A method and apparatus for shale petrophysical modeling

Abstract

This invention discloses a method and apparatus for shale rock physical modeling. The method includes: determining a maturity index curve based on kerogen maturity correlation curves; determining the density, bulk modulus, and shear modulus curves of kerogen based on discrete data of kerogen modulus and the maturity index curve; determining the porosity curves of organic and inorganic matter based on the adsorbed gas and free gas content curves and the maturity index and density curves of kerogen; determining the dry rock density, P-wave and S-wave velocities, and shear modulus curves based on the density, bulk modulus, and shear modulus curves of kerogen, clay minerals, and other minerals, as well as the total porosity curve, and the porosity curves of organic and inorganic matter; and determining a shale rock physical model based on the dry rock density, P-wave and S-wave velocities, and shear modulus curves, and the bulk modulus and density curves of the mixed fluid. This method enables the reasonable establishment of a shale rock physical model based on the changes in organic matter during the maturation process.

Description

Technical Field

[0001] This invention relates to the field of oil and gas exploration technology, and in particular to a method and apparatus for physical modeling of shale rocks. Background Technology

[0002] Shale oil and gas, as an important unconventional resource in oil and gas exploration and development, has become a hot topic in oil and gas resource research both domestically and internationally. Accurate prediction and effective economic development of shale reservoirs rely on seismic prediction technology based on rock physics. In my country, the geological conditions of shale oil and gas vary greatly across different basins, with complex lithology, making exploration and development challenging. The degree of thermal evolution varies across different regions in China, resulting in significant differences in the organic matter content and maturity of shale reservoirs, and even large variations in organic matter content among different sublayers within the same region. Furthermore, organic matter content is a key indicator determining the quality of shale reservoirs. Numerous studies have shown that organic matter has a significant impact on the elastic parameters of shale reservoirs and is one of the key factors affecting seismic response. The accuracy of organic matter characterization affects the accuracy of rock physics models, thereby affecting the accuracy of quantitative seismic characterization, reservoir prediction, and sweet spot selection, and consequently, well location deployment and horizontal well trajectory design. Therefore, developing high-precision organic matter characterization methods and shale rock physics models is of great significance for saving costs in shale oil and gas exploration and development. Summary of the Invention

[0003] For shale reservoir organic matter modeling methods, current models mainly consider the content and distribution of kerogen, incorporating it into the rock physics modeling process in a certain way (Vernik & Liu, 1997; Bandyopadhyay, 2009; Sayer, 2013; Carcione, 2015). However, the inventors found that the content and properties of kerogen change during maturation, and simply adding a fixed content and modulus to the rock physics model is insufficient to reflect the changes in organic matter during maturation, resulting in insufficient accuracy of the rock physics model. Characterization of organic matter needs to consider its changes during maturation. However, establishing shale rock physics models that consider changes in organic matter faces challenges. For example, the change in the elastic modulus of solid kerogen with maturity is an ill-posed problem. Experimentally measured maturity and kerogen content are sparse points, making it difficult to establish a continuous equation to describe the relationship between them (Emmanuel et al., 2016). Some studies have qualitatively classified kerogen maturity and provided modeling methods for immature, mature, and overmature states (Yin Linjie et al., 2020). However, thermal evolution in actual strata is continuous, and the changes in kerogen maturity and properties are not discrete. In summary, although scholars have conducted research on organic matter characterization methods, they are still in the exploratory stage, and a reliable and cost-effective method is still lacking.

[0004] In order to at least partially solve the technical problems existing in the prior art, the inventors made this invention, which provides a shale rock physics modeling method and apparatus through specific implementation methods, which can reasonably establish a shale rock physics model based on the changes of organic matter during the maturation process.

[0005] In a first aspect, embodiments of the present invention provide a shale rock physical modeling method, comprising:

[0006] The maturity index curve of kerogen is determined based on the selected kerogen maturity correlation curve. The density, bulk modulus, and shear modulus curves of kerogen are determined based on the discrete data of kerogen modulus and the maturity index curve.

[0007] Based on the adsorbed gas content and free gas content curves, as well as the maturity index curve and density curve of kerogen, the organic matter porosity curve and inorganic matter porosity curve are determined.

[0008] Based on the density, bulk modulus, and shear modulus curves of kerogen, clay minerals, and other minerals besides kerogen and clay minerals, as well as the porosity curves, the porosity curves of organic matter, and the porosity curves of inorganic matter, the density, P-wave velocity, and shear modulus curves of dry rock are determined.

[0009] Based on the dry rock density, P-wave velocity, and shear modulus curves, and the mixed fluid bulk modulus and density curves, the density and P-wave velocity curves of shale rock are determined, thus constructing a physical model of shale rock.

[0010] Secondly, embodiments of the present invention provide a shale rock physical modeling device, comprising:

[0011] The kerogen modulus curve determination module is used to determine the maturity index curve of kerogen based on the selected kerogen maturity correlation curve, and to determine the density, bulk modulus and shear modulus curves of kerogen based on the discrete data of kerogen modulus and the maturity index curve.

[0012] The organic and inorganic porosity curve determination module is used to determine the organic porosity curve and the inorganic porosity curve based on the adsorbed gas content and free gas content curves and the maturity index curve and density curve of kerogen.

[0013] The dry rock modulus curve determination module is used to determine the dry rock density, P-wave velocity, and shear modulus curves based on the density, bulk modulus, and shear modulus curves of kerogen, clay minerals, and other minerals besides kerogen and clay minerals, as well as the porosity curves, the organic matter porosity curves, and the inorganic matter porosity curves.

[0014] The shale rock physics model building module is used to determine the density and P- ...P- and P-P- and P-P-

[0015] Thirdly, embodiments of the present invention provide a computer program product with the function of establishing a shale rock physical model, including a computer program / instruction, wherein the computer program / instruction implements the above-mentioned shale rock physical modeling method when executed by a processor.

