A fine evaluation method for the lamination and layered shale structure of continental matrix-type shale oil reservoirs

Abstract

The present invention relates to a method for the fine evaluation of the lamination and laminated shale structure of a continental matrix-type shale oil reservoir. It mainly solves the fundamental problems that the existing methods cannot solve the fine evaluation of the lamination and laminated shale structure of the continental matrix-type shale oil reservoir in large freshwater lake basins and shale oil exploration. The evaluation method includes: using core sampling from shale oil exploration wells, accurate description of lithology and lithofacies, and a supporting geological experimental analysis method for lamination and laminated shale to conduct a fine evaluation of the millimeter-scale, micron-scale, and nanoscale of the laminated shale and laminated shale structure. For the first time, it determines the composition of 4 combinations of the ternary structure and 4 combinations of the binary structure of the matrix-type laminated shale; and the characteristics of 7 combinations of the development structure of the matrix-type laminated shale, which supports the accurate evaluation of the lithology and reservoir properties of shale oil, meets the requirements of shale oil exploration and production, and lays the foundation for the fine evaluation of the lithology and reservoir properties of continental matrix-type shale oil exploration.

Description

Technical Field

[0001] The present invention relates to the field of unconventional oil and gas, and particularly relates to a method for fine evaluation of the laminations and laminated shale structures of continental matrix shale oil reservoirs. Background Art

[0002] In China, exploration and development of shale oil have been carried out in many lacustrine basins such as the Songliao Basin, Ordos Basin, Bohai Bay Basin, Nanxiang Basin, and Junggar Basin. Industrial oil flow and positive progress have been achieved in multiple wells, demonstrating good prospects for shale oil exploration and development. According to the shale lithology combination and reservoir characteristics, the currently discovered shale oil can be roughly divided into three types: matrix type, shale interbedded with brittle layers type, and fracture type. Among them, the Bohai Bay Basin, Nanxiang Basin, Junggar Basin, etc. are mainly dominated by interbedded type and fracture type shale oil, while the matrix type shale oil with great potential has been in the exploration stage. Many problems and challenges still exist in the enrichment mechanism, distribution law, sweet spot prediction, etc. of continental matrix shale oil in large freshwater lake basins, which restricts the development speed and scale production of shale oil in China. Therefore, in-depth development of fine evaluation of the laminations and laminated structures of continental matrix shale oil reservoirs in large freshwater lake basins, and strengthening the exploration and development foundation of fine evaluation of shale oil lithology and reservoir properties have important theoretical and practical values for promoting shale oil to become a realistic oil and gas replacement field.

[0003] There are reports in the literature on the study of shale lithofacies, lithology and reservoir evaluation. See (1) Long Yumei et al., "Development characteristics and influencing factors of inter-salt shale oil reservoirs in Qianjiang Formation, Qianjiang Sag" (Petroleum Geology and Recovery Efficiency, No. 1, 2019); (2) Li Tiejun, "Discussion on lithology prediction methods for tight and complex reservoirs" (Petroleum Geology and Engineering, No. 4, 2016); (3) Zhang Linyan et al., "Pore structure characteristics and connectivity of Paleogene mudstones and shales in Dongying Sag" (Xinjiang Petroleum Geology, No. 2, 2018); (4) Yang Kehong et al., "Stratified structure of cold seep carbonates in the northern South China Sea and its geological significance" (Marine Geology & Quaternary Geology, No. 5, 2008), etc. In the above (1), through technical means such as core observation, thin-section identification of rocks, argon ion polishing-scanning electron microscopy, low-temperature nitrogen adsorption and high-pressure mercury injection, the research results on the lithofacies characteristics, reservoir space types, reservoir physical property characteristics and influencing factors of mudstones and shales show that the mineral composition of the inter-salt shale oil reservoirs in the Qian 34 oil group of the Qianjiang Formation is complex, and mainly develops 6 lithofacies types including laminated cloud (mud) gypsum rock facies, laminated argillaceous dolomite facies, laminated dolomitic mudstone facies, laminated argillaceous limestone facies, laminated calcareous mudstone facies and massive dolomite facies; the reservoir spaces include interlayer fractures, intercrystalline pores, intercrystalline dissolved pores and intercrystalline pores of clay minerals; the average porosity of the reservoir is 11.4% - 18.9%, and the average permeability is 2.635 - 4.827 mD, belonging to medium-pore and extra-low permeability reservoirs; the physical properties and oil-bearing properties of the laminated argillaceous dolomite facies and massive dolomite facies are good, being the most favorable lithofacies; compaction and the filling of late sulfate minerals are the main reasons for the deterioration of reservoir physical properties. In the above (2), through rock physics analysis, it is determined that the Young's modulus and the ratio of longitudinal and transverse wave velocities can better distinguish mudstones and shales, and the relationship between dolomite content and Young's modulus is determined through statistical regression of Young's modulus and dolomite content; based on pre-stack elastic parameter inversion, through reconstructing the dolomite content, the dolomite content inversion is carried out, and the planar and vertical distribution characteristics of reservoirs with high dolomite content are determined, and the prediction conclusion has a high degree of coincidence with the actual drilling data results, which can effectively guide the exploration of tight (reservoir) oil in this area. In the above (3), by combining the determination of total porosity of mudstones and shales and high-pressure mercury injection analysis, a quantitative research method for the pore structure characteristics of shale reservoirs is established, and the total porosity, effective pore size distribution and pore connectivity rate of massive mudstones, laminated shales and laminated shales in the Paleogene Shahejie Formation of Dongying Sag are compared.In the above (4), three different layered structures were found: the microlayers of nodular carbonate rocks and the layers parallel and perpendicular to the chimney wall of chimney-shaped carbonate rocks. The research results of the microstructure, chemical composition, minerals, etc. of different layers show that: each microlayer of the nodular carbonate rock layer is different in terms of crystal degree, mineral morphology, porosity, etc., but the chemical composition changes little; for the chimney-shaped carbonate rock, the minerals and diagenetic degree are different between the inner and outer layers parallel to the chimney wall, and the carbonate mineral content is different between the different layers perpendicular to the chimney wall; the different layered structures of carbonate rocks are the reflections of geological, physical, chemical, and biological information during their formation, and are of great significance for restoring the paleoenvironment during their formation. It can be seen that the above methods have achieved many research results in shale lithofacies characteristics and reservoir evaluation, lithology prediction by rock physics technology, carbonate rock layered structure and its geological significance, etc., but cannot solve the basic problems of fine evaluation of the laminae and layered shale structure of continental matrix-type shale oil reservoirs in large freshwater lake basins and shale oil exploration. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the problem in the background technology that the existing methods cannot solve the basic problems of fine evaluation of the laminae and layered shale structure of continental matrix-type shale oil reservoirs in large freshwater lake basins and shale oil exploration, and to provide a method for fine evaluation of the laminae and layered shale structure of continental matrix-type shale oil reservoirs. This method for fine evaluation of the laminae and layered shale structure of continental matrix-type shale oil reservoirs conducts fine evaluation at three scales of millimeter, micrometer, and nanometer on the laminated shale and layered shale structure of shale oil reservoirs, and finely depicts the lamina morphology, thickness, type, and mineral component characteristics of continental matrix-type laminated shale and layered shale, laying the foundation for fine evaluation of the lithology and reservoir performance of continental matrix-type shale oil exploration.

