A shale stress sensitivity analysis method, device, equipment, medium and product

Abstract

The application discloses a shale stress sensitivity analysis method, device, equipment, medium and product. The method comprises the following steps: in response to a shale stress sensitivity analysis request, determining a target shale to be tested, and performing water invasion treatment on the target shale so that the target shale reaches a target water saturation; through a core steady-state permeability testing device, the target shale is controlled to be in a target confining pressure and a target flow pressure, and when it is detected that gas flow reaches a steady state, a target gas-measured permeability of the target shale under a target pressure state is determined; according to the target water saturation, the target confining pressure, the target flow pressure and the target gas-measured permeability of the target shale, the influence of the water invasion treatment on the stress sensitivity of different flow regions of the target shale is analyzed, so as to guide actual gas exploitation. Through the water invasion treatment and the core steady-state permeability testing device, the shale is tested and analyzed in terms of the stress sensitivity, and this is helpful to guide the realization of more efficient and safe shale gas exploitation.

Description

Technical Field

[0001] This invention relates to the field of shale gas exploration and development, and in particular to a method, apparatus, equipment, medium, and product for stress sensitivity analysis of shale. Background Technology

[0002] During volumetric fracturing of shale gas reservoirs, a large amount of fracturing fluid invades the surface of natural fractures or the matrix pores near the fractures, significantly affecting the sensitivity of permeability to stress changes and ultimately impacting shale gas well production. Therefore, it is crucial to study the mechanism by which fracturing fluid intrusion affects reservoir stress sensitivity, as this is essential for achieving safe and efficient gas extraction.

[0003] Therefore, how to test and analyze the stress sensitivity of shale through water intrusion treatment and core steady-state permeability testing devices to guide the realization of more efficient and safer shale gas extraction is an urgent problem to be solved. Summary of the Invention

[0004] This invention provides a method, apparatus, equipment, medium, and product for stress sensitivity analysis of shale. By using water intrusion treatment and a core steady-state permeability testing device, the stress sensitivity of shale is tested and analyzed, which helps guide the realization of more efficient and safer shale gas extraction.

[0005] According to one aspect of the present invention, a method for stress sensitivity analysis of shale is provided, comprising:

[0006] In response to the request for stress sensitivity analysis of shale, the target shale to be tested was identified, and the target shale was subjected to water immersion treatment to bring the target shale to the target water saturation.

[0007] Using a core steady-state permeability testing device, the target shale is controlled under target confining pressure and target flowing pressure, and the target gas permeability of the target shale under the target pressure state is determined when the gas flow is detected to reach a steady state.

[0008] Based on the target water saturation, target confining pressure, target flowing pressure, and target gas permeability of the target shale, the impact of water intrusion treatment on the stress sensitivity of different flow zones of the target shale is analyzed to guide actual gas extraction.

[0009] According to another aspect of the present invention, a stress sensitivity analysis apparatus for shale is provided, comprising:

[0010] The water intrusion module is used to respond to the stress sensitivity analysis request of shale, identify the target shale to be tested, and perform water intrusion treatment on the target shale to make the target shale reach the target water saturation.

[0011] The determination module is used to control the target shale under the target confining pressure and target flowing pressure through the core steady-state permeability testing device, and determine the target gas permeability of the target shale under the target pressure state when the gas flow is detected to reach a steady state.

[0012] The analysis module is used to analyze the impact of water intrusion treatment on the stress sensitivity of different flow zones of the target shale based on the target water saturation, target confining pressure, target flowing pressure, and target gas permeability, so as to guide actual gas extraction.

[0013] According to another aspect of the present invention, an electronic device is provided, the electronic device comprising:

[0014] At least one processor; and

[0015] A memory communicatively connected to the at least one processor; wherein,

[0016] The memory stores a computer program that can be executed by the at least one processor, which enables the at least one processor to perform the stress sensitivity analysis method for shale according to any embodiment of the present invention.

[0017] According to another aspect of the present invention, a computer-readable storage medium is provided, the computer-readable storage medium storing computer instructions for causing a processor to execute and implement the stress sensitivity analysis method for shale according to any embodiment of the present invention.

[0018] According to another aspect of the present invention, a computer program product is also provided, comprising a computer program that, when executed by a processor, implements the stress sensitivity analysis method for shale according to any embodiment of the present invention.

[0019] The technical solution of this invention, in response to a stress sensitivity analysis request for shale, identifies the target shale to be tested and performs water intrusion treatment on it to achieve the target water saturation. Using a core steady-state permeability testing device, the target shale is controlled under target confining pressure and target flowing pressure. When gas flow reaches a steady state, the target gas permeability of the target shale under the target pressure state is determined. Based on the target water saturation, target confining pressure, target flowing pressure, and target gas permeability of the target shale, the impact of water intrusion treatment on the stress sensitivity of different flow regions of the target shale is analyzed to guide actual gas extraction. The testing and analysis of shale stress sensitivity through water intrusion treatment and a core steady-state permeability testing device helps guide the achievement of more efficient and safer shale gas extraction.

[0020] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1A This is a flowchart of a stress sensitivity analysis method for shale provided in Embodiment 1 of the present invention;

[0023] Figure 1B This is a structural diagram of the core steady-state permeability testing device provided in Embodiment 1 of the present invention;

[0024] Figure 1C This is a schematic diagram of the mathematical model of shale matrix permeability stress sensitivity after hydraulic fracturing provided in Embodiment 1 of the present invention;

[0025] Figure 1D This is a schematic diagram of the mathematical model of stress sensitivity of shale fracture permeability after hydraulic fracturing provided in Embodiment 1 of the present invention;

[0026] Figure 2A This is a schematic diagram showing the fitting effect between experimental data and model results of shale matrix permeability stress sensitivity provided in Embodiment 2 of the present invention;

[0027] Figure 2B This is a schematic diagram showing the fitting relationship between the semi-logarithmic ratio of shale matrix permeability and effective stress under different water saturation conditions, as provided in Embodiment 2 of the present invention.

[0028] Figure 2C This is a schematic diagram illustrating the variation of the stress sensitivity coefficient of shale matrix with effective stress under different water saturation conditions, as provided in Embodiment 2 of the present invention.