[0016] Fourthly, embodiments of this disclosure provide a server, 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 above-described shale rock physical modeling method.

[0017] The beneficial effects of the above-described technical solutions provided in the embodiments of the present invention include at least the following:

[0018] The shale rock physics modeling method provided in this embodiment of the invention determines the maturity index curve of kerogen based on a selected kerogen maturity correlation curve. Based on the discrete data of kerogen modulus and the maturity index curve, it determines the density, bulk modulus, and shear modulus curves of kerogen. This solves the problem that experimental data on kerogen modulus consists of very few discrete points, which cannot continuously characterize the maturity of a segment of shale reservoir. It also considers the changes in kerogen properties during the maturation process. Furthermore, based on the adsorbed gas content and free gas content curves, as well as the maturity index and density curves of kerogen, it determines the organic matter porosity curve and inorganic matter porosity curve, considering the influence of changes in rock porosity on the rock's elastic modulus during maturation. Through this method, the quantitative characterization of organic matter in the rock physics model is more accurate, reflecting the changes in organic matter parameters and rock porosity during maturation. The accuracy of shale rock physics modeling is effectively improved, providing a reliable basis for subsequent quantitative characterization studies of shale reservoirs.

[0019] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings.

[0020] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0022] Figure 1 This is a flowchart of the shale rock physical modeling method in Embodiment 1 of the present invention;

[0023] Figure 2 for Figure 1 The detailed implementation flowchart of step S11;

[0024] Figure 3 for Figure 1 The detailed implementation flowchart of step S12 is shown below;

[0025] Figure 4 for Figure 1 The detailed implementation flowchart of step S13 is shown below;

[0026] Figure 5 for Figure 4 The detailed implementation flowchart of step S132 is shown below;

[0027] Figure 6 for Figure 1 The detailed implementation flowchart of step S14 is shown below;

[0028] Figure 7 This is a schematic diagram of the shale rock physical modeling device in an embodiment of the present invention. Detailed Implementation

[0029] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0030] To address the problem in existing technologies that cannot reasonably establish shale rock physics models based on organic matter characterization methods, embodiments of the present invention provide a shale rock physics modeling method and apparatus that can reasonably establish shale rock physics models based on changes in organic matter during the maturation process.

[0031] Example

[0032] This invention provides a shale rock physical modeling method, which first collects the following geological data, core analysis, and well logging data:

[0033] 1) The trends of bulk modulus, shear modulus, density, and content of mineral components (such as quartz, carbonates, pyrite, etc.) with depth.

[0034] 2) Trends in the bulk modulus, shear modulus, density, and volume content of clay minerals with depth;

[0035] 3) The trends of bulk modulus, shear modulus, density, type of kerogen, and volume content of kerogen with depth;

[0036] 4) The type, saturation, bulk modulus, and shear modulus of the pore fluid;

[0037] 5) Laboratory data reflecting kerogen maturity, such as vitrinite reflectance (Ro);

[0038] 6) Well logging curves, including: resistivity, natural gamma, photoelectric absorption index, neutron porosity, P-wave velocity, S-wave velocity, rock density, porosity curves, etc.

[0039] 7) Well logging interpretation results, such as TOC, adsorbed gas and free gas content, water saturation, oil saturation, gas saturation, etc.

[0040] The process of shale rock physical modeling method is as follows: Figure 1 As shown, it includes the following steps:

[0041] Step S11: Determine the maturity index curve of kerogen based on the selected kerogen maturity correlation curve.

[0042] The establishment of the maturity index curve of kerogen can be flexibly achieved by selecting different methods depending on the specific data collected.

[0043] The curves for neutron porosity, total organic carbon content, kerogen content, clay content, rock density, and photoelectric absorption cross section index are the first set of kerogen maturity correlation curves, while the curves for resistivity and pyrite content are the second set of kerogen maturity correlation curves.

[0044] For the method of establishing the maturity index curve of kerogen, please refer to [link to relevant documentation]. Figure 2 As shown, if all the first group of kerogen maturity-related curves are available, proceed to step S111; if all the second group of kerogen maturity-related curves are available, proceed to step S114.

[0045] Step S111: Determine the first maturity index curve of kerogen based on neutron porosity, total organic carbon content, kerogen content, clay content, rock density, and photoelectric absorption cross section index curve.

[0046] Based on the neutron porosity, total organic carbon content, kerogen content, clay content, rock density, and photoelectric absorption cross section index curves, the first maturity index curve of kerogen is determined using the following formula (1):

[0047]

[0048] In formula (1), MI1 is the first maturity index of kerogen, and CNL is the second maturity index of kerogen. measuredFor neutron porosity, CNL clay V is the average neutron response constant of clay. clay Clay content, TOC is total organic carbon content, V k ρ represents the kerogen content. b The density of the rock is measured, and PEF is the photoelectric absorption cross section index. Among them, clay content, total organic carbon content, and kerogen content are all volume contents, that is, the proportion of the rock by volume.

[0049] Step S112: Standardize the first maturity index curve based on the discrete data of vitrinite reflectance.

[0050] Each discrete point in the discrete data of vitrinite reflectance includes depth and vitrinite reflectance R0. The vitrinite reflectance R0 can be a laboratory measurement.