[0005] The present invention can achieve the above object through the following technical solutions: The method for fine evaluation of the laminae and layered shale structure of continental matrix-type shale oil reservoirs includes the following steps:

[0006] 1) Accurately describe the lithology and lithofacies of the drilled core to obtain the description results of the lithology and lithofacies of the shale reservoir;

[0007] 2) Based on the description results of the lithology and lithofacies of the shale reservoir in step 1), collect samples of laminae and layered shale to obtain geological experimental samples of laminae and layered shale;

[0008] 3) Based on the geological experimental samples of laminae and layered shale obtained in step 2), prepare the samples in advance according to the corresponding standards to obtain supporting geological experimental preparation samples of laminae and layered shale;

[0009] 4) Prepare samples for the geological experiments in combination with the laminations and laminated shales obtained in step 3), analyze the rock thin sections and polished sections to obtain the analysis results of the geological experiments in combination with the laminations and laminated shales;

[0010] 5) Based on the analysis results of the geological experiments in combination with the laminations and laminated shales obtained in step 4), realize the continuous characterization of the full-scale lamination structure of the shale; conduct full-scale fine research and evaluation according to two categories of laminated shale and laminated shale, and through the lamination combination modes of laminated shale and laminated shale, obtain the fine evaluation results of the structures of laminated shale and laminated shale, which are used for the fine evaluation of the lithology and reservoir properties of shale oil reservoirs and exploration.

[0011] Furthermore, the items for the preliminary preparation of the samples in step 3) include rock section preparation, field emission electron microscope and energy spectrum sample preparation for the samples.

[0012] Furthermore, the analysis of the rock thin sections and polished sections in step 4) includes: identification of the rock thin sections and testing with a gypsum test plate, and supporting analyses such as field emission electron microscope and energy spectrum scanning. (Among them: the analysis of the rock thin sections includes: identification of the rock thin sections and testing with a gypsum test plate; the analysis of the rock polished sections includes supporting analyses such as field emission electron microscope and energy spectrum scanning.)

[0013] Furthermore, the lamination combination mode of the laminated shale: it is divided into 4 combinations of ternary structure and 4 combinations of binary structure.

[0014] Furthermore, in the lamination combination mode of the laminated shale, the 4 combinations of ternary structure are respectively:

[0015] 21). Ternary structure combination of argillaceous lamination, debris lamination and siltaceous lamination;

[0016] 22). Ternary structure combination of argillaceous lamination, siltaceous lamination and debris lamination;

[0017] 23). Ternary structure combination of high organic matter lamination, debris lamination and siltaceous layer;

[0018] 24). Ternary structure combination of high organic matter lamination, low organic matter lamination and siltaceous layer;

[0019] Furthermore, in the lamination combination mode of the laminated shale, the 4 combinations of binary structure are respectively:

[0020] 31). Binary structure combination of silt-bearing argillaceous lamination and siltaceous lamination;

[0021] 32). Binary structure combination of argillaceous lamination and siltaceous lamination;

[0022] 33). Binary structure combination of dolomite-bearing argillaceous lamination and dolomite-bearing argillaceous lamination;

[0023] 34). Binary structure combination of organic matter-rich laminae and iron-bearing dolomite laminae.

