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

Abstract

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

Description

Technical Field

[0001] This invention relates to the field of oil and gas exploration and development technology, and in particular to a method, apparatus, equipment and medium for determining the fracture pressure of shale gas reservoirs. Background Technology

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

[0003] Core laboratory analysis requires drilling and coring, but shale gas reservoir development does not involve coring. Therefore, the fracture pressure of shale gas reservoirs cannot be obtained through core laboratory analysis. Due to cost and engineering complexity considerations, fracture pressure data cannot be obtained for shale gas development wells that do not log in the horizontal section. The DFIT low-pressure test is carried out during the fracturing operation of the first cluster of the first section and has high accuracy only for the fracture pressure of the first cluster of the first section. Summary of the Invention

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

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

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

[0007] The stress state coefficients are determined based on the vertical stress, minimum horizontal principal stress, and maximum horizontal principal stress.

[0008] The clay coefficient and carbonate rock coefficient are determined based on the mineral content of each mineral.

[0009] The fracturing pressure of shale gas reservoirs is calculated based on the mineral content of each mineral, 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.

[0010] Secondly, embodiments of the present invention also provide an apparatus for determining the fracture pressure of a shale gas reservoir, the apparatus comprising:

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

[0012] The stress state coefficient determination module is used to determine the stress state coefficient based on the vertical stress, minimum horizontal principal stress, and maximum horizontal principal stress.

[0013] The clay coefficient and carbonate rock coefficient determination module is used to determine the clay coefficient and carbonate rock coefficient based on the mineral content of each mineral.

[0014] The fracture pressure determination module is used to calculate the fracture pressure of shale gas reservoirs based on the mineral content of each mineral, 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.

[0015] Thirdly, embodiments of the present invention also provide an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method for determining the shale gas reservoir fracture pressure as described in any of the embodiments of the present invention.

[0016] Fourthly, embodiments of the present invention also provide a storage medium for storing computer-executable instructions, which, when executed by a computer processor, are used to perform a method for determining the fracture pressure of a shale gas reservoir as described in any of the embodiments of the present invention.

[0017] The technical solution of this invention determines various parameters of the shale gas reservoir, including mineral content, rock bulk modulus, framework bulk modulus, vertical stress, pore pressure, minimum horizontal principal stress, and maximum horizontal principal stress. Based on the vertical stress, minimum horizontal principal stress, and maximum horizontal principal stress, it determines the stress state coefficient. Based on the mineral content of each mineral, it determines the clay coefficient and carbonate rock coefficient. Finally, based on the mineral content, minimum horizontal principal stress, maximum horizontal principal stress, pore pressure, rock bulk modulus, framework bulk modulus, stress state coefficient, clay coefficient, and carbonate rock coefficient, it calculates the fracture pressure of the shale gas reservoir. This invention fully considers the influence of different stress states and minerals such as clay and carbonate rocks on the fracture pressure, enabling accurate calculation of the fracture pressure of shale gas reservoirs and providing data support for shale gas reservoir logging.

[0018] 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

[0019] 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.

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

[0021] 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 Embodiment 2 of the present invention;

[0022] Figure 3 This is a schematic diagram of the structure of an electronic device provided in Embodiment 3 of the present invention. Detailed Implementation

[0023] 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.

[0024] It should be noted that the terms "first," "second," etc., 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 a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises 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 apparatus.