[0051] Based on the vitrinite reflectance R0 measured in the laboratory, a relationship between MI1 and R0 is established. MI1 is normalized and calibrated within the range of R0, so that MI1 and R0 have the same indicative meaning for kerogen maturity, denoted as MI. 1_norm The specific calibration process is as follows:

[0052] The vitrinite reflectance R0 obtained in the laboratory consists of laboratory measurements at several different depths. The R0 measurements are anomaly-free, and the maximum and minimum values ​​of R0 are selected. For example, the minimum R0 value corresponding to depth d1 and the calculated MI1 value from the first maturity index curve are denoted as x1 and y1, respectively; the maximum R0 value corresponding to depth d2 and the calculated MI1 value from the first maturity index curve are denoted as x2 and y2, respectively. The MI1 value at each depth point of the MI1 curve is denoted as y, and MI1 is normalized according to the following formula (2):

[0053] MI 1_norm =(y-y1)*(x2-x1) / (y2-y1)+x1 (2).

[0054] Based on the above method, the calculated MI1 curve is normalized to obtain MI 1_norm .

[0055] Step S113: Use the standardized first maturity index curve as the maturity index curve.

[0056] If the second set of kerogen maturity correlation curves is incomplete or not present, proceed to step S113.

[0057] Step S114: Determine the second maturity index curve of kerogen based on the resistivity curve and the pyrite content curve.

[0058] Based on the resistivity curve and the pyrite content curve, the second maturity index curve of kerogen is determined by the following formula (3):

[0059]

[0060] In formula (3), MI2 is the second maturity index of kerogen, f pyrite For pyrite content, f i V represents the content of the i-th mineral in the shale rock. pyrite Rt is the volume percentage of pyrite in the total mineral content, and S is the resistivity. g S represents the gas saturation level. o This represents the oil saturation. The contents of pyrite and each other mineral are by volume.

[0061] Step S115: Standardize the second maturity index curve based on the discrete data of vitrinite reflectance.

[0062] Following the method in step S112, the calculated MI2 curve is normalized to obtain MI. 2_norm .

[0063] Step S116: Use the standardized second maturity index curve as the maturity index curve.

[0064] If the first group of kerogen maturity correlation curves is incomplete or none are present, proceed to step S116.

[0065] Step S117: Determine the maturity index curve of kerogen based on the standardized first maturity index curve and the second maturity index curve.

[0066] If both the first and second sets of kerogen maturity correlation curves are available, proceed to step S117 and determine the kerogen maturity index MI curve based on the standardized first and second maturity index curves using the following formula (4):

[0067] MI = k1 * MI 1_norm +k2*MI 2_norm (4)

[0068] k1 and k2 are respectively MI 1_norm and MI 2_norm The weights satisfy k1+k2=1.

[0069] MI 1_norm MI 2_norm <0.5% indicates that the organic matter is in the immature to low-maturity stage;

[0070] MI 1_norm MI 2_normThe organic matter content is between 0.5% and 1.3%, which is the maturation stage.

[0071] MI 1_norm MI 2_norm The organic matter content is between 1.3% and 2.0%, which represents the early stage of high maturity.

[0072] MI 1_norm MI 2_norm >2.0%, indicating that the organic matter is in the over-mature stage.

[0073] Step S12: Determine the density, bulk modulus, and shear modulus curves of kerogen based on the discrete data of kerogen modulus and the maturity index curve.

[0074] Based on the pyrolysis experimental analysis results of this region or regions with similar geological backgrounds, the relationship between the density, bulk modulus, shear modulus and maturity index (MI) of the cross-cutting kerogen was established, and the relationship between the three and the maturity index (MI) was established.

[0075] The pyrolysis experimental analysis results are discrete experimental data of kerogen modulus. Each discrete data point includes the depth and the corresponding density, bulk modulus and shear modulus of kerogen.

[0076] See Figure 3 As shown, the specific process of establishing the kerogen modulus curve includes the following steps:

[0077] Step S121: If the maturity index is less than the set value, obtain the first curve segments of the density, bulk modulus and shear modulus of kerogen according to the set constants.

[0078] If the maturity index is less than the set value, the increase in the modulus of solid kerogen and the change in the modulus of porous kerogen due to the transformation of kerogen into pores are very small. At this stage, the modulus of kerogen can be taken as a constant.

[0079] Furthermore, the above setting value can be 0.5%.

[0080] Step S122: If the maturity index is not less than the set value, determine the second curve segment of each modulus of kerogen based on the discrete data of kerogen modulus and the maturity index curve.

[0081] If the maturity index is not less than a set value, solid kerogen generates organic pores as maturity increases, adsorbing oil or gas respectively. The adsorption of oil and gas by these organic pores leads to a decrease in the kerogen modulus. In this case, the elastic parameters of the kerogen can be obtained in the following way:

[0082] Based on the discrete data of kerogen modulus and the corresponding maturity index in the maturity index curve, the correlation coefficient in the following formula (5) is fitted. Based on the correlation coefficient and the maturity index curve, the second curve segments of kerogen density, bulk modulus and shear modulus are obtained respectively. Formula (5) is:

[0083]

[0084] In formula (5), ρ k Density of kerogen, in g / cm³ 3 ;k k The bulk modulus of kerogen is expressed in GPa; Mu. k is the shear modulus of kerogen, in GPa; k1, k2, k3, b1, b2, b3, c1, c2, and c3 are correlation coefficients, determined based on the fitting results.

[0085] Step S123: Combine the first and second curve segments of kerogen density to form a kerogen density curve, combine the first and second curve segments of kerogen bulk modulus to form a kerogen bulk modulus curve, and combine the first and second curve segments of kerogen shear modulus to form a kerogen shear modulus curve.

[0086] Step S13: Determine the organic matter porosity curve and the inorganic matter porosity curve based on the adsorbed gas content and free gas content curves, as well as the maturity index curve and density curve of kerogen.

