting point to time t relative to the final amount of gas entering the particles when equilibrium is reached, Kc is the ratio of the volume outside the sample in the standard cylinder and the sample cylinder to the pore volume of the sample, ρ c0 is the average gas density at P1, ρ0 is the gas density at P0, ρ (t) is the gas density at P(t);

[0032] Taking the logarithm of the volume factor, ln(FR(t)) is:

[0033] ln(FR(t))=f6+s1

[0034] The permeability k is calculated according to the following relationship:

[0035]

[0036] Where μ is the viscosity of the gas and cg is the compressibility factor.

[0037] The technical solution provided by this application can at least achieve the following beneficial effects:

[0038] The method for quickly measuring the porosity and permeability of dense rocks provided in the present application uses a hydraulic cylinder body with a mechanical locking mechanism to replace the standard cylinder and the sample cylinder in the conventional experimental device. The volume of the hydraulic cylinder is variable, and the cylinder body is locked by a mechanical locking device, thereby realizing the change of the volume ratio of the upstream and downstream cavities of the experimental device; an anti-backflow device is added to the pipeline port where the injection valve leads to the sample cylinder to realize the test of powdered shale; at the same time, the present application uses a gas source conversion device, which makes it more convenient to change the gas source for different experiments, and the experimental operation steps are also simpler; and compared with the conventional pulse attenuation method for measuring the permeability and porosity of low permeability rocks, the present method has no specific requirements for the shape and volume of the shale sample, and the test accuracy is higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0040] Figure 1 It is a schematic structural diagram of a device for rapidly measuring the porosity and permeability of dense rocks shown in an exemplary embodiment of the present application;

[0041] Figure 2 is a structural schematic diagram of an anti-backflow device shown in an exemplary embodiment of the present application;

[0042] Figure 3 It is a schematic flow chart of a method for quickly measuring the porosity and permeability of dense rocks shown in an exemplary embodiment of the present application;

[0043] Figure 4It is a schematic diagram of the ln(FR(t))-t function of a deep shale sample in the Sichuan Basin shown in an exemplary embodiment of the present application.

[0044] Reference numerals:

[0045] 1. Gas source; 2. Gas source conversion device; 3. Standard cylinder; 4. Gas source valve; 5. Inlet valve; 6. Six-way valve; 7. Pressure sensor; 8. Computer; 9. Hand-cranked booster pump; 10. Boosting valve; 11. Vacuum pump; 12. Exhaust valve; 13. Sample cylinder; 14. Pipeline. DETAILED DESCRIPTION

[0046] In order to make the purpose, implementation mode and advantages of the present application clearer, the exemplary implementation mode of the present application will be clearly and completely described below in conjunction with the drawings in the exemplary embodiments of the present application. Obviously, the described exemplary embodiments are only part of the embodiments of the present application, not all of the embodiments. It should be understood that the specific embodiments described here are only used to explain the present application and are not used to limit the present application.

[0047] It should be noted that the brief description of terms in this application is only for the convenience of understanding the embodiments described below, and is not intended to limit the embodiments of this application. Unless otherwise specified, these terms should be understood according to their common and usual meanings.

[0048] The terms "first", "second", "third", etc. in the specification and claims of this application and the above drawings are used to distinguish similar or similar objects or entities, and do not necessarily mean to limit a specific order or sequence, unless otherwise noted. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances.

[0049] The terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover but not exclude inclusion, for example, a product or device comprising a list of components is not necessarily limited to all the components expressly listed but may include other components not expressly listed or inherent to such product or device.

[0050] Before explaining the method for quickly measuring the porosity and permeability of dense rocks provided in the embodiment of the present application, the application scenario and implementation environment of the embodiment of the present application are first introduced.

[0051] The world's energy development has entered a critical period of transition from fossil energy to new energy. Natural gas, as the cleanest fossil energy, is the "bridge" or the best "partner" for the transition from fossil energy to new energy. The success of the North American "shale gas revolution" has transformed the United States from a major natural gas importer to a major exporter, profoundly changing the world's natural gas supply structure. Driven by the demonstration effect of U.S. shale gas, China has also achieved effective development of shale gas resources, with continued rapid growth in production.