[0029] Figure 2D This is a schematic diagram of the correlation between the initial stress sensitivity coefficient and water saturation of shale matrix core provided in Embodiment 2 of the present invention;

[0030] Figure 2E This is a schematic diagram showing the fitting effect between experimental data and model results of shale fracture permeability stress sensitivity provided in Embodiment 2 of the present invention;

[0031] Figure 2FThis is a schematic diagram of the semi-logarithmic fitting relationship between crack dimensionless permeability and effective stress under different water saturation levels, provided in Embodiment 2 of the present invention.

[0032] Figure 2G This is a schematic diagram illustrating the variation of the stress sensitivity coefficient of shale fracture core with effective stress, provided in Embodiment 2 of the present invention.

[0033] Figure 2H This is a schematic diagram of the correlation between the initial stress sensitivity coefficient and water saturation of shale fracture cores provided in Embodiment 2 of the present invention;

[0034] Figure 3 This is a structural block diagram of a stress sensitivity analysis device for shale provided in Embodiment 3 of the present invention;

[0035] Figure 4 This is a schematic diagram of the structure of the electronic device provided in Embodiment 4 of the present invention. Detailed Implementation

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

[0037] It should be noted that the terms "first," "second," "target," "candidate," and "alternative," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices. The acquisition, storage, use, and processing of data in the technical solutions of this application all comply with the relevant provisions of national laws and regulations.

[0038] Example 1

[0039] Figure 1A This is a flowchart of a stress sensitivity analysis method for shale provided in Embodiment 1 of the present invention; Figure 1B This is a structural diagram of the core steady-state permeability testing device provided in Embodiment 1 of the present invention; Figure 1C This is a schematic diagram of the mathematical model of shale matrix permeability stress sensitivity after hydraulic fracturing provided in Embodiment 1 of the present invention; Figure 1D This is a schematic diagram of the mathematical model of stress sensitivity of shale fracture permeability after hydraulic fracturing provided in Embodiment 1 of the present invention. This embodiment is applicable to situations where the analysis system uses a core steady-state permeability testing device to perform stress sensitivity testing and analysis on the target shale. This method can be executed by a shale stress sensitivity analysis device, which can be implemented in hardware and / or software. The shale stress sensitivity analysis device can be configured in an electronic device and executed by the analysis system. The analysis system can control the confining pressure and flowing pressure of the target shale using the core steady-state permeability testing device. Figure 1A As shown, the stress sensitivity analysis method for this shale includes:

[0040] S101. In response to the stress sensitivity analysis request of shale, identify the target shale to be tested and perform water immersion treatment on the target shale to make the target shale reach the target water saturation.

[0041] The stress sensitivity analysis request refers to a request to perform water intrusion treatment on the target shale and analyze the impact of the water intrusion treatment on the stress sensitivity of different flow zones of the target shale using a core steady-state permeability testing device. The number of target shale pieces can be at least two, for example, six. The target shale can include original matrix shale and unsupported fractured shale; for example, it can include three untreated original matrix shale cores and three unsupported fractured shale cores obtained after artificial fracture treatment. The target water saturation refers to a parameter characterizing the water content in the target shale. Specifically, the target water saturation can be dry, 20%, 40%, 60%, and 80%.

[0042] For example, six core samples from the main layer of a shale gas well in a basin can be selected. Three of these core samples are artificially fractured to form unsupported, through-fractured shale core samples, while the other three are used as the original matrix shale. The six shale core samples are then placed in a 105°C oven and thoroughly dried for more than 72 hours until their weight remains constant. After that, the core samples are removed and placed in a desiccator to cool to room temperature. The dry weight and other basic data of the shale samples are then tested to determine the target shale to be tested.

[0043] Optionally, the target shale is subjected to water immersion treatment to achieve the target water saturation, including: determining the target temperature and target humidity corresponding to the target water saturation based on the steam method, and controlling the target oven containing the target shale to be at the target temperature and target humidity; monitoring the mass change of the target shale placed in the target oven based on a preset period, and determining the real-time water saturation of the target shale based on the mass change, until the target shale reaches the target water saturation.

[0044] For example, shale cores with different water saturations can be established using the steam method, allowing the target shale to sequentially reach the corresponding water saturation levels. This simulates the change in reservoir water saturation before and after fracturing, and explores the impact of different water saturations on shale gas flow. Specifically, the target shale (including matrix-type and fracture-type cores) is suspended in a target oven with target humidity and temperature. When the moisture content in the target shale is lower than the ambient humidity, water vapor diffusion and adsorption occur, increasing the water content and causing a change in mass.

[0045] Optionally, the real-time water saturation of the target shale can be determined based on the mass change, including: determining the mass deviation of the target shale before and after water intrusion based on the mass change; and determining the real-time water saturation of the target shale based on the mass deviation, water density, core cross-sectional area, core length, and porosity. The mass deviation refers to the change in mass of the target shale before and after water intrusion.

[0046] For example, the real-time water saturation of the target shale can be determined according to the following formula:

[0047]

[0048] Among them, S w ρ represents the water saturation of the shale core, dimensionless; m2 represents the mass of the shale core after steam treatment, kg; m1 represents the mass of the shale core before steam treatment, kg; ρ w The density of water, i.e., the density value of water, kg / m³ 3 A represents the cross-sectional area of ​​the shale core, in meters. 2 L represents the core length, in meters. ρ represents the porosity of shale, dimensionless. m2-m1 represents the mass deviation value.

[0049] S102. Using a core steady-state permeability testing device, the target shale is controlled under target confining pressure and target flowing pressure, and when the gas flow is detected to reach a steady state, the target gas permeability of the target shale under the target confining pressure is determined.

[0050] The target confining pressure can be 10 MPa, 15 MPa, 20 MPa, 25 MPa, or 30 MPa. The core steady-state permeability testing device includes at least one of the following: a preset measuring pump, an intermediate container, a pressure sensor, a core holder, a confining pressure pump, a gas flow meter, a pressure monitoring instrument, and a constant temperature chamber; the preset measuring pump can be, for example, an ISCO pump.