[0087] The adsorbed gas content and free gas content curves were determined by the following formulas (6) and (7), respectively:

[0088]

[0089]

[0090] In formulas (6) and (7), g adsorb The adsorbed gas content is expressed in m³. 3 / t indicates how many cubic meters of gas are contained in each ton of gas (because natural gas also contains moisture and impurities); V l The Langmuir volume, m, is the TOC-corrected volume at reservoir temperature. 3 / t;P l RL is the Langmuir pressure at reservoir temperature, MPa; P is the reservoir pressure, MPa; g free Free gas content, unit: m 3 / t; ψ is the transformation constant, dimensionless; ρ b Density of rock, g / cm³ 3 B g φ is the gas compressibility coefficient, dimensionless; eEffective porosity, dimensionless; S w The value represents water saturation, which is dimensionless.

[0091] For the specific execution flow of step S13, please refer to [link / reference]. Figure 4 As shown, it includes the following steps:

[0092] Step S131: Determine the inorganic porosity curve based on the adsorbed gas content and free gas content curves.

[0093] Based on the adsorbed gas content and free gas content curves, the inorganic porosity curve is determined using the following formula (8):

[0094]

[0095] In formula (8), φ nk φ represents inorganic porosity, dimensionless; φ represents total porosity, dimensionless; g adsorb For adsorbed gas content, g free This represents the free gas content.

[0096] Step S132: Determine the organic matter porosity curve based on the inorganic matter porosity curve and the maturity index curve and density curve of kerogen.

[0097] See Figure 5 As shown, the specific steps include the following:

[0098] Step S1321: Determine the proportion curve of organic carbon in kerogen based on the maturity index curve of kerogen.

[0099] The proportion curve of organic carbon in kerogen is determined by the following formula (9):

[0100]

[0101] In formula (9), C k denoted as the proportion of organic carbon in kerogen, dimensionless; MI is the maturity index of kerogen; and b is an empirical constant.

[0102] Step S1322: Determine the curve of kerogen content in shale rock solids based on the density curve of organic carbon in kerogen, the density curve of kerogen, and the density curve of mixed minerals other than kerogen.

[0103] The curve representing the kerogen content of shale solids is determined using the following formula (10):

[0104]

[0105] In formula (10), K represents the kerogen content of shale solids; TOC represents the total organic carbon content; ρ kThe density of kerogen, in g / cm³ 3 ;ρ nk Density of mixed minerals other than kerogen, g / cm³ 3 .

[0106] Furthermore, ρ nk It can be calculated using the following formula (11):

[0107]

[0108] In formula (11), f i ρ represents the content of the i-th mineral in the shale rock, specifically its volume content, where i = 1, 2, ..., n, and n is the number of minerals other than kerogen; i The density of the i-th mineral.

[0109] Step S1323: Determine the organic matter porosity curve based on the kerogen content curve of shale rock solids, the inorganic porosity curve, the total porosity curve, and the kerogen volume curve.

[0110] The organic matter porosity curve is determined using the following formulas (12) and (13):

[0111]

[0112] φ=V k φ k +(1-V k )φ nk (13)

[0113] In formulas (12) and (13), V k φ represents the kerogen content. k For organic matter porosity, φ nk φ represents the inorganic porosity, and φ represents the total porosity. Both are dimensionless.

[0114] Step S14: Determine the density, P-wave velocity, and shear modulus curves of dry rock based on the density, bulk modulus, and shear modulus curves of kerogen, clay minerals, and other minerals besides kerogen and clay minerals, as well as the porosity curves, organic matter porosity curves, and inorganic matter porosity curves.

[0115] For details, see Figure 6 As shown, it includes the following steps:

[0116] Step S141: Based on the bulk modulus and shear modulus curves of kerogen and other minerals besides kerogen and clay minerals, determine the bulk modulus and shear modulus curves of the mixed minerals composed of kerogen and other minerals using the Hashin-Shriktman boundary average model.

[0117] Other minerals include quartz, calcite, dolomite, and pyrite.

[0118] Step S142: Based on the density, bulk modulus, and shear modulus curves of the mixed minerals and clay minerals, establish the stiffness modulus matrix of the dry skeleton composed of the mixed minerals and clay minerals.

[0119] Based on the Backus model, the stiffness modulus matrix of the solid dry skeleton containing oriented clay minerals is calculated.

[0120] Based on the bulk modulus and shear modulus curves of the mixed minerals and clay minerals, their longitudinal and transverse wave velocity curves are determined respectively; based on the density and longitudinal and transverse wave velocity curves of the mixed minerals and clay minerals, the stiffness modulus influence factors λ and μ of the mixed minerals and clay minerals are determined respectively using the following formula (14):

[0121]

[0122] In formula (14), ρ is density, v p Let v be the longitudinal wave velocity. s The transverse wave velocity;

[0123] Substituting the stiffness modulus influence factors λ and μ of the mixed minerals and clay minerals into the following formula (15), the stiffness modulus parameters A, B, C, D, F and M of the skeleton composed of mixed minerals and clay minerals are obtained:

[0124]

[0125]

[0126]

[0127]

[0128]

[0129] M = <μ> (15)

[0130] In formula (15), <g>This indicates a weighted average of the attributes within the parentheses based on volume ratio;

[0131] The stiffness modulus matrix of the skeleton is established using the stiffness modulus parameters A, B, C, D, F, and M:

[0132]

[0133] Step S143: Calculate the specified stiffness modulus parameters in the stiffness modulus matrix of dry rock containing pores and microcracks based on the stiffness modulus matrix and the total porosity, vertical effective stress and microcrack density curves.

[0134] Based on the VK model, the stiffness modulus parameters of dry shale containing pores and microcracks were calculated.