[0024] Furthermore, the lamina combination patterns of laminated shale include 7 combination patterns, namely:

[0025] 41. Composed of argillaceous laminae with alternating light and dark of different mineral compositions, the laminae are thinner and pyrite is developed;

[0026] 42. Composed of argillaceous laminae with alternating light and dark of different organic matter contents, with thin sandy laminae intercalated;

[0027] 43. Composed of a ternary structure of organic matter-rich laminae, organic matter-poor laminae, and silty laminae;

[0028] 44. Composed of clay and felsic, the laminae or bedding are not obvious, with cross-layered authigenic quartz developed and calcareous shell laminae developed;

[0029] 45. Composed of clay and felsic, the bedding or schistosity is not obvious, and calcite is filled along the rock fractures;

[0030] 46. Composed of clay and felsic, with authigenic quartz and pyrite relatively developed;

[0031] 47. Composed of clay and felsic, with stripes of different colors developed, reflecting the changes in the contents of clay and felsic.

[0032] Furthermore, the full scale in realizing the continuous characterization of the shale full-scale lamina structure in step 5) includes millimeter scale, micrometer scale, and nanometer scale.

[0033] Furthermore, the full scale in the full-scale fine research and evaluation of step 5) according to two categories of laminated shale and layered shale includes millimeter scale, micrometer scale, and nanometer scale.

[0034] The present invention may have the following beneficial effects compared with the above background technology:

[0035] A fine evaluation method for the bedding and laminated shale structures of continental matrix shale oil reservoirs. This method uses conventional coring of shale oil exploration wells, precise description of lithology and lithofacies, and a supporting geological experimental analysis method for bedding and laminated shale to conduct a fine evaluation of the millimeter-scale, micron-scale, and nanometer-scale structures of laminated shale and bedded shale in shale oil reservoirs. For the first time, it determines 4 combinations of millimeter-scale ternary structures and 4 combinations of binary structures, 4 combinations of micron-scale structure compositions, and nanometer-scale structure compositions in matrix laminated shale. For the first time, it determines 3 combinations of millimeter-scale structures, 4 combinations of micron-scale structure compositions, and nanometer-scale structure compositions developed in matrix bedded shale (oil shale). It finely depicts the bedding morphology, thickness, types, and mineral component characteristics of continental matrix laminated shale and bedded shale, laying the foundation for the fine evaluation of lithology and reservoir performance in continental matrix shale oil exploration. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Appendix Figure 1 is a schematic flow chart of the method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0037] The present invention will be further described below with reference to the accompanying drawings:

[0038] The present invention mainly proposes an evaluation method for the bedding and laminated shale structures of continental matrix shale oil reservoirs. It mainly uses conventional coring of shale oil exploration wells, precise description of lithology and lithofacies, and a supporting geological experimental analysis method for bedding and laminated shale to conduct a fine evaluation of the millimeter-scale, micron-scale, and nanometer-scale structures of laminated shale and bedded shale in shale oil reservoirs.

[0039] The present invention will be described in detail from the following aspects.

[0040] I. Geological experimental evaluation method for shale oil reservoirs

[0041] 1. Fine and accurate description method for the lithology and lithofacies of shale oil reservoirs

[0042] The drilling cores are described in detail and accurately according to the method for fine and accurate description of the lithology of unconventional tight sandstone and mud shale cores (the specific description method can be found in the patented application with the patent number ZL201310659696.4), and the description results of the lithology and lithofacies of the tight reservoir cores are obtained.

[0043] 2. Geological experimental analysis method for bedding and laminated shale

[0044] For the geological experimental analysis of laminations and laminated shales, industry standards or enterprise standards are adopted. For rock section preparation, the industry standard "Rock Section Preparation Method" (SY / T 5913-2004) is used. For thin section identification, the industry standard "Rock Thin Section Identification" (SY / T 5368-2000) is used. For nano-pore structure, the enterprise standard "Analysis Technology of Nano-pore Structure in Unconventional Reservoirs" (Q / SY DQ1667-2015) is used, etc.

[0045] 3. Fine Evaluation Method for the Structure of Laminations and Laminated Shales

[0046] (1) Lithofacies Types of Shale Oil Reservoirs

[0047] Apply technologies such as detailed lithology description, rock thin sections, and field emission electron microscopy to determine the lithofacies types of shale oil reservoirs.

[0048] (2) Fine Evaluation of the Structure of Laminated Shales

[0049] Use rock thin section identification and gypsum test plate testing, etc. to conduct a detailed study on the millimeter-scale structure of laminated shales, and evaluate the combination mode and characteristics of the millimeter-scale structure of laminated shales in the Qingshankou Formation. Use field emission electron microscopy and energy spectrum scanning, etc. to conduct a detailed study on the micron-scale structure of laminated shales, and evaluate the combination mode and characteristics of the micron-scale structure of laminated shales in the Qingshankou Formation.