[0052] At present, the United States has commercially exploited shale gas in seven major shale oil and gas producing areas represented by the Marcellus, Permian Basin, Hinesville, Eagle Ford, and Bakken. However, with the deepening of shale oil and gas development, many theoretical and technical difficulties have been encountered. Compared with North America, my country's shale gas reservoirs have strong heterogeneity, large cumulative thickness, small distribution area, relatively low degree of thermal evolution, and diverse organic matter types, which makes the problems encountered in my country's shale development more complicated. Porosity and permeability are the basis for understanding the seepage conditions of shale formations. To solve these problems, the measurement of shale porosity and permeability is particularly critical.

[0053] The diameter of shale pore throats is mostly nanometers, and its permeability measurement is more difficult than that of high-permeability media. The existing methods for measuring shale permeability mainly include steady-state method and non-steady-state method. The steady-state method calculates the permeability by measuring the pressure difference and flow rate when the flow of the tested fluid reaches a stable condition, and uses Darcy's law; the non-steady-state method obtains the permeability based on the pressure decay law at both ends of the sample with time and the corresponding mathematical model, mainly including pulse decay method, oscillation pressure method and GRI method. Among them, the steady-state method and pulse decay method are commonly used methods for indoor measurement of shale permeability.

[0054] However, the steady-state method for measuring shale permeability requires measuring steady-state flow. It takes a long time (several days or even weeks) to establish Darcy steady-state flow, and it is not suitable for ultra-low permeability shales. The pulse decay method was first proposed by Brace (1968) when testing granite permeability. The dimensionless pressure-time response solution is obtained by calculating the material balance in the upstream and downstream chambers and the core to measure the shale permeability. The conventional pulse decay method for measuring shale permeability is very complicated. There are pressure pulses between the upstream and downstream chambers during the experiment, and there is back suction when testing powdered shale. Therefore, there is an urgent need for an experimental device that is simple and can be used for testing powdered shale using the pulse decay method to measure shale permeability and porosity.

[0055] Example: Chinese patent CN107014731B, a low-permeability rock gas-liquid two-drive pressure pulse attenuation permeability test method, uses a low-permeability rock gas-liquid two-drive pressure pulse attenuation permeability test device to measure the permeability and permeability coefficient of low-permeability rocks. Its disadvantages are: more devices, complex installation, cumbersome operation steps, and inability to test powdered shale, resulting in a long test time.

[0056] Furthermore, Lin et al. (1977) analyzed the influence of the upstream and downstream chamber volumes on the experimental results based on Brace's research. For experimental shale cores of different volumes, the optimal ratio of the upstream and downstream chamber volumes of their experimental devices is also different. Conventional pulse attenuation method experimental devices for measuring shale permeability and porosity mostly use cylinders to replace the upstream and downstream chambers, and the upstream and downstream chamber volume ratio is fixed. Therefore, the existing conventional pulse attenuation method for measuring the permeability and porosity of low permeability rocks also urgently needs an experimental device that can adjust the upstream and downstream chamber volume ratio.

[0057] Therefore, in order to solve the problems existing in the existing pulse attenuation method for measuring the permeability and porosity of low permeability rocks, such as complex equipment, inability to perform powdered shale testing, long testing time, and fixed upstream and downstream chamber volumes, there is an urgent need for an experimental device with a simple equipment, which can perform powdered shale testing, has a short testing time, and has an adjustable upstream and downstream chamber volume ratio, as well as a method for using the device.

[0058] Based on this, the present application provides a device and method for quickly measuring the porosity and permeability of dense rocks, using a hydraulic cylinder body with a mechanical locking mechanism to replace the standard cylinder and sample cylinder in a conventional experimental device, the volume of the hydraulic cylinder is variable, and the cylinder body is locked by a mechanical locking device, thereby realizing the change of the volume ratio of the upstream and downstream cavities of the experimental device; an anti-backflow device is added to the pipeline port where the injection valve enters the sample cylinder (mechanical locking hydraulic cylinder 2) to realize the test of powdered shale; at the same time, the present invention uses a gas source conversion device, which makes it more convenient to change the gas source for different experiments, and the experimental operation steps are also simpler; and, compared with the conventional pulse attenuation method for measuring the permeability and porosity of low permeability rocks using a shale plunger experiment, the present invention uses powdered shale, which increases the contact area between the experimental gas and the shale sample, and the test time is shorter.

[0059] Next, the technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems will be described in detail through embodiments and in combination with the accompanying drawings. The embodiments may be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. Obviously, the described embodiments are part of the embodiments of the present application, not all of them.

[0060] Figure 1 It is a schematic diagram of the structure of a device for rapidly measuring the porosity and permeability of dense rocks shown in an exemplary embodiment of the present application.

