Method, device and equipment for determining fracture pressure of shale gas reservoir and medium

Abstract

The invention discloses a shale gas reservoir fracture pressure determination method and device, equipment and a medium. The method comprises the following steps: determining the mineral content, the rock bulk modulus, the skeleton bulk modulus, the vertical stress, the pore pressure, the minimum horizontal principal stress and the maximum horizontal principal stress of each mineral of the shale gas reservoir; determining a stress state coefficient according to the vertical stress, the minimum horizontal principal stress and the maximum horizontal principal stress; according to the mineral content of each mineral, determining a clay coefficient and a carbonate rock coefficient; and calculating the fracture pressure of the shale gas reservoir according to the mineral content, the minimum horizontal principal stress, the maximum horizontal principal stress, the pore pressure, the rock bulk modulus, the skeleton bulk modulus, the stress state coefficient, the clay coefficient and the carbonate rock coefficient of each mineral. According to the method, the fracture pressure of the shale gas reservoir can be accurately calculated, and data support is provided for shale gas reservoir logging.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas exploration and development, and in particular to a method, device, equipment and medium for determining the fracture pressure of a shale gas reservoir. Background Art

[0002] In the logging industry, fracture pressure is mainly obtained through the following three methods: core laboratory analysis, logging fracture pressure and DFIT (Diagnostic Fluid Injection Tests) low pressure test.

[0003] Among them, core laboratory analysis requires drilling and coring, but the development of shale gas reservoirs does not involve coring. Therefore, the fracture pressure of shale gas reservoirs cannot be obtained through core laboratory analysis. Due to considerations of cost and engineering complexity, fracture pressure data cannot be obtained for shale gas development wells that do not perform well logging in the horizontal section. The DFIT low-pressure test is implemented during the fracturing construction of the first cluster of the first section, and only has a high accuracy for the fracture pressure of the first cluster of the first section. Summary of the invention

[0004] The present invention provides a method, device, equipment and medium for determining the fracture pressure of a shale gas reservoir, so as to accurately calculate the fracture pressure of a shale gas reservoir and provide data support for well logging of the shale gas reservoir.

[0005] In a first aspect, an embodiment of the present invention provides a method for determining a shale gas reservoir fracture pressure, the method comprising:

[0006] Determine the mineral content of each mineral in the shale gas reservoir, rock bulk modulus, skeleton bulk modulus, vertical stress, pore pressure, minimum horizontal principal stress, and maximum horizontal principal stress;

[0007] Determine the stress state coefficient based on the vertical stress, the minimum horizontal principal stress, and the maximum horizontal principal stress;

[0008] Determine the clay coefficient and carbonate coefficient based on the mineral content of each mineral;

[0009] The fracture pressure of shale gas reservoir is calculated based on the mineral content of each mineral, the minimum horizontal principal stress, the maximum horizontal principal stress, the pore pressure, the rock bulk modulus, the skeleton bulk modulus, the stress state coefficient, the clay coefficient and the carbonate coefficient.

[0010] In a second aspect, an embodiment of the present invention further provides a device for determining a shale gas reservoir fracture pressure, the device comprising:

[0011] A shale gas reservoir parameter determination module is used to determine the mineral content of each mineral in the shale gas reservoir, rock bulk modulus, skeleton bulk modulus, vertical stress, pore pressure, minimum horizontal principal stress and maximum horizontal principal stress;

[0012] A stress state coefficient determination module is used to determine the stress state coefficient according to the vertical stress, the minimum horizontal principal stress, and the maximum horizontal principal stress;

[0013] A clay coefficient and a carbonate coefficient determination module, used to determine the clay coefficient and the carbonate coefficient according to the mineral content of each mineral;

[0014] The fracture pressure determination module is used to calculate the fracture pressure of the shale gas reservoir according to the mineral content of each mineral, the minimum horizontal principal stress, the maximum horizontal principal stress, the pore pressure, the rock bulk modulus, the skeleton bulk modulus, the stress state coefficient, the clay coefficient and the carbonate coefficient.

[0015] In a third aspect, an embodiment of the present invention further provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, a method for determining the shale gas reservoir fracture pressure as described in any one of the embodiments of the present invention is implemented.

[0016] In a fourth aspect, an embodiment of the present invention further provides a storage medium storing computer executable instructions, wherein the computer executable instructions, when executed by a computer processor, are used to execute a method for determining a shale gas reservoir fracture pressure as described in any one of the embodiments of the present invention.