[0135] Based on the stiffness modulus parameters C and D in the stiffness modulus matrix and the curves of total porosity, vertical effective stress, and microcrack density, the specified stiffness modulus parameter C in the stiffness modulus matrix of dry rock containing pores and microcracks is calculated using the following formulas (17) and (18). 33d and C 44d :

[0136]

[0137]

[0138] In formulas (17) and (18), d is the pore shape factor, φ is the total porosity, η0 is the crack density, d is the stress sensitivity factor, σ is the vertical effective stress, and f1 and f2 are parameters related to the Poisson's ratio of the matrix, with values ​​generally between 1 and 3.

[0139] Step S144: Determine the density curve of dry rock based on the porosity curves of organic matter, inorganic matter, and kerogen. Determine the longitudinal and transverse wave velocities and shear modulus curves of dry rock based on the specified stiffness modulus parameters.

[0140] The longitudinal and transverse wave velocities of dry rock were calculated using the Thomsen formula, and the density of dry rock was calculated based on the volume of rock components.

[0141] Based on the porosity curves of organic matter and inorganic matter, and the density curve of kerogen, the density curve of dry rock is determined using the following formula (19):

[0142] ρ dry =V k [ρ k -φ k (ρ k -ρ hc )]+(1-V k )[ρ nk -φ nk (ρ nk -ρ w (19)

[0143] In formula (19), ρ dry V is the density of dry rock. k φ represents the kerogen content. k For organic matter porosity, φ nk For inorganic porosity, ρ k ρ is the density of kerogen. hc ρ is the density of the mixed oil and gas. nk ρ represents the density of mixed minerals other than kerogen. w This is the density of water.

[0144] Based on the specified stiffness modulus parameters, the longitudinal and transverse wave velocities and shear modulus curves of dry rock are determined using the following formulas (20)-(22):

[0145]

[0146]

[0147] Mu dry =C 44d (twenty two)

[0148] In formulas (20)-(22), V Pdry V represents the longitudinal wave velocity of dry rock. Sdry For the shear wave velocity of dry rock, Mu dry This represents the dry rock shear modulus.

[0149] Step S15: Based on the dry rock density, P-wave velocity, and shear modulus curves, and the mixed fluid bulk modulus and density curves, determine the density and P-wave velocity curves of shale rock to construct a shale rock physical model.

[0150] First, calculate the bulk modulus and density curve of the mixed fluid according to Wood's formula.

[0151] Then, the shear modulus curve of dry rock is determined as the shear modulus curve of shale rock, and the bulk modulus curve of shale rock is determined based on the longitudinal and transverse wave velocity curves of dry rock and the bulk modulus and density curves of mixed fluid.

[0152] Based on the dry rock density curve, the shear modulus curve and the bulk modulus curve of shale rock, the density and longitudinal and transverse wave velocity curves of shale rock are determined by the following formulas (23)-(25):

[0153] ρ * =(1-φ)ρ dry +φS g ρ g +φS o ρ o +φS w ρ w (twenty three)

[0154]

[0155]

[0156] In formulas (23)-(25), ρ * The density of shale rock, The longitudinal wave velocity of the shale rock. k represents the transverse wave velocity of shale rock. * (w) represents the bulk modulus of shale rock, Mu * ρ is the shear modulus of shale rock, φ is the total porosity, and ρ is the total porosity. dry ρ is the density of dry rock. g ρ is the density of gas. o Let ρ be the density of the oil. w S is the density of water. g S represents the gas saturation level. o S represents oil saturation. w This represents the water saturation level.

[0157] The shale rock physics modeling method provided in this embodiment of the invention determines the maturity index curve of kerogen based on a selected kerogen maturity correlation curve. Based on the discrete data of kerogen modulus and the maturity index curve, it determines the density, bulk modulus, and shear modulus curves of kerogen. This solves the problem that experimental data on kerogen modulus consists of very few discrete points, which cannot continuously characterize the maturity of a segment of shale reservoir. It also considers the changes in kerogen properties during the maturation process. Furthermore, based on the adsorbed gas content and free gas content curves, as well as the maturity index and density curves of kerogen, it determines the organic matter porosity curve and inorganic matter porosity curve, considering the influence of changes in rock porosity on the rock's elastic modulus during maturation. Through this method, the quantitative characterization of organic matter in the rock physics model is more accurate, reflecting the changes in organic matter parameters and rock porosity during maturation. The accuracy of shale rock physics modeling is effectively improved, providing a reliable basis for subsequent quantitative characterization studies of shale reservoirs.

[0158] Based on the inventive concept of this invention, embodiments of this invention also provide a device for determining the content and distribution of asphalt, the structure of which is as follows: Figure 7 As shown, it includes:

[0159] The kerogen modulus curve determination module 71 is used to determine the maturity index curve of kerogen based on the selected kerogen maturity correlation curve, and to determine the density, bulk modulus and shear modulus curves of kerogen based on the discrete data of kerogen modulus and the maturity index curve.

[0160] The organic and inorganic porosity curve determination module 72 is used to determine the organic porosity curve and the inorganic porosity curve based on the adsorbed gas content and free gas content curves and the maturity index curve and density curve of kerogen.

[0161] The dry rock modulus curve determination module 73 is used to determine the dry rock density, longitudinal and transverse wave velocities, and shear modulus curves based on the density, bulk modulus, and shear modulus curves of kerogen, clay minerals, and other minerals besides kerogen and clay minerals, as well as the porosity curves, the organic matter porosity curves, and the inorganic matter porosity curves.

[0162] Shale rock physics model building module 74 is used to determine the density and longitudinal and transverse wave velocity curves of shale rock based on the dry rock density, longitudinal and transverse wave velocities and shear modulus curves and the mixed fluid bulk modulus and density curves, thereby constructing a shale rock physics model.

[0163] Regarding the apparatus in the above embodiments, the specific manner in which each module performs its operation has been described in detail in the embodiments related to the method, and will not be elaborated upon here.

