Method and device for evaluating dynamic sealing property of gas reservoir type gas storage cover layer

Abstract

The application relates to a kind of gas reservoir type gas storage cover layer dynamic sealing evaluation method and device;It is based on the existing cyclic loading and unloading triaxial cyclic test, and multiple cycle injection and production test is added, in the injection and production test process, the influence of injection and production pressure on rock is considered, and then the internal cohesion of rock under actual injection and production conditions and the internal friction angle of rock are determined according to the relationship between the internal cohesion of rock obtained under injection and production conditions and injection and production pressure, and the internal friction angle of rock, and the injection and production pressure is combined to calculate the gas storage safety operation pressure of gas storage in actual injection and production process, which can more truly reflect the actual situation, improve the accuracy of actual gas storage sealing evaluation, and ensure the safety of actual injection and production process.

Description

TECHNICAL FIELD

[0001] The application relates to a dynamic sealing property evaluation method and device for a gas reservoir type gas storage cover layer and belongs to the field of petroleum and natural gas. BACKGROUND

[0002] Dynamic sealing property evaluation of the cover layer is an important basis for construction of the underground gas storage. For the underground gas storage, cyclic injection and production will cause periodic disturbance of the regional stress field, resulting in changes in the mechanical properties of the cover layer, and thus changes in the sealing property of the cover layer. Therefore, research on the mechanical stability of the cover layer rock under alternating stress is the core content of dynamic sealing property evaluation of the underground gas storage cover layer.

[0003] At present, research on the rock mechanical properties of the underground gas storage is all aimed at salt rock. For example, Malin et al. conducted cyclic loading and unloading tests on salt rock samples under different load waveform parameters (upper and lower limit stress, stress amplitude and frequency) and different confining pressures by using a TAW-2000 type microcomputer servo rock triaxial testing machine. Research shows that under the action of cyclic loading, the elastic modulus of the salt rock decreases exponentially with the number of cycles or loading time.

[0004] Lu Gaoming et al. carried out rock mechanical tests under different stress paths such as uniaxial compression, triaxial compression, uniaxial and triaxial cyclic loading and unloading, and obtained the strength, deformation characteristics and cyclic loading and unloading stress-strain curve variation law of the brittle rock under uniaxial and triaxial conditions.

[0005] Han Lin et al. designed a test scheme for testing the deformation characteristics of limestone under the action of different confining pressures and constant cyclic upper limit stress under triaxial variable confining pressure cyclic loading and unloading. Through analysis of the test results, it is shown that in the whole cyclic loading and unloading process, the deformation modulus values are different in each loading and unloading stage, and the deformation modulus in the unloading stage is higher than that in the loading stage.

[0006] Wang Ruihong et al. studied the influence of different confining pressures, different stress states and different unloading amounts on the deformation characteristics and parameters of sandstone based on triaxial cyclic loading and unloading tests. The test results show that the variation law of the rock deformation modulus in the unloading process is different from that in the loading process: under the same stress difference, the greater the confining pressure, the smaller the deformation modulus reduction caused by the same unloading amount.

[0007] Rong Haoyu carried out true triaxial loading and unloading tests under different confining pressures and true triaxial tests under different unloading paths by using laboratory true triaxial tests, theoretical analysis and numerical simulation, and compared and analyzed the mechanical characteristics of the rock under the loading and unloading conditions and the deformation and failure law and the variation law of the mechanical parameters of the rock under different unloading paths through the test data.

[0008] Xu et al. used advanced acoustic emission test analysis system to carry out acoustic emission positioning test on fine-grained sandstone. Through the acoustic emission positioning test of fine-grained sandstone under cyclic loading, the space-time evolution characteristics and damage evolution law of rock deformation and failure process under cyclic loading are analyzed. The test results show that the acoustic emission information in the static loading stage well reflects the damage evolution law of rock in the compaction stage and elastic-plastic deformation stage; the acoustic emission in the early stage of the cycle is composed of small events generated by small cracks, and the duration and energy value are small.