[0017] The technical solution of the embodiment of the present invention determines various parameters of the shale gas reservoir, such as the mineral content, rock bulk modulus, skeleton bulk modulus, vertical stress, pore pressure, minimum horizontal principal stress, and maximum horizontal principal stress, and determines the stress state coefficient according to the vertical stress, minimum horizontal principal stress, and maximum horizontal principal stress, determines the clay coefficient and the carbonate rock coefficient according to the mineral content of each mineral, and finally calculates the fracture pressure of the shale gas reservoir according to the mineral content, minimum horizontal principal stress, maximum horizontal principal stress, pore pressure, rock bulk modulus, skeleton bulk modulus, stress state coefficient, clay coefficient, and carbonate rock coefficient. The present invention fully considers the influence of different stress states and minerals such as clay and carbonate on the fracture pressure, can accurately calculate the fracture pressure of the shale gas reservoir, and provides data support for shale gas reservoir logging.

[0018] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 This is a flow chart of a method for determining the fracture pressure of a shale gas reservoir provided in Example 1 of the present invention;

[0021] Figure 2 This is a schematic structural diagram of a device for determining shale gas reservoir fracture pressure provided in Embodiment 2 of the present invention;

[0022] Figure 3 It is a structural schematic diagram of an electronic device provided in Embodiment 3 of the present invention. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0024] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, 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 that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0025] Embodiment 1

[0026] Figure 1A flow chart of a method for determining a shale gas reservoir fracture pressure is provided for the first embodiment of the present invention. This embodiment is applicable to the case of calculating a shale gas reservoir fracture pressure. The method can be executed by a device for determining a shale gas reservoir fracture pressure. The device for determining a shale gas reservoir fracture pressure can be implemented in the form of hardware and / or software. The device for determining a shale gas reservoir fracture pressure can be configured in an electronic device.

[0027] like Figure 1 As shown, the method includes:

[0028] S110. Determine the mineral content of each mineral in the shale gas reservoir, rock bulk modulus, skeleton bulk modulus, vertical stress, pore pressure, minimum horizontal principal stress, and maximum horizontal principal stress.

[0029] Among them, the minerals in the shale gas reservoir mainly include quartz, albite, calcite, dolomite, pyrite, illite, montmorillonite, kaolinite and mica, etc. The mineral types contained in the shale gas reservoir and the mineral content of each mineral can be determined by element logging mineral inversion. However, this embodiment does not limit the specific method for determining the content of each mineral in the shale gas reservoir.

[0030] The bulk modulus can describe the elasticity of homogeneous isotropic solids and can be expressed as force per unit area, indicating incompressibility. The rock bulk modulus is a common mechanical parameter of rock, which is used to measure the compressive stress resistance of rock. The skeleton bulk modulus refers to the bulk modulus of the rock skeleton. Vertical stress refers to the internal force of the interaction between the internal parts of the shale gas reservoir in the vertical direction. The pore pressure is equal to the liquid column pressure when the fluid in the rock pores can flow directly to the surface, and is equal to the pore wall pressure when the fluid cannot flow to the surface. The maximum horizontal principal stress and the minimum horizontal principal stress refer to the maximum and minimum values ​​of the tensile stress and compressive stress at the midpoint of the load-bearing structure, respectively.

[0031] Furthermore, S110 may include:

[0032] A1. Determine the mineral content, total organic carbon, water saturation and porosity of each mineral in the shale gas reservoir.

[0033] The total organic carbon and water saturation can be calculated based on the mineral content of each mineral in the shale gas reservoir. Specifically, the total organic carbon (TOC) in the shale gas reservoir can be calculated based on the nickel element fitting curve measured by element logging. According to the different total organic carbon contents, the porosity of the shale gas reservoir is calculated based on the quartz, calcite, dolomite and clay in the reservoir minerals. The water saturation of the shale gas reservoir is calculated based on the illite content in the reservoir minerals.

[0034] A2. Determine the skeleton density and rock density of the shale gas reservoir based on the mineral content, total organic carbon, water saturation and porosity of each mineral.

[0035] Specifically, the skeleton density can be obtained by taking the inverse of the sum of the ratios of the content of each mineral and its density. Shale gas reservoirs are composed of rock skeletons, total organic carbon, formation water and formation gas. The rock density can be obtained based on the skeleton density, formation gas density, formation water density and organic matter density.

[0036] A3. According to the mineral content, total organic carbon, water saturation, porosity, skeleton density and rock density of each mineral, determine the skeleton longitudinal wave time difference, skeleton shear wave time difference, longitudinal wave time difference, shear wave time difference, rock Poisson's ratio and rock Young's modulus.

[0037] The skeleton longitudinal wave time difference and the skeleton shear wave time difference are the difference in the arrival time of the acoustic longitudinal wave and the difference in the arrival time of the acoustic shear wave on different paths during the vibration propagation process. The longitudinal wave time difference and the shear wave time difference can be extracted based on the full-wave logging data. According to the logging acoustic wave time difference and the rock density, the rock Poisson's ratio and the rock Young's modulus can be calculated. This embodiment does not limit the specific calculation method of the skeleton longitudinal wave time difference, the skeleton shear wave time difference, the longitudinal wave time difference, the shear wave time difference, the rock Poisson's ratio and the rock Young's modulus.