[0164] Based on the inventive concept of this invention, embodiments of this invention also provide a computer program product with the function of establishing a shale rock physical model, including a computer program / instruction, wherein the computer program / instruction implements the above-mentioned shale rock physical modeling method when executed by a processor.

[0165] Based on the inventive concept of the present invention, an embodiment of the present invention also provides a server, 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 above-described shale rock physical modeling method.

[0166] Unless otherwise specifically stated, terms such as processing, calculation, operation, determination, display, etc., may refer to the actions and / or processes of one or more processing or computing systems or similar devices that represent the manipulation and conversion of data representing physical (e.g., electronic) quantities within the registers or memory of the processing system into other data similarly representing physical quantities within the memory, registers, or other such information storage, transmission, or display devices of the processing system. Information and signals can be represented using any of a variety of different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips mentioned throughout the above description can be represented by voltage, current, electromagnetic waves, magnetic fields or particles, light fields or particles, or any combination thereof.

[0167] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process may be rearranged without departing from the scope of this disclosure. The appended method claims provide elements of various steps in an exemplary order and are not intended to limit the scope to the specific order or hierarchy described.

[0168] In the detailed description above, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, the invention is presented with fewer features than all of the features in a single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, with each claim representing a separate preferred embodiment of the invention.

[0169] Those skilled in the art will also understand that the various illustrative logic blocks, modules, circuits, and algorithm steps described in conjunction with the embodiments herein can be implemented as electronic hardware, computer software, or a combination thereof. To clearly illustrate the interchangeability between hardware and software, the various illustrative components, blocks, modules, circuits, and steps described above are generally described in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. Those skilled in the art can implement the described functionality in alternative ways for each specific application; however, such implementation decisions should not be construed as departing from the scope of this disclosure.

[0170] The steps of the methods or algorithms described in conjunction with the embodiments herein can be directly embodied in hardware, software modules executed by a processor, or a combination thereof. The software modules can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium well known in the art. An exemplary storage medium is connected to the processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and storage medium can reside in an ASIC. The ASIC can reside in a user terminal. Alternatively, the processor and storage medium can exist as discrete components in the user terminal.

[0171] For software implementation, the techniques described in this application can be implemented using modules (e.g., procedures, functions, etc.) that perform the functions described in this application. This software code can be stored in memory units and executed by a processor. The memory units can be implemented within the processor or outside the processor; in the latter case, they are communicatively coupled to the processor via various means, as is well known in the art.

[0172] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Furthermore, the term "comprising" as used in the specification or claims is interpreted in a manner similar to the term "including," as it is understood when used as a conjunction in the claims. Additionally, the use of any term "or" in the specification of the claims is intended to mean "non-exclusive or." The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.< / g>

Claims

1. A method of shale petrophysical modeling, characterized in that, include: The maturity index curve of kerogen is determined based on the selected kerogen maturity correlation curve. The density, bulk modulus, and shear modulus curves of kerogen are determined based on the discrete data of kerogen modulus and the maturity index curve. Based on the adsorbed gas content and free gas content curves, as well as the maturity index curve and density curve of kerogen, the organic matter porosity curve and inorganic matter porosity curve are determined. Based on the density, bulk modulus, and shear modulus curves of kerogen, clay minerals, and other minerals besides kerogen and clay minerals, as well as the porosity curves, the porosity curves of organic matter, and the porosity curves of inorganic matter, the density, P-wave velocity, and shear modulus curves of dry rock are determined. Based on the dry rock density, P-wave velocity, and shear modulus curves, and the mixed fluid bulk modulus and density curves, the density and P-wave velocity curves of shale rock are determined, thus constructing a physical model of shale rock. Specifically, determining the density, bulk modulus, and shear modulus curves of kerogen based on the discrete data of kerogen modulus and the maturity index curve includes: If the maturity index is less than the set value, the first curve segments of the density, bulk modulus and shear modulus of kerogen are obtained according to the set constants respectively. If the maturity index is not less than the set value, based on the discrete data of kerogen modulus and the corresponding maturity index in the maturity index curve, the correlation coefficient in the following formula (1) is fitted, and the second curve segments of the density, bulk modulus and shear modulus of kerogen are obtained according to the correlation coefficient and the maturity index curve, respectively. The formula (1) is: （1） In formula (1), is the density of kerogen, is the bulk modulus of kerogen, is the shear modulus of kerogen, and MI is the kerogen maturity index, , , , , , , , and is the correlation coefficient; The kerogen density curve is formed by combining the first and second curve segments of the kerogen density curve, the kerogen bulk modulus curve is formed by combining the first and second curve segments of the kerogen bulk modulus curve, and the kerogen shear modulus curve is formed by combining the first and second curve segments of the kerogen shear modulus curve.

2. The method of claim 1, wherein, The step of determining the maturity index curve of kerogen based on the selected kerogen maturity correlation curve specifically includes: The first maturity index curve of kerogen was determined based on the curves of neutron porosity, total organic carbon content, kerogen content, clay content, rock density, and photoelectric absorption cross section. The second maturity index curve of kerogen was determined based on the resistivity curve and the pyrite content curve. Based on the discrete data of vitrinite reflectance, the first maturity index curve and the second maturity index curve are standardized respectively. The maturity index curve of kerogen is determined based on the standardized first maturity index curve and the second maturity index curve.

3. The method of claim 1, wherein, The step of determining the maturity index curve of kerogen based on the selected kerogen maturity correlation curve specifically includes: The first maturity index curve of kerogen was determined based on the curves of neutron porosity, total organic carbon content, kerogen content, clay content, rock density, and photoelectric absorption cross section. Based on the discrete data of vitrinite reflectance, the first maturity index curve is standardized, and the standardized first maturity index curve is used as the maturity index curve.

