Novel hydrocarbon generation potential evaluation method and system for marine facies mixed-product shale

Abstract

The invention provides a novel hydrocarbon generation potential evaluation method and system for marine facies mixed shale. The hydrocarbon generation potential evaluation method comprises the following steps: determining different lithofacies types in mixed shale, mineral component characteristics of the lithofacies types and a sedimentary environment change rule of the marine facies mixed shale; the hydrocarbon generation capacity of different lithofacies of the marine facies mixed and accumulated shale is judged; a marine facies mixed shale hydrocarbon generation capacity, lithofacies type and deposition characteristic linkage evaluation model is constructed, and a formation mechanism of marine facies mixed shale high-quality hydrocarbon source lithofacies development is determined; therefore, the control effect of spatial and temporal changes of pressure conditions in a sedimentary environment, a sedimentary product and a diagenetic environment on the final hydrocarbon generation capacity is defined, and the hydrocarbon generation capacity of a specific lithofacies type is quantitatively evaluated by integrating all influence parameters; the hydrocarbon generation potential evaluation method and system have important guiding significance for oil-gas exploration and actual development.

Description

Technical Field

[0001] The invention belongs to the technical field of shale oil and gas exploration, and particularly relates to a method and system for evaluating the hydrocarbon generation potential of a novel marine mixed-accumulation shale. Background Art

[0002] In 2020, an organic-rich marine shale oil and gas reservoir was discovered in the third section of the Leikoupo Formation in the CT1 well in the central Sichuan Basin, with a tested daily production of 108,700 cubic meters of natural gas and 40 tons of condensate. Therefore, the challenge of forming such an unconventional oil and gas reservoir aroused the curiosity of researchers. A large amount of preliminary work by the relevant research team revealed that the marine tight limestone reservoir of the Leikoupo Formation is located under the thick evaporite, and preliminarily determined that the main lithology of this marine shale is shale with a high calcium content. At the same time, it is clear that it is rich in organic matter, high maturity, ultra-low porosity, low permeability, and source-reservoir integrated characteristics. Since this is the first discovery of marine mixed shale in the Leikoupo Formation, the research results on its source rock formation mechanism, hydrocarbon generation capacity and control factors are still relatively few, which hinders the exploration of unconventional marine mixed shale oil and gas.

[0003] The formation mechanism of mixed shale source rocks is complex and is mainly affected by factors such as material supply, changes in sedimentary environment, sedimentary dynamics and hydrothermal activity. The diversity of material supply is one of the important characteristics of mixed shale. The combined effect of terrigenous organic matter and marine organic matter makes shale have complex organic matter composition and diverse hydrocarbon generation potential. Terrigenous organic matter mainly comes from the remains of terrestrial plants, while marine organic matter mainly comes from the remains of plankton. Changes in the sedimentary environment have an important impact on the formation of mixed shale.

[0004] In recent years, the study of shale source rocks has made significant progress. Through systematic geological surveys and experimental analysis, researchers have revealed the geological characteristics and formation mechanism of shale. Although the study of shale source rocks has made significant progress, there are still some problems and challenges, especially for the new type of shale, mixed shale, which is different from traditional shale. Although mixed shale also has certain hydrocarbon generation potential, its frequent sediment changes, complex geological characteristics and diverse sources of organic matter make its mineralization conditions and hydrocarbon generation process more complex and uncertain. In some areas with complex geological conditions or low exploration level, the lack of systematic geological surveys and drilling data has led to insufficient understanding of mixed shale source rocks. Therefore, the study and evaluation of mixed shale requires a more comprehensive and multidisciplinary approach to reveal its true hydrocarbon generation potential and oil and gas resource value. Summary of the invention

[0005] The present invention provides a novel method and system for evaluating the hydrocarbon generation potential of marine mixed shale. The method takes the evaluation of the hydrocarbon generation potential of marine mixed shale as the starting point, takes the marine mixed shale of the Leikoupo Formation in the Sichuan Basin as the object, adopts a combination of multiple cutting-edge research methods, comprehensively analyzes the hydrocarbon generation capacity of the mixed shale of the Leikoupo Formation in the Sichuan Basin through multiple factors, clarifies the lithofacies type of high-quality source rocks, and constructs a method for evaluating the hydrocarbon generation potential of marine mixed shale, thereby providing support for the prediction, exploration and development of unconventional oil and gas in the Sichuan Basin.

[0006] To solve the above problems, the technical solution provided by the present invention is as follows:

[0007] The embodiment of the present invention provides a novel method for evaluating the hydrocarbon generation potential of marine mixed shale, comprising the following steps:

[0008] Step S1, for the marine mixed shale, through logging analysis, core observation and field profile observation, combined with microscopic rock thin section analysis, comprehensive XRD and electron probe test to obtain the major element composition, perform lithofacies type classification, and clarify the mineral components of the mixed shale; through the element combination forms of (copper + molybdenum) / zinc, vanadium / (vanadium + nickel), vanadium / chromium, and the ratio of pristane Pr / Ph in the biomarker compound, judge the oxidation or reduction environment during deposition, use carbon and oxygen isotope changes to identify productivity and sea level changes, use barium / titanium and phosphorus / titanium to identify ancient productivity changes, and clarify different lithofacies types in the mixed shale and the characteristics of the mineral components of the lithofacies type;

[0009] Step S2, using the total organic carbon (TOC) value to characterize the abundance of organic matter in different facies in the mixed shale, using the Ts / Tm parameter in the biomarker compound and the vitrinite reflectance Ro to identify the maturity, combining the kerogen carbon morphology and isotope distribution to determine the kerogen type, and discriminating the hydrocarbon generation capacity of different facies in the marine mixed shale;

[0010] Step S3, constructing a linkage evaluation model between the hydrocarbon generation capacity of marine mixed shale and lithofacies type and sedimentary characteristics, which simulates the control effect of environmental changes in the target layer during the sedimentation-diagenesis process on the final hydrocarbon generation capacity, thereby clarifying the genetic mechanism of the development of high-quality source lithofacies in marine mixed shale.

