Method and system for establishing shale gas microscopic reservoir model and storage medium

Abstract

The invention discloses a method and system for establishing a shale gas microscopic reservoir model and a storage medium. The method comprises the steps that a shale layer drilling rock core sample is obtained; performing a fluid analysis experiment, a material composition experiment and a storage physical property experiment on the shale layer drilling core sample to obtain various geological parameters of the shale layer; based on various geological parameters of a shale layer, performing control analysis of total organic carbon on the gas content of the shale, control analysis of clay minerals on the water content and the gas content of the shale, control analysis of storage physical properties on the gas content of the shale and quantitative analysis of the occurrence state of the shale gas; and based on a geological parameter correlation analysis conclusion, determining a constraint relationship among geological parameters, and further establishing a semi-quantitative shale gas microscopic reservoir model based on correlation analysis. According to the method, data fusion analysis is carried out based on various geological parameters of the shale gas reservoir, the constraint relation between the parameters is determined, a more comprehensive shale gas microscopic reservoir model is formed, and a scientific basis is provided for shale gas geological evaluation.

Description

Technical Field

[0001] The present invention relates to the technical field of shale gas geological exploration, and in particular to a method, system and storage medium for establishing a shale gas microscopic reservoir model. Background Art

[0002] As a clean energy source, shale gas has made significant breakthroughs in the deepwater shelf shale formations of the Sichuan Basin. However, because shale gas is primarily present in tiny pores and fractures in adsorbed, free, and slightly dissolved states, there is currently a lack of effective methods for accurately and quantitatively evaluating its microscopic state in reservoirs. The occurrence of shale gas depends not only on the organic matter content but also on multiple factors such as mineral composition, pore type, and fluid composition. Traditional evaluation methods have the following limitations:

[0003] Mainly static characterization: Conventional scanning electron microscopy (SEM) and adsorption experiments can only observe pore morphology statically, but it is difficult to dynamically reveal the dynamic changes of pores during diagenetic evolution or fracturing;

[0004] Insufficient multi-factor coupling analysis: Existing technologies often analyze organic matter content or mineral composition in isolation, and fail to systematically establish quantitative correlations between pore structure, geochemistry, and fluid occurrence.

[0005] In summary, traditional evaluation methods are difficult to fully reveal the microscopic occurrence mechanism of shale gas, which restricts the development of shale gas microscopic storage theory and slows down the pace of shale gas exploration and development in my country from deepwater shelf phase to other sedimentary phases. It directly affects the progress of shale gas exploration and development and economic and social benefits in my country, and urgently needs innovative breakthroughs in effective methods. Summary of the Invention

[0006] The purpose of the present invention is to provide a method, system and storage medium for establishing a shale gas micro-reservoir model, perform data fusion analysis based on various geological parameters of shale gas reservoirs, clarify the constraint relationship between various geological parameters, form a more comprehensive shale gas micro-reservoir model, and provide a scientific basis for shale gas geological evaluation.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] A method for establishing a shale gas microscopic reservoir model comprises the following steps:

[0009] Obtaining drill core samples from shale formations;

[0010] Conduct fluid analysis experiments, material composition experiments, and reservoir property experiments on shale drilling core samples to obtain various geological parameters of the shale layer;

[0011] Conduct correlation analysis of geological parameters based on various geological parameters of shale formations, including analysis of the control of total organic carbon on shale gas content, analysis of the control of clay minerals on shale water and gas content, analysis of the control of reservoir properties on shale gas content, and quantitative analysis of shale gas occurrence status;

[0012] Based on the conclusions of geological parameter correlation analysis, determine the constraint relationship between geological parameters;

[0013] Based on the constraint relationship between geological parameters, a semi-quantitative shale gas micro-reservoir model based on correlation analysis was established.

[0014] Furthermore, the method for obtaining shale layer drilling core samples is:

[0015] The sealed coring technology is used to obtain shale drilling core samples.