[0050] (3) Fine Evaluation of the Structure of Laminated Shales (Oil Shales)

[0051] Use rock thin section identification and gypsum test plate testing, etc. to conduct a detailed study on the millimeter-scale structure of laminated shales (oil shales), and evaluate the combination mode and characteristics of the millimeter-scale structure of laminated shales (oil shales) in the Qingshankou Formation. Use field emission electron microscopy and energy spectrum scanning, etc. to conduct a detailed study on the micron-scale structure of laminated shales (oil shales), and evaluate the combination mode and characteristics of the micron-scale structure of laminated shales (oil shales) in the Qingshankou Formation.

[0052] A fine evaluation method for the structure of laminations and laminated shales in continental matrix-type shale oil reservoirs includes the following steps:

[0053] 1) Conduct a detailed and accurate description of the lithology and lithofacies of the cored rock to obtain the description results of the lithology and lithofacies of the shale reservoir;

[0054] 2) According to the description results of the lithology and lithofacies of the shale reservoir in step 1), collect samples of laminations and laminated shales to obtain geological experimental samples of laminations and laminated shales;

[0055] 3) For the geological experimental samples of laminations and laminated shales obtained in step 2), conduct rock section preparation, field emission electron microscopy and energy spectrum sample preparation, etc. according to the corresponding standards to obtain the supporting geological experimental preparation samples of laminations and laminated shales;

[0056] 4) Prepare samples by conducting geological experiments on the laminations obtained in step 3) in combination with laminated shale, and perform supporting analyses such as rock thin-section identification, testing with a gypsum test plate, field emission electron microscopy, and energy spectrum scanning to obtain the results of the geological experiments on the laminations in combination with laminated shale;

[0057] 5) Use the results of the geological experiments on the laminations in combination with laminated shale obtained in step 4) to achieve continuous characterization of the millimeter-scale, micron-scale, and nanometer-scale lamination structures of shale; conduct three-scale fine research and evaluation on the structural compositions at the millimeter, micron, and nanometer scales respectively for the two types of laminated shale and laminated shale, and obtain the fine evaluation results of the structures of laminated shale and laminated shale, which are used for the fine evaluation of the lithology and reservoir properties of shale oil reservoirs and exploration.

[0058] Example 1

[0059] As Figure 1 shown below, the implementation process of the method of the present invention is illustrated by taking the method for evaluating the structures of laminations and laminated shale in the continental matrix-type shale oil reservoir in the northern Songliao Basin in the Daqing exploration area as an example.

[0060] 1. Research background

[0061] The upper Cretaceous in the Songliao Basin is characterized by large-scale continental freshwater lake basin sediments, with large-scale delta sediments, semi-deep lake and deep lake facies sediments with a thickness exceeding 1500 m. During the periodic cyclic changes in the depth of the lake water body, corresponding to two large-scale marine transgression events globally during the same period, two large-scale marine transgressions occurred during the deposition periods of the Qingshankou Formation (Cenomanian stage) and the Nenjiang Formation (Turonian stage), forming two sets of semi-deep lake - deep lake facies shale deposits with a distribution area of more than 100,000 - 180,000 square kilometers. Among them, the shale thickness of the first member of the Qingshankou Formation is 40 - 110 m, and the shale thickness of the second member of the Qingshankou Formation is 50 - 250 m. The lateral lithology changes little and the thickness distribution is relatively stable. After the shale deposition, during the tectonic evolution process, it is mainly buried stably, without experiencing large uplift and erosion and large fault damage, providing important conditions for the formation and preservation of shale oil. The organic matter content of the Qingshankou Formation shale is high, with an average TOC content greater than 2.13%. The parent material type is mainly type I and type II. The activation energy distribution range of kerogen is narrow, and the organic matter has a fast oil generation rate and a high conversion rate. With the increase of burial depth, the thermal evolution degree of the source rock increases, generating a large amount of oil and gas and discharging them from the source rock into the sandstone reservoir. At the same time, the oil and gas in the thick shale fail to be fully discharged, resulting in retention or enrichment in the shale, becoming the material basis for the formation of shale oil. At present, a series of industrial oil flows and exploration breakthroughs have been achieved in key exploration wells such as Yx58, Gy1, Zhao2911, Syy2, and Chao21. They are mainly located in the lower-middle parts of the first and second members of the Qingshankou Formation with large shale thickness and high organic matter abundance. Controlled by the quantity of shale oil generation, preservation conditions and shale reservoir capacity, the shale oil in the main hydrocarbon generation sags is vertically stacked in multiple layers and horizontally shows a continuous distribution characteristic, demonstrating good prospects and huge resource potential for shale oil exploration in the northern Songliao Basin, and becoming an important area for the continuous stable production of the Daqing Oilfield and the establishment of a century-old oilfield.

[0062] 2. Lithofacies types of shale reservoirs in the Qingshankou Formation

[0063] Using technologies such as detailed lithology description, thin section identification, and field emission electron microscopy to accurately describe the shale, five lithofacies types are developed in the Qingshankou Formation, namely laminated shale, bedded shale (oil shale), siltstone, debris limestone, and micritic dolomite, accounting for 84.6%, 6.1%, 5.8%, 1.0%, and 2.5% respectively. Laminated shale and bedded shale (oil shale) are the main reservoir lithofacies.