[0011] According to an alternative embodiment of the present invention, step S1 specifically includes: step S11, based on logging and seismic data, combined with core and section observations, clarify the planar distribution characteristics; use major element analysis to clarify the mixed sedimentary mineral composition and divide the lithofacies types within the mixed sedimentary shale; comprehensively utilize the major element composition obtained from XRD and electron microprobe tests, and use the ternary diagram of shale to divide the lithofacies types, clarify the mineral composition and variation law of this mixed sedimentary shale; based on sedimentology and geochemical experiments, determine the sedimentary environment, such as the spatio-temporal evolution law of paleoclimate, paleohydrology, paleoproductivity, and sedimentary mineral changes.

[0012] According to an alternative embodiment of the present invention, step S1 specifically includes: step S12, before using each element index, it is necessary to calculate the excess value to exclude the interference of terrigenous input; clarify the influencing factors during the actual sedimentation process and clarify the variation law of the sedimentary environment of marine mixed sedimentary shale.

[0013] According to an alternative embodiment of the present invention, step S2 specifically further includes: step S21, when the total organic carbon TOC content exceeds 0.5%, it can have a certain hydrocarbon generation potential, and the higher the content, the greater the hydrocarbon generation potential; the vitrinite reflectance Ro is an important indicator to measure the maturity of organic matter, indicating the maturity of organic matter after being subjected to thermal metamorphism in the geological history; Ro < 0.5%: immature stage, mainly generating biogas and a small amount of liquid hydrocarbons; 0.5% < Ro < 1.0%: low maturity stage, starting to enter the oil generation window and generating liquid hydrocarbons; 1.0% < Ro < 1.3%: peak oil generation stage, generating a large amount of liquid hydrocarbons; 1.3% < Ro < 2.0%: high maturity stage, the liquid hydrocarbons begin to crack and generate gaseous hydrocarbons; Ro > 2.0%: over-mature stage, mainly generating gaseous hydrocarbons; at the same time, use biomarker compound analysis, use the Ts / Tm ratio to identify the maturation conditions, and jointly limit its thermal evolution stage with Ro.

[0014] According to an alternative embodiment of the present invention, step S2 includes: step S22, further refining the hydrocarbon generation potential evaluation through rock pyrolysis data. A higher S1 peak in the pyrolysis data indicates that a certain amount of hydrocarbons have been generated in the sample, and a higher S2 peak in the pyrolysis data indicates that the sample has a greater potential hydrocarbon generation capacity. Tmax is used to identify the thermal evolution stage of the source rock. The higher the pyrolysis index HI value, the stronger the ability of organic matter to generate hydrocarbons during pyrolysis and the greater the hydrocarbon generation potential. The HI value is an important parameter for evaluating the hydrocarbon generation potential of rocks. HI > 300 mg HC / g TOC: indicates good organic matter type and high hydrocarbon generation potential, mainly generating liquid hydrocarbon petroleum; 150 mg HC / g TOC < HI < 300 mg HC / g TOC: indicates average organic matter type and medium hydrocarbon generation potential, capable of generating both liquid hydrocarbons and gaseous hydrocarbons; HI < 150 mg HC / g TOC: indicates poor organic matter type and low hydrocarbon generation potential, mainly generating gaseous hydrocarbons.

[0015] According to an alternative embodiment of the present invention, step S3 includes: step S31, using the pyrolysis index HI as an indicator parameter for its hydrocarbon generation potential, constructing the relationship between hydrocarbon generation potential and lithofacies type; understanding the material basis of hydrocarbon generation ability from the sedimentary environment for organic matter enrichment and preservation, and clarifying the thermal evolution conditions of hydrocarbon generation ability through rock pyrolysis parameters and maturity-related indicators. In addition, formation pressure is also an important factor hindering hydrocarbon generation. As an element for evaluating hydrocarbon generation ability, the formation pressure corresponding to the sample obtained from well logging data is used to participate in the calculation; constructing a five-element coupling model of HI with sedimentary environment indicators, organic matter condition indicators, thermal evolution condition indicators, and pressure condition indicators, simulating the control effect of the environmental changes during sedimentation - diagenesis of the target horizon on the final hydrocarbon generation ability, so as to clarify the genetic mechanism of the development of high-quality hydrocarbon source rock facies in marine mixed shale.

[0016] According to an alternative embodiment of the present invention, step S3 includes: step S32, using the AI model to analyze data, constructing a function model of hydrocarbon generation ability and correlation evaluation, linking the relevant elements and isotope indicators in step S1 with the hydrocarbon generation ability indicators in step S2, and through a large amount of data training by Chatgpt, constructing a function model of hydrocarbon generation ability with the pyrolysis index HI as the evaluation standard and sedimentary environment indicators, organic matter condition indicators, thermal evolution condition indicators, and pressure condition indicators, quantitatively evaluating the genetic mechanism of high-quality hydrocarbon source rocks, and quantitatively analyzing the contribution degree of each control factor, analyzing the contribution degrees of paleoproductivity, paleo-hydrography, and formation pressure.

[0017] An embodiment of the present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, a new method for evaluating the hydrocarbon generation potential of marine mixed-accumulation shale is implemented as in the above-mentioned embodiment.

[0018] An embodiment of the present invention further provides a non-transitory computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, a method for evaluating the hydrocarbon generation potential of a new type of marine mixed-accumulation shale is implemented as described in the above embodiment.