[0016] Furthermore, the fluid analysis experiment includes:

[0017] Conduct water saturation tests, on-site analytical experiments, and methane high-pressure isothermal adsorption experiments to measure the water saturation, gas content, and theoretical maximum value of adsorbed methane in shale core samples;

[0018] The material composition experiment includes:

[0019] The mineral content, total organic carbon content, microscopic components and reflectivity of shale layer drilling core samples are measured by rock and mineral identification and X-ray diffraction technology to determine geochemical parameters, including major lithofacies types, organic matter abundance, type and maturity;

[0020] The reservoir property experiments include:

[0021] Helium porosity testing is used to determine the porosity of shale drill core samples;

[0022] The specific surface area, pore volume, and pore size distribution were measured using nitrogen adsorption analysis;

[0023] Combined with field emission scanning electron microscopy, different pore types were observed and analyzed, including organic pores, clay mineral intergranular pores, clay mineral intragranular pores and microcracks.

[0024] Furthermore, the control analysis of total organic carbon on shale gas content includes:

[0025] The linear fitting method was used to analyze the correlation between total organic carbon content and pore volume, porosity, specific surface area, Langmuir volume, and shale gas content, as well as the correlation between shale gas content and Langmuir volume, to clarify the influence of total organic carbon content on shale gas content and reveal the influence of organic pores on shale gas occurrence.

[0026] Furthermore, the control analysis of clay minerals on the water and gas content of shale includes:

[0027] The linear fitting method was used to analyze the correlation between clay mineral content and pore volume, porosity, water saturation, shale gas content, and Langmuir volume, as well as the correlation between pore volume and water saturation, to clarify the effect of clay mineral content on the occurrence of water and shale gas, and to reveal the competitive adsorption capacity of water and methane gas in clay minerals.

[0028] Furthermore, the control analysis of reservoir properties on shale gas-bearing properties includes:

[0029] The linear fitting method is used to analyze the correlation between porosity volume and Langmuir volume and Langmuir pressure, and the correlation between shale gas content and pore volume and porosity, clarify the impact of pores of different sizes on shale gas content, and reveal the pore space location where shale gas mainly exists.

[0030] Furthermore, the quantitative analysis of the shale gas occurrence state includes:

[0031] Determine the actual values of desorbed gas, lost gas and total gas content in shale through field analytical experiments;

[0032] Considering the influence of geological conditions on shale gas occurrence, the theoretical values of total gas content, free gas content and adsorbed gas content in shale are calculated according to formulas (1)-(3):

[0033]

[0034] in, Indicates the total gas content corresponding to the burial depth H, represents the excess adsorption capacity corresponding to the burial depth H, S w represents water saturation, Φ represents porosity, ρ apparent represents the apparent density, represents the gas phase density of methane gas under reservoir conditions, represents the density of methane gas under standard conditions, represents the maximum absolute adsorption capacity corresponding to the burial depth H, represents the methane adsorption phase density;

[0035] The theoretical values of total gas content, free gas content and adsorbed gas content are compared with the actual values of desorbed gas, lost gas and total gas content to analyze the ratio of adsorbed gas to free gas in shale and clarify the occurrence status of adsorbed gas and free gas in pores of different types and sizes.

[0036] Furthermore, the constraint relationship between geological parameters is determined based on the conclusion of the geological parameter correlation analysis, specifically including:

[0037] Based on the conclusions of the geological parameter correlation analysis, combined with the characteristics of the occurrence locations of different types of minerals, organic matter, different types of pores, and water obtained by field emission scanning electron microscopy and their influence on the occurrence of adsorbed gas and free gas, the distribution of adsorbed gas, free gas and water molecules in organic matter pores, clay mineral pores, dissolution pores and microcracks was clarified, and the constraint relationship between geological parameters was determined.

[0038] The present invention also provides a system for establishing a shale gas microscopic reservoir model, which is applied to the above-mentioned method for establishing a shale gas microscopic reservoir model. The system comprises:

[0039] The data acquisition module is used to obtain various geological parameters of the shale layer based on the experimental results of fluid analysis experiments, material composition experiments and reservoir physical property experiments on shale layer drilling core samples;

[0040] The data analysis module is used to conduct geological parameter correlation analysis based on various geological parameters of shale layers, including analysis of the control of total organic carbon on shale gas content, analysis of the control of clay minerals on shale water and gas content, analysis of the control of reservoir properties on shale gas content, and quantitative analysis of shale gas occurrence status. It is also used to determine the constraint relationship between geological parameters based on the conclusions of geological parameter correlation analysis;

[0041] The model building module is used to establish a semi-quantitative shale gas micro-reservoir model based on correlation analysis based on the constraint relationship between geological parameters.