[0064] 3. Fine evaluation of the structure of laminated shale in the Qingshankou Formation

[0065] The structure of laminated shale in the Qingshankou Formation is divided into millimeter-scale, micron-scale, and nanometer-scale structures for composition and characteristic fine evaluation.

[0066] (1) Millimeter-scale structure and characteristics of laminated shale in the Qingshankou Formation

[0067] There are 8 combinations of millimeter-scale structures developed in the laminated shales of the Qingshankou Formation, including 4 combinations of ternary structures and 4 combinations of binary structures.

[0068] Combination 1: Ternary structure combination of argillaceous lamina + debris lamina + silt lamina. Lithology and morphology: The laminated silt-bearing debris shale has a wavy lamina morphology, with a lamina thickness of 0.08 - 0.55 mm (Table 1) and a lamina density of 1.8 strips / mm. The lamina thickness, type, and mineral composition of the millimeter-scale ternary structure combination 1 of laminated shale are shown in the table.

[0069] Table 1 Lamina thickness, type, and mineral composition of the millimeter-scale ternary structure combination 1 of laminated shale

[0070] Lamina number Lamina thickness Lamina type Lamina mineral composition 1 0.3mm Lamina containing debris and fine sand coarse silt Mainly felsic clasts, calcareous cement, containing debris 2 0.53mm Lamina containing silt and debris Mainly continuously distributed debris, containing a small amount of silt 3 0.28mm Lamina containing fine sand and silt Mainly felsic clasts, calcareous cement 4 0.55mm Debris lamina Mainly continuously distributed debris, containing a very small amount of silt 5 0.08mm Clay lamina Thin and discontinuous, mainly clay minerals, containing pyrite 6 0.13mm Lamina containing silt and debris Thin and discontinuous, mainly debris, containing silt 7 0.3mm Lamina containing silt and clay Thin and continuous, mainly clay minerals, containing a small amount of silt and pyrite

[0071] Combination 2: Ternary structure combination of argillaceous lamina + silt lamina + debris lamina. Lithology and morphology: The laminated debris-bearing silt shale has a relatively straight lamina morphology, with a lamina thickness of 0.13 - 0.93 mm (see Table 2) and a lamina density of 2.87 strips / mm. The lamina thickness, type, and mineral composition of the millimeter-scale ternary structure combination 2 of laminated shale are shown in Table 2.

[0072] Table 2

[0073]

[0074]

[0075] Combination 3: Ternary structure combination of high-organic-matter lamina + debris lamina + silt layer. Lithology and morphology: The laminated shale has relatively straight and continuous laminae, with a lamina thickness of 0.6 - 1.5 mm and a lamina density of 1.7 - 0.7 strips / mm. The lamina thickness, type, and mineral composition of the millimeter-scale ternary structure combination 3 of laminated shale are shown in Table 3.

[0076] Table 3

[0077] Lamina number Lamina thickness Lamina type Lamina mineral composition 1 0.8mm Silt lamina Silty, calcareous cement 2 1mm High organic matter lamina Organic matter and clay, mixed with a small amount of silt 3 0.6mm Debris lamina Debris and silty 4 0.92mm Silt lamina Silty, calcareous cement 5 1.08mm High organic matter lamina Organic matter and clay, mixed with a small amount of silt 6 1.5mm Silt lamina Silty, calcareous cement

[0078] Combination 4: Ternary structure combination of high-organic-matter lamina + low-organic-matter lamina + silt layer. Lithology and morphology: The laminated shale has relatively straight laminae, with a lamina thickness of 0.3 - 0.62 mm and a lamina density of 3.3 - 1.6 strips / mm. The lamina thickness, type, and mineral composition of the millimeter-scale ternary structure combination 4 of laminated shale are shown in Table 4.

[0079] Table 4

[0080] Lamina number Lamina thickness Lamina type Lamina mineral composition 1 0.7mm Silt lamina Silty and clay 2 1.1mm High organic matter lamina Organic matter and clay, mixed with a small amount of silt 3 0.6mm Silt lamina Silty 4 1.9mm Low organic matter lamina Clayey and silt 5 0.7mm High organic matter lamina Organic matter and clay, mixed with a small amount of silt 6 1.4mm Silt lamina Silty and clay

[0081] Combination 5: A binary structure combination of silt-bearing argillaceous laminae + silty laminae. Lithology and morphology: The laminae of laminated silty shale are relatively straight, with a lamina thickness of 0.22 - 0.54 mm and a lamina density of 2.1 laminae / mm. The lamina thickness, type, and mineral composition of the millimeter-scale binary structure combination 1 of laminated shale are shown in Table 5.

[0082] Table 5

[0083] Lamina number Lamina thickness Lamina type Lamina mineral composition 1 0.54mm Lamina containing silt and clay Mainly clay minerals, silt is dispersed, containing pyrite 2 0.22mm Silt lamina Mainly felsic clasts 3 0.32mm Lamina containing silt and clay Mainly clay minerals, silt is dispersed, containing pyrite 4 0.31mm Silt lamina Mainly felsic clasts

[0084] Combination 6: A binary structure combination of argillaceous laminae + silty laminae. Lithology and morphology: The laminae of laminated shale are relatively straight, with a lamina thickness of 0.25 - 2 mm and a lamina density of 0.89 laminae / mm. The lamina thickness, type, and mineral composition of the millimeter-scale binary structure combination 2 of laminated shale are shown in Table 6.