[0019] Beneficial effects: The embodiment of the present invention provides a novel method and system for evaluating the hydrocarbon generation potential of marine mixed shale. The method for evaluating the hydrocarbon generation potential clarifies the different lithofacies types in mixed shale, the mineral component characteristics of the lithofacies type, and the changing laws of the sedimentary environment of marine mixed shale; distinguishes the hydrocarbon generation capacity of different lithofacies of marine mixed shale; constructs an evaluation model for the linkage between the hydrocarbon generation capacity of marine mixed shale and the lithofacies type and sedimentary characteristics, and clarifies the causal mechanism of the development of high-quality source lithofacies of marine mixed shale; therefore, the present invention clarifies the control effect of the temporal and spatial changes of the pressure conditions in the sedimentary environment, sedimentary products and diagenetic environment on the final hydrocarbon generation capacity, comprehensively integrates various influencing parameters, and quantitatively evaluates the hydrocarbon generation capacity of a specific lithofacies type; the method and system for evaluating the hydrocarbon generation potential have important guiding significance for oil and gas exploration and actual development. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 A flow chart of a novel method for evaluating the hydrocarbon generation potential of marine mixed shale provided in an embodiment of the present application.

[0022] Figure 2 A schematic diagram of a new type of hydrocarbon generation potential evaluation system for marine mixed shale provided in an embodiment of the present application.

[0023] Figure 3 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application.

[0024] Figures 4 to 12 A hydrocarbon generation capacity correlation parameter identification diagram provided in an embodiment of the present application. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0026] The present invention takes the evaluation of the hydrocarbon generation potential of marine mixed shale as the starting point, takes the marine mixed shale of the Leikoupo Formation in the Sichuan Basin as the object, combines a variety of cutting-edge research methods, comprehensively analyzes the hydrocarbon generation capacity of the mixed shale of the Leikoupo Formation in the Sichuan Basin by multi-factor quantitative analysis, clarifies the lithofacies types of high-quality source rocks, and constructs a hydrocarbon generation potential evaluation method for marine mixed shale, so as to provide support for the prediction, exploration and development of unconventional oil and gas in the Sichuan Basin.

[0027] The indoor test and analysis methods used in the present invention are as follows:

[0028] Polarized light microscope: used to observe the microstructure of mixed shale and identify the mineral composition. The DM4500P polarized light microscope produced by Leica of Germany purchased by the State Key Laboratory of Oil and Gas Reservoir Geology and Development Engineering can meet the needs of this project. High-resolution scanning electron microscope (SEM): used to observe the ultra-microscopic morphology and structure of dolomite and gypsum-salt rock minerals. The Quanta250 FEG field emission scanning electron microscope manufactured by FEI of the United States purchased by the State Key Laboratory of Oil and Gas Reservoir Geology and Development Engineering has a resolution of up to 1.2nm, a maximum magnification of 1 million times, and can be imaged instantly, which can meet the research needs of this project. X-ray diffraction (XRD): used to identify the mineral composition of different mixed shale phases and clarify the changes in the content of some elements (Fe, Mn, etc.). The Japanese Rigaku D / Max IIICX-ray diffractometer purchased by the State Key Laboratory of Oil and Gas Reservoir Geology and Development Engineering has successfully provided services for many scientific research projects with high test accuracy.

[0029] Electron Probe Analysis (EPMA): can obtain micro-area morphological images of the survey area, the corresponding components, and quantitative analysis of the constituent elements. The State Key Laboratory of Oil and Gas Reservoir Geology and Development Engineering purchased the latest product produced in Japan, the EPMA-17200H Series electron probe micro-area analyzer, with element analysis range: 5B-92U, analysis accuracy: main elements (content>5%), can reach ≤1%. Major and trace elements: can be used to study the ancient sedimentary environment of shale, element migration rules, property discrimination, etc. The laboratory of the School of Earth Sciences of Chengdu University of Technology is equipped with a PerkinElmer Elan DRC-e inductively coupled ison mass spectrometer (ICP-MS) that can meet the research needs of this project. O isotope analysis: used to analyze the ancient environment and trace carbon sources, and determine the properties and sources of fluids. The Finnigan MAT253IRMS gas isotope mass spectrometer purchased by the Geochemistry Laboratory of the School of Earth Sciences of Chengdu University of Technology is connected to the GasBench II, TC / EA element analyzer and GC gas chromatograph ConfloⅣ device, which can meet the C and O isotope determination needs of this project.

[0030] Biomarker compounds: Identify the sedimentary environment and the source of organic matter, clarify the rules of organic matter enrichment, and complete the study of the genesis of high-quality lithofacies. The ISQ gas chromatography-mass spectrometer produced by ThermoFisher, USA, purchased by the National Key Laboratory of Oil and Gas Reservoir Geology and Development Engineering of Southwest Petroleum University, can provide support for this research. Kerogen detection: Complete kerogen microscopy, vitrinite reflectivity measurement and carbon isotope characteristic analysis to clarify the hydrocarbon generation conditions of mixed shale and the transformation capacity of hydrocarbon generation pressurization. The vitrinite reflectivity measurement instrument of the National Key Laboratory of Oil and Gas Reservoir Geology and Development Engineering of Southwest Petroleum University can provide support for observing kerogen characteristics and measuring vitrinite reflectivity; the MAT 253 stable isotope mass spectrometer manufactured by ThermoFisher, USA, can provide support for kerogen carbon isotope analysis. TOC detection: Clarify the abundance of organic matter in marine mixed shale lithofacies, which is used to determine the basic characteristics of mixed shale hydrocarbon generation conditions. The CS230SH organic carbon and sulfur analyzer produced by the American Leco Company purchased by the National Key Laboratory of Oil and Gas Reservoir Geology and Development Engineering of Southwest Petroleum University can provide support for this.