[0025] Example 1

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

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

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

[0029] The minerals in shale gas reservoirs mainly include quartz, albite, calcite, dolomite, pyrite, illite, montmorillonite, kaolinite, and mica. The types of minerals in the shale gas reservoir and their content can be determined through elemental 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] Bulk modulus describes the elasticity of a homogeneous, isotropic solid; it can be expressed as force per unit area and represents incompressibility. Rock bulk modulus is a common mechanical parameter used to measure the compressive stress of rocks. Skeleton bulk modulus refers to the bulk modulus of the rock skeleton. Vertical stress refers to the internal forces interacting between different parts of a shale gas reservoir in the vertical direction. Pore pressure is equal to the liquid column pressure when fluid in the rock pores can flow directly to the surface; when the fluid cannot flow to the surface, it is equal to the pore wall pressure. Maximum and minimum horizontal principal stresses refer to the maximum and minimum values ​​of tensile and compressive stresses at the midpoint of a stressed 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] Total organic carbon (TOC) and water saturation can be calculated based on the mineral content of each mineral in the shale gas reservoir. Specifically, TOC can be calculated using a fitted curve of nickel obtained from elemental logging measurements. Based on the TOC content, the porosity of the shale gas reservoir is calculated using quartz, calcite, dolomite, and clay in the reservoir minerals. The water saturation is calculated using 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 skeletal density can be obtained by summing the ratios of the content of each mineral to its density and taking the reciprocal. Shale gas reservoirs consist of a rock skeleton, total organic carbon, formation water, and formation gas. The rock density can be obtained from the skeletal density, formation gas density, formation water density, and organic matter density.

[0036] A3. Based on the mineral content, total organic carbon, water saturation, porosity, framework density, and rock density of each mineral, determine the framework longitudinal wave transit time, framework transverse wave transit time, longitudinal wave transit time, transverse wave transit time, rock Poisson's ratio, and rock Young's modulus.

[0037] The longitudinal wave (P-wave) and transverse wave (S-wave) transit times of the skeleton are the differences in arrival times of the P-wave and S-wave, respectively, along different paths during vibration propagation. These transit times can be extracted from full-wave logging data. Based on the logging sonic transit times and rock density, the Poisson's ratio and Young's modulus of the rock can be calculated. This embodiment does not impose any restrictions on the specific calculation methods for the P-wave, S-wave, P-wave, S-wave, Poisson's ratio, and Young's modulus of the skeleton.

[0038] A4. Calculate the bulk modulus of the rock based on the rock density, P-wave transit time, and S-wave transit time, and calculate the bulk modulus of the skeleton based on the skeleton density, P-wave transit time, and S-wave transit time.

[0039] Specifically, the bulk modulus of rock can be calculated using the following formula: Among them, K b-el The bulk modulus of rock is expressed in GPa, ρ. b-el This indicates the density of the rock, expressed in g / cm³. 3 DT sb-el This represents the transverse wave time difference, expressed in μs / m, DT. pb-el This represents the longitudinal wave time difference, expressed in μs / m.

[0040] The bulk modulus of the skeleton can be calculated using the following formula: Among them, K s-el The bulk modulus of the skeleton is expressed in GPa, ρ. s-el This represents the skeletal density, expressed in g / cm³. 3 DT ss-el This represents the frame shear wave time difference, in μs / m, DT. ps-el This represents the longitudinal wave time difference of the skeleton, in μs / m.

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

[0042] Specifically, the vertical stress can be calculated using the following formula: Among them, SV el Represents vertical stress, with units of MPa, ρ a This represents the average density of the overlying strata, usually taken as a constant. g is the acceleration due to gravity, taken as 9.8 m / s². 2 H0 represents the vertical depth of the overlying strata, in meters (m), and ρ b-el Density of rock, in g / cm³ 3 ΔH represents the vertical depth variable between the two points, in meters (m). The vertical depth can be calculated from the well inclination data, and the hydrostatic pressure can be calculated from the vertical depth and water density.

[0043] Specifically, pore pressure can be calculated using the following formula: Among them, P p-el P represents pore pressure, with units of MPa. p hydro This represents hydrostatic pressure, with units of MPa. Porosity is expressed as a percentage (%). This represents the normal compaction porosity of shale, expressed as a percentage (%). x is an empirical coefficient that can be corrected based on the results of the DFIT low-pressure test.

[0044] A6. Calculate the minimum horizontal principal stress based on the rock's 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 using the following formula: Among them, SX el V represents the minimum horizontal principal stress, in MPa. b-el This represents Poisson's ratio, which is dimensionless.