[0042] The present invention also provides a computer-readable storage medium storing executable instructions, which, when executed, enable a processor to execute the method for establishing a shale gas microscopic reservoir model as described above.

[0043] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects: the method, system and storage medium for establishing a shale gas micro-reservoir model provided by the present invention first obtain various geological parameters of the shale gas reservoir through fluid analysis experiments, material composition experiments and reservoir property experiments of samples, and overcome the limitation of traditional methods relying on a single parameter by integrating multi-source data such as fluid analysis (water saturation, gas content), material composition (TOC, mineral content) and reservoir properties (porosity, pore type); then, analysis of the control of total organic carbon on shale gas content, analysis of the control of clay minerals on shale water and gas content, analysis of the control of reservoir properties on shale gas content, and quantitative analysis of shale gas occurrence state are conducted to determine the constraint relationship between geological parameters, thus achieving a leap from "qualitative description" to "semi-quantitative prediction" in shale gas micro-reservoir evaluation; finally, based on the constraint relationship between geological parameters, a semi-quantitative shale gas micro-reservoir model based on correlation analysis is established. The shale gas micro-reservoir model established through the above steps integrates multiple geological parameters, provides a more comprehensive analysis, and reveals the controlling factors of shale gas occurrence and content. It helps to enrich the shale gas micro-reservoir theory, solves the problems of low precision and poor adaptability of traditional methods, and provides key technical support for the exploration and development of shale gas in non-deepwater shelf phases in my country. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0045] Figure 1 A flow chart of the method for establishing a shale gas microscopic reservoir model of the present invention;

[0046] Figure 2 Schematic diagram of parameter correlation curves for the control analysis of total organic carbon on shale gas content in an embodiment of the present invention, wherein (a) is the correlation curve between total organic carbon content and pore volume; (b) is the correlation curve between total organic carbon content and porosity; (c) is the correlation curve between total organic carbon content and specific surface area; (d) is the correlation curve between total organic carbon content and Langmuir volume (V L ) correlation curve; (e) is the correlation curve between total organic carbon content and shale gas content; (f) is the Langmuir volume (V L ) and shale gas content correlation curve;

[0047] Figure 3Schematic diagram of parameter correlation curves for the control analysis of clay minerals on shale water and gas content in an embodiment of the present invention, wherein (a) is the correlation curve between clay mineral content and pore volume; (b) is the correlation curve between clay mineral content and porosity; (c) is the correlation curve between pore volume and water saturation; (d) is the correlation curve between clay mineral content and water saturation; (e) is the correlation curve between clay mineral content and shale gas content; (f) is the correlation curve between clay mineral content and Langmuir volume (V L )Correlation curve;

[0048] Figure 4 The porosity volume and Langmuir volume (V L ), Langmuir pressure (P L ) parameter correlation curve diagram, where (a) is the relationship between porosity volume and Langmuir volume (V L ) correlation curve, (b) is the correlation curve between porosity volume and Langmuir pressure (P L )Correlation curve;

[0049] Figure 5 Schematic diagram of the correlation curves between shale gas content, pore volume, and porosity according to an embodiment of the present invention, wherein (a) is the correlation curve between micropore volume and shale gas content, (b) is the correlation curve between mesopore volume and shale gas content; (c) is the correlation curve between macropore volume and shale gas content; and (d) is the correlation curve between porosity and shale gas content.