[0031] The research ideas of the present invention are as follows:

[0032] Geological survey and sampling are the basic work for studying mixed shale source rocks. Through systematic geological survey and drilling sampling, detailed geological data and samples can be obtained, and the lithofacies division can be clarified, providing basic data for subsequent experimental analysis and model simulation. Due to the complexity of the sedimentary process and sedimentary products of mixed shale, it is necessary to conduct a detailed analysis of the main mineral components and conduct lithofacies division based on the mineral composition and structural characteristics. On this basis, the hydrocarbon generation capacity of different lithofacies types can be explored and the controlling factors that restrict the hydrocarbon generation capacity can be clarified. XRD technology has been widely used in geology and resource exploration. By quantitatively analyzing the mineral composition in rocks, soils and ores, researchers can reveal geological processes, sedimentary environments and the formation mechanism of ore deposits. In paleoclimate and paleoenvironmental studies, XRD technology is used to quantitatively analyze the mineral composition in sediments and core samples. By revealing the changes in mineral phases, researchers can reconstruct the evolution of paleoclimate and paleoenvironment, help clarify the mineral composition and genetic mechanism of various mixed shale lithofacies, provide a basis for further determining the organic geochemical characteristics of each lithofacies, and is an important basis for detailed evaluation.

[0033] As an important type of sedimentary rock, shale records a wealth of geological information. The distribution and variation of trace elements reflect the impact of paleoenvironmental and paleoclimate evolution on the characteristics of its original organic matter. Therefore, studying the distribution of trace elements in shale is of great significance for understanding the process of organic matter enrichment during the sedimentary period and is an important factor in clarifying the characteristics of each lithofacies of mixed shale. For example, a suitable sedimentary environment (water reduction, paleoproductivity, chemical weathering, etc.) may provide more favorable conditions for organic matter enrichment (better quality types, higher abundance).

[0034] Trace elements can not only indicate changes in sedimentary environments, but also reveal the evolution of lithofacies. Lithology refers to the overall performance of the sedimentary structure, composition and combination characteristics of rocks. Different lithofacies reflect different sedimentary environments and sedimentary processes. By analyzing the distribution of trace elements in different lithofacies, the evolution law of lithofacies can be revealed. For example, the paleoproductivity indicators (Ba / Ti, P / Ti) of shale lithofacies with higher calcium content are relatively low. In specific research applications, trace elements have achieved remarkable results in the study of shale sedimentary environments in different geological periods and regions. For example, when studying shale deposits in the Paleozoic and Mesozoic eras, by analyzing the distribution of trace elements, the changes in the marine environment and climate fluctuations at that time can be reconstructed, thereby revealing the environmental background of global geological events and mass extinction events. Similarly, in modern sedimentary environments, the study of trace elements also provides important information for understanding current geological processes and environmental changes. For example, by studying trace elements in modern river sediments, we can understand the impact of human activities on the environment and its potential risks. In recent years, with the advancement of analytical technology, especially the application of high-precision instruments such as mass spectrometers (ICP-MS) and electron probe microscopy (EPMA), the analysis of trace elements has become more accurate and rapid. The development of these technologies has greatly promoted the application of trace elements in shale sedimentary environment and lithofacies research. For example, through ICP-MS technology, trace elements in shale samples can be quantitatively analyzed with high precision to obtain element abundance and ratio data. These data can be used to establish trace element geochemical indicators, such as Eu / Eu*, La / Yb, Th / U, etc., to distinguish sedimentary environment and lithofacies changes.

[0035] Stable carbon and oxygen isotopes are also important indicator parameters for identifying changes in the sedimentary environment of different mixed facies within mixed shales. Fluctuations in δ13C values ​​can reflect changes in the sedimentary environment. For example, a positive shift in δ13C values ​​(increase in value) may indicate a change in the source of organic matter, an increase in productivity, or a change in atmospheric CO2 concentration; a negative shift (decrease in value) may indicate an anaerobic event in the ocean or degradation of organic matter. Combining δ13C and δ18O values, changes in the sedimentary environment can be reconstructed. For example, during periods of sea level rise, fresh water mixes with seawater, resulting in a decrease in δ18O values; during periods of sea level drop, seawater salinity increases and δ18O values ​​increase.

[0036] Organic geochemical analysis includes methods such as total organic carbon (TOC) analysis, rock pyrolysis (Rock-Eval) analysis, and organic microscopic component analysis, which are used to study the organic matter content, type, and pyrolysis characteristics of shale. Mineral composition analysis uses X-ray diffraction (XRD) analysis and scanning electron microscope (SEM) analysis to study the mineral composition and microstructure of shale, revealing the influence of mineral composition on the preservation and pyrolysis of organic matter. Isotope analysis uses carbon, hydrogen, and oxygen isotope analysis to study the source and genesis of organic matter and reveal the formation mechanism of mixed shale. Geological models and simulations include sedimentary simulation, pyrolysis simulation, and basin simulation, which are used to study the sedimentary environment, material supply, thermal history, and pressure conditions of mixed shale, revealing the formation and evolution mechanism of shale. By analyzing the pyrolysis products of rock samples, researchers can determine the type of organic matter (such as kerogen type), organic matter content, and pyrolysis characteristics (such as hydrocarbon generation potential) in the rock, understand the pyrolysis characteristics and hydrocarbon generation potential of mixed shale, and provide important geological information and resource evaluation basis for oil exploration. Commonly used pyrolysis parameters include Tmax, S1, S2 and HI hydrogen index. These parameters reflect the thermal maturity and hydrocarbon generation capacity of shale: Tmax reflects the pyrolysis temperature of organic matter and is used to judge the thermal maturity of shale; S1 and S2 represent the free hydrocarbons released by shale during pyrolysis and the hydrocarbons generated by cracking, respectively, which are used to evaluate the hydrocarbon generation potential of shale; the pyrolysis index HI (hydrogen index) represents the amount of hydrocarbons generated per gram of organic carbon, which is used to distinguish different types of organic matter. The pyrolysis characteristics of mixed shale source rocks are affected by multiple factors such as sedimentary environment, organic matter type and thermal history, and show complex changes. Therefore, rock pyrolysis technology can be used for different lithofacies to identify high-quality lithofacies with the greatest hydrocarbon generation potential, and based on the previous research on major and trace elements, factors with high correlation with hydrocarbon generation potential can be identified.