[0051] For example, see Figure 1B The core steady-state permeability testing device may specifically include an ISCO pump, an intermediate container, a pressure sensor, a core holder, a confining pressure pump, a gas flow meter, a pressure monitoring instrument, a constant temperature chamber, and a computer equipped with an analysis system. The core holder is used to hold the target shale. Pressure sensors 1, 2, and 3 are connected to the inlet, outlet, and confining pressure side of the holder, respectively, to measure the inlet, outlet, and confining pressure of the target shale. A pressure monitoring instrument and a computer are used to measure the inlet, outlet, and confining pressure of the experimental setup in real time. An ISCO pump, intermediate container, and high-pressure gas source are connected to the inlet of the holder to apply pore pressure (i.e., flow pressure) to the target shale. A regulating valve, check valve, and flow controller on the inlet side of the holder are used to control the gas velocity and flow rate from the inlet to the core holder. A confining pressure pump and confining pressure pipeline are connected to the confining pressure chamber of the holder to apply confining pressure to the target shale. A constant temperature chamber is used to control the range of experimental temperature changes. A test tube and water tank system are connected to the outlet of the core holder to collect and measure the gas flow rate at the outlet of the target shale.

[0052] Optionally, the target shale can be controlled to be under target confining pressure and target flowing pressure using a core steady-state permeability testing device. This includes: applying confining pressure to the target shale using a confining pressure pump and a core holder in the core steady-state permeability testing device to control the target shale to be under target confining pressure; and delivering a high-pressure gas source to the target shale using a preset measuring pump, an intermediate container, and a core holder in the core steady-state permeability testing device to apply flowing pressure, i.e., pore pressure, to the target shale.

[0053] Optionally, upon detecting that the gas flow has reached a steady state, the target gas permeability of the target shale under the target pressure state is determined. This includes: based on a preset detection cycle, performing a preset number of gas flow and pressure detections using the pressure sensor and gas flow meter in the core steady-state permeability testing device, and determining, based on the detection results, whether the target shale is under the target confining pressure and target flowing pressure, and whether the gas flow has reached a steady state; if so, the Darcy formula is used to calculate the target gas permeability of the target shale under the target pressure state. Here, the target pressure state refers to the pressure state under the target confining pressure and target flowing pressure.

[0054] Optionally, for each target shale, water intrusion treatment can be performed separately to achieve different target water saturation levels. Target shale cores at different water saturation levels are placed in a core holder, and the confining pressure is stabilized at 40 MPa using a confining pressure pump. A pore pressure (i.e., flow pressure) of 30 MPa is applied at the inlet end of the holder, and air is connected to the outlet end. Gas flows from the inlet end to the outlet end under pressure. After the gas flow rate through the core pores and the pressure at both ends of the core stabilize, measurements are taken every 2 hours for three consecutive tests. If the error is within 0.1%, the gas flow is considered to have reached a steady state.

[0055] Optionally, the target gas permeability of the target shale under the target pressure state can be calculated using the following Darcy formula:

[0056]

[0057] Where Q is the gas flow rate through the target shale core, m 3 / s; K is the gas permeability measured in the target shale core, in m 2 p1 is the flow pressure at the inlet of the target shale core, Pa; p2 is the flow pressure at the outlet of the target shale core, Pa; μ is the gas viscosity, Pa·s; A is the cross-sectional area of ​​the target shale core, m³. 2 L represents the core length, in meters.

[0058] For example, the core pore pressure can be applied sequentially to 30 MPa, 25 MPa, 20 MPa, 15 MPa, and 10 MPa. After the measured flow rate and pressure stabilize, the gas permeability of the core under different pressure conditions can be solved based on the Darcy permeability formula. This will help to establish a graph of the change of matrix-fracture core permeability with respect to effective stress under different water saturation states, which will help to understand the influence mechanism of water intrusion on the stress sensitivity of shale.

[0059] S103. Based on the target water saturation, target confining pressure, target flowing pressure, and target gas permeability of the target shale, analyze the impact of water intrusion treatment on the stress sensitivity of different flow zones of the target shale to guide actual gas extraction.

[0060] The flow region of the target shale refers to the matrix region and the fracture region. Specifically, the impact of water intrusion treatment on the stress sensitivity of the matrix region can be obtained by using relevant data of matrix-type shale in the target shale, and the impact of water intrusion treatment on the stress sensitivity of the fracture region can be obtained by using relevant data of unsupported through-fracture shale in the target shale.

[0061] Optionally, based on the target water saturation, target confining pressure, target flowing pressure, and target gas permeability of the target shale, the impact of water intrusion treatment on the stress sensitivity of different flow zones of the target shale is analyzed, including:

[0062] (1) Based on the mathematical model of stress sensitivity of shale matrix permeability after hydraulic fracturing, the influence of water intrusion treatment on the stress sensitivity of the matrix region of the target shale is analyzed according to the target water saturation, target confining pressure, target flowing pressure and target gas permeability of the target shale.

[0063] Optional, see Figure 1C The mathematical model of permeability stress sensitivity of shale matrix after hydraulic fracturing can be specifically a physical model of the pore compressibility coefficient of a one-dimensional plunger shale matrix core after water intrusion. Specifically, the following assumptions can be made: (1) One-dimensional water intrusion of shale matrix occurs parallel to the matrix bedding direction, and the core after water intrusion is divided into a water-intruded zone and a non-water-intruded zone; (2) After the water intrusion process is completed, the core volume, pore volume, pore compressibility coefficient and water saturation of the water-intruded zone are V1, Vp1, Cp1, and S, respectively. w1 The volume, pore volume, pore compressibility coefficient, and water saturation of the shale in the un-water-intruded area are V2, Vp2, Cp2, and S, respectively. w2 The thickness of the water-eroded rock zone is d. m The length of the matrix core is L m .

[0064] The porosity compressibility of the shale matrix is ​​defined by the following formula (3):

[0065]

[0066] In the formula: c pm The comprehensive porosity compressibility coefficient of the shale matrix after water intrusion, Pa -1 V p1 The volume of the matrix pores in the water-swept zone is m. 3 V p2 The matrix pore volume in the non-water-intrusive zone, m 3 σ represents the overburden stress of the rock matrix, in Pa; p represents the pore pressure of the matrix, in Pa. α represents the effective stress coefficient, dimensionless; d represents the mathematical differential symbol.

[0067] The matrix porosity compressibility in the water-infiltrated and non-water-infiltrated zones is defined by the following equations (4) and (5):

[0068]

[0069] In the formula: c p1 The matrix porosity compressibility coefficient in the water-swept zone is given by Pa. -1 ;c p2 The matrix porosity compressibility in the un-water-infiltrated zone is given by Pa. -1 .