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

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

[0048] The stress state coefficient reflects the influence of different stress states on the fracture pressure. In this embodiment, based on the calculation of fracture pressure according to pore pressure, minimum horizontal principal stress, maximum horizontal principal stress, Biot constant and uniaxial tensile strength, the influence of different stress states on fracture pressure is considered, which improves the accuracy of shale gas reservoir fracture pressure calculation.

[0049] Furthermore, S120 may include:

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

[0051] Specifically, the positive fault coefficient can be calculated using the following formula: Furthermore, the reverse fault coefficient is calculated using the following formula:

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

[0053] When C nf >B f When SS = 1, the stress state coefficient is Among them, B f The fault characteristic identification constant typically ranges from 0 to 0.3. SS represents the stress state, is dimensionless, and takes values ​​of 1, 0, or -1. C s is the stress state coefficient, which is dimensionless.

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

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

[0056] B4. If the normal fault coefficient is determined to be 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 to the difference between the vertical stress and the minimum horizontal principal stress shall be used as the stress state coefficient.

[0057] When C nf ≤B f At that time, or, C rf ≤B f When 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 to the difference between the maximum horizontal principal stress and the minimum horizontal principal stress shall be used as the stress state coefficient.

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

[0060] S130. Determine the clay coefficient and carbonate rock coefficient based on the mineral content of each mineral.

[0061] In this embodiment, the influence of different lithologies of shale gas reservoirs on fracture pressure is fully considered. In 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 content of clay and carbonate rocks, 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 using the following formula: Among them, C clay This represents the clay coefficient, expressed as %, ω. clay-el This indicates the clay content, expressed as %, ω calcite-el This indicates the calcite content, expressed in %, ω dolomite-el This indicates the dolomite content, expressed as a percentage.

[0065] C2. Determine the carbonatite coefficient based on the calcite and dolomite contents.

[0066] Specifically, the carbonatite coefficient can be calculated using the following formula: Among them, C car This represents the carbonatite coefficient.

[0067] S140. Calculate the fracturing pressure of the shale gas reservoir based on 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 of each mineral.

[0068] This embodiment, based on the existing technology for calculating rupture pressure, considers different stress states and the influence of minerals such as clay and carbonate rocks, thus improving the accuracy of the calculated rupture pressure.

[0069] Furthermore, S140 may include:

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

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

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

[0073] Specifically, the tensile strength of rock can be calculated using the following formula: Where T0 represents the tensile strength of the rock, in MPa, and E b-el This represents the Young's modulus of rock, expressed in GPa, ω. clay-el This indicates the clay content.

[0074] D3. Calculate the fracture pressure of the 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 a shale gas reservoir is calculated using 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 This represents the fracture pressure of a shale gas reservoir, expressed in MPa (sq.a.). el This represents the minimum horizontal principal stress, in MPa, SY el P represents the maximum horizontal principal stress, with units of MPa. p-el This represents pore pressure, expressed in MPa and C.clay C represents the clay coefficient, dimensionless. car Represents the carbonatite coefficient, dimensionless, C s This represents the stress state coefficient, which is dimensionless.

[0076] The technical solution of this invention determines various parameters of the shale gas reservoir, including mineral content, rock bulk modulus, framework bulk modulus, vertical stress, pore pressure, minimum horizontal principal stress, and maximum horizontal principal stress. Based on the vertical stress, minimum horizontal principal stress, and maximum horizontal principal stress, it determines the stress state coefficient. Based on the mineral content of each mineral, it determines the clay coefficient and carbonate rock coefficient. Finally, based on the mineral content, minimum horizontal principal stress, maximum horizontal principal stress, pore pressure, rock bulk modulus, framework bulk modulus, stress state coefficient, clay coefficient, and carbonate rock coefficient, it calculates the fracture pressure of the shale gas reservoir. This invention fully considers the influence of different stress states and minerals such as clay and carbonate rocks on the fracture pressure, enabling accurate calculation of the fracture pressure of shale gas reservoirs and providing data support for shale gas reservoir logging.