[0061] In an exemplary embodiment, Figure 1As shown, a device for quickly measuring the porosity and permeability of dense rocks is provided, which includes a gas source, a gas source conversion device 2, a gas source valve 4, an air inlet valve 5, a standard cylinder 3, a six-way valve 6, a pressure sensor 7, a booster valve 10, a hand-cranked booster pump 9, an air outlet valve 12, a vacuum pump 11, an injection valve, an anti-backflow device, a sample cylinder 13, a constant temperature oil bath, an auxiliary heater and a pipeline 14;

[0062] The gas source is connected to the gas source conversion device, the gas source conversion device is connected to the standard cylinder through a pipeline, the gas source valve is located between the gas source conversion device and the pipeline, the air inlet valve is located between the standard cylinder and the pipeline connected to the gas source, the standard cylinder is connected to the six-way valve through a pipeline, the detection end of the pressure sensor is connected to the six-way valve through bolts, the booster pump is connected to the six-way valve through a pipeline, the booster valve is located between the booster pump and the pipeline, the vacuum pump is connected to the six-way valve through a pipeline, the air outlet valve is located between the vacuum pump and the pipeline, the anti-backflow device is located inside the sample cylinder, and is connected to the air inlet of the sample cylinder, the standard cylinder and the sample cylinder are placed in the constant temperature oil bath, and the auxiliary heater is wrapped around the outside of the pipeline.

[0063] Figure 2 It is a schematic structural diagram of an anti-backflow device shown in an exemplary embodiment of the present application.

[0064] In a possible implementation, specific components of the device include an air source, an air source conversion device, an air source valve, an air inlet valve, a standard cylinder (mechanically locked hydraulic cylinder 1), a six-way valve (the six-way valve includes a valve 1 connected to the standard cylinder (mechanically locked hydraulic cylinder 1), a valve 2 connected to the sample cylinder (mechanically locked hydraulic cylinder 2), a valve 3 connected to a vacuum pump, a valve 4 connected to a booster pump, and valves 5 and 6 that are always kept closed), a pressure sensor, a booster valve, a hand-cranked booster pump (compared to an electronic booster pump, the experimental cost is greatly reduced), an air outlet valve, a vacuum pump, an injection valve, an anti-backflow device, a sample cylinder (mechanically locked hydraulic cylinder 2), a constant temperature oil bath, an auxiliary heater and pipelines.

[0065] The installation structure is as follows:

[0066] The gas source is connected to the gas source conversion device, and the gas source conversion device is connected to the mechanical locking hydraulic cylinder 1 through a pipeline;

[0067] The gas source valve is located between the gas source conversion device and the pipeline;

[0068] The gas source conversion device is used for gas source replacement;

[0069] The air inlet valve is located between the standard cylinder (mechanical locking hydraulic cylinder 1) and the pipeline connected to the air source;

[0070] The standard cylinder (mechanical locking hydraulic cylinder 1) is connected to the six-way valve through a pipeline;

[0071] The detection end of the pressure sensor is connected to the six-way valve by bolts. The detection end converts the collected millivolt signal into a digital communication signal RS232, and then connects to the computer via USB. The computer collects real-time data of pipeline pressure, which is convenient for adjusting the pressure in the mechanical locking hydraulic cylinder 1;

[0072] The booster pump is connected to the six-way valve via a pipeline;

[0073] The boost valve is located between the hand-operated boost pump and the pipeline;

[0074] The vacuum pump is connected to the six-way valve through a pipeline;

[0075] The gas outlet valve is located between the vacuum pump and the pipeline;

[0076] like Figure 2 As shown, the anti-backflow device is located inside the sample cylinder and connected to the air inlet of the sample cylinder;

[0077] The standard cylinder (mechanical locking hydraulic cylinder 1) and the sample cylinder (mechanical locking hydraulic cylinder 2) are placed in the constant temperature oil bath to ensure that the temperature of the two cylinders is stable;

[0078] The auxiliary heater is wrapped around the outside of the pipeline to maintain a stable temperature of the pipeline.

[0079] It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the instructions, these steps are not necessarily executed in sequence according to the order of the instructions. Unless there is a clear explanation in this article, the execution of these steps is not strictly limited in order, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the flowcharts involved in the above-mentioned embodiments may include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of the steps or stages in other steps.

[0080] Corresponding to the aforementioned embodiment of the device for rapidly measuring the porosity and permeability of dense rock, and adopting the same technical concept, the present application also provides an embodiment of a method for rapidly measuring the porosity and permeability of dense rock.