[0085] Table 6

[0086] Lamina number Lamina thickness Lamina type Lamina mineral composition 1 0.38 - 2mm Lamina containing silt and clay Mainly clay minerals, silty is dispersed or discontinuously banded 2 0.25mm Silt lamina Mainly felsic clasts 3 0.38 - 2mm Lamina containing silt and clay Mainly clay minerals, silty is discontinuously banded

[0087] Combination 7: A binary structure combination of dolomitic argillaceous laminae + argillaceous dolomitic laminae. Lithology and morphology: The laminae of laminated shale are relatively straight, with a lamina thickness of 0.21 - 0.83 mm and a lamina density of 2.4 laminae / mm. The lamina thickness, type, and mineral composition of the millimeter-scale binary structure combination 3 of laminated shale are shown in Table 7.

[0088] Table 7

[0089]

[0090]

[0091] Combination 8: A binary structure combination of organic-rich laminae + iron-bearing dolomite laminae. Lithology and morphology: The laminae of laminated dolomitic shale are straight, with a lamina thickness of 0.03 - 0.17 mm (Table 8) and a lamina density of 9.43 laminae / mm. The lamina thickness, type, and mineral composition of the millimeter-scale binary structure combination 4 of laminated shale are shown in Table 8.

[0092] Table 8

[0093] Lamina number Lamina thickness Lamina type Lamina mineral composition 1 0.06mm Rich organic matter lamina Clay minerals and organic matter 2 0.17mm Ferroan dolomite lamina Micritic dolomite 3 0.03mm Rich organic matter lamina Clay minerals and organic matter 4 0.16mm Ferroan dolomite lamina Micritic dolomite

[0094] (2) Micron-scale structure and characteristics of laminated shale in the Qingshankou Formation

[0095] The micron-scale structure of laminated shale in the Qingshankou Formation mainly consists of 4 combinations.

[0096] Combination 1: A combination composed of clay and felsic, with calcareous shell laminae developed.

[0097] Combination 2: A combination composed of clay and felsic components, with calcareous shell laminae developed, and authigenic quartz dispersed in clay minerals.

[0098] Combination 3: A combination composed of clay and felsic components, with felsic laminae developed.

[0099] Combination 4: A combination composed of clay and felsic components, with dolomite laminae and felsic laminae developed.

[0100] (3) Nanoscale structure and characteristics of laminated shale in the Qingshankou Formation

[0101] The nanoscale structure composition of laminated shale in the Qingshankou Formation: Felsic minerals are scattered in clay minerals, which is not conducive to the development of intergranular pores.

[0102] 4. Fine evaluation of the structure of laminated shale in the Qingshankou Formation

[0103] The structure of laminated shale (oil shale) in the Qingshankou Formation is divided into millimeter-scale, micrometer-scale, and nanoscale structure compositions and characteristics for fine evaluation.

[0104] (1) Millimeter-scale structure and characteristics of laminated shale in the Qingshankou Formation

[0105] Three main combinations are developed in the millimeter-scale structure of laminated shale in the Qingshankou Formation.

[0106] Combination 1: Composed of argillaceous laminae with different mineral compositions showing alternating light and dark, the laminae are thinner, and pyrite is developed.

[0107] The laminated shale (oil shale) in the first member of the Qingshankou Formation in Well Gy1 is composed of argillaceous laminae with alternating light and dark. The laminae are denser, the lamina thickness is thin, ranging from 0.01 - 0.3 mm, the lamina shape is straight, and the lamina density is 9 strips / mm. The lamina thickness, type, and mineral components of the millimeter-scale combination 1 of laminated shale are shown in Table 9.

[0108] Table 9

[0109] Lamina number Lamina thickness Lamina type Lamina mineral composition 1 0.3mm Clay lamina Mainly clay minerals, felsic 2 0.01mm Dark clay lamina Mainly clay minerals, containing pyrite 3 0.02mm Clay lamina Mainly clay minerals, felsic 4 0.02mm Dark clay lamina Mainly clay minerals, containing pyrite 5 0.02mm Clay lamina Mainly clay minerals, felsic 6 0.04mm Dark clay lamina Mainly clay minerals, containing pyrite 7 0.02mm Clay lamina Mainly clay minerals, felsic 8 0.03mm Dark clay lamina Mainly clay minerals, containing pyrite 9 0.24 mm Argillaceous lamina Mainly clay minerals, felsic

[0110] Combination 2: A combination composed of argillaceous laminae with different organic matter contents showing alternating light and dark, with thin sandy laminae intercalated.

[0111] The laminated shale in Well Yx58 is composed of argillaceous laminae with alternating light and dark, with thin sandy laminated shale intercalated. The lamina thickness is larger, ranging from 0.03 - 0.7 mm (Table 10), the lamina shape is straight, and the lamina density is 1.5 - 33 strips / mm. The lamina thickness, type, and mineral components of the millimeter-scale combination 2 of laminated shale are shown in Table 10.

