CN111694068B - Large-scale fresh water lake basin continental facies mud shale oil formation and enrichment evaluation method - Google Patents
Large-scale fresh water lake basin continental facies mud shale oil formation and enrichment evaluation method Download PDFInfo
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Abstract
The invention discloses a method for forming and enriching evaluation of land-phase shale oil of a large-scale fresh water lake basin, which utilizes exploration drilling coring, lithology and lithology precision description and geological experiment matching analysis of shale oil to form and enrich evaluation of land-phase shale oil, and adopts parameter indexes such as depth, Ro, diagenesis stage, kerogen, free oil quantity and the like, total porosity, organic shale seam, inorganic shale seam and the like, reservoir evolution mode, shale oil evolution mode and the like to establish a matching relation of land-phase shale oil forming and evolution mode, reservoir pore forming and evolution mode, reservoir evolution history and evolution history, and exploration history generation, and firstly determines that the land-phase shale oil forms windows and secondary pore development zones for the shale oil in the later rock formation stage of Ro1.1-1.6 percent to create necessary conditions for large-scale accumulation of shale oil by high-degree coupling in time and space, and guides the land-phase shale oil of Songliao to be preferred and break through desserts, the lower limit of the favorable exploration depth is expanded to 2600m, and the sweet spot area is 5800km2Extended to 13000km2。
Description
Technical Field
The invention relates to the technical field of unconventional oil and gas exploration of oil fields, in particular to a large-scale fresh water lake basin continental facies mud shale oil formation and enrichment evaluation method.
Background
The breakthrough of shale oil in the North America area brings a new technical revolution of the global oil and gas industry, and China obtains multi-well industrial oil flow and active progress in Songliao, Ordos, Bohai Bay, Nanxiang, Quasoler basin and the like, thereby showing good prospects of exploration and development of shale oil. The shale oil formation and enrichment evaluation research aims to solve the problems of shale oil formation in the best period, favorable storage space, time-space matching and enrichment, and is an important basis for guiding shale oil stratum selection and exploration deployment. For a long time, the shale is researched as a hydrocarbon source rock or an oil gas cover layer instead of a reservoir layer in China, the scientific research of the integration of shale oil source and reservoir is neglected, the particularity and complexity of the deposition evolution of the large-scale fresh water lakes in Songliao basin provide challenges for the exploration of the continental facies shale oil, and the scientific evaluation problem of the formation and enrichment of the continental facies shale oil of the large-scale fresh water lakes is urgently needed to be solved.
There are reports of methods for evaluating formation and enrichment of oil and gas, see (1) Liubo et al, "continental facies shale layer lithofacies characteristics and shale oil enrichment conditions" (oil exploration and development, 5 th 2018); (2) yangwnli et al "migration and aggregation of oil and gas generation in continental facies of Songliao basin" (Heilongjiang scientific and technological publishing Co., 1985); (3) zhouyi et al, "shale oil formation mechanism, geological features and development strategies" (oil exploration and development, No. 1 in 2013); (4) tissot, et al, "infection of nature and dialesis of organic matter in formation of petroleum" (AAPG Bull, 1974); (5) yellow, clear, and the like, "study on the type and characteristics of the pore space of continental shale and the oil-gas copolymerization process," taking the depression of the west depression of the Liaohe river as an example "(natural gas geoscience, phase 7 in 2015); (6) zhuruka et al, "development of unconventional hydrocarbon tight reservoir microstructure research" (ancient geological report, 4 th 2013), and the like. The above (1) considers that the medium organic matter content striated lamellar long-grained quartz shale phase has better hydrocarbon generation potential, develops a reservoir space and is a dominant shale phase of in-situ retention matrix type shale oil; under the background of abnormal high pressure, the medium organic matter content striated long-grained quartz shale phase which develops on the SSC2 rotary top surface-SSC 3 rotary bottom surface is transversely and stably distributed in an delta-lake phase deposition area, the continuous thickness is more than 30m, and the high organic matter content blocky long-grained quartz shale phase and the medium organic matter content blocky long-grained quartz shale phase which develop in the middle part of the 2-stage rotary are used as top plate and bottom plate sealing covers, so that the method has the advantage of forming matrix type shale oil; the step (2) is that according to the globalization characteristics of the Songliao basin, a Songliao basin continental phase oil-hydrocarbon formation mode is established, the problems of cause and hydrocarbon evolution of conventional oil gas are solved, the exploration of continental phase conventional oil gas is guided, but the formation and evolution of shale oil are lack of research; the shale pore evolution and shale oil retention and aggregation mode is disclosed in the step (3), and the reservoir space, brittleness index, viscosity, pressure, retention amount and the like are the key points of the evaluation of the shale oil core area; the marine kerogen hydrocarbon generation mode is established in the step (4), the problems of cause and hydrocarbon evolution of conventional marine oil gas are solved, and