[0070] When the overlying pressure remains constant, considering only the change in pore pressure, the change in effective stress equals the change in pore pressure. Assuming the rock particles are incompressible, the pore compressibility coefficients defined in equations (3), (4), and (5) can be converted into equations (6), (7), and (8), respectively:

[0071]

[0072] Substituting equations (7) and (8) into equation (6), and simplifying equation (6), we obtain equation (9):

[0073]

[0074] In the formula: d m Thickness of the water-swept zone in the shale matrix, in meters (m); L m denoted as the length of the shale matrix, in meters (m).

[0075] Introducing dε p1 The change in pore volumetric strain in the water-swept zone is represented by the following equation (10):

[0076]

[0077] Where: ε p1 The deformation of the matrix pores in the water-swept area is dimensionless; K p1 K is the bulk modulus of the matrix pores in the water-swept zone, Pa; K is the bulk modulus of the matrix skeleton, Pa; ε s1 The deformation is due to the adsorption, expansion, and deformation of matrix clay mineral particles in the water-swept area; it is dimensionless.

[0078] Substituting equation (10) into equation (7) and transforming it, we obtain the simplified matrix porosity compressibility coefficient c in the water-swept zone. p1 As shown in equation (11):

[0079]

[0080] In the formula: R h1 The relative humidity of the matrix in the water-inundated area is dimensionless.

[0081] Since the bulk modulus of the skeletal particles is much greater than that of the porous region, i.e., K >> K p1 ,therefore Assuming the shale matrix porosity power exponent α = 1 here, then the compressibility coefficient c of the water-swept matrix in equation (11) is... p1 Simplifying, we get equation (12):

[0082]

[0083] Substituting equations (8) and (12) into equation (9), the expression for the comprehensive porosity compressibility coefficient of water-infiltrated shale matrix can be rewritten as equation (13):

[0084]

[0085] The overall compressibility coefficient of the matrix core after water intrusion can also be defined as (14):

[0086]

[0087] In the formula: The effective porosity of the shale matrix is ​​dimensionless.

[0088] By transforming both ends of equation (14), we can obtain equation (15):

[0089]

[0090] The porosity and pore pressure at both ends of equation (15) are respectively expressed in intervals. Integrating with [p0,p], we obtain the following equation (16):

[0091]

[0092] In the formula: σ0 represents the initial porosity of the rock matrix, dimensionless; σ0 refers to the initial overburden stress of the matrix, Pa; p0 is the initial pore pressure of the matrix, Pa. This represents the effective porosity of the shale matrix.

[0093] The permeability-porosity cubic law is used to characterize the evolution of the inherent permeability of dense sedimentary rocks, such as shale, with changes in porosity. Combined with equation (16), the law of permeability of shale matrix with pressure can be solved, as shown in equation (17):

[0094]

[0095] In the formula: k0 is the initial permeability of the rock matrix, m 2 ; k is the matrix permeability under arbitrary pressure conditions, m 2 .

[0096] In summary, the expression for the change in shale matrix permeability with pore stress is given by the following equation (18):

[0097] k = k0exp[-3c] pm [(σ-σ0)-(p-p0)]] (18)

[0098] Using permeability modulus γ m The sensitivity of shale matrix permeability to stress changes is quantified as shown in equation (19):

[0099]

[0100] The relationship between permeability modulus, shale matrix permeability and comprehensive pore compressibility coefficient of shale matrix after water intrusion is expressed by Equation (19), which helps to analyze the impact of water intrusion treatment on the stress sensitivity of the matrix region of the target shale.

[0101] It should be noted that formula (18) can characterize the relationship between shale permeability and pore stress after water intrusion treatment, and formula (19) can characterize the shale permeability and sensitivity to stress changes after water intrusion treatment, thus helping to analyze the impact of water intrusion treatment on the stress sensitivity of the matrix area of ​​the target shale.

[0102] (2) Based on the mathematical model of stress sensitivity of shale fracture permeability after hydraulic fracturing, the influence of water intrusion treatment on stress sensitivity of fracture area of ​​target shale is analyzed according to the target water saturation, target confining pressure, target flowing pressure and target gas permeability of target shale.

[0103] Optionally, the thickness of the water molecule layer can be determined, and the equivalent width of the unsupported shale fracture after water intrusion can be calculated based on the thickness of the water molecule layer; the fracture porosity can be determined based on the equivalent width, fracture length, and fracture cross-sectional area; the expression for the shale fracture compressibility coefficient with respect to effective stress can be determined based on the fracture porosity; and the expression for the change of shale fracture permeability with pore stress can be determined to characterize the effect of water intrusion treatment on the stress sensitivity of the fracture region of the target shale.

[0104] Optional, see Figure 1D The mathematical model for the stress sensitivity of shale fracture permeability after hydraulic fracturing can be specifically a one-dimensional physical model of the compressibility coefficient of unsupported shale fractures after water intrusion. This model simplifies unsupported shale fractures into flat plate fractures and, combined with a multilayer adsorption model of water molecules, establishes a one-dimensional mathematical equation for the stress sensitivity of water-intruded shale fracture permeability to analyze the variation characteristics of unsupported shale fracture permeability with effective stress after water intrusion. This model assumes a fracture aperture of w. f The length is L f The water molecule adsorption characteristics on the crack surface follow a multilayer adsorption law, with an adsorption layer thickness of d. f The maximum water saturation at the water absorption end of the crack is S. wfmax .

[0105] For example, the thickness of the water molecule layer adsorbed on the surface of an unsupported crack can be characterized using a multilayer adsorption model of water molecules, as shown in equation (20) below:

[0106]

[0107] In the formula: d Hx is the diameter of a water molecule, taken as 4e-10m; cf R represents the clay mineral content on the surface of the crack, dimensionless; hf This refers to the relative humidity of water vapor within the crack, and is dimensionless; R Lf This refers to the relative humidity when 50% of the surface inside the crack is covered by a single adsorption layer of water molecules; it is dimensionless. cc represents the clay mineral content, which is also dimensionless.

[0108] Therefore, considering the influence of the adsorbed water film remaining on the crack surface on the width, the equivalent width of the unsupported shale crack after water intrusion can be calculated as Equation (21):

[0109] w f =w f0 -2d f (twenty one)

[0110] In the formula: w f0 The width of the crack before water intrusion is represented in meters (m).