[0038] A4. Calculate the rock bulk modulus based on rock density, longitudinal wave time difference, and shear wave time difference. Calculate the skeleton bulk modulus based on skeleton density, skeleton longitudinal wave time difference, and skeleton shear wave time difference.

[0039] Specifically, the rock bulk modulus can be calculated using the following formula: Among them, K b-el represents the bulk modulus of rock in GPa, ρ b-el Indicates rock density in g / cm 3 , DT sb-el Indicates the shear wave time difference, in μs / m, DT pb-el It represents the longitudinal wave time difference, and its unit is μs / m.

[0040] The skeleton bulk modulus can be calculated by the following formula: Among them, K s-el represents the bulk modulus of the skeleton, in GPa, ρ s-el Indicates skeleton density in g / cm 3 , DT ss-el Indicates the time difference of the skeleton shear wave, in μs / m, DT ps-el It represents the skeleton longitudinal wave time difference, in μs / m.

[0041] A5. Calculate vertical stress based on rock density and vertical depth, and calculate pore pressure based on vertical stress, porosity, vertical depth and hydrostatic pressure.

[0042] Specifically, the vertical stress can be calculated by the following formula: Among them, SV el Represents vertical stress in MPa, ρ a It represents the average density of the overlying strata, which is usually taken as a constant. g is the acceleration due to gravity, which is taken as 9.8m / s 2 , H0 represents the vertical depth of the overlying stratum, in m, ρ b-el is the rock density, in g / cm 3 , ΔH is the vertical depth variable between two points, in meters. The vertical depth can be calculated based on the well inclination data, and the hydrostatic pressure can be calculated based on the vertical depth and water density.

[0043] Specifically, the pore pressure can be calculated by the following formula: Among them, P p-el Indicates pore pressure in MPa, P p hydro Indicates hydrostatic pressure in MPa. Indicates porosity, unit is %, It represents the normal compaction porosity of shale in %, and x is the empirical coefficient, which can be corrected according to the DFIT small pressure test results.

[0044] A6. Calculate the minimum horizontal principal stress based on the rock Poisson's ratio, vertical stress, and pore pressure, and calculate the maximum horizontal principal stress based on the minimum horizontal principal stress and pore pressure.

[0045] Specifically, the minimum horizontal principal stress can be calculated by the following formula: Among them, SX el Indicates the minimum horizontal principal stress in MPa, v b-el Represents Poisson's ratio, dimensionless.

[0046] The maximum horizontal principal stress can be calculated by the following formula: SY el =3×SX el -2×P p-el ; Among them, SY el Represents the maximum horizontal principal stress in MPa.

[0047] S120. Determine the stress state coefficient based on the vertical stress, the minimum horizontal principal stress, and the maximum horizontal principal stress.

[0048] The stress state coefficient reflects the influence of different stress states on the fracture pressure. This embodiment, on the basis of calculating the fracture pressure according to the pore pressure, the minimum horizontal principal stress, the maximum horizontal principal stress, the Biot constant and the uniaxial tensile strength, considers the influence of different stress states on the fracture pressure, thereby improving the accuracy of the calculation of the fracture pressure of the shale gas reservoir.

[0049] Furthermore, S120 may include:

[0050] B1. Calculate the normal rupture coefficient based on the vertical stress and the maximum horizontal principal stress, and calculate the reverse rupture coefficient based on the vertical stress and the minimum horizontal principal stress.

[0051] Specifically, the positive break coefficient can be calculated by the following formula: And, the reverse breaking coefficient is calculated by the following formula:

[0052] B2. If it is determined that the normal fault coefficient is greater than the fault property identification constant, the ratio of the difference between the vertical stress and the maximum horizontal principal stress and the difference between the vertical stress and the minimum horizontal principal stress is used as the stress state coefficient.

[0053] When C nf >B f When SS=1, the stress state coefficient is Among them, B f It represents the fault property identification constant, which can generally be 0 to 0.3. SS is the stress state, dimensionless, with values ​​of 1, 0, and -1. s is the stress state coefficient, dimensionless.

[0054] B3. If it is determined that the reverse fault coefficient is greater than the fault property identification constant, the ratio of the difference between the vertical stress and the minimum horizontal principal stress and the difference between the maximum horizontal principal stress and the vertical stress is used as the stress state coefficient.