[0009] Sui Yiyong et al. simulated the sand production law of injection-production well under the action of strong injection and strong mining alternating load through experiment, used damage quantity, loading frequency and other parameters to correct the sand production index formula, analyzed the sand production risk of injection-production well and predicted the sand production time, and obtained the influence law of injection-production cycle on sand production of injection-production well. The corrected sand production index formula can predict the sand production cycle and sand production degree of injection-production well, can effectively guide the selection of early sand prevention completion mode of injection-production well of gas storage, reasonably formulate production system to control sand production of injection-production well, and ensure stable operation of gas storage.

[0010] The above method is mainly applied to the research on the construction and operation of salt cavern type underground gas storage, most of which focuses on the volume loss of the cavity of underground gas storage, and the existing multi-cycle cyclic loading and unloading triaxial test of rock for gas storage is carried out on the outside of the rock. However, the actual operation of the gas storage will cause changes in the internal pore pressure of the rock with the cyclic injection and production, therefore, the existing test means for the gas storage does not match the actual conditions of the gas storage, and the sealing monitoring of the gas storage is not accurate. SUMMARY

[0011] The purpose of the present application is to provide a dynamic sealing evaluation method and device for the gas reservoir type gas storage cover layer, so as to solve the problem that the existing test means for the gas storage does not match the actual conditions of the gas storage, resulting in inaccurate sealing monitoring of the gas storage.

[0012] To achieve the above purpose, the technical scheme of the dynamic sealing evaluation method for the gas reservoir type gas storage cover layer of the present application comprises the following steps:

[0013] 1) Obtain the core at the cover layer of the region to be tested;

[0014] 2) Perform rock mechanics test on the obtained core at the cover layer to obtain dynamic elastic modulus and rock static strength, and determine the dynamic-static mechanical relationship;

[0015] 3) According to the rock mechanics test in step 2), obtain stress-strain curve data, calculate the rock internal cohesion and rock internal friction angle according to the obtained stress-strain curve data, and determine the relationship between the rock internal cohesion and the rock internal friction angle and the relationship between the rock internal cohesion and the rock static strength.

[0016] 4) cyclic loading and unloading triaxial test is carried out on the obtained core at the cap layer, dynamic elastic modulus of different loading cycles is obtained, and rock static strength of different loading cycles is obtained according to the determined dynamic-static mechanical relationship;

[0017] 5) rock internal cohesion force under different loading cycles is calculated according to the rock static strength of different loading cycles and the relationship between the rock internal cohesion force and the rock static strength, and rock internal friction angles of different loading cycles are obtained according to the relationship between the rock internal cohesion force and the rock internal friction angle;

[0018] 6) the relationship between the rock internal cohesion force and the cyclic loading and unloading cycle and the relationship between the rock internal friction angle and the cyclic loading and unloading cycle are established according to the rock internal cohesion force and the rock internal friction angle under different loading cycles;

[0019] 7) cyclic injection and production test is carried out on the obtained core, dynamic elastic modulus under injection and production conditions is obtained, rock static strength under injection and production cycles is obtained, and rock internal cohesion force and rock internal friction angle under injection and production conditions are calculated;

[0020] 8) rock internal cohesion force and rock internal friction angle corresponding to the cyclic loading and unloading cycle under injection and production cycles are obtained according to the relationship between the rock internal cohesion force and the cyclic loading and unloading cycle and the relationship between the rock internal friction angle and the cyclic loading and unloading cycle;

[0021] 9) injection and production internal cohesion force relationship and injection and production internal friction angle relationship are determined according to injection and production pressure, the rock internal friction angle and the rock internal cohesion force under injection and production conditions and the rock internal cohesion force and the rock internal friction angle of the cyclic loading and unloading cycle;

[0022] 10) rock internal cohesion force and rock internal friction angle under actual injection and production conditions are determined according to the injection and production internal cohesion force relationship and the injection and production internal friction angle relationship by obtaining actual injection and production cycle and actual injection and production pressure of the measured gas storage;

[0023] 11) the safety operation pressure of the gas storage under actual injection and production cycle is calculated according to the rock internal cohesion force, the rock internal friction angle and the actual injection and production pressure under actual injection and production conditions; the safety operation pressure of the gas storage is compared with the actual formation pressure of the measured gas storage in real time, and when the actual formation pressure is less than the safety operation pressure of the gas storage, the sealing property of the measured gas storage is good.