4. The method of claim 2 or 3, wherein, The determination of the first maturity index curve of kerogen based on neutron porosity, total organic carbon content, kerogen content, clay content, rock density, and photoelectric absorption cross-section index curves specifically includes: Based on the neutron porosity, total organic carbon content, kerogen content, clay content, rock density, and photoelectric absorption cross section index curves, the first maturity index curve of kerogen is determined by the following formula (2): （2） In Equation (2), MI1 is the first maturity index of kerogen, is the neutron porosity, is the average neutron response constant of clay, is the clay content, is the rock density, and TOC is the total organic carbon content, is the kerogen content, and PEF is the photoelectric absorption cross section index.

5. The method of claim 1, wherein, The step of determining the maturity index curve of kerogen based on the selected kerogen maturity correlation curve specifically includes: The second maturity index curve of kerogen was determined based on the resistivity curve and the pyrite content curve. Based on the discrete data of vitrinite reflectance, the second maturity index curve is standardized, and the standardized second maturity index curve is used as the maturity index curve.

6. The method of claim 2 or 5, wherein, The determination of the second maturity index curve of kerogen based on the resistivity curve and the pyrite content curve specifically includes: Based on the resistivity curve and the pyrite content curve, the second maturity index curve of kerogen is determined by the following formula (3): （3） In formula (3), MI2 is a second maturity index of kerogen, is pyrite content, is content of the i th mineral in shale rock, is pyrite content as a volume percentage of total mineral content, is resistivity, is gas saturation, is oil saturation.

7. The method as described in claim 1, characterized in that, The adsorbed gas content and free gas content curves are determined by the following formulas (4) and (5), respectively: （4） （5） In formulas (4) and (5), For the adsorbed gas content, The Langmuir volume after TOC correction at reservoir temperature. The Langmuir pressure at reservoir temperature. For reservoir pressure, Free gas content, The transformation constant, For rock density, The gas compressibility coefficient, For effective porosity, This represents the water saturation level.

8. The method as described in claim 1, characterized in that, The determination of organic matter porosity curves and inorganic matter porosity curves based on the adsorbed gas content and free gas content curves, and the maturity index curve and density curve of kerogen, specifically includes: The inorganic porosity curve was determined based on the adsorbed gas content and free gas content curves. The organic matter porosity curve is determined based on the inorganic matter porosity curve and the maturity index curve and density curve of kerogen.

9. The method as described in claim 8, characterized in that, The determination of the inorganic porosity curve based on the adsorbed gas content and free gas content curves specifically includes: Based on the adsorbed gas content and free gas content curves, the inorganic porosity curve is determined using the following formula (6): （6） In formula (6), Porosity of inorganic materials Total porosity For the adsorbed gas content, This represents the free gas content.

10. The method as described in claim 8, characterized in that, The determination of the organic matter porosity curve based on the inorganic matter porosity curve and the maturity index curve and density curve of kerogen specifically includes: Based on the maturity index curve of kerogen, the proportion curve of organic carbon in kerogen is determined by the following formula (7): （7） In formula (7), This represents the proportion of organic carbon in kerogen. The maturity index of kerogen. These are empirical constants; Based on the density curve of organic carbon in kerogen, the density curve of kerogen, and the density curve of mixed minerals other than kerogen, the curve of kerogen content in shale rock solids is determined by the following formula (8): （8） In formula (8), K represents the percentage of kerogen in the solid content of shale rock, and TOC represents the total organic carbon content. The density of kerogen, Density of mixed minerals other than kerogen; Based on the kerogen content curve of shale rock solids, the inorganic porosity curve, the total porosity curve, and the kerogen volume curve, the organic porosity curve is determined using the following formulas (9) and (10): （9） （10） In formulas (9) and (10), For kerogen content, For organic matter porosity, Porosity of inorganic materials Total porosity.

11. The method as described in claim 1, characterized in that, The determination of dry rock density, P-wave and S-wave velocities, and shear modulus curves based on the density, bulk modulus, and shear modulus curves of kerogen, clay minerals, and other minerals besides kerogen and clay minerals, as well as the porosity curves of organic matter and inorganic matter, specifically includes: Based on the bulk modulus and shear modulus curves of kerogen and other minerals besides kerogen and clay minerals, the bulk modulus and shear modulus curves of the mixed minerals composed of kerogen and the other minerals were determined by the Hashin-Shriktman boundary average model. Based on the density, bulk modulus, and shear modulus curves of the mixed minerals and clay minerals, the stiffness modulus matrix of the skeleton composed of the mixed minerals and clay minerals is established. Based on the stiffness modulus matrix and the curves of total porosity, vertical effective stress, and microcrack density, calculate the specified stiffness modulus parameters in the stiffness modulus matrix of dry rock containing pores and microcracks. The density curve of dry rock is determined based on the organic matter porosity curve, the inorganic matter porosity curve, and the density curve of kerogen. The longitudinal and transverse wave velocities and shear modulus curves of dry rock are determined based on the specified stiffness modulus parameters.