[0112] Table 10

[0113]

[0114]

[0115] Combination 3: It is composed of a ternary structure of organic-rich laminae, organic-poor laminae, and siltstone laminae

[0116] The laminated shale in Well Zhao2911 is composed of alternately light and dark muddy laminae. The laminae are dense and thin, with a range of 0.03 - 0.23 mm. The lamina morphology is straight, and the lamina density is 11.09 - 24.57 strips / mm. The thickness, type, and mineral composition of the millimeter-scale combination 3 of the laminated shale are shown in Table 11

[0117] Table 11

[0118] Lamina number Lamina thickness Lamina type Lamina mineral composition 1 0.09 mm Silty lamina Mainly felsic clasts 2 0.03 mm Clay lamina Clay minerals 3 0.01 mm Organic-rich lamina Clay minerals and organic matter 4 0.04 mm Silty clay lamina Clay minerals, a small amount of felsic clasts 5 0.01 mm Clay lamina Clay minerals 6 0.02 mm Organic-rich lamina Clay minerals and organic matter 7 0.23 mm Silty clay lamina Clay minerals, a small amount of felsic clasts

[0119] (2) Micron-scale structure and characteristics of the laminated shale in the Qingshankou Formation

[0120] The micron-scale structure of the laminated shale (oil shale) in the Qingshankou Formation mainly has 4 combinations

[0121] Combination 1: It is composed of clay minerals and felsic minerals. The laminae or bedding are not obvious, with cross-layered authigenic quartz developed, and calcareous shell laminae developed

[0122] Combination 2: It is composed of clay minerals and felsic minerals. The bedding or schistosity is not obvious, and calcite is filled along the rock fractures

[0123] Combination 3: It is composed of clay minerals and felsic minerals. Authigenic quartz and pyrite are relatively developed

[0124] Combination 4: It is composed of clay minerals and felsic minerals, with stripes of different colors developed, reflecting the changes in the contents of clay minerals and felsic minerals

[0125] (3) Nanoscale structure and characteristics of the laminated shale in the Qingshankou Formation

[0126] The nanoscale structure of the laminated shale (oil shale) in the Qingshankou Formation: Granular minerals are dispersed in clay minerals, and the particles are finer

[0127] The above specifically illustrates the whole process of the method for evaluating the laminae of continental matrix-type shale oil reservoirs and the structure of laminated shale through examples. The evaluation results of the laminae of continental matrix-type shale oil reservoirs and the structure of laminated shale by this method can be used for shale oil exploration and production. The present invention has the following characteristics

[0128] (1) A method for evaluating the laminations and layered shale structures of continental matrix-type shale oil reservoirs was proposed and established. It mainly uses core samples from shale oil exploration wells, precise lithological and lithofacies descriptions, and a set of geological experimental analysis methods for laminations and layered shale to conduct a fine evaluation of the millimeter-scale, micron-scale, and nanometer-scale structures of laminated shale and layered shale. For the first time, 4 combinations of millimeter-scale ternary structures and 4 combinations of binary structures, 4 combinations of micron-scale structures, and the composition of nanometer-scale structures were determined for matrix-type laminated shale. For the first time, 3 combinations of millimeter-scale structures, 4 combinations of micron-scale structures, and the characteristics of nanometer-scale structure composition were determined for matrix-type layered shale (oil shale). The lamination morphology, thickness, type, and mineral composition of continental matrix-type laminated shale and layered shale were finely characterized, supporting the precise evaluation of shale oil lithology and reservoir performance and meeting the needs of shale oil exploration and production.

[0129] (2) When this evaluation method was applied in the shale oil exploration of the Songliao Basin, 8 combinations of millimeter-scale ternary and binary structures of laminated shale in the Qingshankou Formation were determined for the first time: ① The ternary structure combination of argillaceous lamination + debris lamination + siltaceous lamination; ② The ternary structure combination of argillaceous lamination + siltaceous lamination + debris lamination; ③ The ternary structure combination of high organic matter lamination + debris lamination + siltaceous layer; ④ The ternary structure combination of high organic matter lamination + low organic matter lamination + siltaceous layer; ⑤ The binary structure combination of silt-bearing argillaceous lamination + siltaceous lamination; ⑥ The binary structure combination of argillaceous lamination + siltaceous lamination; ⑦ The binary structure combination of dolomite-bearing argillaceous lamination + argillaceous dolomite lamination; ⑧ The binary structure combination of organic matter-rich lamination + iron-bearing dolomite lamination.

[0130] For the first time, 4 combinations of micron-scale structure compositions of laminated shale in the Qingshankou Formation were determined: ① The combination composed of clay minerals and felsic minerals, with calcareous shell laminations developed; ② The combination composed of clay minerals and felsic minerals, with calcareous shell laminations developed, and authigenic quartz dispersed in clay minerals; ③ The combination composed of clay minerals and felsic minerals, with felsic laminations developed; ④ The combination composed of clay minerals and felsic minerals, with dolomite laminations and felsic laminations developed. The nanometer-scale structure composition of laminated shale in the Qingshankou Formation was determined: Felsic minerals are scattered in clay minerals, which is not conducive to the development of intergranular pores.