[0055] When C rf >B f When SS=-1, the stress state coefficient is

[0056] B4. If it is determined that the normal fault coefficient is less than or equal to the fault property identification constant, or the reverse fault coefficient is less than or equal to the fault property identification constant, and the vertical stress is greater than the maximum horizontal principal stress, then the ratio of the difference between the maximum horizontal principal stress and the vertical stress and the difference between the vertical stress and the minimum horizontal principal stress is used as the stress state coefficient.

[0057] When C nf ≤B f When, or, C rf ≤B f SS=0. If SVel >SY el ,but

[0058] B5. If it is determined that the normal fault coefficient is less than or equal to the fault property identification constant, or the reverse fault coefficient is less than or equal to the fault property identification constant, and the vertical stress is less than or equal to the maximum horizontal principal stress, then the ratio of the difference between the vertical stress and the maximum horizontal principal stress and the difference between the maximum horizontal principal stress and the minimum horizontal principal stress is used as the stress state coefficient.

[0059] When C nf ≤B f When, or, C rf ≤B f SS=0. If SV el ≤SY el ,but

[0060] S130. Determine the clay coefficient and the carbonate coefficient according to the mineral content of each mineral.

[0061] In this embodiment, the influence of different lithologies of shale gas reservoirs on the fracture pressure is fully considered. In the shale gas reservoirs, the content of clay and carbonate rocks such as calcite and dolomite is positively correlated with the fracture pressure gradient. The higher the clay and carbonate content, the higher the fracture pressure.

[0062] Furthermore, S130 may include:

[0063] C1. Determine the clay coefficient based on the clay content, calcite content and dolomite content.

[0064] Specifically, the clay coefficient can be calculated by the following formula: Among them, C clay Indicates the clay coefficient, unit is %, ω clay-el Indicates clay content, unit is %, ω calcite-el Indicates the calcite content, unit is %, ω dolomite-el Indicates the dolomite content in %.

[0065] C2. Determine the carbonate coefficient based on the calcite content and dolomite content.

[0066] Specifically, the carbonate coefficient can be calculated by the following formula: Among them, C car Represents the carbonate coefficient.

[0067] S140. Calculate the fracture pressure of the shale gas reservoir based on the mineral content of each mineral, the minimum horizontal principal stress, the maximum horizontal principal stress, the pore pressure, the rock bulk modulus, the skeleton bulk modulus, the stress state coefficient, the clay coefficient and the carbonate rock coefficient.

[0068] Based on the calculation of the fracture pressure in the prior art, this embodiment takes into account the influence factors of different stress states and minerals such as clay and carbonate rock, thereby improving the accuracy of the calculation result of the fracture pressure.

[0069] Furthermore, S140 may include:

[0070] D1. Determine the biot constant based on the rock bulk modulus and skeleton bulk modulus.

[0071] Specifically, the biot constant can be calculated by the following formula: Where α is the biot constant, dimensionless, and K b-el represents the rock bulk modulus, K s-el represents the skeleton bulk modulus.

[0072] D2. Determine the tensile strength of rock based on its Young's modulus and clay content.

[0073] Specifically, the tensile strength of rock can be calculated by the following formula: Among them, T0 represents the tensile strength of rock, in MPa, E b-el Represents the Young's modulus of rock in GPa, ω clay-el Indicates the clay content.

[0074] D3. Calculate the fracture pressure of shale gas reservoir based on the minimum horizontal principal stress, maximum horizontal principal stress, biot constant, pore pressure, rock tensile strength, stress state coefficient, clay coefficient and carbonate rock coefficient.

[0075] Specifically, the fracture pressure of shale gas reservoir is calculated by the following formula: FFP el =3×SX el -SY el -α×P p-el +3×T0×(1-C clay -C car )×C s Among them, FFP el Indicates the fracture pressure of shale gas reservoir, in MPa, SX el Represents the minimum horizontal principal stress, in MPa, SY el Indicates the maximum horizontal principal stress, in MPa, P p-el Indicates pore pressure in MPa, C clay represents the clay coefficient, dimensionless, Ccar represents the carbonate coefficient, dimensionless, C s Represents the stress state coefficient, dimensionless.

[0076] The technical solution of the embodiment of the present invention determines various parameters of the shale gas reservoir, such as the mineral content, rock bulk modulus, skeleton bulk modulus, vertical stress, pore pressure, minimum horizontal principal stress, and maximum horizontal principal stress, and determines the stress state coefficient according to the vertical stress, minimum horizontal principal stress, and maximum horizontal principal stress, determines the clay coefficient and the carbonate rock coefficient according to the mineral content of each mineral, and finally calculates the fracture pressure of the shale gas reservoir according to the mineral content, minimum horizontal principal stress, maximum horizontal principal stress, pore pressure, rock bulk modulus, skeleton bulk modulus, stress state coefficient, clay coefficient, and carbonate rock coefficient. The present invention fully considers the influence of different stress states and minerals such as clay and carbonate on the fracture pressure, can accurately calculate the fracture pressure of the shale gas reservoir, and provides data support for shale gas reservoir logging.