[0037] At the same time, formation pressure is an important factor affecting hydrocarbon generation from organic matter, but there is still a lack of intuitive expression of its influence. Its constraints on hydrocarbon generation capacity are mainly manifested in: (1) Inhibition of organic matter decomposition: High formation pressure will increase the fluid pressure in the formation, thereby inhibiting the pyrolysis and decomposition process of organic matter. This is because under high pressure conditions, the activation energy required for the decomposition of organic matter is higher and the reaction rate is slower. From a chemical point of view, due to the volume expansion of hydrocarbon generation products, high pressure will cause the chemical reaction to proceed in the forward direction, so high pressure will lead to the obstruction of the hydrocarbon generation process. (2) Reduce porosity and permeability: High formation pressure will reduce the porosity and permeability in the sediment, affecting the fluidity and migration path of organic matter into hydrocarbons. This makes it difficult for the generated hydrocarbons to effectively migrate and accumulate in the reservoir, affecting the formation and enrichment of oil and gas. (3) Affecting heat flow conduction: Formation pressure also affects the conduction of heat flow. High pressure may change the thermal conductivity of the formation, making it difficult for heat to be effectively conducted to the organic matter-rich area, thereby affecting the pyrolysis process of hydrocarbon generation. (4) Dissolution and escape of cracking gas: High formation pressure may cause the gas generated by cracking to dissolve more in the formation fluid or escape into the surrounding formation through tiny cracks, reducing the efficiency of hydrocarbon generation.

[0038] Because it has the characteristics of integrated source and reservoir, and the lateral lamellar fractures are the main reservoir space. Therefore, CT scanning can be used to determine its oil and gas migration path, and it is clear that it does not have the ability of oil and gas escape in the vertical direction. Therefore, most of the hydrocarbon generation products of different shale phases are retained in situ, so the high-quality source rock section and the best reservoir section may have a strong coupling relationship, which is of great significance for the mixed shale with high calcium content. Therefore, based on the complex characteristics of the lithofacies combination and lithofacies heterogeneity of mixed shale, the present invention targets the lithofacies combination changes of mixed shale, evaluates it in conjunction with the changes in hydrocarbon generation capacity, quantifies the fluctuation law of hydrocarbon generation capacity under different lithofacies changes (mineral combination changes, sedimentary environment changes), and combines the pressure conditions under the diagenetic environment to construct a five-element coupling evaluation model of "sedimentary environment-organic matter conditions-thermal evolution conditions-pressure conditions-hydrocarbon generation capacity", which provides guidance for clarifying high-quality source rock sections in actual oil and gas exploration. The main advantage of the present invention is the multi-dimensional linkage evaluation of hydrocarbon generation potential from macroscopic sedimentary diagenetic control to microscopic sedimentary product changes, organic matter evolution and lamination.

[0039] According to the above-mentioned indoor test analysis means and technical route, the embodiment of the present invention provides a new method for evaluating the hydrocarbon generation potential of marine mixed shale, such as Figure 1 As shown, the hydrocarbon generation potential evaluation method comprises the following steps:

[0040] Step S1, for the marine mixed shale, through logging analysis, core observation and field profile observation, combined with microscopic rock thin section analysis, comprehensive XRD and electron probe test obtained by major element composition, the lithofacies type classification is carried out to clarify the mineral components of the mixed shale; through the element combination form of (copper + molybdenum) / zinc, vanadium / (vanadium + nickel), vanadium / chromium, and the pristane ratio Pr / Ph in the biomarker compound, the oxidation or reduction environment during deposition is judged, the productivity and sea level changes are identified by the changes in carbon and oxygen isotopes, and the paleoproductivity changes are identified by barium / titanium and phosphorus / titanium, and the different lithofacies types in the mixed shale and the characteristics of the mineral components of the lithofacies type.

[0041] Step S2, using the total organic carbon (TOC) value to characterize the abundance of organic matter in different facies in the mixed shale, using the Ts / Tm parameter in the biomarker compound and the vitrinite reflectance Ro to identify the maturity, combining the kerogen carbon morphology and isotope distribution to determine the kerogen type, and discriminate the hydrocarbon generation capacity of different facies in the marine mixed shale.

[0042] Step S3: construct a linkage evaluation model between the hydrocarbon generation capacity of marine mixed shale and lithofacies type and sedimentary characteristics (refer to Figures 4 to 12 ), which simulates the control of the environmental changes of the target strata during the sedimentation-diagenesis process on the final hydrocarbon generation capacity, thereby clarifying the genetic mechanism of the development of high-quality source rock phases in marine mixed-accumulation shales.

[0043] Step S1 specifically includes: Step S11, based on logging and seismic data, combined with core and profile observations, clarify the plane distribution characteristics; use major element analysis to clarify the mixed mineral composition and classify the lithofacies type within the mixed shale; based on the major element composition obtained by XRD and electron probe testing, use the three-terminal projection of shale to classify the lithofacies type and clarify the mineral composition and change law of the mixed shale; based on sedimentology and geochemical experiments, determine the sedimentary environment, such as paleoclimate, paleohydrology, paleoproductivity, and the spatiotemporal evolution law of sedimentary mineral changes.

[0044] Step S1 specifically includes: Step S12, before using each element index, it is necessary to calculate the excess value to eliminate the interference of terrestrial input; clarify the influencing factors in the actual deposition process, and clarify the change law of the marine mixed shale deposition environment.