[0077] Example 2

[0078] Figure 2 This is a schematic diagram of a device for determining the fracture pressure of a shale gas reservoir, provided in Embodiment 2 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. Wherein:

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

[0080] The stress state coefficient determination module 220 is used to determine the stress state coefficient based on the vertical stress, the minimum horizontal principal stress, and the maximum horizontal principal stress.

[0081] Clay coefficient and carbonate rock coefficient determination module 230 is used to determine the clay coefficient and carbonate rock coefficient based on the mineral content of each mineral;

[0082] The fracture pressure determination module 240 is used to calculate the fracture pressure of shale gas reservoirs based on the mineral content of each mineral, 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.

[0083] The technical solution of this invention determines various parameters of the shale gas reservoir, including mineral content, rock bulk modulus, framework bulk modulus, vertical stress, pore pressure, minimum horizontal principal stress, and maximum horizontal principal stress. Based on the vertical stress, minimum horizontal principal stress, and maximum horizontal principal stress, it determines the stress state coefficient. Based on the mineral content of each mineral, it determines the clay coefficient and carbonate rock coefficient. Finally, based on the mineral content, minimum horizontal principal stress, maximum horizontal principal stress, pore pressure, rock bulk modulus, framework bulk modulus, stress state coefficient, clay coefficient, and carbonate rock coefficient, it calculates the fracture pressure of the shale gas reservoir. This invention fully considers the influence of different stress states and minerals such as clay and carbonate rocks on the fracture pressure, enabling accurate calculation of the fracture pressure of shale gas reservoirs and providing data support for shale gas reservoir logging.

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

[0085] The unit for calculating the normal fracture coefficient and the reverse fracture coefficient is used to calculate the normal fracture coefficient based on the vertical stress and the maximum horizontal principal stress, and to calculate the reverse fracture coefficient based on the vertical stress and the minimum horizontal principal stress.

[0086] The first 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 vertical stress and the minimum horizontal principal stress as the stress state coefficient if the normal fault coefficient is determined to be greater than the fault property identification constant.

[0087] The second stress state coefficient calculation unit is used to take 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 the reverse fault coefficient is determined to be greater than the fault property identification constant.

[0088] The third stress state coefficient calculation unit is used to determine the ratio of the difference between the maximum horizontal principal stress and the vertical stress to the difference between the vertical stress and the minimum horizontal principal stress if 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 determine the ratio of the difference between the vertical stress and the maximum horizontal principal stress to the difference between the maximum horizontal principal stress and the minimum horizontal principal stress if 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 embodiments, the clay coefficient and carbonate rock coefficient determination module 230 includes:

[0091] The clay coefficient determination unit is used to determine the clay coefficient based on the clay content, calcite content, and dolomite content.

[0092] The carbonatite coefficient determination unit is used to determine the carbonatite coefficient based on the calcite and dolomite contents.

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

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

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

[0096] The unit for determining the coefficient of carbonate rocks is specifically used for:

[0097] The carbonate rock coefficient is calculated using the following formula:

[0098] Among them, C car This represents the carbonatite coefficient.

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

[0100] The biot constant determination unit is used to determine the biot constant based on the rock bulk modulus and the skeleton bulk modulus.

[0101] The rock tensile strength determination unit is used to determine the rock tensile strength based on the rock's Young's modulus and clay content.

[0102] The fracture pressure calculation unit is used to calculate the fracture pressure of shale gas reservoirs 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.

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

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

[0105] Where α represents the biot constant, K b-el K represents the bulk modulus of rock. s-el This represents the bulk modulus of the skeleton.

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

[0107] The tensile strength of rock can be calculated using the following formula:

[0108] Where T0 represents the tensile strength of the rock, E b-el ω represents the Young's modulus of rock. clay-el This indicates the clay content.