[0050] Figure 6 Schematic diagram of parameter correlation curves for quantitative analysis of shale gas occurrence status according to an embodiment of the present invention, wherein (a) is a schematic diagram showing shale gas content at different depths, and (b) is a schematic diagram showing consistency analysis between theoretical gas content and measured gas content;

[0051] Figure 7 The present invention takes the Wufeng-Longmaxi Formation shale in Guizhou as an example to obtain a microscopic aggregation pattern diagram of shale gas, wherein (a) is the distribution and aggregation of free gas, adsorbed gas and water molecules in organic matter; (b) is the distribution and aggregation of free gas and adsorbed gas in organic matter pores; (c) is the distribution and aggregation of free gas and adsorbed gas at the edge of organic matter; (d)-(e) are the distribution and aggregation states of free gas and adsorbed gas in clay mineral pores under different diagram scales; (f) is the distribution and aggregation pattern of free gas, adsorbed gas and water molecules in clay minerals; (g) is the distribution and aggregation of free gas in dissolution pores; (h) is the distribution and aggregation of free gas and adsorbed gas in pyrite / organic matter composite pores; and (i) is the distribution and aggregation of free gas and adsorbed gas in microcracks. DETAILED DESCRIPTION

[0052] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0053] The purpose of the present invention is to provide a method, system and storage medium for establishing a shale gas micro-reservoir model. On the basis of clarifying the constraint relationship between geological parameters, a complete shale gas micro-reservoir model is established to provide a scientific basis for shale gas geological evaluation.

[0054] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0055] Example 1

[0056] like Figure 1 As shown, an embodiment of the present invention provides a method for establishing a shale gas microscopic reservoir model, comprising the following steps:

[0057] S1, Sample acquisition: Obtain shale layer drilling core samples using closed coring technology.

[0058] S2, conduct fluid analysis experiments, material composition experiments and reservoir physical property experiments on shale layer drilling core samples to obtain various geological parameters of the shale layer;

[0059] (1) The fluid analysis experiment includes:

[0060] Water saturation tests, on-site analytical experiments, and methane high-pressure isothermal adsorption experiments were conducted to measure the water saturation, gas content, and theoretical maximum value of adsorbed methane in shale layer drilling core samples; so as to further understand the occurrence state of water and methane gas in shale. Among them, measuring the water saturation of shale layer drilling core samples is conducive to understanding the content of water molecules in the pores of shale in different facies. Methane high-pressure isothermal adsorption experiments were conducted to determine the adsorption capacity of shale under simulated formation conditions, including Langmuir volume (V L ) and Langmuir pressure (P L ). The desorbed gas, lost gas and total gas content in shale are measured and calculated through field analytical experiments.

[0061] (2) The material composition experiment includes:

[0062] Through rock and mineral identification and X-ray diffraction (XRD) technology, the mineral content (such as quartz, carbonate, clay minerals, pyrite, etc.), total organic carbon (TOC) content, microscopic components and reflectivity of shale drilling core samples are determined to determine the main lithofacies type, organic matter abundance, type and maturity and other geochemical parameters of the shale;

[0063] (3) The reservoir property experiment includes:

[0064] Helium porosity testing is used to determine the porosity of shale drill core samples;

[0065] The specific surface area, pore volume, and pore size distribution were measured using nitrogen adsorption analysis;

[0066] Combined with field emission scanning electron microscopy (FE-SEM), different pore types were observed and analyzed, including organic pores, clay mineral intergranular pores, clay mineral intragranular pores and microcracks.

[0067] S3, based on various geological parameters of the shale layer, conduct correlation analysis of geological parameters, including analysis of the control of total organic carbon on shale gas content, analysis of the control of clay minerals on shale water and gas content, analysis of the control of reservoir properties on shale gas content, and quantitative analysis of shale gas occurrence status;

[0068] (1) The control analysis of total organic carbon on shale gas content includes:

[0069] like Figure 2 As shown, using a linear fitting method, the correlation between total organic carbon (TOC) and pore volume, porosity, specific surface area, Langmuir volume, and shale gas content was analyzed. The correlation between shale gas content and Langmuir volume was also analyzed to clarify the extent of the influence of total organic carbon (TOC) on shale gas content and reveal the influence of organic pores on shale gas occurrence. Taking the Wufeng-Longmaxi Formation shale in Guizhou as an example, the control of total organic carbon (TOC) on shale gas content was analyzed, combined with field emission scanning electron microscopy analysis of shale pore type and morphology. It was found that organic matter provides a large number of micropores and mesopores. When the overall contribution exceeds 70% of the porosity, it also plays an absolutely dominant role in the contribution to the shale specific surface area and Langmuir volume, thus dominating the positive correlation with shale gas content (including desorbed gas, lost gas, and total gas content).