[0045] Step S2 specifically further includes: Step S21, when the total organic carbon (TOC) content exceeds 0.5%, it has a certain hydrocarbon generation potential. The higher the content, the greater the hydrocarbon generation potential. Vitrinite reflectance (Ro) is an important indicator to measure the maturity of organic matter, indicating the maturity of organic matter after thermal metamorphism in the geological history. Ro < 0.5%: immature stage, mainly generating biogas and a small amount of liquid hydrocarbons; 0.5% < Ro < 1.0%: low-maturity stage, starting to enter the oil generation window and generating liquid hydrocarbons; 1.0% < Ro < 1.3%: peak oil generation stage, generating a large amount of liquid hydrocarbons; 1.3% < Ro < 2.0%: high-maturity stage, liquid hydrocarbons begin to crack and generate gaseous hydrocarbons; Ro > 2.0%: over-mature stage, mainly generating gaseous hydrocarbons. At the same time, biomarker compound analysis is used to identify the maturation conditions using the Ts / Tm ratio, which jointly restricts its thermal evolution stage with Ro.

[0046] Step S2 includes: Step S22, further refining the hydrocarbon generation potential assessment through rock pyrolysis data. A higher S1 peak in the pyrolysis data indicates that a certain amount of hydrocarbons have been generated in the sample, and a higher S2 peak in the pyrolysis data indicates that the sample has a greater potential hydrocarbon generation capacity. Tmax is used to identify the thermal evolution stage of the source rock. The higher the pyrolysis index HI value, the stronger the ability of organic matter to generate hydrocarbons during pyrolysis and the greater the hydrocarbon generation potential. The HI value is an important parameter for evaluating the hydrocarbon generation potential of rocks. HI > 300 mg HC / g TOC: indicating good organic matter type and high hydrocarbon generation potential, mainly generating liquid hydrocarbon petroleum; 150 mg HC / g TOC < HI < 300 mg HC / g TOC: indicating average organic matter type and medium hydrocarbon generation potential, capable of generating both liquid hydrocarbons and gaseous hydrocarbons; HI < 150 mg HC / g TOC: indicating poor organic matter type and low hydrocarbon generation potential, mainly generating gaseous hydrocarbons.

[0047] Step S3 includes: Step S31, using the pyrolysis index HI as an indicator parameter for its hydrocarbon generation potential, constructing the relationship between hydrocarbon generation potential and lithofacies type; understanding the material basis of hydrocarbon generation ability from the sedimentary environment for organic matter enrichment and preservation, and clarifying the thermal evolution conditions of hydrocarbon generation ability through rock pyrolysis parameters and maturity-related indicators. In addition, formation pressure is also an important factor hindering hydrocarbon generation. As an element for evaluating hydrocarbon generation ability, the formation pressure corresponding to the sample obtained from well logging data is used to participate in the calculation; constructing a five-element coupling model of HI with sedimentary environment indicators, organic matter condition indicators, thermal evolution condition indicators, and pressure condition indicators to simulate the control effect of the environmental changes during sedimentation - diagenesis of the target horizon on the final hydrocarbon generation ability, thereby clarifying the genetic mechanism of the development of high-quality hydrocarbon source rock facies in marine mixed sedimentary shales.

[0048] Step S3 includes: step S32, using the AI ​​model to analyze data, constructing a hydrocarbon generation capacity and correlation evaluation function model, linking the relevant elements and isotope indicators in step S1 with the hydrocarbon generation capacity indicators in step S2, and conducting a large amount of data training through Chatgpt to construct a hydrocarbon generation capacity function model with the pyrolysis index HI as the evaluation standard and the sedimentary environment index, organic matter condition index, thermal evolution condition index, and pressure condition index, quantitatively evaluate the genetic mechanism of high-quality source rocks, and quantitatively analyze the contribution of each control factor, and analyze the contribution of paleoproductivity, paleohydrology, and formation pressure.

[0049] The novel method for evaluating the hydrocarbon generation potential of marine mixed shale of the present invention clarifies the hydrocarbon generation capacity and differences of each lithofacies, determines the high-quality lithofacies, and constructs a linkage evaluation model of the sedimentary characteristics and hydrocarbon generation capacity of mixed shale. Key technologies: the technology of linking the biomarker compounds, trace elements and carbon and oxygen isotopes to evaluate the sedimentary environment and genetic mechanism of mixed shale lithofacies; the technology of accurately identifying the lithofacies type and mineral composition change law of mixed shale by XRD and electron probe; the technology of linking the biomarker compounds, TOC, kerogen testing and rock pyrolysis to evaluate the hydrocarbon generation capacity. Technical innovation: The evaluation of the hydrocarbon generation capacity of marine mixed shale integrates multiple factors such as sedimentary environment, organic matter enrichment and preservation, organic matter thermal evolution, and formation pressure conditions. The contribution of each controlling factor of mixed shale source rock is quantitatively evaluated.

[0050] like Figure 2 As shown, an embodiment of the present invention also provides a novel hydrocarbon generation potential evaluation system for marine mixed shale, including a system for the lithofacies type and sedimentary environment change law of marine mixed shale, a system for distinguishing the hydrocarbon generation capacity of different lithofacies of marine mixed shale, and a system for evaluating the hydrocarbon generation capacity of marine mixed shale and the lithofacies type-sedimentary characteristics linkage.

[0051] The marine mixed shale lithofacies type and sedimentary environment change law system is used for marine mixed shale, and through well logging analysis, core observation and field profile observation, combined with microscopic rock thin section analysis, comprehensive XRD and electron probe test to obtain major element composition, the lithofacies type is divided, and the mineral components of the mixed shale are clarified; the oxidizing or reducing environment during deposition is judged by the element combination forms of (copper + molybdenum) / zinc, vanadium / (vanadium + nickel), vanadium / chromium, and the pristane ratio Pr / Ph in the biomarker compound, the productivity and sea level changes are identified by using carbon and oxygen isotope changes, and the ancient productivity changes are identified by using barium / titanium and phosphorus / titanium, so as to clarify the different lithofacies types in the mixed shale and the mineral component characteristics of the lithofacies type.