[0111] Furthermore, the porosity equation for flat cracks can be characterized as equation (22):

[0112]

[0113] In the formula: This refers to crack porosity; L f This refers to the crack length, in meters (m); A f This represents the cross-sectional area of ​​the crack, m 2 .

[0114] Based on the definition of the pore compressibility coefficient, the expression for the shale fracture compressibility coefficient with respect to the effective stress can be calculated, as shown in equation (23):

[0115]

[0116] In the formula: V f This refers to the crack volume, m 3 ;σ e The effective stress of the crack is expressed in Pa and C. f This refers to the crack compressibility coefficient, Pa. -1 ;p e For overburden stress, Pa; p f The crack pressure is expressed in Pa.

[0117] Considering the slight compressibility of the rock skeleton particles and assuming that the reservoir overburden pressure remains constant, equation (23) can be transformed into equation (24) for the fracture compressibility coefficient with respect to pore stress:

[0118]

[0119] Substituting equation (22) into equation (24), equation (24) can be simplified to:

[0120]

[0121] Assume the initial compressibility of the cracks after water intrusion is C. f0 Its representation is shown in the following formula (26):

[0122]

[0123] In the formula: d f0 This refers to the initial thickness of the water molecule layer on the surface of the crack, in meters (m).

[0124] Substituting equation (26) into equation (25), the compressibility coefficient of the unsupported crack after water intrusion can be simplified to equation (27):

[0125]

[0126] For both ends of equation (24), porosity is respectively... and pore stress [p f0 ,p f By performing interval integration, we can simplify to obtain equation (28):

[0127]

[0128] In the formula: The initial crack porosity is under stress-free conditions. p represents the crack porosity under arbitrary stress conditions. f0 This refers to the initial pressure of the crack, in Pa.

[0129] Based on the permeability-porosity cubic law, a mathematical equation is established for the change of shale fracture permeability with porosity, as shown in equation (29):

[0130]

[0131] In the formula: k f The initial permeability of shale fractures under stress-free conditions, m 2 ;k f0 Let m be the fracture permeability under any pressure state. 2 .

[0132] Therefore, substituting equation (28) into equation (29), we obtain the expression for the change of shale fracture permeability with pore stress, as shown in equation (30) below:

[0133]

[0134] Among them, C f This refers to the crack compressibility coefficient; pf0 This refers to the initial pressure of the crack, in Pa. f The crack pressure is expressed in Pa. f0 Let m be the fracture permeability under any pressure state. 2 k f The initial permeability of shale fractures under stress-free conditions.

[0135] It should be noted that formula (30) is an expression that can characterize the relationship between permeability and water intrusion and effective stress. This expression can be used to predict the influence of different water saturation and different effective stress on the gas flow capacity in the matrix or fracture during actual gas development. It has certain theoretical guiding significance for optimizing the degree of gas extraction.

[0136] The technical solution of this invention, in response to a request for stress sensitivity analysis of shale, identifies the target shale to be tested and performs water intrusion treatment on it to achieve the target water saturation. Using a core steady-state permeability testing device, the target shale is controlled under target confining pressure and target flow pressure (i.e., target flow pressure), and when gas flow reaches a steady state, the target gas permeability of the target shale under the target pressure state is determined. Based on the target water saturation, target confining pressure, target flow pressure, and target gas permeability of the target shale, the impact of water intrusion treatment on the stress sensitivity of different flow regions of the target shale is analyzed to guide actual gas extraction. The testing and analysis of shale stress sensitivity through water intrusion treatment and a core steady-state permeability testing device helps guide the achievement of more efficient and safer shale gas extraction.

[0137] Example 2

[0138] Figure 2A This is a schematic diagram showing the fitting effect between experimental data and model results of shale matrix permeability stress sensitivity provided in Embodiment 2 of the present invention; Figure 2B This is a schematic diagram showing the fitting relationship between the semi-logarithmic ratio of shale matrix permeability and effective stress under different water saturation conditions, as provided in Embodiment 2 of the present invention. Figure 2C This is a schematic diagram illustrating the variation of the stress sensitivity coefficient of shale matrix with effective stress under different water saturation conditions, as provided in Embodiment 2 of the present invention. Figure 2D This is a schematic diagram of the correlation between the initial stress sensitivity coefficient and water saturation of shale matrix core provided in Embodiment 2 of the present invention; Figure 2E This is a schematic diagram showing the fitting effect between experimental data and model results of shale fracture permeability stress sensitivity provided in Embodiment 2 of the present invention; Figure 2F This is a schematic diagram of the semi-logarithmic fitting relationship between crack dimensionless permeability and effective stress under different water saturation levels, provided in Embodiment 2 of the present invention. Figure 2GThis is a schematic diagram illustrating the variation of the stress sensitivity coefficient of shale fracture core with effective stress, provided in Embodiment 2 of the present invention. Figure 2H This is a schematic diagram of the correlation between the initial stress sensitivity coefficient and water saturation of shale fracture cores provided in Embodiment 2 of the present invention;

[0139] Based on the above embodiments, this embodiment presents the analytical results obtained from analyzing the impact of water intrusion treatment on the stress sensitivity of different flow regions of the target shale, as detailed below:

[0140] Preferably, by analyzing the impact of water intrusion treatment on the stress sensitivity of the target shale matrix region, the fitting effect between the experimental data and model results of shale matrix permeability stress sensitivity can be obtained (e.g., Figure 2A As shown), the fitting relationship between the half-logarithmic ratio of shale matrix permeability and effective stress under different water saturation conditions (e.g.) Figure 2B (As shown), the variation of shale matrix stress sensitivity coefficient with effective stress under different water saturation conditions (e.g.) Figure 2C (As shown), a chart relating the initial stress sensitivity coefficient of shale matrix core to water saturation (as shown). Figure 2D (As shown).

[0141] Specifically, this invention selected experimental data on the permeability stress sensitivity of shale matrix with a water saturation of 80% to verify the one-dimensional water-infiltrated matrix stress sensitivity theoretical model, and analyzed the influence mechanism of effective stress and water saturation on the stress sensitivity of shale matrix. Figure 2A The experimental characteristics and the fitting effect of the theoretical model on the permeability of shale matrix with effective stress at a water saturation of 0.8 were analyzed. The figures show that the experimental curves of permeability stress sensitivity of water-impregnated shale matrix are in good agreement with the model calculations, with permeability decreasing exponentially with increasing effective stress. When the effective stress increases from 5 MPa to 20 MPa, the pore channels within the water-impregnated shale matrix are gradually compacted, and the permeability rapidly decreases by more than 98%. At this point, the gas within the matrix essentially loses its flow capacity. When the effective stress further increases, the effective permeability of the water-impregnated matrix essentially no longer changes.