[0070] (2) Analysis of the control of clay minerals on the water and gas content of shale, including:

[0071] like Figure 3As shown in the figure, linear fitting was used to analyze the correlations between clay mineral content and pore volume, porosity, water saturation, shale gas content, and Langmuir volume. The correlation between pore volume and water saturation was also analyzed, clarifying the influence of clay mineral content on the occurrence of water and shale gas and revealing the competitive adsorption capacity of water and methane in clay minerals. Taking the Wufeng-Longmaxi Formation shale in Guizhou as an example, the control of clay minerals on shale gas content was analyzed, and combined with the above conclusions, it was found that clay minerals primarily provide a large amount of intergranular pores and a small amount of intragranular pores and macropores (including microfractures). However, due to the small proportion of inorganic pores, clay minerals are negatively correlated with shale porosity and gas content (including desorbed gas, lost gas, and total gas content). Furthermore, due to the hydrophilicity of clay minerals, shale water saturation is positively correlated with clay mineral content, indicating that the pore space within clay minerals is the primary reservoir for formation water, significantly reducing the storage capacity of shale gas.

[0072] (3) Analysis of the control of reservoir properties on shale gas-bearing properties, including:

[0073] like Figure 4 As shown in the figure, the linear fitting method was used to analyze the relationship between porosity volume and Langmuir volume (V L ), the correlation of Langmuir pressure (P L ),like Figure 5 As shown, the correlation between shale gas content and pore volume and porosity is analyzed, clarifying the impact of pores of different sizes on shale gas content and revealing the pore space location where shale gas primarily exists. Taking the Wufeng-Longmaxi Formation shale in Guizhou as an example, the control of reservoir properties on shale gas content is further clarified through analysis of the influence of reservoir properties on shale gas content. The shale pore system is dominated by micropores and mesopores, and shale gas is mainly stored in micropores and mesopores.

[0074] (4) Quantitative analysis of the occurrence state of shale gas, based on different geological conditions, calculates the amount of free gas and adsorbed gas in shale, compares them with measured data, and analyzes the distribution of shale gas in microscopic pores, specifically including:

[0075] Determine the actual values of desorbed gas, lost gas and total gas content in shale through field analytical experiments;

[0076] Considering the influence of geological conditions (such as burial depth and formation pressure) on the occurrence of shale gas, the theoretical values of total gas content, free gas content and adsorbed gas content in shale are calculated according to formulas (1)-(3):

[0077]

[0078] in, Indicates the total gas content corresponding to the burial depth H, represents the excess adsorption capacity corresponding to the burial depth H, S w represents water saturation, Φ represents porosity, ρ apparent represents the apparent density, represents the gas phase density of methane gas under reservoir conditions, represents the density of methane gas under standard conditions, represents the maximum absolute adsorption capacity corresponding to the burial depth H, represents the methane adsorption phase density;

[0079] The theoretical values of total gas content, free gas content and adsorbed gas content are compared with the actual values of desorbed gas, lost gas and total gas content to analyze the ratio of adsorbed gas to free gas in shale and clarify the occurrence status of adsorbed gas and free gas in pores of different types and sizes.

[0080] like Figure 6 As shown in the data, using the Wufeng-Longmaxi Formation shale in Guizhou as an example, a comparison of theoretical and measured gas contents reveals that the proportion of adsorbed gas in shale in the normal pressure zone is slightly higher than that of free gas. Furthermore, when TOC is >3%, the theoretical and measured gas contents are highly consistent, which helps predict shale gas reserves in organic-rich shales when field gas content is unavailable.

[0081] S4, based on the conclusions of the geological parameter correlation analysis, determine the constraint relationship between geological parameters; specifically including:

[0082] Based on the conclusions of the geological parameter correlation analysis, combined with the characteristics of the occurrence locations of different types of minerals, organic matter, different types of pores, and water in FE-SEM photographs obtained by field emission scanning electron microscopy and their influence on the occurrence of adsorbed gas and free gas, the distribution of adsorbed gas, free gas and water molecules in organic matter pores, clay mineral pores, dissolution pores and microcracks was clarified, and the constraint relationship between geological parameters was determined.