[0052] The hydrocarbon generation capacity discrimination system of different lithologies of marine mixed shale uses total organic carbon (TOC) value to characterize the abundance of organic matter in different lithologies of mixed shale, uses Ts / Tm parameter and vitrinite reflectance Ro in biomarker compounds to identify maturity, combines kerogen carbon morphology and isotope distribution to determine kerogen type, and discriminates the hydrocarbon generation capacity of different lithologies of marine mixed shale.

[0053] The system for evaluating the hydrocarbon generation capacity of marine mixed shale and its lithofacies type-sedimentary characteristics linkage constructs an evaluation model for the hydrocarbon generation capacity of marine mixed shale and its lithofacies type and sedimentary characteristics linkage, which simulates the control effect of environmental changes in the target strata during the deposition-diagenesis process on the final hydrocarbon generation capacity, thereby clarifying the genetic mechanism of the development of high-quality source lithofacies in marine mixed shale.

[0054] An embodiment of the present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, a new method for evaluating the hydrocarbon generation potential of marine mixed-accumulation shale is implemented as in the above-mentioned embodiment.

[0055] Figure 3 An example of a physical structure diagram of an electronic device is shown in FIG. Figure 3 As shown, the electronic device may include: a processor 210, a communications interface 220, a memory 230 and a communications bus 240, wherein the processor 210, the communications interface 220 and the memory 230 communicate with each other via the communications bus 240. The processor 210 may call the logic instructions in the memory 230 to execute a novel method for evaluating the hydrocarbon generation potential of marine mixed shale.

[0056] In addition, the logic instructions in the above-mentioned memory 230 can be implemented in the form of software functional units and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0057] On the other hand, an embodiment of the present invention further provides a non-transitory computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, a method for evaluating the hydrocarbon generation potential of a new type of marine mixed shale is implemented as in the above embodiment.

[0058] On the other hand, the present invention also provides a computer program product, which includes a computer program. The computer program can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute a new method for evaluating the hydrocarbon generation potential of marine mixed shale provided by the above methods.

[0059] In summary, although the present invention has been disclosed as above in terms of preferred embodiments, the above preferred embodiments are not intended to limit the present invention. A person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined in the claims.

Claims

1. A novel method for evaluating the hydrocarbon generation potential of marine mixed shale, characterized in that: Including the following steps: Step S1: For marine mixed shale, through logging analysis, core observation and field profile observation, combined with microscopic thin-section analysis of rocks, and integrating the major element composition obtained from XRD and electron probe tests, conduct lithofacies type division to clarify the mineral components of this mixed shale; through the elemental combination forms of (copper + molybdenum) / zinc, vanadium / (vanadium + nickel), and vanadium / chromium, as well as the pristane / phytane ratio Pr / Ph in biomarker compounds, judge the oxidation or reduction environment during deposition, respectively use the changes in carbon and oxygen isotopes to identify productivity and sea-level changes, and use barium / titanium and phosphorus / titanium to identify paleoproductivity changes, so as to clarify the different lithofacies types in the mixed shale and the characteristics of the mineral components of this lithofacies type; Step S2: Use the total organic carbon TOC value to characterize the organic matter abundance of different lithofacies in the marine mixed shale, use the Ts / Tm parameter and vitrinite reflectance Ro in biomarker compounds to identify maturity, and combine the kerogen carbon form and isotope distribution to determine the kerogen type, and distinguish the hydrocarbon generation ability of different lithofacies in the marine mixed shale; Step S3: Construct a linkage evaluation model of the hydrocarbon generation ability of marine mixed shale with lithofacies type and sedimentary characteristics, which simulates the control effect of the environmental changes during the sedimentation-diagenesis process of the target layer on the final hydrocarbon generation ability, so as to clarify the genetic mechanism of the development of high-quality hydrocarbon source rock facies in marine mixed shale.

2. The method for evaluating the hydrocarbon generation potential of a novel marine mixed-deposit shale according to claim 1, characterized in that: Step S1 specifically includes: Step S11, based on logging and seismic data, combined with core and profile observations, clarify the planar distribution characteristics; use major element analysis to clarify the mixed mineral composition and divide the lithofacies types within the mixed shale; integrate the major element composition obtained from XRD and electron probe tests, and use the ternary diagram of shale to conduct lithofacies type division to clarify the mineral composition and variation law of this mixed shale; based on sedimentology and geochemical experiments, determine the sedimentary environment, such as the spatio-temporal evolution law of paleoclimate, paleohydrology, paleoproductivity, and sedimentary mineral changes.

3. The method for evaluating the hydrocarbon generation potential of a novel marine mixed shale according to claim 2, characterized in that: Step S1 specifically includes: Step S12, before using each element index, it is necessary to calculate the excess value to exclude the interference of terrigenous input; clarify the influencing factors during the actual sedimentation process and clarify the variation law of the sedimentary environment of marine mixed shale.

4. The method for evaluating the hydrocarbon generation potential of a novel marine mixed shale according to claim 3, characterized in that: Step S2 specifically further includes: Step S21, when the total organic carbon TOC content exceeds 0.5%, it can have a certain hydrocarbon generation potential, and the higher the content, the greater the hydrocarbon generation potential; the vitrinite reflectance Ro is an important indicator to measure the maturity of organic matter, indicating the maturity of organic matter after being subjected to thermal metamorphism in the geological history; Ro < 0.5%: immature stage, mainly generating biogas and a small amount of liquid hydrocarbons; 0.5% < Ro < 1.0%: low maturity stage, starting to enter the oil generation window and generating liquid hydrocarbons; 1.0% < Ro < 1.3%: oil generation peak stage, generating a large amount of liquid hydrocarbons; 1.3% < Ro < 2.0%: high maturity stage, liquid hydrocarbons start to crack to generate gaseous hydrocarbons; Ro > 2.0%: over-mature stage, mainly generating gaseous hydrocarbons; at the same time, use biomarker compound analysis, use the Ts / Tm ratio to identify the maturation conditions, and jointly limit its thermal evolution stage with Ro.