[0142] To simplify and intuitively investigate the relationship between matrix permeability and effective stress under different water intrusion conditions, the calculation results of the permeability stress sensitivity model were subjected to binomial data fitting. The fitting curve is shown in [Figure number missing]. Figure 2B The study found that the binomial equation for permeability under different water saturation conditions achieved a good fit of over 99%, indicating that this binomial equation can effectively characterize the variation of permeability with effective stress in water-infiltrated shale. Figure 2B and Figure 2CAs shown, for shale matrix cores under the same water-intrusion state, the greater the effective stress Δp, the more significant the volume compression of the rock matrix skeleton, leading to a reduction in pore volume. The pore compressibility coefficient decreases with increasing effective stress, and the stress sensitivity coefficient γ... m It can be linearly reduced from 16.67% to 35.71%, satisfying the expression γ. m =C·Δp+γ m0 Where C is a preset constant (negative correlation slope), γ m0 Here, Δp is the initial stress sensitivity coefficient, and Δp is the effective stress. The higher the water saturation, the less the stress sensitivity decreases with increasing effective stress; conversely, the more severe the loss of matrix permeability. When the matrix water saturation is as high as 48%–70%, its permeability can decrease by 4 to 5 orders of magnitude under a stress of 35 MPa.

[0143] Figure 2D The initial stress sensitivity coefficient γ of the shale matrix was established when the effective stress was 0 MPa. m0 With water saturation S wa The mathematical relationship of linear positive correlation between them, i.e., γ m0 =A·S wa +B, where γ m0 Let A be the initial stress sensitivity coefficient, and A and B be the corresponding positive correlation slope and bias, respectively. When the water saturation increases to 0.7, the initial stress sensitivity coefficient increases from 0.15 MPa. -1 Increased to 0.21 MPa -1 This represents a 40% increase. Consequently, water intrusion into the matrix causes clay minerals to expand, weakens the cementation between rock matrix skeleton particles, reduces mechanical properties, exacerbates stress sensitivity, and decreases the effective permeability of the rock matrix.

[0144] Preferably, by analyzing the impact of water intrusion treatment on the stress sensitivity of the fractured region of the target shale, the fitting effect between the experimental data and model results of the shale fracture permeability stress sensitivity can be obtained (e.g., Figure 2E (As shown), the semi-logarithmic fitting relationship between crack dimensionless permeability and effective stress under different water saturation levels (e.g.) Figure 2F As shown), the variation law of shale fracture core stress sensitivity coefficient with effective stress (e.g.) Figure 2G (As shown), a chart relating the initial stress sensitivity coefficient of shale fracture cores to water saturation (as shown). Figure 2H (As shown).

[0145] Specifically, based on experimental understanding of the stress sensitivity of permeability in fractured cores with a water saturation of 75%, this invention uses an established stress sensitivity model for unsupported fracture permeability to analyze the variation law of unsupported fracture permeability with effective stress and water saturation from a mechanistic perspective, and to verify the reliability of the empirical equation for stress sensitivity index. Figure 2E The fitting effect between experimental curves and model calculations of permeability stress sensitivity was compared when the water saturation of unsupported fractured shale core samples was 0.75. For example... Figure 2E As shown, the theoretical model for the permeability stress sensitivity of water-infiltrated shale fractures fits the experimental data with an accuracy of over 80%. The decrease in permeability with effective stress can be characterized by an exponential model. When the effective stress applied to an unsupported shale fracture core reaches 30 MPa, the permeability of the fracture after water infiltration can decrease by two orders of magnitude, and the effective flow channels in the fracture are significantly reduced. When the effective stress continues to increase to 55 MPa, the permeability decreases by one order of magnitude, the flow channels are essentially closed, and the permeability hardly changes anymore.

[0146] To investigate the variation of fracture permeability in unsupported shale with effective stress under different water saturation levels, this invention fitted a polynomial equation to the correlation between the logarithm of dimensionless fracture permeability and effective stress, and analyzed the sensitivity of fracture permeability to stress changes under water saturation conditions of 0.90, 0.75, 0.60, and 0.45. (See attached text.) Figure 2F .from Figure 2F and Figure 2G It can be seen that the logarithmic value of dimensionless permeability of water-infiltrated shale fractures decreases nonlinearly with increasing effective stress. Based on the exponential stress sensitivity model, the slope of the curve representing the logarithmic value of dimensionless permeability with respect to effective stress is the stress sensitivity of permeability. Furthermore, the stress sensitivity coefficient of shale fractures is not constant; on the contrary, it exhibits a linear negative correlation with effective stress, satisfying γ... f =C f ·Δp f +γ f0 C f This refers to the rate of change of fracture permeability stress sensitivity with respect to effective stress, Δp f γ represents the change in fracture pressure. f0 This is the initial crack stress sensitivity coefficient.

[0147] When the water saturation of shale fractures is higher, the mechanical properties of the particles on the fracture surface weaken, the volume compression rate increases significantly, and the permeability decreases exponentially with increasing effective stress, meaning the stress sensitivity is higher and the permeability loss is greater. For example... Figure 2H As shown, when the water saturation of the shale fracture core is between 0.45 and 0.90, the initial stress sensitivity coefficient can range from 0.14 MPa. -1 Linear growth to 0.30 MPa -1 Shale fractures can lose 3 to 5 orders of magnitude of permeability under high stress of 55 MPa. Based on this, a linear positive correlation function was established between the initial stress sensitivity coefficient of shale fracture cores and water saturation, namely: γf0 =A f ·S waf +B f , where γ f0 S represents the initial crack stress sensitivity coefficient. waf This represents the water saturation level. A f and B f These represent the corresponding positive correlation slope and bias, respectively.