[0024] The beneficial effects of the present application are:

[0025] The method for evaluating the dynamic sealing property of the gas reservoir type gas storage reservoir cover layer of the application is based on the existing cyclic loading and unloading triaxial cyclic test, and a multi-cycle injection and production test is added, in which the influence of injection and production pressure on the rock is considered, and then the rock internal cohesion and the rock internal friction angle under the actual injection and production conditions are determined according to the relationship between the rock internal cohesion and the injection and production pressure and the relationship between the rock internal friction angle and the injection and production pressure under the injection and production conditions, and the gas storage reservoir safe operation pressure in the actual injection and production process is calculated in combination with the injection and production pressure, which can more truly reflect the actual situation, improve the accuracy of the actual gas storage reservoir sealing property evaluation, and ensure the safety in the actual injection and production process.

[0026] Further, the injection and production internal cohesion relationship is:

[0027] C * =(C-1)+e op

[0028] Wherein, C * is the rock internal cohesion under the injection and production conditions, the unit is MPa; o is a fitting parameter; P is the injection and production pressure, the unit is MPa; C is the rock internal cohesion of the cyclic loading and unloading cycle, the unit is MPa;

[0029] The injection and production internal friction angle relationship is:

[0030]

[0031] Wherein, is the rock internal friction angle under the injection and production conditions, the unit is degree; q is a fitting parameter, is the rock internal friction angle of the cyclic loading and unloading cycle, the unit is degree.

[0032] Further, the calculation expression of the gas storage reservoir safe operation pressure is:

[0033]

[0034] Wherein σ h is the minimum horizontal principal stress, the unit is MPa; is the maximum value of the maximum horizontal principal stress and the vertical stress, the unit is MPa.

[0035] Further, the relationship between the rock internal cohesion and the cyclic loading and unloading cycle is:

[0036] C=C0+i×(j n-1 -1)

[0037] Wherein: C0 is the internal cohesion of the rock in the first cycle, the unit is MPa, i and j are fitting parameters, and n is the cyclic loading and unloading cycle, dimensionless.

[0038] The relationship between the rock internal friction angle and the cyclic loading and unloading period is:

[0039]

[0040] Wherein: is the first period rock internal friction angle, unit: degree, l, m are fitting parameters, n is the cyclic loading and unloading period, dimensionless.

[0041] Further, the dynamic-static mechanical relationship is:

[0042] σ s =aE d

[0043] Wherein, σ s is the rock static strength, unit: MPa; a is the fitting parameter related to the rock argillaceous content and rock mechanical properties, E d is the dynamic elastic modulus, unit: GPa.

[0044] Further, the relationship between the rock internal cohesion and the rock static strength is:

[0045] C=bσ s -c

[0046] Wherein, b, c are fitting parameters, σ s is the rock static strength, unit: MPa;

[0047] The relationship between the rock internal friction angle and the rock internal cohesion is:

[0048]

[0049] M=f-gC

[0050] Wherein, d, t, f, g are all fitting parameters; M is the intermediate variable between the fitting internal cohesion C and internal friction angle .

[0051] The application also provides a technical scheme of a dynamic sealing property evaluation device for a gas reservoir type gas storage reservoir cover layer, which comprises a processor and a memory, and the processor executes the technical scheme of the above-mentioned dynamic sealing property evaluation method for the gas reservoir type gas storage reservoir cover layer stored in the memory. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 is a flow chart of the dynamic sealing property evaluation method for the gas reservoir type gas storage reservoir cover layer;

[0053] Figure 2 is a structural schematic diagram of the dynamic sealing property evaluation device for the gas reservoir type gas storage reservoir cover layer. DETAILED DESCRIPTION

[0054] The scheme of the present application will be specifically described below in combination with the drawings and specific embodiments.