12. The method as described in claim 11, characterized in that, The process of establishing the stiffness modulus matrix of the skeleton composed of mixed minerals and clay minerals based on the density, bulk modulus, and shear modulus curves of the mixed minerals and clay minerals specifically includes: Based on the bulk modulus and shear modulus curves of the mixed minerals and clay minerals, their longitudinal and transverse wave velocity curves are determined respectively. Based on the density and P-wave and S-wave velocity curves of the mixed minerals and clay minerals, the stiffness modulus influence factors of the mixed minerals and clay minerals are determined by the following formula (11). and : （11） In formula (11), For mineral density, For mineral longitudinal wave velocity, This refers to the transverse wave velocity of the mineral. Influence factors on stiffness modulus of mixed minerals and clay minerals respectively and Substituting these values ​​into the following formula (12), we obtain the stiffness modulus parameters A, B, C, D, F, and M of the dry skeleton composed of mixed minerals and clay minerals: （12） In formula (12), This indicates a weighted average of the attributes within the parentheses based on volume ratio; Based on the stiffness modulus parameters A, B, C, D, F, and M, the following stiffness modulus matrix of the skeleton is established: （13）。 13. The method as described in claim 12, characterized in that, The step of calculating a specified stiffness modulus parameter in the stiffness modulus matrix of dry rock containing pores and microcracks based on the stiffness modulus matrix and the total porosity, vertical effective stress, and microcrack density curves specifically includes: Based on the stiffness modulus parameters C and D in the stiffness modulus matrix and the curves of total porosity, vertical effective stress, and microcrack density, the specified stiffness modulus parameters in the stiffness modulus matrix of dry rock containing pores and microcracks are calculated using the following formulas (14) and (15). and : （14） （15） In formulas (14) and (15), d is the pore shape factor. Total porosity Where is the crack density, and d is the stress sensitivity factor. For vertical effective stress, f1 and f2 are parameters related to the Poisson's ratio of the matrix.

14. The method as described in claim 13, characterized in that, The process of determining the dry rock density curve based on the organic matter porosity curve, inorganic matter porosity curve, and kerogen density curve, and determining the dry rock longitudinal and transverse wave velocities and shear modulus curves based on the specified stiffness modulus parameters, specifically includes: Based on the organic matter porosity curve, inorganic matter porosity curve, and kerogen density curve, the dry rock density curve is determined using the following formula (16): （16） In formula (16), The density of dry rock, For kerogen content, For organic matter porosity, Porosity of inorganic materials The density of kerogen, The density of the mixed oil and gas, The density of mixed minerals other than kerogen. The density of water; Based on the specified stiffness modulus parameters, the longitudinal and transverse wave velocities and shear modulus curves of dry rock are determined using the following formulas (17)-(19): （17） （18） （19） In formulas (17)-(19), For the longitudinal wave velocity of dry rock, For dry rock shear wave velocity, This is the dry rock shear modulus.

15. The method as described in claim 1, characterized in that, The determination of the density and P- and S-wave velocity curves of shale rock based on the dry rock density, P- and S-wave velocities, and shear modulus curves, and the mixed fluid bulk modulus and density curves, specifically includes: The shear modulus curve of the dry rock is determined as the shear modulus curve of the shale rock. Based on the longitudinal and transverse wave velocity curves of the dry rock and the bulk modulus and density curves of the mixed fluid, the bulk modulus curve of the shale rock is determined. Based on the dry rock density curve, shale rock shear modulus curve, and bulk modulus curve, the density and longitudinal and transverse wave velocity curves of the shale rock are determined using the following formulas (20)-(22): （20） （21） （22） In formula (20)-(22), The density of shale rock, The longitudinal wave velocity of the shale rock. The transverse wave velocity of shale rock. The bulk modulus of shale rock. The shear modulus of shale rock. Total porosity The density of dry rock, The density of gas, The density of the oil, The density of water, For gas saturation, Oil saturation This represents the water saturation level.

16. A shale rock physical modeling device, characterized in that, include: The kerogen modulus curve determination module is used to determine the maturity index curve of kerogen based on the selected kerogen maturity correlation curve, and to determine the density, bulk modulus and shear modulus curves of kerogen based on the discrete data of kerogen modulus and the maturity index curve. The organic and inorganic porosity curve determination module is used to determine the organic porosity curve and the inorganic porosity curve based on the adsorbed gas content and free gas content curves and the maturity index curve and density curve of kerogen. The dry rock modulus curve determination module is used to determine the dry rock density, P-wave velocity, and shear modulus curves based on the density, bulk modulus, and shear modulus curves of kerogen, clay minerals, and other minerals besides kerogen and clay minerals, as well as the porosity curves, the organic matter porosity curves, and the inorganic matter porosity curves. The shale rock physical model building module is used to determine the density and P- and P- and P- and P- and P- and P- and P- and P- and P- and P- and P- and P- and P- and P- and P- and P- and P- and P- and P- and P- and P- and P- and P- and P- and P- and P- and P- and P- and P- and P- and P- and P- and P- and P-P ... The kerogen modulus curve determination module determines the density, bulk modulus, and shear modulus curves of kerogen based on the discrete kerogen modulus data and the maturity index curve. Specifically, it is used for: If the maturity index is less than the set value, the first curve segments of the density, bulk modulus, and shear modulus of kerogen are obtained according to the set constants; if the maturity index is not less than the set value, the correlation coefficient in the following formula (1) is fitted according to the discrete data of kerogen modulus and the corresponding maturity index in the maturity index curve, and the second curve segments of the density, bulk modulus, and shear modulus of kerogen are obtained according to the correlation coefficient and the maturity index curve, respectively. The formula (1) is: （1） In formula (1), The density of kerogen, Let be the bulk modulus of kerogen. Here, is the shear modulus of kerogen, and MI is the kerogen maturity index. , , , , , , , and The correlation coefficient is mentioned above; The kerogen density curve is formed by combining the first and second curve segments of the kerogen density curve, the kerogen bulk modulus curve is formed by combining the first and second curve segments of the kerogen bulk modulus curve, and the kerogen shear modulus curve is formed by combining the first and second curve segments of the kerogen shear modulus curve.

17. A computer program product with the function of establishing a shale rock physical model, comprising a computer program / instructions, characterized in that, When the computer program / instruction is executed by the processor, it implements the shale rock physical modeling method according to any one of claims 1 to 15.

18. A server, characterized in that, include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the program, implements the shale rock physical modeling method according to any one of claims 1 to 15.

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