[0148] Example 3

[0149] Figure 3 This is a structural block diagram of a shale stress sensitivity analysis device provided in Embodiment 3 of the present invention. This embodiment is applicable to situations where the analysis system uses a core steady-state permeability testing device to perform stress sensitivity testing and analysis on the target shale. The shale stress sensitivity analysis device provided in this embodiment can execute the shale stress sensitivity analysis method provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method. The shale stress sensitivity analysis device can be implemented in hardware and / or software and configured in an electronic device with shale stress sensitivity analysis function, executed by the analysis system. The analysis system can control the confining pressure of the target shale by the core steady-state permeability testing device. Figure 3 As shown, the stress sensitivity analysis device for this shale specifically includes:

[0150] The water intrusion module 301 is used to respond to the stress sensitivity analysis request of shale, identify the target shale to be tested, and perform water intrusion treatment on the target shale so that the target shale reaches the target water saturation.

[0151] The determination module 302 is used to control the target shale under the target confining pressure and target flowing pressure through the core steady-state permeability testing device, and determine the target gas permeability of the target shale under the target pressure state when the gas flow is detected to reach a steady state.

[0152] Analysis module 303 is used to analyze the impact of water intrusion treatment on the stress sensitivity of different flow zones of the target shale based on the target water saturation, target confining pressure, target flowing pressure and target gas permeability of the target shale, so as to guide actual gas extraction.

[0153] The technical solution of this invention, in response to a stress sensitivity analysis request for shale, identifies the target shale to be tested and performs water intrusion treatment on it to achieve the target water saturation. Using a core steady-state permeability testing device, the target shale is controlled under target confining pressure and target flowing pressure. When gas flow reaches a steady state, the target gas permeability of the target shale under the target pressure state is determined. Based on the target water saturation, target confining pressure, target flowing pressure, and target gas permeability of the target shale, the impact of water intrusion treatment on the stress sensitivity of different flow regions of the target shale is analyzed to guide actual gas extraction. The testing and analysis of shale stress sensitivity through water intrusion treatment and a core steady-state permeability testing device helps guide the achievement of more efficient and safer shale gas extraction.

[0154] Furthermore, the water intrusion module 301 may include:

[0155] The control unit is used to determine the target temperature and target humidity corresponding to the target water saturation based on the steam method, and to control the target oven containing the target shale to be at the target temperature and target humidity.

[0156] The monitoring unit is used to monitor the quality changes of the target shale placed in the target oven based on a preset period, and to determine the real-time water saturation of the target shale based on the quality changes until the target shale reaches the target water saturation.

[0157] Furthermore, the monitoring unit is specifically used for:

[0158] Based on the changes in quality, determine the mass deviation of the target shale before and after water intrusion;

[0159] The real-time water saturation of the target shale is determined based on the mass deviation value, water density value, core cross-sectional area, core length, and porosity.

[0160] Furthermore, the core steady-state permeability testing device includes at least one of the following: a preset measuring pump, an intermediate container, a pressure sensor, a core holder, a confining pressure pump, a gas flow metering device, a pressure monitoring instrument, and a constant temperature chamber.

[0161] Accordingly, module 302 is specifically used for:

[0162] The confining pressure is applied to the target shale by using the confining pressure pump and core holder in the core steady-state permeability testing device to control the target shale to be under the target confining pressure.

[0163] High-pressure gas is delivered to the target shale through a pre-set measuring pump, intermediate container, and core holder in the core steady-state permeability testing device to apply flow pressure to the target shale.

[0164] Furthermore, the determining module 302 is also used for:

[0165] Based on a preset detection cycle, the gas flow and pressure are detected a preset number of times using the pressure sensor and gas flow meter in the core steady-state permeability testing device. Based on the detection results, it is determined whether the target shale is under the target confining pressure and target flowing pressure, and whether the gas flow has reached a steady state.

[0166] If so, the Darcy formula is used to calculate the target gas permeability of the target shale under the target pressure state.

[0167] Furthermore, the analysis module 303 is specifically used for:

[0168] Based on the mathematical model of stress sensitivity of shale matrix permeability after hydraulic fracturing, the influence of water intrusion treatment on the stress sensitivity of the matrix region of the target shale is analyzed according to the target water saturation, target confining pressure, target flowing pressure and target gas permeability of the target shale.

[0169] Based on a mathematical model of stress sensitivity of shale fracture permeability after hydraulic fracturing, the influence of water intrusion treatment on the stress sensitivity of the fractured area of ​​the target shale is analyzed according to the target water saturation, target confining pressure, target flowing pressure and target gas permeability of the target shale.

[0170] Example 4

[0171] Figure 4 This is a schematic diagram of the structure of the electronic device provided in Embodiment 4 of the present invention. Figure 4 A schematic diagram of an electronic device 10 that can be used to implement embodiments of the present invention is shown. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices (e.g., helmets, glasses, watches, etc.), and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the invention described and / or claimed herein.

[0172] like Figure 4As shown, the electronic device 10 includes at least one processor 11 and a memory, such as a read-only memory (ROM) 12 or a random access memory (RAM) 13, communicatively connected to the at least one processor 11. The memory stores computer programs executable by the at least one processor. The processor 11 can perform various appropriate actions and processes based on the computer program stored in the ROM 12 or loaded from storage unit 18 into the RAM 13. The RAM 13 may also store various programs and data required for the operation of the electronic device 10. The processor 11, ROM 12, and RAM 13 are interconnected via a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0173] Multiple components in electronic device 10 are connected to I / O interface 15, including: input unit 16, such as keyboard, mouse, etc.; output unit 17, such as various types of displays, speakers, etc.; storage unit 18, such as disk, optical disk, etc.; and communication unit 19, such as network card, modem, wireless transceiver, etc. Communication unit 19 allows electronic device 10 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0174] Processor 11 can be a variety of general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. Processor 11 performs the various methods and processes described above, such as the stress sensitivity analysis method for shale.

[0175] In some embodiments, the shale stress sensitivity analysis method can be implemented as a computer program tangibly contained in a computer-readable storage medium, such as storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed on electronic device 10 via ROM 12 and / or communication unit 19. When the computer program is loaded into RAM 13 and executed by processor 11, one or more steps of the shale stress sensitivity analysis method described above can be performed. Alternatively, in other embodiments, processor 11 can be configured to perform the shale stress sensitivity analysis method by any other suitable means (e.g., by means of firmware).

[0176] Various embodiments of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), system-on-a-chip (SoCs), complex programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include implementations in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which may be a dedicated or general-purpose programmable processor, capable of receiving data and instructions from a storage system, at least one input device, and at least one output device, and transmitting data and instructions to the storage system, the at least one input device, and the at least one output device.