[0055] The embodiment of the method for evaluating the dynamic sealing property of the cap rock of a gas reservoir type gas storage is as follows:

[0056] As shown in the method for evaluating the dynamic sealing property of the cap rock of a gas reservoir type gas storage provided by the present application, the method comprises the following steps: Figure 1

[0057] 1) Obtain a core sample at the cap rock of a target area to be measured;

[0058] The core at the cap rock of the target area to be measured in this embodiment is processed according to the test standard in Part 18 of the “Geological and Mineral Resources Department of the People’s Republic of China Rock Physical and Mechanical Property Test Procedures” DZ / T 0276.19-2015, and then the two ends of the sample are ground flat on a grinding machine to ensure that the two ends of the sample are smooth, parallel and perpendicular to the central axis, and the processing accuracy is ensured to control the parallelism of the cross section within ±0.01 mm according to the “Standard for Engineering Rock Mass Test” (GB / T 50266-2013).

[0059] The core sample obtained in this embodiment is divided into four groups, namely a first group of cores, a second group of cores, a third group of cores and a fourth group of cores.

[0060] 2) Perform a rock mechanics test on the obtained core at the cap rock to obtain a dynamic elastic modulus and a rock static strength, and determine a dynamic-static mechanical relationship;

[0061] The process for determining the dynamic-static mechanical relationship is as follows:

[0062] S1, perform an acoustic dynamic mechanical property test on the obtained first group of cores to obtain a dynamic elastic modulus;

[0063] S11, place the first group of core samples in the middle of the pressure plate, adjust the pressure plate with a spherical seat so that the sample is uniformly stressed, install a heat shrink tube on the sample, install a sealing ring to seal the sample, and blow the heat shrink tube tightly with a heat gun; set the test temperature to a predetermined value (the predetermined value is determined according to the actual reservoir temperature at the gas storage of the core to be measured) to warm the sample, and stop warming when the sample deforms stably;

[0064] S12, simultaneously load the axial load and the confining pressure, and always maintain the axial load greater than the confining pressure, when the confining pressure and the axial load are respectively added to the set confining pressure and the set load, test the transverse wave and the longitudinal wave of the sample using an acoustic emission device, and then unload the axial pressure and the confining pressure;

[0065] ​S13, the dynamic elastic modulus of the test sample under different confining pressures is calculated according to the core sample shear wave and longitudinal wave data obtained by experimental testing (see Table 1 for specific calculation data);

[0066]

[0067] wherein: E d is the dynamic elastic modulus of the rock, with the unit of GPa; v p is the acoustic wave longitudinal wave velocity, with the unit of m / s; v s is the acoustic wave shear wave velocity, with the unit of m / s; and p is the density of the rock, with the unit of kg / m 3 .

[0068] S2, triaxial compression static mechanical property experimental testing is performed on the obtained second group of core samples to obtain the static strength of the rock;

[0069] S21, the core sample is placed in the middle of the pressure plate of the press, the pressure plate with a spherical seat is adjusted to make the sample bear uniform force, the heat shrink tube is installed on the sample, the sealing ring is installed to seal the sample, and the heat shrink tube is blown tight by the heat gun; the test temperature is set to the predetermined value to warm the sample, and the warming is stopped when the sample deformation is stable;

[0070] S22, the axial load and the confining pressure are simultaneously loaded, and the axial load is always greater than the confining pressure; when the confining pressure and the axial load are added to the predetermined value, the axial load is added at a loading speed of 0.5 MPa / s to 1 MPa / s until the sample is destroyed, and the destruction load is recorded, and then the axial pressure and the confining pressure are unloaded;

[0071] S23: the stress and strain data of the sample obtained by experimental testing are used to draw the full stress-strain curve of the core sample, and the static strength of the rock of the core sample is obtained according to the full stress-strain curve of the sample.

[0072] S3, the dynamic-static mechanical relationship is determined according to the dynamic elastic modulus obtained in step S1 and the static strength of the rock obtained in step S2:

[0073] σ s =aE d (2)

[0074] wherein: s s is the static strength of the rock, with the unit of MPa; a is a fitting parameter related to the argillaceous content of the rock and the mechanical properties of the rock; E d is the dynamic elastic modulus, with the unit of GPa.