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

[0110] The fracture pressure of a shale gas reservoir is calculated using 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 SX represents the fracture pressure of a shale gas reservoir. el Represents the minimum horizontal principal stress, SY el P represents the maximum horizontal principal stress. p-el C represents pore pressure. clay C represents the clay coefficient. car C represents the carbonatite coefficient. s This represents the stress state coefficient.

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

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

[0114] The density determination unit is used to determine the skeleton density and rock density of shale gas reservoirs 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 longitudinal wave time difference, transverse wave time difference, longitudinal wave time difference, transverse wave time difference, Poisson's ratio, and Young's modulus of the rock based on the mineral content, total organic carbon, water saturation, porosity, framework density, and rock density of each mineral.

[0116] The bulk modulus determination unit is used to calculate the bulk modulus of rock based on rock density, P-wave transit time, and S-wave transit time, and to calculate the bulk modulus of skeleton based on skeleton density, skeleton P-wave transit time, and skeleton S-wave transit time.

[0117] The vertical stress and pore pressure determination unit is used to calculate the vertical stress based on rock density and vertical depth, and to calculate the pore pressure based on 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 based on the rock's Poisson's ratio, vertical stress, and pore pressure, and to calculate the maximum horizontal principal stress based on the minimum horizontal principal stress and pore pressure.

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

[0120] Example 3

[0121] Figure 3 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.

[0122] like Figure 3 As 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.

[0123] 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.

[0124] 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, digital signal processors (DSPs), and any suitable processor, controller, microcontroller, etc. Processor 11 performs the various methods and processes described above, such as methods for determining shale gas reservoir fracture pressure.

[0125] In some embodiments, the method for determining the fracture pressure of a shale gas reservoir 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 method for determining the fracture pressure of a shale gas reservoir described above can be performed. Alternatively, in other embodiments, processor 11 can be configured to perform the method for determining the fracture pressure of a shale gas reservoir by any other suitable means (e.g., by means of firmware).

[0126] 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), systems-on-a-chip (SoCs), payload-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.

[0127] 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.

[0128] 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, or semiconductor systems, apparatus, or devices, or any suitable combination thereof. 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 thereof.

[0129] 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).

[0130] 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.

[0131] A computing system can include clients and servers. Clients and servers are generally located far apart and typically interact through 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.

[0132] 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.

[0133] 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 determining the fracture pressure of a shale gas reservoir, characterized in that, include: Determine the mineral content, rock bulk modulus, framework bulk modulus, vertical stress, pore pressure, minimum horizontal principal stress, and maximum horizontal principal stress of each mineral in the shale gas reservoir. Determine the stress state coefficients based on the vertical stress, minimum horizontal principal stress, and maximum horizontal principal stress, including: The normal fracture coefficient is calculated based on the vertical stress and the maximum horizontal principal stress, and the reverse fracture coefficient is calculated based on the vertical stress and the minimum horizontal principal stress. If the normal fault coefficient is determined to be greater than the fault property identification constant, then the ratio of the difference between the vertical stress and the maximum horizontal principal stress to the difference between the vertical stress and the minimum horizontal principal stress is taken as the stress state coefficient. If the reverse fault coefficient is determined to be greater than the fault property identification constant, then the ratio of the difference between the vertical stress and the minimum horizontal principal stress to the difference between the maximum horizontal principal stress and the vertical stress is taken as the stress state coefficient. If the normal fault coefficient is determined to be 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 to the difference between the vertical stress and the minimum horizontal principal stress is taken 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 to the difference between the maximum horizontal principal stress and the minimum horizontal principal stress is taken as the stress state coefficient. Based on the mineral content of each mineral, the clay coefficient and carbonate rock coefficient are determined, including: The clay coefficient is determined based on the clay content, calcite content, and dolomite content. The clay coefficient is calculated using the following formula: ； in, Indicates the clay coefficient. Indicates clay content, Indicates calcite content, Indicates the dolomite content; The carbonatite coefficient is determined based on the calcite and dolomite contents. The carbonate rock coefficient is calculated using the following formula: ； in, Indicates the carbonatite coefficient; The fracturing pressure of shale gas reservoirs is calculated based on the mineral content of each mineral, 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 fracture pressure of a shale gas reservoir can be calculated using the following formula: ； in, This indicates the fracture pressure of the shale gas reservoir. Indicates the minimum horizontal principal stress. Indicates the maximum horizontal principal stress. Represents the biot constant. Indicates pore pressure, Indicates the tensile strength of rock. Indicates the clay coefficient. Indicates the carbonatite coefficient. This represents the stress state coefficient.