5. The method for evaluating the hydrocarbon generation potential of a novel marine mixed shale according to claim 4, characterized in that: Step S2 includes: Step S22, further refining the hydrocarbon generation potential assessment through rock pyrolysis data. A higher S1 peak in the pyrolysis data indicates that a certain amount of hydrocarbons have been generated in the sample, and a higher S2 peak in the pyrolysis data indicates that the sample has a greater potential hydrocarbon generation capacity. Tmax is used to identify the thermal evolution stage of the source rock. The higher the pyrolysis index HI value, the stronger the ability of organic matter to generate hydrocarbons during pyrolysis and the greater the hydrocarbon generation potential. The HI value is an important parameter for evaluating the hydrocarbon generation potential of rocks. HI > 300 mg HC / g TOC: indicates good organic matter type and high hydrocarbon generation potential, mainly generating liquid hydrocarbon petroleum; 150 mg HC / g TOC < HI < 300 mg HC / g TOC: indicates average organic matter type and medium hydrocarbon generation potential, capable of generating both liquid and gaseous hydrocarbons; HI < 150 mg HC / g TOC: indicates poor organic matter type and low hydrocarbon generation potential, mainly generating gaseous hydrocarbons.

6. The method for evaluating the hydrocarbon generation potential of a novel marine mixed shale according to claim 5, characterized in that: Step S3 includes: Step S31, using the pyrolysis index HI as an indicator parameter for its hydrocarbon generation potential, constructing the relationship between hydrocarbon generation potential and lithofacies type; understanding the material basis of hydrocarbon generation ability from the sedimentary environment for organic matter enrichment and preservation, and clarifying the thermal evolution conditions of hydrocarbon generation ability through rock pyrolysis parameters and maturity-related indicators. In addition, formation pressure is also an important factor hindering hydrocarbon generation. As an element for evaluating hydrocarbon generation ability, the formation pressure corresponding to the sample depth obtained from well logging data is used to participate in the calculation; constructing a five-element coupling model of HI with sedimentary environment indicators, organic matter condition indicators, thermal evolution condition indicators, and pressure condition indicators, simulating the control effect of environmental changes during sedimentation - diagenesis of the target horizon on the final hydrocarbon generation ability, so as to clarify the genetic mechanism of the development of high-quality source rock facies in marine mixed shale.

7. The method for evaluating the hydrocarbon generation potential of a novel marine mixed shale according to claim 6, characterized in that: Step S3 includes: Step S32, using the AI model to analyze data, constructing a function model of hydrocarbon generation ability and correlation evaluation, linking relevant elements and isotope indicators in Step S1 with hydrocarbon generation ability indicators in Step S2, and through a large amount of data training by Chatgpt, constructing a function model of hydrocarbon generation ability with the pyrolysis index HI as the evaluation standard and sedimentary environment indicators, organic matter condition indicators, thermal evolution condition indicators, and pressure condition indicators, quantitatively evaluating the genetic mechanism of high-quality source rocks, and quantitatively analyzing the contribution degree of each control factor, analyzing the contribution degree of paleoproductivity, paleo-hydrology, and formation pressure.

8. A new type of marine mixed shale hydrocarbon generation potential evaluation system, characterized in that: It includes a system for the variation law of the lithofacies type and sedimentary environment of marine mixed shale, a discrimination system for the hydrocarbon generation ability of different lithofacies of marine mixed shale, and a linkage evaluation system for the hydrocarbon generation ability and lithofacies type - sedimentary characteristics of marine mixed shale; The marine mixed shale lithofacies type and sedimentary environment change law system is used for marine mixed shale, through logging analysis, core observation and field profile observation, combined with microscopic rock thin section analysis, comprehensive XRD and electron probe test to obtain major element composition, to classify lithofacies, and clarify the mineral components of the mixed shale; through the element combination forms of (copper + molybdenum) / zinc, vanadium / (vanadium + nickel), vanadium / chromium, and the pristane ratio Pr / Ph in the biomarker compound, to judge the oxidation or reduction environment during deposition, respectively use carbon and oxygen isotope changes to identify productivity and sea level changes, use barium / titanium and phosphorus / titanium to identify ancient productivity changes, and clarify different lithofacies types in mixed shale and the characteristics of the mineral components of the lithofacies type; The system for distinguishing the hydrocarbon generation capacity of different facies of marine mixed shale uses the total organic carbon (TOC) value to characterize the abundance of organic matter in different facies of mixed shale, uses the Ts / Tm parameter and vitrinite reflectance Ro in the biomarker compound to identify the maturity, and combines the kerogen carbon morphology and isotope distribution to determine the kerogen type, so as to distinguish the hydrocarbon generation capacity of different facies of marine mixed shale; The system for evaluating the hydrocarbon generation capacity of marine mixed shale and its lithofacies type-sedimentary characteristics linkage constructs an evaluation model for the hydrocarbon generation capacity of marine mixed shale and its lithofacies type and sedimentary characteristics linkage, which simulates the control effect of environmental changes in the target strata during the deposition-diagenesis process on the final hydrocarbon generation capacity, thereby clarifying the genetic mechanism of the development of high-quality source lithofacies in marine mixed shale.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, a new method for evaluating the hydrocarbon generation potential of marine mixed shale as described in any one of claims 1 to 7 is implemented.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, a method for evaluating the hydrocarbon generation potential of a new type of marine mixed-accumulation shale is implemented as described in any one of claims 1 to 7.

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