[0075] 3) Calculate the rock internal cohesion and the rock internal friction angle according to the stress-strain curve data obtained in the rock mechanics test in step 2), and determine the relationship between the rock internal cohesion and the rock internal friction angle and the relationship between the rock internal cohesion and the rock static strength;

[0076] Specifically, the process of determining the relationship between the rock internal cohesion and the rock internal friction angle is as follows:

[0077] S41, according to the measured full stress-strain test data in step S3, using formula (3), taking the first group of data as the reference value, and establishing equation groups by combining the remaining data with the first group of data respectively, to calculate the rock internal cohesion and the internal friction angle under different experimental stress conditions, as shown in Table 1;

[0078]

[0079] Wherein, σ1 is the axial pressure of the experiment, the unit is MPa; σ3 is the confining pressure of the experiment, the unit is MPa; C is the rock internal cohesion, the unit is MPa; is the rock internal friction angle, the unit is degree.

[0080] Table 1: Rock triaxial compression static mechanical property experiment test related data

[0081]

[0082] S42, according to the obtained rock internal cohesion and internal friction angle under different experimental stress conditions, determine the relationship between the rock internal cohesion and the internal friction angle:

[0083]

[0084] Wherein: d, t, f, g are fitting parameters; M is the intermediate variable between the fitting internal cohesion C and the internal friction angle .

[0085] Meanwhile, the relationship between the rock internal cohesion and the rock static strength in the embodiment is determined by the rock static strength obtained in step 2) and the rock internal cohesion obtained above;

[0086] Wherein, the relationship between the rock internal cohesion and the rock static strength is:

[0087] C=bσ s -c (5)

[0088] Wherein, b, c are fitting parameters, σ s is the rock static strength, the unit is MPa.

[0089] 4) The obtained core at the cap rock is subjected to cyclic loading and unloading triaxial test, dynamic elastic modulus of different loading cycles is obtained, and static strength of the rock of different loading cycles is obtained according to the determined dynamic-static mechanical relationship;

[0090] In the embodiment, the obtained third group of core samples is subjected to cyclic loading and unloading triaxial test, specifically:

[0091] S51, the sample is placed in the middle of the pressure plate of the press, the pressure plate with a spherical seat is adjusted to make the sample bear uniform force, the heat shrink tube is installed on the sample, the sealing ring is installed to seal the sample, and the heat shrink tube is blown tight by a heat gun; the test temperature is set to a predetermined value to warm the sample, and the warming is stopped when the sample deformation is stable;

[0092] S52, the confining pressure is loaded to a predetermined value, the axial load is loaded to a predetermined value at a loading speed of 0.5 MPa / s, and the data is recorded when the deformation is stable, and the transverse wave and longitudinal wave of the sample are tested once by the acoustic emission device every certain load; the axial load is unloaded to 0 MPa at a loading speed of 0.5 MPa / s, and the transverse wave and longitudinal wave of the sample are tested once by the acoustic emission device every certain load, and finally, the process is repeated for multiple times.

[0093] In this step, in order to keep consistent with the calculation conditions of the dynamic elastic modulus in the conventional triaxial test in step 2), the data of the loading process is selected in the triaxial cyclic loading and unloading test to calculate and analyze the parameters such as dynamic elastic modulus, rock strength and Poisson's ratio.

[0094] S53, the static strength of the rock under the set confining pressure and different loads is obtained, as shown in Table 2.

[0095] Table 2 cyclic loading and unloading triaxial test data

[0096]

[0097]

[0098] 5) According to the rock static strength of different loading cycles and the relationship between the rock internal cohesion and the rock static strength in step 4), the rock internal cohesion under different loading cycles is calculated, and according to the rock internal cohesion under different loading cycles and the relationship between the rock internal cohesion and the rock internal friction angle in step 3), the rock internal friction angle under different loading cycles is obtained, as shown in Table 2;

[0099] 6) According to the rock internal cohesion and the rock internal friction angle of different loading cycles obtained in step 5), the relationship between the rock internal cohesion and the cycle and the relationship between the rock internal friction angle and the cycle are established;

[0100] Wherein, the relationship between the internal cohesion of the rock and the cyclic loading and unloading cycle is:

[0101] C=C0+i×(j n-1 -1) (6)

[0102] Wherein: C0 is the internal cohesion of the rock in the first cycle, the unit is MPa, i, j are fitting parameters, n is the cyclic loading and unloading cycle, dimensionless;

[0103] The relationship between the internal friction angle of the rock and the cyclic loading and unloading cycle is:

[0104]

[0105] Wherein: is the internal friction angle of the rock in the first cycle, the unit is degree; l, m are fitting parameters, n is the cyclic loading and unloading cycle, dimensionless.