[0131] (3) For the first time, 3 combinations of millimeter-scale structures developed in layered shale of the Qingshankou Formation were determined: ① Composed of argillaceous laminations with different mineral components showing alternating light and dark, the laminations are relatively thin, and pyrite is developed; ② The combination composed of argillaceous laminations with different organic matter contents showing alternating light and dark, with thin sandy laminations intercalated; ③ Composed of a ternary structure of organic matter-rich laminations, organic matter-poor laminations, and siltaceous laminations.

[0132] Four combinations of the micron-scale structural composition of the laminated shale in the Qingshankou Formation were first determined: ① composed of clay minerals and felsic minerals, with indistinct laminations or bedding, developed cross-layered authigenic quartz, and developed calcareous shell laminations; ② composed of clay minerals and felsic minerals, with indistinct bedding or foliation, and calcite filled along the rock fractures; ③ composed of clay minerals and felsic minerals, with relatively developed authigenic quartz and pyrite; ④ composed of clay minerals and felsic minerals, with developed stripes of different colors, reflecting the changes in the contents of clay minerals and felsic minerals. The nano-scale structural composition of the laminated shale in the Qingshankou Formation was determined: granular minerals were dispersed in clay minerals, and the particles were finer.

Claims

1. A fine evaluation method for the lamination and laminated shale structure of continental matrix shale oil reservoirs, characterized in that: It includes the following steps: 1) Conduct a precise and accurate lithology and lithofacies description of the drilled core to obtain the lithology and lithofacies description results of the shale reservoir; 2) Based on the lithology and lithofacies description results of the shale reservoir in step 1), collect laminar and laminated shale samples to obtain geological experiment samples of laminar and laminated shale; 3) Based on the geological experiment samples of laminar and laminated shale obtained in step 2), conduct preliminary preparation of the samples according to the corresponding standards to obtain supporting geological experiment preparation samples of laminar and laminated shale; 4) Based on the supporting geological experiment preparation samples of laminar and laminated shale obtained in step 3), analyze the thin sections and polished sections of the rock to obtain the supporting geological experiment analysis results of laminar and laminated shale; 5) Based on the supporting geological experiment analysis results of laminar and laminated shale obtained in step 4), realize the continuous characterization of the full-scale laminar structure of the shale; conduct full-scale fine research and evaluation according to two categories of laminated shale and laminated shale, and through the laminar combination patterns of laminated shale and the laminar combination patterns of laminated shale, obtain the fine evaluation results of the structures of laminated shale and laminated shale, which are used for the fine evaluation of the lithology and reservoir properties of the shale oil reservoir and exploration; The laminar combination pattern of the laminated shale: It is divided into 4 combinations of ternary structure and 4 combinations of binary structure; In the laminar combination pattern of the laminated shale, the 4 combinations of ternary structure are respectively: Ternary structure combination of argillaceous lamina, debris lamina and silt lamina; Ternary structure combination of argillaceous lamina, silt lamina and debris lamina; Ternary structure combination of high organic matter lamina, debris lamina and silt layer; Ternary structure combination of high organic matter lamina, low organic matter lamina and silt layer; In the laminar combination pattern of the laminated shale, the 4 combinations of binary structure are respectively: Binary structure combination of silt-bearing argillaceous lamina and silt lamina; Binary structure combination of argillaceous lamina and silt lamina; Binary structure combination of dolomite-bearing argillaceous lamina and argillaceous dolomite lamina; Binary structure combination of organic matter-rich lamina and iron-bearing dolomite lamina; The laminar combination pattern of laminated shale: It includes 7 combination patterns, which are respectively: Composed of alternating light and dark argillaceous laminae with different mineral compositions, the laminae are thinner and pyrite is developed; Combination composed of alternating light and dark argillaceous laminae with different organic matter contents, with thin sandy laminae intercalated; Composed of a ternary structure of organic matter-rich lamina, organic matter-poor lamina and silt lamina; Composed of clay and felsic, the laminae or bedding are not obvious, with cross-layered authigenic quartz developed and calcareous shell laminae developed; Composed of clay and felsic, the bedding or schistosity is not obvious, and calcite is filled along the rock fractures; Composed of clay and felsic, authigenic quartz and pyrite are relatively developed; Clay and felsic, with stripes of different colors developed, reflecting the changes in the contents of clay and felsic.

2. The fine evaluation method for the lamination and layered shale structure of continental matrix shale oil reservoirs according to claim 1, characterized in that: The items for preliminary preparation of the samples in step 3) include rock section preparation, field emission electron microscope and energy spectrum sample preparation of the samples.

3. The fine evaluation method for the laminations and laminated shale structures of continental matrix shale oil reservoirs according to claim 1, characterized in that: The analysis of the thin sections and polished sections of the rock in step 4) includes: identification of the thin sections of the rock and testing with a gypsum compensator, field emission electron microscope and energy spectrum scanning.

4. The fine evaluation method for the lamination and laminated shale structure of the continental matrix shale oil reservoir according to claim 1, characterized in that: The "full scale" in realizing the continuous characterization of the full-scale laminar structure of the shale in step 5) includes millimeter scale, micrometer scale and nanometer scale.

5. The fine evaluation method for the laminations and laminated shale structures of continental matrix shale oil reservoirs according to claim 1, characterized in that: In step 5), for laminated shale and bedded shale, full-scale fine research and evaluation are carried out, and the full scale includes millimeter scale, micron scale, and nanometer scale.

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