[0077] Embodiment 2

[0078] Figure 2 This is a schematic diagram of the structure of a device for determining the fracture pressure of a shale gas reservoir provided in the second embodiment of the present invention. Figure 2 As shown, the device includes: a shale gas reservoir parameter determination module 210, a stress state coefficient determination module 220, a clay coefficient and carbonate rock coefficient determination module 230 and a fracture pressure determination module 240. Among them:

[0079] A shale gas reservoir parameter determination module 210 is used to determine the mineral content of each mineral in the shale gas reservoir, rock bulk modulus, skeleton bulk modulus, vertical stress, pore pressure, minimum horizontal principal stress and maximum horizontal principal stress;

[0080] A stress state coefficient determination module 220 is used to determine the stress state coefficient according to the vertical stress, the minimum horizontal principal stress, and the maximum horizontal principal stress;

[0081] A clay coefficient and carbonate coefficient determination module 230 is used to determine the clay coefficient and carbonate coefficient according to the mineral content of each mineral;

[0082] The fracture pressure determination module 240 is used to calculate the fracture pressure of the shale gas reservoir based on the mineral content of each mineral, the minimum horizontal principal stress, the maximum horizontal principal stress, the pore pressure, the rock bulk modulus, the skeleton bulk modulus, the stress state coefficient, the clay coefficient and the carbonate coefficient.

[0083] The technical solution of the embodiment of the present invention determines various parameters of the shale gas reservoir, such as the mineral content, rock bulk modulus, skeleton bulk modulus, vertical stress, pore pressure, minimum horizontal principal stress, and maximum horizontal principal stress, and determines the stress state coefficient according to the vertical stress, minimum horizontal principal stress, and maximum horizontal principal stress, determines the clay coefficient and the carbonate rock coefficient according to the mineral content of each mineral, and finally calculates the fracture pressure of the shale gas reservoir according to the mineral content, minimum horizontal principal stress, maximum horizontal principal stress, pore pressure, rock bulk modulus, skeleton bulk modulus, stress state coefficient, clay coefficient, and carbonate rock coefficient. The present invention fully considers the influence of different stress states and minerals such as clay and carbonate on the fracture pressure, can accurately calculate the fracture pressure of the shale gas reservoir, and provides data support for shale gas reservoir logging.

[0084] Based on the above embodiment, the stress state coefficient determination module 220 includes:

[0085] A normal breaking coefficient and reverse breaking coefficient calculation unit is used to calculate the normal breaking coefficient according to the vertical stress and the maximum horizontal principal stress, and to calculate the reverse breaking coefficient according to the vertical stress and the minimum horizontal principal stress;

[0086] A first stress state coefficient calculation unit is used to use the ratio of the difference between the vertical stress and the maximum horizontal principal stress and the difference between the vertical stress and the minimum horizontal principal stress as the stress state coefficient if it is determined that the normal fault coefficient is greater than the fault property identification constant;

[0087] a second stress state coefficient calculation unit, for taking the ratio of the difference between the vertical stress and the minimum horizontal principal stress and the difference between the maximum horizontal principal stress and the vertical stress as the stress state coefficient if it is determined that the reverse fault coefficient is greater than the fault property identification constant;

[0088] a third stress state coefficient calculation unit, for taking the ratio of the difference between the maximum horizontal principal stress and the vertical stress and the difference between the vertical stress and the minimum horizontal principal stress as the stress state coefficient if it is determined that the normal fault coefficient is less than or equal to the fault property identification constant, or the reverse fault coefficient is less than or equal to the fault property identification constant, and the vertical stress is greater than the maximum horizontal principal stress;

[0089] The fourth stress state coefficient calculation unit is used to take the ratio of the difference between the vertical stress and the maximum horizontal principal stress and the difference between the maximum horizontal principal stress and the minimum horizontal principal stress as the stress state coefficient if it is determined that the normal fault coefficient is less than or equal to the fault property identification constant, or the reverse fault coefficient is less than or equal to the fault property identification constant, and the vertical stress is less than or equal to the maximum horizontal principal stress.

[0090] Based on the above embodiment, the clay coefficient and carbonate coefficient determination module 230 includes:

[0091] A clay coefficient determination unit is used to determine the clay coefficient according to the clay content, the calcite content and the dolomite content;

[0092] The carbonate coefficient determination unit is used to determine the carbonate coefficient according to the calcite content and the dolomite content.

[0093] Based on the above embodiment, the clay coefficient determination unit is specifically used for:

[0094] The clay coefficient is calculated by the following formula:

[0095] Among them, C clay represents the clay coefficient, ω clay-el Indicates the clay content, ω calcite-el Indicates the calcite content, ω dolomite-el Indicates the dolomite content.