[0106] The embodiment is fitted by the data of the cycle, the internal friction angle of the rock and the internal cohesion of the rock, and the above-mentioned fitting form is only one of them, and it is not unique, because the form of the fitted formula is changed according to the actual situation of the rock data.

[0107] 7) The obtained core is subjected to cyclic injection and production test, the dynamic elastic modulus under injection and production condition is obtained, the rock static strength under injection and production cycle is obtained, and the internal cohesion of the rock and the internal friction angle of the rock under injection and production condition are calculated;

[0108] The specific process is:

[0109] S61, the fourth group of core samples obtained are subjected to cyclic injection and production test, the samples are pretreated, the axial load and the confining pressure are loaded at the same time, and are loaded to the set threshold value respectively; the core is injected with pore pressure at a rate of 1MPa / min, the pore pressure is kept at 2MPa, and the stress and strain and acoustic time difference data are recorded; 2MPa is injected as a gradient to the predetermined value, and then unloaded to 0MPa as a gradient of 2MPa, when the pore pressure is loaded or unloaded to the target pressure, the corresponding stress and strain are recorded, and the cycle is repeated for several times;

[0110] S62, according to the sample shear wave and longitudinal wave data obtained by experimental test, the dynamic elastic modulus of the test sample under different confining pressures is calculated by formula (1);

[0111] S63, the rock static strength under different injection and production cycles is determined by the dynamic-static mechanical relationship (formula (2)) in step 2);

[0112] S64, calculating the rock internal cohesion force under different injection-production cycles according to the rock static strength under different injection-production cycles and the relationship between the rock internal cohesion force and the rock static strength in step 3);

[0113] S65, obtaining the rock internal friction angle under different injection-production cycles according to the obtained rock internal cohesion force under different injection-production cycles and the relationship between the rock internal cohesion force and the rock internal friction angle in step 3);

[0114] 8) obtaining the rock internal cohesion force and the rock internal friction angle corresponding to the cyclic loading and unloading cycle under the injection-production cycle according to the relationship between the rock internal cohesion force and the cyclic loading and unloading cycle, the relationship between the rock internal friction angle and the cyclic loading and unloading cycle;

[0115] 9) determining the injection-production internal cohesion force relationship and the injection-production internal friction angle relationship according to the injection-production pressure, the rock internal friction angle under the injection-production condition, the rock internal cohesion force, and the rock internal cohesion force and the rock internal friction angle under the cyclic loading and unloading cycle;

[0116] Wherein, the injection-production internal cohesion force relationship is:

[0117] C * =(C-1)+e op (8)

[0118] Wherein, C * is the rock internal cohesion force under the injection-production condition, the unit is MPa; o is a fitting parameter; P is the injection-production pressure, the unit is MPa; C is the rock internal cohesion force under the cyclic loading and unloading cycle, the unit is MPa;

[0119] The injection-production internal friction angle relationship is:

[0120]

[0121] Wherein, is the rock internal friction angle under the injection-production condition, the unit is degree; q is a fitting parameter, is the rock internal friction angle under the cyclic loading and unloading cycle, the unit is degree.

[0122] 10) obtaining the actual injection-production cycle and the actual injection-production pressure of the measured gas storage, and determining the rock internal cohesion force and the rock internal friction angle under the actual injection-production condition according to the injection-production internal cohesion force relationship and the injection-production internal friction angle relationship;

[0123] The actual injection-production cycle and the actual injection-production pressure in the embodiment are the cycle and the pressure of the target area gas storage in the actual injection-production process.

[0124] 11) According to the rock internal cohesion force, the rock internal friction angle and the actual injection-production pressure under the actual injection-production condition, the gas storage safe operation pressure under the actual injection-production cycle is calculated; the gas storage safe operation pressure is compared with the actual formation pressure of the to-be-tested gas storage obtained in real time, and when the actual formation pressure is less than the gas storage safe operation pressure, the to-be-tested gas storage is good in sealing performance.