[0081] Figure 3 It is a flow chart of a method for rapidly measuring the porosity and permeability of dense rocks shown in an exemplary embodiment of the present application.

[0082] In an exemplary embodiment, Figure 3As shown, the method for quickly measuring the porosity and permeability of dense rocks includes the following steps:

[0083] Step 100: Dry a powder sample of a deep shale in the Sichuan Basin at 105° C. for 50 h, measure the mass of the shale sample (powder sample or plunger), and obtain the volume of the shale sample to be tested based on its density.

[0084] Step 200: Fill a known volume of shale sample into the sample cylinder. At the same time, adjust the mechanical locking mechanism to make the sample cylinder and the shale sample in close contact, ensuring that the volume in the cylinder other than the apparent volume is minimized.

[0085] Step 300: Open the vacuum valve and use the vacuum pump to evacuate the experimental device for 600 seconds.

[0086] Step 400: Close the vacuum valve and the third valve of the six-way valve, open the air intake valve, injection valve and the first, second and fourth valves on the six-way valve, then open the air source valve, inflate the device to the preset pressure P0 (5Mpa, 7Mpa, 9Mpa), and proceed to the next experiment.

[0087] Step 500: Close the gas source valve, gas injection valve and air intake valve, open the boost valve and the third valve on the six-way valve, then use a hand-cranked boost pump to increase the pressure in the standard cylinder by 0.5 MPa, so that there is a pressure pulse of 0.5 MPa in the sample cylinder and the standard cylinder, record the pressure P1, and proceed to the next step of the experiment.

[0088] Step 600: Close the intake valve, the boost valve and the third valve on the six-way valve, open the gas injection valve at a speed of 1 / 4 turn per second, record the elapsed time and pressure, until the pressure change is less than 200Pa for 1,200 consecutive seconds (the final pressure is called P2), and the test is completed.

[0089] Step 700: Process the experimental data to obtain shale porosity and permeability.

[0090] Figure 4 It is a schematic diagram of the ln(FR(t))-t function of a deep shale sample in a Sichuan Basin shown in an exemplary embodiment of the present application.

[0091] In a possible implementation, the data processing process is as follows:

[0092] By formula Calculate the pore volume of shale powder;

[0093] Temperature: 40℃ Sample water saturation: 0%

[0094]

[0095] The porosity calculation formula is:

[0096] The volume fraction FR(t) is calculated using the following formula:

[0097]

[0098] Where 1-FR(t) represents the fraction of the amount of gas entering the powdered shale particles from the starting point to time t relative to the final amount of gas entering the particles when equilibrium is reached, Kc is the ratio of the volume outside the sample in the standard cylinder and the sample cylinder to the pore volume of the sample, ρ c0 is the average gas density at P1, ρ 0 is the gas density at P0, ρ (t) is the gas density at P(t);

[0099] Taking the logarithm of the volume factor, Figure 4 As shown, ln(FR(t)) is:

[0100] ln(FR(t))=f6+s1

[0101] The permeability k is calculated according to the following relationship:

[0102]

[0103] Where μ is the viscosity of the gas and cg is the compressibility factor

[0104] The specific limitations on the method for rapidly measuring the porosity and permeability of dense rocks can be found in the above-mentioned limitations on the device for rapidly measuring the porosity and permeability of dense rocks, which will not be repeated here.

[0105] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0106] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A device for rapidly measuring the porosity and permeability of dense rocks, characterized in that: Including gas source, gas source conversion device, gas source valve, air inlet valve, standard cylinder, six-way valve, pressure sensor, booster valve, hand-cranked booster pump, outlet valve, vacuum pump, injection valve, anti-backflow device, sample cylinder, constant temperature oil bath, auxiliary heater and pipeline; The gas source is connected to the gas source conversion device, the gas source conversion device is connected to the standard cylinder through a pipeline, the gas source valve is located between the gas source conversion device and the pipeline, the air inlet valve is located between the standard cylinder and the pipeline connected to the gas source, the standard cylinder is connected to the six-way valve through a pipeline, the detection end of the pressure sensor is connected to the six-way valve through bolts, the booster pump is connected to the six-way valve through a pipeline, the booster valve is located between the booster pump and the pipeline, the vacuum pump is connected to the six-way valve through a pipeline, the air outlet valve is located between the vacuum pump and the pipeline, the anti-backflow device is located inside the sample cylinder, and is connected to the air inlet of the sample cylinder, the standard cylinder and the sample cylinder are placed in the constant temperature oil bath, and the auxiliary heater is wrapped around the outside of the pipeline.