[0096] Carbonate rock coefficient determination unit, specifically used for:

[0097] The carbonatite coefficient is calculated by the following formula:

[0098] Among them, C car Represents the carbonate coefficient.

[0099] Based on the above embodiment, the rupture pressure determination module 240 includes:

[0100] A biot constant determination unit is used to determine the biot constant according to the rock bulk modulus and the skeleton bulk modulus;

[0101] A rock tensile strength determination unit is used to determine the rock tensile strength according to the rock Young's modulus and clay content;

[0102] The fracture pressure calculation unit is used to calculate the fracture pressure of shale gas reservoir according to the minimum horizontal principal stress, the maximum horizontal principal stress, the biot constant, the pore pressure, the rock tensile strength, the stress state coefficient, the clay coefficient and the carbonate coefficient.

[0103] Based on the above embodiment, the biot constant determination unit is specifically used for:

[0104] The biot constant is calculated by the following formula:

[0105] Among them, α represents the biot constant, K b-el represents the rock bulk modulus, K s-el represents the skeleton bulk modulus.

[0106] The rock tensile strength determination unit is specifically used for:

[0107] The tensile strength of rock is calculated by the following formula:

[0108] Among them, T0 represents the tensile strength of rock, E b-el represents the Young's modulus of rock, ω clay-el Indicates the clay content.

[0109] The burst pressure calculation unit is specifically used for:

[0110] The fracture pressure of shale gas reservoirs is calculated by the following formula: FFP el =3×SX el -SY el -α×P p-el +3×T0×(1-C clay -C car )×C s ;

[0111] Among them, FFP el represents the fracture pressure of shale gas reservoir, SX el represents the minimum horizontal principal stress, SY el represents the maximum horizontal principal stress, P p-el represents the pore pressure, C clay represents the clay coefficient, C car represents the carbonate coefficient, C s represents the stress state coefficient.

[0112] Based on the above embodiment, the shale gas reservoir parameter determination module 210 includes:

[0113] A shale gas reservoir parameter determination unit, used to determine the mineral content, total organic carbon, water saturation and porosity of each mineral in the shale gas reservoir;

[0114] A density determination unit for determining the skeleton density and rock density of the shale gas reservoir based on the mineral content, total organic carbon, water saturation and porosity of each mineral;

[0115] The time difference determination unit is used to determine the skeleton longitudinal wave time difference, skeleton shear wave time difference, longitudinal wave time difference, shear wave time difference, rock Poisson's ratio and rock Young's modulus according to the mineral content, total organic carbon, water saturation, porosity, skeleton density and rock density of each mineral;

[0116] The bulk modulus determination unit is used to calculate the rock bulk modulus according to the rock density, the longitudinal wave time difference and the transverse wave time difference, and to calculate the skeleton bulk modulus according to the skeleton density, the skeleton longitudinal wave time difference and the skeleton transverse wave time difference;

[0117] A vertical stress and pore pressure determination unit, for calculating vertical stress according to rock density and vertical depth, and for calculating pore pressure according to vertical stress, porosity, vertical depth and hydrostatic pressure;

[0118] The maximum and minimum horizontal principal stress determination unit is used to calculate the minimum horizontal principal stress according to the Poisson's ratio of the rock, the vertical stress and the pore pressure, and to calculate the maximum horizontal principal stress according to the minimum horizontal principal stress and the pore pressure.

[0119] The device for determining the shale gas reservoir fracture pressure provided in the embodiment of the present invention can execute the method for determining the shale gas reservoir fracture pressure provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method.

[0120] Embodiment 3

[0121] Figure 3 A schematic diagram of the structure of an electronic device 10 that can be used to implement an embodiment 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 processing, cellular phones, smart phones, wearable devices (such as helmets, glasses, watches, etc.) and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present invention described and / or required herein.

[0122] like Figure 3 As shown, the electronic device 10 includes at least one processor 11, and a memory connected to the at least one processor 11, such as a read-only memory (ROM) 12, a random access memory (RAM) 13, etc., wherein the memory stores a computer program that can be executed by at least one processor, and the processor 11 can perform various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 12 or the computer program loaded from the storage unit 18 to the random access memory (RAM) 13. In the RAM 13, various programs and data required for the operation of the electronic device 10 can also be stored. The processor 11, the ROM 12, and the RAM 13 are connected to each other through a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0123] A number of components in the electronic device 10 are connected to the I / O interface 15, including: an input unit 16, such as a keyboard, a mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a disk, an optical disk, etc.; and a communication unit 19, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 19 allows the electronic device 10 to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0124] The processor 11 may be a variety of general and / or special processing components with processing and computing capabilities. Some examples of the processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, digital signal processors (DSPs), and any appropriate processors, controllers, microcontrollers, etc. The processor 11 executes the various methods and processes described above, such as a method for determining the fracture pressure of a shale gas reservoir.