[0125] The calculation expression of the gas storage safe operation pressure in the embodiment is as follows:

[0126]

[0127] In the formula, σ h is the minimum horizontal principal stress, in MPa; is the maximum value of the maximum horizontal principal stress and the vertical stress, in MPa.

[0128] In the embodiment, the rock internal cohesion force and the internal friction angle under the multi-cycle injection-production condition are respectively substituted into the gas storage safe operation pressure prediction model established in formula 10, the gas storage safe operation pressure under a certain injection-production cycle is predicted, and the dynamic sealing performance of the gas storage caprock under different injection-production cycles is evaluated.

[0129] It should be noted that steps 2) and 3) in the above embodiment are equivalent to the test when the pore pressure is 0 MPa, and the pore pressure in the injection-production experiment is the force of the fluid inside the rock, which itself cannot cause obvious deformation or strength change of the rock, and its role in the experiment is to simulate the stress condition in the actual injection-production process.

[0130] The device for evaluating the dynamic sealing performance of the gas reservoir type gas storage caprock embodiment:

[0131] The device for evaluating the dynamic sealing performance of the gas reservoir type gas storage caprock proposed in the embodiment, as shown in Figure 2 the memory, the memory stores a computer program capable of running on the processor, and the processor realizes the method of the dynamic sealing performance evaluation method embodiment of the gas reservoir type gas storage caprock when executing the computer program.

[0132] That is, the above method of the dynamic sealing performance evaluation method embodiment of the gas reservoir type gas storage caprock should be understood as the flow of the dynamic sealing performance evaluation method of the gas reservoir type gas storage caprock realized by the computer program instructions. These computer program instructions can be provided to the processor, so that the functions specified by the above method flow are realized by executing these instructions through the processor.

[0133] The processor referred to in the embodiment refers to a processing device such as a microprocessor MCU or a programmable logic device FPGA.

[0134] The memory referred to in the embodiments includes a physical device for storing information, usually after digitizing the information and storing it in a medium using electricity, magnetism or optics. For example: various types of memory that store information using electrical energy, such as RAM, ROM, etc.; various types of memory that store information using magnetic energy, such as hard drives, floppy disks, magnetic tapes, magnetic core memories, bubble memories, U disks; various types of memory that store information using optical methods, such as CDs or DVDs. Of course, there are other types of memory, such as quantum memory, graphene memory, etc.

[0135] The device composed of the above-mentioned memory, processor and computer program is realized by executing the corresponding program instructions in the computer by the processor. The processor can be equipped with various operating systems, such as windows operating system, linux system, android, iOS system, etc.

[0136] As other embodiments, the device can further include a display for displaying the test results for reference by the staff.

[0137] The above only describes the preferred embodiments of the present application, and the present application has been described in detail by general description and specific embodiments, but is not used to limit the present application. For those skilled in the art, the present application can have various modifications or improvements. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the scope of the claims of the present application.