[0083] Among them, the gas-water storage locations in the FE-SEM images and the gas-water distribution ratios in different pore types are marked.

[0084] Statistical and machine learning methods used: Principal component analysis (PCA) and random forests are used to identify key control factors and construct mathematical relationships between parameters (such as multiple regression equations).

[0085] The pore type proportions statistically obtained from FE-SEM images were matched with the experimentally measured TOC, clay content, and pore size distribution data to establish a mapping matrix of pore structure-mineral composition-gas content.

[0086] S5. Based on the constraint relationship between geological parameters, a semi-quantitative shale gas micro-reservoir model based on correlation analysis is established.

[0087] Among them, the semi-quantitative shale gas micro-reservoir model integrates geological parameters and their constraints, including the following sub-models:

[0088] Pore structure model: simulates organic / inorganic pore networks based on TOC and mineral composition.

[0089] Gas-water distribution model: Combines clay content and wettability analysis to predict the effect of water saturation on gas content.

[0090] Occurrence state model: Calculate the adsorbed gas / free gas ratio through adsorption isotherms and pore volume.

[0091] Semi-quantitative implementation: Use weight assignment or empirical formula (such as TOC-porosity conversion coefficient) to simplify complex physical processes and facilitate practical application.

[0092] Through these steps, a systematic shale gas micro-occurrence model analysis method can be established to provide a scientific basis for shale gas exploration and development.

[0093] Taking the Wufeng-Longmaxi Formation shale in Guizhou as an example, a semi-quantitative microscopic reservoir model of shale gas can be gradually established through the above steps.

[0094] The four stages of shale gas storage are divided into adsorption stage, pore filling stage, fracture filling stage and natural gas accumulation stage. The generated natural gas first meets physical adsorption and dissolution, and then exists in free gas, which is similar to the shale gas desorption process. Therefore, a microscopic model of shale gas existence is proposed based on FE-SEM images, such as Figure 7 As shown. The dots of different colors (yellow, red and blue) represent three types of gas molecules (adsorbed gas, free gas and water molecules), and the density of the dots indicates the main occurrence locations of gas / water molecules. Figure 7 As shown in Figure 2, shale gas exists in different states in different pore types. Figure 7In the figure, (a)-(c) indicate that organic pores and surfaces are the primary spaces for adsorbed gas and the majority of free gas; (d) and (e) indicate that clay mineral pores are primarily filled with water molecules, contributing only a limited amount to adsorbed and free gas; (f) indicates that adsorbed gas, free gas, and molecular water are present in clay minerals; (g) indicates that dissolved pores can provide space for free gas; (h) indicates that the pyrite / organic complex contains organic pores and interstitial spaces, contributing primarily to adsorbed gas and secondarily to free gas; and (i) indicates that microcracks contribute primarily to free gas and a small amount of adsorbed gas. With increasing thermal maturity, natural gas primarily meets the adsorption requirements of organic matter particles and mineral particle surfaces. During this period, adsorbed gas dominates. Simultaneously, limited natural gas dissolves in water, kerogen, bitumen, and residual oil. With the production of large amounts of natural gas, the adsorbed gas becomes saturated, and excess gas migrates as free gas into organic pores, interstitial pores, and microcracks. However, clay mineral pores are almost entirely occupied by water molecules, with water saturations ranging from 18.41% to 69.33%, with an average of 43.87%. Overall, OM pores within solid bitumen, sedimentary organic matter, and mineral / organic matter complexes preferentially store adsorbed gas, followed by free gas. Free gas content increases significantly with increasing TOC, as more OM pores larger than 3-4 nm are developed. Clay minerals have limited contributions to both adsorbed and free gas. Although fractures are filled or sealed by calcite and solid bitumen under actual geological conditions, they can still provide some space for free gas. Therefore, shale gas potential is controlled primarily by the level of organic pore development and, to a lesser extent, by fractures.

[0095] In summary, the specific elements of shale gas in this example include: (1) organic pores and surfaces are the main spaces for adsorbed gas and most free gas; (2) clay mineral pores are mainly filled with water molecules, which have limited contribution to adsorbed gas and free gas; (3) microcracks mainly contribute to free gas and limited adsorbed gas.