[0125] In some embodiments, the method for determining the fracture pressure of a shale gas reservoir may be implemented as a computer program, which is tangibly contained in a computer-readable storage medium, such as a storage unit 18. In some embodiments, part or all of the computer program may be loaded and / or installed on the electronic device 10 via the ROM 12 and / or the communication unit 19. When the computer program is loaded into the RAM 13 and executed by the processor 11, one or more steps of the method for determining the fracture pressure of a shale gas reservoir described above may be performed. Alternatively, in other embodiments, the processor 11 may be configured to perform the method for determining the fracture pressure of a shale gas reservoir in any other appropriate manner (e.g., by means of firmware).

[0126] Various implementations 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), systems on chips (SOCs), load programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various implementations can include: being implemented in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0127] Computer programs for implementing 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, so that when the computer program is executed by the processor, the functions / operations specified in the flow chart and / or block diagram are implemented. The computer program may be executed entirely on the machine, partially on the machine, partially on the machine and partially on a remote machine as a stand-alone software package, or entirely on a remote machine or server.

[0128] In the context of the present invention, a computer-readable storage medium may be a tangible medium that may contain or store a computer program for use by or in combination with an instruction execution system, device or equipment. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices or equipment, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0129] To provide interaction with a user, the systems and techniques described herein may 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 a pointing device (e.g., a mouse or trackball) through which the user can provide input to the electronic device. Other types of devices may also be used to provide interaction with the user; for example, the feedback provided to the user may be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user may be received in any form (including acoustic input, voice input, or tactile input).

[0130] The systems and techniques described herein may be implemented in a computing system that includes backend components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes frontend components (e.g., a user computer with a graphical user interface or a web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such backend components, middleware components, or frontend components. The components of the system may be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), a blockchain network, and the Internet.

[0131] A computing system may include a client and a server. The client and the server are generally remote from each other and usually interact through a communication network. The client and server relationship is generated by computer programs running on the corresponding computers and having a client-server relationship with each other. The server may be a cloud server, also known as a cloud computing server or cloud host, which is a host product in the cloud computing service system to solve the defects of difficult management and weak business scalability in traditional physical hosts and VPS services.

[0132] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0133] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for determining the fracture pressure of a shale gas reservoir, characterized in that: include: Determine the mineral content of each mineral in the shale gas reservoir, rock bulk modulus, skeleton bulk modulus, vertical stress, pore pressure, minimum horizontal principal stress, and maximum horizontal principal stress; Determine the stress state coefficient based on the vertical stress, the minimum horizontal principal stress, and the maximum horizontal principal stress; Determine the clay coefficient and carbonate coefficient based on the mineral content of each mineral; The fracture pressure of shale gas reservoir is calculated based on the mineral content of each mineral, the minimum horizontal principal stress, the maximum horizontal principal stress, the pore pressure, the rock bulk modulus, the skeleton bulk modulus, the stress state coefficient, the clay coefficient and the carbonate coefficient.

2. The method according to claim 1, characterized in that: According to the vertical stress, the minimum horizontal principal stress and the maximum horizontal principal stress, the stress state coefficient is determined, including: Calculate the normal shear coefficient based on the vertical stress and the maximum horizontal principal stress, and calculate the reverse shear coefficient based on the vertical stress and the minimum horizontal principal stress; If it is determined that the normal fault coefficient is greater than the fault property identification constant, the ratio of the difference between the vertical stress and the maximum horizontal principal stress and the difference between the vertical stress and the minimum horizontal principal stress is used as the stress state coefficient; If it is determined that the reverse fault coefficient is greater than the fault property identification constant, the ratio of the difference between the vertical stress and the minimum horizontal principal stress and the difference between the maximum horizontal principal stress and the vertical stress is used as the stress state coefficient; If it is determined that the normal fault coefficient is less than or equal to the fault property identification constant, or the reverse fault coefficient is less than or equal to the fault property identification constant, and the vertical stress is greater than the maximum horizontal principal stress, then the ratio of the difference between the maximum horizontal principal stress and the vertical stress and the difference between the vertical stress and the minimum horizontal principal stress is used as the stress state coefficient; If it is determined that the normal fault coefficient is less than or equal to the fault property identification constant, or the reverse fault coefficient is less than or equal to the fault property identification constant, and the vertical stress is less than or equal to the maximum horizontal principal stress, then the ratio of the difference between the vertical stress and the maximum horizontal principal stress and the difference between the maximum horizontal principal stress and the minimum horizontal principal stress is used as the stress state coefficient.