2. The device for rapidly measuring the porosity and permeability of dense rocks according to claim 1, characterized in that: The six-way valve comprises a first valve connected to a standard cylinder, a second valve connected to a sample cylinder, a third valve connected to a vacuum pump, a fourth valve connected to a booster pump, and fifth and sixth valves that are always kept in a closed state.

3. The device for rapidly measuring the porosity and permeability of dense rocks according to claim 1, characterized in that: The detection end of the pressure sensor converts the collected millivolt signal into a digital communication signal RS232, and then connects to a computer via USB. The computer collects real-time data of pipeline pressure to facilitate the adjustment of the pressure in the standard cylinder.

4. A method for rapidly measuring the porosity and permeability of dense rocks, characterized in that: include: A deep shale sample from the Sichuan Basin was dried at 105°C for 50 hours, the mass of the shale sample (powder sample or plunger) was measured, and the volume of the shale sample to be tested was obtained based on its density; Fill the sample cylinder with a known volume of shale sample. At the same time, adjust the mechanical locking mechanism to make the sample cylinder and the shale sample in close contact, ensuring that the volume in the cylinder other than the apparent volume is minimized. Open the vacuum valve and use the vacuum pump to evacuate the experimental device for 600 s; Close the vacuum valve and the third valve of the six-way valve, open the air inlet valve, injection valve, and the first, second, and fourth valves on the six-way valve, then open the gas source valve, inflate the device to the preset pressure P0 (5MPa, 7MPa, 9MPa), and proceed to the next step of the experiment; Close the gas source valve, gas injection valve and air intake valve, open the booster valve and the third valve on the six-way valve, then use a hand-cranked booster pump to increase the pressure in the standard cylinder by 0.5 MPa, so that there is a pressure pulse of 0.5 MPa in the sample cylinder and the standard cylinder, record the pressure P1, and proceed to the next step of the experiment; Close the intake valve, boost valve and the third valve on the six-way valve, open the gas injection valve at a speed of 1 / 4 turn per second, and record the elapsed time and pressure until the pressure change is less than 200Pa for 1,200 consecutive seconds (the final pressure is called P2), and the test is completed; The test data are processed to obtain the shale porosity and permeability.

5. The method for rapidly measuring the porosity and permeability of dense rocks according to claim 1, characterized in that: When the vacuum valve is opened and the experimental device is evacuated for 600 seconds using a vacuum pump, the pressure measured by the sensor in the device must not fluctuate by more than 200 Pa within 120 seconds.

6. The method for rapidly measuring the porosity and permeability of dense rocks according to claim 5, characterized in that: When closing the vacuum valve and the third valve of the six-way valve, opening the air intake valve, the injection valve and the first, second and fourth valves on the six-way valve, and then opening the air source valve to inflate the device to a preset pressure P0 (5Mpa, 7Mpa, 9Mpa), it is necessary to control the pressure measured by the sensor in the device to not fluctuate by more than 200Pa within 120s.

7. The method for rapidly measuring the porosity and permeability of dense rocks according to claim 1, characterized in that: When closing the gas source valve, the gas injection valve and the air intake valve, open the boost valve and the third valve on the six-way valve, and then use a hand-cranked boost pump to increase the pressure in the standard cylinder by 0.5 MPa, so that there is a pressure pulse of 0.5 MPa in the sample cylinder and the standard cylinder. When recording the pressure P1 step, it is necessary to control the pressure measured by the sensor in the device to not fluctuate by more than 200 Pa within 120 seconds.

8. The method for rapidly measuring the porosity and permeability of dense rocks according to claim 1, characterized in that: The processing of the test data to obtain the shale porosity and permeability further includes: By formula Calculate the pore volume of shale powder; The porosity calculation formula is: The volume fraction FR(t) is calculated using the following formula: Where 1-FR(t) represents the fraction of the amount of gas entering the powdered shale particles from the starting point to time t relative to the final amount of gas entering the particles when equilibrium is reached, Kc is the ratio of the volume outside the sample in the standard cylinder and the sample cylinder to the pore volume of the sample, ρ c0 is the average gas density at P1, ρ 0 is the gas density at P0, ρ (t) is the gas density at P(t); Taking the logarithm of the volume factor, ln(FR(t)) is: ln(F R (t))=f0+s1t; The permeability k is calculated according to the following relationship: Where μ is the viscosity of the gas and cg is the compressibility factor.

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