[0096] The establishment of a shale gas micro-reservoir model reveals the controlling factors of shale gas occurrence and content, which helps to enrich the shale gas micro-reservoir theory and provide an important reference for the exploration and development of shale gas in non-deepwater shelf facies in my country.

[0097] Example 2

[0098] The present invention also provides a system for establishing a shale gas microscopic reservoir model, which is applied to the above-mentioned method for establishing a shale gas microscopic reservoir model. The system comprises:

[0099] The data acquisition module is used to obtain various geological parameters of the shale layer based on the experimental results of fluid analysis experiments, material composition experiments and reservoir physical property experiments on shale layer drilling core samples;

[0100] The data analysis module is used to conduct geological parameter correlation analysis based on various geological parameters of shale layers, including analysis of the control of total organic carbon on shale gas content, analysis of the control of clay minerals on shale water and gas content, analysis of the control of reservoir properties on shale gas content, and quantitative analysis of shale gas occurrence status. It is also used to determine the constraint relationship between geological parameters based on the conclusions of geological parameter correlation analysis;

[0101] The model building module is used to establish a semi-quantitative shale gas micro-reservoir model based on correlation analysis based on the constraint relationship between geological parameters.

[0102] Example 3

[0103] The present invention also provides a computer-readable storage medium storing executable instructions, which, when executed, enable a processor to execute the method for establishing a shale gas microscopic reservoir model as described above.

[0104] The remaining technical features of this embodiment can be flexibly selected by those skilled in the art to meet different specific practical needs based on actual circumstances. However, it is obvious to those skilled in the art that these specific details are not required to practice the present invention. In other examples, to avoid obscuring the present invention, well-known components, structures, or parts are not described in detail, and are therefore within the scope of the technical solutions claimed in the claims of the present invention.

[0105] Modifications and variations made by those skilled in the art without departing from the spirit and scope of the present invention are intended to be within the scope of the claims appended hereto. In the foregoing description, numerous specific details are set forth to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that these specific details are not necessarily required to practice the present invention. In other instances, well-known techniques, such as specific construction details, operating conditions, and other technical requirements, are not described in detail to avoid obscuring the present invention.

[0106] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A method for establishing a shale gas microscopic reservoir model, characterized in that: The following steps are involved: Obtaining drill core samples from shale formations; Conduct fluid analysis experiments, material composition experiments, and reservoir property experiments on shale drilling core samples to obtain various geological parameters of the shale layer; Conduct correlation analysis of geological parameters based on various geological parameters of shale formations, including analysis of the control of total organic carbon on shale gas content, analysis of the control of clay minerals on shale water and gas content, analysis of the control of reservoir properties on shale gas content, and quantitative analysis of shale gas occurrence status; Based on the conclusions of geological parameter correlation analysis, determine the constraint relationship between geological parameters; Based on the constraint relationship between geological parameters, a semi-quantitative shale gas micro-reservoir model based on correlation analysis was established.

2. The method for establishing a shale gas microscopic reservoir model according to claim 1, characterized in that: The method for obtaining shale layer drilling core samples is: The sealed coring technology is used to obtain shale drilling core samples.

3. The method for establishing a shale gas microscopic reservoir model according to claim 1, characterized in that: The fluid analysis experiment includes: Conduct water saturation tests, on-site analytical experiments, and methane high-pressure isothermal adsorption experiments to measure the water saturation, gas content, and theoretical maximum value of adsorbed methane in shale core samples; The material composition experiment includes: The mineral content, total organic carbon content, microscopic components and reflectivity of shale layer drilling core samples are measured by rock and mineral identification and X-ray diffraction technology to determine geochemical parameters, including major lithofacies types, organic matter abundance, type and maturity; The reservoir property experiments include: Helium porosity testing is used to determine the porosity of shale drill core samples; The specific surface area, pore volume, and pore size distribution were measured using nitrogen adsorption analysis; Combined with field emission scanning electron microscopy, different pore types were observed and analyzed, including organic pores, clay mineral intergranular pores, clay mineral intragranular pores and microcracks.