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

3. The method according to claim 2, characterized in that, The biot constant is calculated using the following formula: ； in, Represents the biot constant. Indicates the bulk modulus of rock. Indicates the bulk modulus of the skeleton; The tensile strength of rock can be calculated using the following formula: ； in, Indicates the tensile strength of rock. This indicates the Young's modulus of the rock. This indicates the clay content.

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

5. A device for determining the fracture pressure of a shale gas reservoir, characterized in that, include: The shale gas reservoir parameter determination module is used to determine the mineral content, rock bulk modulus, framework bulk modulus, vertical stress, pore pressure, minimum horizontal principal stress, and maximum horizontal principal stress of each mineral in the shale gas reservoir. The stress state coefficient determination module is used to determine the stress state coefficient based on the vertical stress, minimum horizontal principal stress, and maximum horizontal principal stress. The stress state coefficient determination module includes: The unit for calculating the normal fracture coefficient and the reverse fracture coefficient is used to calculate the normal fracture coefficient based on the vertical stress and the maximum horizontal principal stress, and to calculate the reverse fracture coefficient based on the vertical stress and the minimum horizontal principal stress. The first 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 vertical stress and the minimum horizontal principal stress as the stress state coefficient if the normal fault coefficient is determined to be greater than the fault property identification constant. The second stress state coefficient calculation unit is used to take 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 the reverse fault coefficient is determined to be greater than the fault property identification constant. The third stress state coefficient calculation unit is used to determine the ratio of the difference between the maximum horizontal principal stress and the vertical stress to the difference between the vertical stress and the minimum horizontal principal stress if 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. The fourth stress state coefficient calculation unit is used to determine the ratio of the difference between the vertical stress and the maximum horizontal principal stress to the difference between the maximum horizontal principal stress and the minimum horizontal principal stress if 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. The clay coefficient and carbonate rock coefficient determination module is used to determine the clay coefficient and carbonate rock coefficient based on the mineral content of each mineral. The module for determining clay coefficient and carbonate rock coefficient includes: The clay coefficient determination unit is used to determine the clay coefficient based on the clay content, calcite content, and dolomite content. The clay coefficient determination unit is specifically used to calculate the clay coefficient using the following formula: ;in, Indicates the clay coefficient. Indicates clay content, Indicates calcite content, Indicates the dolomite content; The carbonatite coefficient determination unit is used to determine the carbonatite coefficient based on the calcite and dolomite contents. The carbonate rock coefficient determination unit is specifically used to calculate the carbonate rock coefficient using the following formula: ;in, Indicates the carbonatite coefficient; The fracture pressure determination module is used to calculate the fracture pressure of shale gas reservoirs based on the mineral content of each mineral, 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 fracture pressure determination module includes a fracture pressure calculation unit, specifically used to calculate the fracture pressure of shale gas reservoirs using the following formula: ; in, This indicates the fracture pressure of the shale gas reservoir. Indicates the minimum horizontal principal stress. Indicates the maximum horizontal principal stress. Represents the biot constant. Indicates pore pressure, Indicates the tensile strength of rock. Indicates the clay coefficient. Indicates the carbonatite coefficient. This represents the stress state coefficient.

6. 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, it implements the method for determining the fracture pressure of a shale gas reservoir as described in any one of claims 1-4.

7. A storage medium for storing computer-executable instructions, characterized in that, The computer-executable instructions, when executed by a computer processor, are used to perform the method for determining the fracture pressure of a shale gas reservoir as described in any one of claims 1-4.

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