Claims

1. A method for evaluating the dynamic sealability of a gas reservoir type storage gasholder, characterized by, The method comprises the following steps: 1) obtaining a core at a cap layer of a region to be measured; 2) performing a rock mechanics test on the obtained core at the cap layer to obtain a dynamic elastic modulus and a rock static strength, and determining a dynamic-static mechanical relationship; 3) obtaining stress-strain curve data according to the rock mechanics test in step 2), calculating a rock internal cohesion and a rock internal friction angle according to the obtained stress-strain curve data, and determining a relationship between the rock internal cohesion and the rock internal friction angle and a relationship between the rock internal cohesion and the rock static strength; 4) performing a cyclic loading and unloading triaxial test on the obtained core at the cap layer to obtain a dynamic elastic modulus at different loading cycles, and obtaining a rock static strength at different loading cycles according to the determined dynamic-static mechanical relationship; 5) calculating a rock internal cohesion at different loading cycles according to the rock static strength at different loading cycles and the relationship between the rock internal cohesion and the rock static strength, and obtaining a rock internal friction angle at different loading cycles according to the relationship between the rock internal cohesion and the rock internal friction angle; 6) establishing a relationship between the rock internal cohesion and a cyclic loading and unloading cycle and a relationship between the rock internal friction angle and the cyclic loading and unloading cycle according to the rock internal cohesion and the rock internal friction angle at different loading cycles; 7) performing a cyclic injection and production test on the obtained core to obtain a dynamic elastic modulus under injection and production conditions, obtaining a rock static strength under an injection and production cycle, and calculating a rock internal cohesion and a rock internal friction angle under the injection and production conditions; 8) obtaining a rock internal cohesion and a rock internal friction angle at a cyclic loading and unloading cycle corresponding to the injection and production cycle according to the relationship between the rock internal cohesion and the cyclic loading and unloading cycle and the relationship between the rock internal friction angle and the cyclic loading and unloading cycle; 9) determining an injection and production internal cohesion relationship and an injection and production internal friction angle relationship according to an injection and production pressure, the rock internal friction angle and the rock internal cohesion under the injection and production conditions, and the rock internal cohesion and the rock internal friction angle at the cyclic loading and unloading cycle; 10) obtaining an actual injection and production cycle and an actual injection and production pressure of a gas storage to be measured, and determining a rock internal cohesion and a rock internal friction angle under actual injection and production conditions according to the injection and production internal cohesion relationship and the injection and production internal friction angle relationship; 11) calculating a gas storage safe operation pressure under an actual injection and production cycle according to the rock internal cohesion and the rock internal friction angle under the actual injection and production conditions and the actual injection and production pressure, and comparing the gas storage safe operation pressure with an actual formation pressure of the gas storage to be measured in real time, and if the actual formation pressure is less than the gas storage safe operation pressure, the gas storage to be measured has good sealing performance.

2. The method according to claim 1, wherein the injection and production internal cohesion relationship is: the injection and production internal friction angle relationship is: C * = (C - 1) + e op where C * is the internal cohesion of the rock under injection-production conditions, in MPa; o is a fitting parameter; P is the injection-production pressure, in MPa; C is the internal cohesion of the rock for a cycle of loading and unloading, in MPa; and the calculation expression of the gas storage safe operation pressure is: wherein, is the internal friction angle of the rock under injection-production conditions, in degrees; q is a fitting parameter, is the internal friction angle of the rock under cyclic loading and unloading, in degrees.

3. The method for evaluating the dynamic sealability of the cap rock of the gas reservoir type gas storage according to claim 2, characterized by, 4. The method according to claim 1, wherein the relationship between the rock internal cohesion and the cyclic loading and unloading cycle is: where σ h is the minimum horizontal principal stress in MPa; is the maximum of the maximum horizontal principal stress and the vertical stress in MPa. wherein C0 is a rock internal cohesion of a first cycle, in MPa, i and j are fitting parameters, and n is a cyclic loading and unloading cycle, dimensionless. ​ C = C0+ i x (j n-1 -1) ​ The relationship between the rock internal friction angle and the cyclic loading and unloading period is: wherein: is the first cycle rock internal friction angle in degrees, and l, m are fitting parameters, and n is the cyclic loading and unloading cycle, dimensionless.

5. The method of claim 1, wherein the method is a method for evaluating the dynamic sealability of a gas reservoir-type gas storage reservoir cover layer, characterized by, The dynamic-static mechanical relationship is: σ s = aE d wherein σ s is the static strength of the rock, in MPa; a is a fitting parameter related to the argillaceous content of the rock and to the mechanical properties of the rock, E d is the dynamic modulus of elasticity, in GPa.

6. The method according to claim 5, characterized in that, The relationship between the rock internal cohesion and the rock static strength is: C = bσ s -c wherein b, c are fitting parameters, σ s is the static strength of the rock, in MPa; The relationship between the rock internal friction angle and the rock internal cohesion is: M = f - gC where d, t, f, g are fitting parameters; M is the intermediate variable between the fitting internal cohesion C and internal friction angle between the fitting internal cohesion C and internal friction angle 7. A device for evaluating the dynamic sealability of a gas reservoir type storage gasholder, comprising a processor and a memory, characterized in that, The processor executes the program stored in the memory for evaluating the dynamic sealing property of the gas reservoir type gas storage reservoir cover layer according to any one of claims 1-6.

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