marine conventional oil gas exploration is guided; researching large-aperture holes and cracks which are beneficial to shale oil aggregation and migration, such as layer section development corrosion hole cracks, structural cracks and the like; under a scanning electron microscope, 3 types of micro-pores of inorganic mineral pores, organic pores and microcracks in interval development are researched, wherein the formation of large-aperture organic pores under the condition of low maturity is mainly related to the corrosion reformation of organic acid; the research on the microcracks shows that the edge and the interior of the organic matter can develop various cracks, and the massive development of hydrocarbon generation and discharge cracks in the organic matter is an important difference between continental low-maturity shale and southern high-maturity shale. The (6) above considers that the reservoir performance of the compact reservoir is poor, the pore throat is mainly nano-scale, and the pore throat communication is complex; the sizes of the nano-pores and the intra-granular pores of the organic matter of the super-mature marine shale in south China are about 20-890 nm; the continental facies shale pore throat type is an organic matter pore and a matrix pore, and the main body is between 30 and 200 nm; the micron-sized pore throats of the compact sandstone are inter-granular dissolution pores, granular dissolution pores and microcracks, the main body is 10-200 mu m, the size of the nano-scale pores is 70-400 nm, and primary inter-granular pores and autogenous mineral inter-granular pores are mainly used; the pore throat type of the dense limestone is calcite intragranular pores, intergranular pores and microcracks, and the size of the pore throat type of the dense limestone is 50-500 nm. Therefore, the method is used for formation and evolution of marine phase oil gas and land phase conventional oil gas, research on control factors of land phase shale oil favorable for enriching lithofacies and conditions, a land phase shale oil retention mode, pore type and diversity of shale, causes, pore development and the like, and obtains a plurality of research results, but the method cannot solve the problems of formation and enrichment of large freshwater lake basin land phase shale oil in Songliao basin and effective guidance of exploration and deployment.
Disclosure of Invention
The invention provides a method for evaluating formation and enrichment of large-scale fresh water lake basin continental facies mud shale oil, aiming at overcoming the problems that the existing method in the background technology can not solve the problems of formation and enrichment of large-scale fresh water lake basin continental facies mud shale oil and effective guidance of exploration deployment. According to the method for evaluating the formation and enrichment of the continental facies mud shale oil of the large fresh water lake basin, a continental facies mud shale oil formation and evolution mode, a reservoir pore formation and evolution mode and a mud shale oil reservoir evolution history and evolution history generation matching relation graph are established, the formation and enrichment of the continental facies mud shale oil are evaluated, and the requirement of mud shale oil exploration is met.
The invention can solve the problems by the following technical scheme: a large-scale fresh water lake basin continental facies mud shale oil formation and enrichment evaluation method comprises the following steps:
1) accurately describing lithology and lithofacies of a core drilled by shale oil exploration, and collecting geological experiment matched samples according to the formation and evolution of shale oil reservoir pores and the formation and evolution of shale oil to obtain shale oil formation and enrichment evaluation geological experiment samples;
2) forming an evolution and enrichment evaluation geological experimental sample of the shale oil obtained in the step 1), carrying out matching analysis on geological experimental projects such as rock slice identification, a nano-pore structure, a micro-nano pore structure full-scale field emission electron microscope, all-rock minerals, total porosity, permeability, matrix permeability and the like according to a corresponding standard method, and carrying out evolution evaluation on shale oil reservoir pore formation to obtain a shale reservoir pore formation evolution mode and an evaluation result;
3) forming and enriching evaluation geological experimental samples of the shale oil obtained in the step 1), carrying out geological experimental project matching analysis such as rock pyrolysis, organic carbon, chloroform bitumen 'A', vitrinite reflectivity, kerogen, hydrocarbon generation and discharge thermal simulation experiment, rock pyrolysis gas chromatography, porosity, permeability, crude oil physical property and the like according to corresponding standards, and carrying out oil content recovery and formation evolution evaluation on a shale oil reservoir to obtain a shale oil formation evolution mode and an evaluation result;
4) forming evolution of the shale oil reservoir pores obtained in the step 2)3), forming evolution evaluation results by shale oil, performing oil and storage time space matching relation research on the shale oil to form a favorable window, favorable reservoir space and enrichment, and obtaining a shale oil reservoir evolution history and generated evolution history coupling relation and evaluation results;
5) and (3) carrying out longitudinal and plane shale oil enrichment evaluation research on the north of the Songliao basin according to the evolution mode, the coupling relation and the evaluation result obtained in the step 2)3)4), and obtaining shale oil enrichment longitudinal dessert layers and plane dessert zones and control factor evaluation results for guiding shale oil exploration and deployment.