3. The method according to claim 1, characterized in that: According to the mineral content of each mineral, the clay coefficient and carbonate coefficient are determined, including: Determine the clay coefficient based on the clay content, calcite content and dolomite content; The carbonate coefficient is determined based on the calcite content and dolomite content.

4. The method according to claim 3, characterized in that The clay coefficient is calculated by the following formula: Among them, C clay represents the clay coefficient, ω clay-el Indicates the clay content, ω calcite-el Indicates the calcite content, ω dolomite-el Indicates dolomite content; The carbonatite coefficient is calculated by the following formula: Among them, C car Represents the carbonate coefficient.

5. The method according to claim 1, characterized in that The fracture pressure of shale gas reservoir is calculated based on the mineral content of each mineral, the minimum horizontal principal stress, the maximum horizontal principal stress, the pore pressure, the rock bulk modulus, the skeleton bulk modulus, the stress state coefficient, the clay coefficient and the carbonate coefficient, including: According to the rock bulk modulus and skeleton bulk modulus, the biot constant is determined; Determine the rock tensile strength based on the rock's Young's modulus and clay content; The fracture pressure of shale gas reservoir is calculated based on the minimum horizontal principal stress, maximum horizontal principal stress, biot constant, pore pressure, rock tensile strength, stress state coefficient, clay coefficient and carbonate rock coefficient.

6. The method according to claim 5, characterized in that The biot constant is calculated by the following formula: Among them, α represents the biot constant, K b-el represents the rock bulk modulus, K s-el represents the skeleton bulk modulus; The tensile strength of rock is calculated by the following formula: Among them, T0 represents the tensile strength of rock, E b-el represents the Young's modulus of rock, ω clay-el Indicates clay content; The fracture pressure of shale gas reservoir is calculated by the following formula: FFP el =3×SX el -YES el -α×P p-el +3×T0×(1-C clay -C car )×C s ; Among them, FFP el represents the fracture pressure of shale gas reservoir, SX el represents the minimum horizontal principal stress, SY el represents the maximum horizontal principal stress, P p-el represents the pore pressure, C clay represents the clay coefficient, C car represents the carbonate coefficient, C s represents the stress state coefficient.

7. The method according to claim 1, characterized in that Determine the mineral content of each mineral in the shale gas reservoir, rock bulk modulus, skeleton bulk modulus, vertical stress, pore pressure, minimum horizontal principal stress, and maximum horizontal principal stress, including: Determine the mineral content, total organic carbon, water saturation, and porosity of shale gas reservoirs; Determine the skeleton density and rock density of the shale gas reservoir based on the mineral content, total organic carbon, water saturation and porosity of each mineral; According to the mineral content, total organic carbon, water saturation, porosity, skeleton density and rock density of each mineral, determine the skeleton P-wave time difference, skeleton S-wave time difference, P-wave time difference, S-wave time difference, rock Poisson's ratio and rock Young's modulus; The rock bulk modulus is calculated according to the rock density, the longitudinal wave time difference and the transverse wave time difference, and the skeleton bulk modulus is calculated according to the skeleton density, the skeleton longitudinal wave time difference and the skeleton transverse wave time difference; Calculate vertical stress based on rock density and vertical depth, and calculate pore pressure based on vertical stress, porosity, vertical depth and hydrostatic pressure; The minimum horizontal principal stress is calculated based on the Poisson's ratio, vertical stress and pore pressure of the rock, and the maximum horizontal principal stress is calculated based on the minimum horizontal principal stress and pore pressure.

8. A device for determining the fracture pressure of a shale gas reservoir, characterized in that: include: A shale gas reservoir parameter determination module is used to determine the mineral content of each mineral in the shale gas reservoir, rock bulk modulus, skeleton bulk modulus, vertical stress, pore pressure, minimum horizontal principal stress and maximum horizontal principal stress; A stress state coefficient determination module is used to determine the stress state coefficient according to the vertical stress, the minimum horizontal principal stress, and the maximum horizontal principal stress; A clay coefficient and a carbonate coefficient determination module, used to determine the clay coefficient and the carbonate coefficient according to the mineral content of each mineral; The fracture pressure determination module is used to calculate the fracture pressure of the shale gas reservoir according to the mineral content of each mineral, the minimum horizontal principal stress, the maximum horizontal principal stress, the pore pressure, the rock bulk modulus, the skeleton bulk modulus, the stress state coefficient, the clay coefficient and the carbonate coefficient.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the method for determining the shale gas reservoir fracture pressure as described in any one of claims 1-7 is implemented.

10. A storage medium storing computer executable instructions, characterized in that: The computer executable instructions are used to execute the method for determining the fracture pressure of a shale gas reservoir as described in any one of claims 1 to 7 when executed by a computer processor.

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