[0177] Computer programs used to implement the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when executed by the processor, the computer programs cause the functions / operations specified in the flowcharts and / or block diagrams to be performed. The computer programs may be executed entirely on a machine, partially on a machine, or as a standalone software package, partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0178] In the context of this invention, a computer-readable storage medium can be a tangible medium that may contain or store a computer program for use by or in conjunction with an instruction execution system, apparatus, or device. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0179] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user provides input to the electronic device. Other types of devices can also be used to provide interaction with the user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including sound input, voice input, or tactile input).

[0180] The systems and technologies described herein can be implemented in computing systems that include backend components (e.g., as data servers), or computing systems that include middleware components (e.g., application servers), or computing systems that include frontend components (e.g., user computers with graphical user interfaces or web browsers through which users can interact with implementations of the systems and technologies described herein), or any combination of such backend, middleware, or frontend components. The components of the system can be interconnected via digital data communication of any form or medium (e.g., communication networks). Examples of communication networks include local area networks (LANs), wide area networks (WANs), blockchain networks, and the Internet.

[0181] A computing system can include clients and servers. Clients and servers are generally located far apart and typically interact via communication networks. The client-server relationship is created by computer programs running on the respective computers and having a client-server relationship with each other. The server can be a cloud server, also known as a cloud computing server or cloud host, which is a hosting product within the cloud computing service system to address the shortcomings of traditional physical hosts and VPS services, such as high management difficulty and weak business scalability.

[0182] In one embodiment, the present invention further includes a computer program product, which includes a computer program that, when executed by a processor, implements the stress sensitivity analysis method for shale according to any embodiment of the present invention.

[0183] In the implementation of a computer program product, computer program code for performing the operations of this invention can be written in one or more programming languages ​​or a combination thereof. Programming languages ​​include object-oriented programming languages ​​as well as conventional procedural programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or it can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0184] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0185] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for stress sensitivity analysis of shale, characterized in that, include: In response to the request for stress sensitivity analysis of shale, the target shale to be tested was identified, and the target shale was subjected to water immersion treatment to bring the target shale to the target water saturation. Using a core steady-state permeability testing device, the target shale is controlled under target confining pressure and target flowing pressure, and the target gas permeability of the target shale under the target pressure state is determined when the gas flow is detected to reach a steady state. Based on the target water saturation, target confining pressure, target flowing pressure, and target gas permeability of the target shale, the impact of water intrusion treatment on the stress sensitivity of different flow zones of the target shale is analyzed to guide actual gas extraction.

2. The method according to claim 1, characterized in that, The target shale is subjected to water immersion treatment to achieve the target water saturation level, including: Based on the steam method, the target temperature and target humidity corresponding to the target water saturation are determined, and the target oven containing the target shale is controlled at the target temperature and target humidity. The quality changes of the target shale placed in the target drying oven are monitored based on a preset cycle, and the real-time water saturation of the target shale is determined according to the quality changes until the target shale reaches the target water saturation.

3. The method according to claim 2, characterized in that, Determine the real-time water saturation of the target shale based on changes in mass, including: Based on the changes in quality, determine the mass deviation of the target shale before and after water intrusion; The real-time water saturation of the target shale is determined based on the mass deviation value, water density value, core cross-sectional area, core length, and porosity.

4. The method according to claim 1, characterized in that, in, The core steady-state permeability testing device includes at least one of the following: a preset measuring pump, an intermediate container, a pressure sensor, a core holder, a confining pressure pump, a gas flow metering device, a pressure monitoring instrument, and a constant temperature chamber. Accordingly, the target shale is controlled under target confining pressure and target flowing pressure using a core steady-state permeability testing device, including: High-pressure gas is delivered to the target shale through the preset measuring pump, intermediate container and core holder in the core steady-state permeability testing device to apply flow pressure to the target shale; The confining pressure is applied to the target shale using the confining pressure pump and core holder in the core steady-state permeability testing device to control the target shale under the target confining pressure.

5. The method according to claim 1, characterized in that, When the gas flow reaches a steady state, the target gas permeability of the target shale under the target pressure state is determined, including: Based on a preset detection cycle, the gas flow and pressure are detected a preset number of times using the pressure sensor and gas flow meter in the core steady-state permeability testing device. Based on the detection results, it is determined whether the target shale is under the target confining pressure and target flowing pressure, and whether the gas flow has reached a steady state. If so, the Darcy formula is used to calculate the target gas permeability of the target shale under the target pressure state.

6. The method according to claim 1, characterized in that, Based on the target water saturation, target confining pressure, target flowing pressure, and target gas permeability of the target shale, the effects of water intrusion treatment on the stress sensitivity of different flow zones of the target shale are analyzed, including: Based on the mathematical model of stress sensitivity of shale matrix permeability after hydraulic fracturing, the influence of water intrusion treatment on the stress sensitivity of the matrix region of the target shale is analyzed according to the target water saturation, target confining pressure, target flowing pressure and target gas permeability of the target shale. Based on a mathematical model of stress sensitivity of shale fracture permeability after hydraulic fracturing, the influence of water intrusion treatment on the stress sensitivity of the fractured area of ​​the target shale is analyzed according to the target water saturation, target confining pressure, target flowing pressure and target gas permeability of the target shale.

7. A stress sensitivity analysis device for shale, characterized in that, include: The water intrusion module is used to respond to the stress sensitivity analysis request of shale, identify the target shale to be tested, and perform water intrusion treatment on the target shale to make the target shale reach the target water saturation. The determination module is used to control the target shale under the target confining pressure and target flowing pressure through the core steady-state permeability testing device, and determine the target gas permeability of the target shale under the target pressure state when the gas flow is detected to reach a steady state. The analysis module is used to analyze the impact of water intrusion treatment on the stress sensitivity of different flow zones of the target shale based on the target water saturation, target confining pressure, target flowing pressure, and target gas permeability, so as to guide actual gas extraction.

8. An electronic device, characterized in that, The electronic device includes: At least one processor; and A memory communicatively connected to the at least one processor; wherein, The memory stores a computer program that is executed by the at least one processor to enable the at least one processor to perform the stress sensitivity analysis method for shale according to any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that cause a processor to execute the stress sensitivity analysis method for shale as described in any one of claims 1-6.

10. A computer program product, characterized in that, The computer program product includes a computer program that, when executed by a processor, implements the stress sensitivity analysis method for shale according to any one of claims 1-6.

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