The geological experimental sample for shale oil formation and enrichment evaluation in the step 1) comprises a shale oil reservoir pore formation and evolution experimental sample matched with shale oil formation and evolution.
The geological experimental items in the step 2) comprise rock slice identification, a nano pore structure, a micro-nano pore structure full-scale field emission electron microscope, full-rock minerals, total porosity, permeability, matrix permeability and other items; carrying out quantitative evaluation on the evolution evaluation of the pore formation of the shale oil reservoir according to the pore type, the pore area, the distribution, the evolution characteristics, the control factors and different shale lithofacies; the shale reservoir pore formation evolution mode and the evaluation result adopt parameters such as depth (m), Ro (%), ground temperature (DEG C), diagenesis stage, total porosity (%), organic shale seam (surface porosity,%), inorganic pore (surface porosity,%), and inorganic pore (surface porosity,%) to evaluate in diagenesis late stage and Ro1.1% -1.6% evolution stage, organic shale seam is formed by shrinking of algae hydrocarbon, clay mineral illite/montmorillonite mixed layer and illite conversion (temperature >105 ℃), inorganic shale seam and inorganic pore are formed by shrinking of shale, and a reservoir space with secondary pore development zone mainly formed by combination of inorganic shale oil large-scale gathering is provided.
The geological experimental project of the step 3) comprises rock pyrolysis, organic carbon, chloroform bitumen A, vitrinite reflectivity, kerogen, hydrocarbon generation and discharge thermal simulation experiment, rock pyrolysis gas chromatography, porosity, permeability, crude oil physical property and the like; the oil content recovery of the shale oil reservoir is carried out by two methods, namely simulating hydrocarbon generation dynamics experiment analysis by utilizing shale hydrocarbon generation and discharge heat, and carrying out on-site pressure maintaining, sealing, coring and freezing sample pyrolysis gas chromatography analysis and calibration to obtain shale oil light hydrocarbon recovery curves and coefficients with different maturity (Ro); secondly, the oil content of the shale non-cored well or the oil content of the interval are calculated and recovered by adopting a logging delta logR method and establishing a relation model of the oil content and logging parameters by utilizing the cored well or the interval, calibrating and verifying an actual measurement sample of the cored well, and calculating and recovering the oil content of the shale non-cored well or the interval; the shale oil formation evolution mode and the evaluation result adopt depth (m), Ro (%), kerogen (mg/g), traditional crude oil mode (chloroform bitumen 'A',), free oil quantity (mg/g), adsorbed oil quantity (mg/g), crude oil density (g/cm)3) Gas-oil ratio (cm)3/cm3) Determining that the conversion of a large amount of adsorbed oil to free oil at Ro1.1-1.6 percent is the most favorable stage of shale oil formation, and the maturity and high maturity are the most favorable stagesThe stage shale oil is 1.5-3.5 times of the classical crude oil mode.
In the step 4), parameter indexes such as depth (m), Ro (%), diagenetic stage, reservoir evolution mode (porosity,%), shale oil evolution mode (S1, mg/g), oil gas property and the like are adopted for the coupling relation and evaluation result of the shale oil reservoir evolution history and the generated evolution history, so that the high coupling of a large amount of shale oil forming windows and a secondary reservoir zone favorable for shale development in space and time is determined, and the necessary condition for large-scale gathering of continental facies shale oil is formed.
In the step 5), the shale oil-enriched longitudinal dessert layer, the planar dessert area and the control factor evaluation result are determined to be mainly a green section and a green section by utilizing the theory of continental shale oil formation and enrichment, so that the lower limit of exploration depth is favorably expanded to 2600 m; the sweet spot with shale oil content is mainly distributed in regions of Qijia south-gulong and Sanzhao (green section), the favorable exploration area of the green section of shale oil is increased to 2.24 times than that of the classical crude oil mode, and the sweet spot area is increased from 5800km2Extended to 13000km2And guides the optimization and exploration of the land shale oil dessert in the Songliao basin to make a new breakthrough.