4. The method for establishing a shale gas microscopic reservoir model according to claim 3, characterized in that: The control analysis of total organic carbon on shale gas content includes: The linear fitting method was used to analyze the correlation between total organic carbon content and pore volume, porosity, specific surface area, Langmuir volume, and shale gas content, as well as the correlation between shale gas content and Langmuir volume, to clarify the influence of total organic carbon content on shale gas content and reveal the influence of organic pores on shale gas occurrence.

5. The method for establishing a shale gas microscopic reservoir model according to claim 3, characterized in that: The control analysis of clay minerals on the water and gas content of shale includes: The linear fitting method was used to analyze the correlation between clay mineral content and pore volume, porosity, water saturation, shale gas content, and Langmuir volume, as well as the correlation between pore volume and water saturation, to clarify the effect of clay mineral content on the occurrence of water and shale gas, and to reveal the competitive adsorption capacity of water and methane gas in clay minerals.

6. The method for establishing a shale gas microscopic reservoir model according to claim 3, characterized in that: The analysis of the control of reservoir properties on shale gas-bearing properties includes: The linear fitting method is used to analyze the correlation between porosity volume and Langmuir volume and Langmuir pressure, and the correlation between shale gas content and pore volume and porosity, clarify the impact of pores of different sizes on shale gas content, and reveal the pore space location where shale gas mainly exists.

7. The method for establishing a shale gas microscopic reservoir model according to claim 3, characterized in that: The quantitative analysis of the shale gas occurrence state includes: Determine the actual values of desorbed gas, lost gas and total gas content in shale through field analytical experiments; Considering the influence of geological conditions on shale gas occurrence, the theoretical values of total gas content, free gas content and adsorbed gas content in shale are calculated according to formulas (1)-(3): in, Indicates the total gas content corresponding to the burial depth H, represents the excess adsorption capacity corresponding to the burial depth H, S w represents water saturation, Φ represents porosity, ρ apparent represents the apparent density, represents the gas phase density of methane gas under reservoir conditions, represents the density of methane gas under standard conditions, represents the maximum absolute adsorption capacity corresponding to the burial depth H, represents the methane adsorption phase density; The theoretical values of total gas content, free gas content and adsorbed gas content are compared with the actual values of desorbed gas, lost gas and total gas content to analyze the ratio of adsorbed gas to free gas in shale and clarify the occurrence status of adsorbed gas and free gas in pores of different types and sizes.

8. The method for establishing a shale gas microscopic reservoir model according to claim 3, characterized in that: The determination of the constraint relationship between geological parameters based on the conclusion of the geological parameter correlation analysis specifically includes: Based on the conclusions of the geological parameter correlation analysis, combined with the characteristics of the occurrence locations of different types of minerals, organic matter, different types of pores, and water obtained by field emission scanning electron microscopy and their influence on the occurrence of adsorbed gas and free gas, the distribution of adsorbed gas, free gas and water molecules in organic matter pores, clay mineral pores, dissolution pores and microcracks was clarified, and the constraint relationship between geological parameters was determined.

9. A system for establishing a shale gas microscopic reservoir model, applied to the method for establishing a shale gas microscopic reservoir model according to any one of claims 1 to 8, characterized in that: The system comprises: The data acquisition module is used to obtain various geological parameters of the shale layer based on the experimental results of fluid analysis experiments, material composition experiments and reservoir physical property experiments on shale layer drilling core samples; The data analysis module is used to conduct geological parameter correlation analysis based on various geological parameters of shale layers, including analysis of the control of total organic carbon on shale gas content, analysis of the control of clay minerals on shale water and gas content, analysis of the control of reservoir properties on shale gas content, and quantitative analysis of shale gas occurrence status. It is also used to determine the constraint relationship between geological parameters based on the conclusions of geological parameter correlation analysis; The model building module is used to establish a semi-quantitative shale gas micro-reservoir model based on correlation analysis based on the constraint relationship between geological parameters.

10. A computer-readable storage medium storing executable instructions, wherein when the instructions are executed, the processor executes the method for establishing a shale gas microscopic reservoir model according to any one of claims 1 to 8.

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