Compared with the background technology, the invention has the following beneficial effects: the invention provides a method for evaluating formation and enrichment of land facies shale oil of a large freshwater lake basin, which mainly utilizes a shale oil exploration drilling coring, lithology and lithofacies accurate description and a matching geological experimental analysis method to carry out formation and evolution of shale oil, formation and evolution evaluation of reservoir layer pores, research on the matching relationship between shale oil formation favorable windows and reservoir space and oil and reservoir time space and enrichment, and method verification is carried out by taking the formation and enrichment evaluation of land facies shale oil of the large freshwater lake basin in Songliao basin as an example, so that the formation of favorable windows and a secondary pore development zone of shale oil are firstly determined to be Ro1.1-1.6% in an evolution stage, and the formation and enrichment of shale oil of the land facies of the large freshwater lake basin in the Songqing exploration area are highly coupled in time and space, and the shale oil of the large freshwater basin has necessary conditions for large-scale accumulation. Makes up the shortage that the classical kerogen crude oil mode is popularized to the shale oil exploration, and determines that the quantity of continental shale oil in the high maturity stage is classical1.5-3.5 times of the crude oil mode, and the continental shale oil has a resource foundation of large-scale aggregation; the micron-sized pores are the main storage space of the continental facies shale oil, the shale cracks make an important contribution to the continental facies shale storage space, the shale oil has a large-scale accumulated storage space, and the view that the shale pores of foreign scholars are mainly honeycomb organic matter pores is broken through; the longitudinal dessert layer of shale oil is mainly enriched in the green first section and the green second section, and the plane dessert area is mainly enriched in Qijia-Gulong and Sanzhao areas. Effectively guides the optimization and exploration breakthrough of the continental facies shale oil dessert in the Songliao basin, is favorable for expanding the lower limit of the exploration depth to 2600m and the dessert area from 5800km2Extended to 13000km2The method lays a theoretical foundation for exploration of continental facies shale oil of the large freshwater lakes and enriches unconventional geological connotations of oil and gas and basic theories of exploration of shale oil.
Description of the drawings:
FIG. 1 is a diagram of main development matrix pores and cracks of shale in a Qingshan Kou group in a Songliao basin;
FIG. 2 is a lithofacies diagram of shale mainly in the Qingshan Kou group of Songliao basin;
FIG. 3 is a graph showing a distribution of porosity of a lamellar shale phase pore type surface;
FIG. 4 is a diagram showing the distribution of pore areas of different pore diameters of the lamellar shale;
FIG. 5 is a graph showing the total porosity and effective porosity of different facies of the Mount Qingshan group;
FIG. 6 is a graph showing the evolution of organic shale seams in the Songliao basin and the organic pores in the North American shale;
FIG. 7 is a diagram of a characteristic evolution pattern of a pore type of a continental facies shale oil reservoir;
FIG. 8 is a shale lamellar joint diagram of a bi-directional argon ion profile optical field transmission electron microscope;
FIG. 9 is a schematic representation of a Gy1 shale geochemical parameter profile of a Mount Jing group shale;
FIG. 10 is a diagram of the land phase shale oil formation and evolution model;
FIG. 11 is a graph of the relationship between the evolution history of a continental facies shale oil reservoir and the generated evolution history;
FIG. 12 is a graph of a distribution of a shale oil level enrichment zone in the northern part of the Songliao basin;
FIG. 13 is a graph showing the relationship between organic carbon and hydrocarbon conversion index and oil content in different matured shales of the green stage.
The specific implementation mode is as follows:
the invention will be further described with reference to the following drawings and specific embodiments:
the method mainly comprises the steps of utilizing shale oil exploration drilling coring, lithology and lithofacies accurate description and a matched geological experimental analysis method, adopting parameter indexes such as depth (m), Ro (%), ground temperature (DEG C), total porosity (%), organic shale seams (surface porosity,%), inorganic pores (surface porosity,%), kerogen (HI, mg/g), chloroform bitumen' A "(%), free oil quantity (mg/g), adsorbed oil quantity (mg/g), oil content (mg/g) and the like, establishing a land-phase shale oil formation and evolution mode, a reservoir pore formation and evolution mode, a shale oil reservoir evolution history and evolution history matching relationship diagram, and evaluating land-phase shale oil formation and enrichment, so as to meet the demand of shale oil exploration.
First, fine and accurate description of lithology and lithofacies of shale oil reservoir
And (3) accurately describing the lithological characters of the drilling core according to an unconventional tight sandstone and shale core lithological character precise description method (patent number zl 201310659696.4) to obtain the lithological character and lithofacies description results of the tight reservoir core.
Second, shale oil reservoir pore formation and evolution evaluation method
1. Shale oil reservoir formation matching geological experimental analysis
The shale oil reservoir layer matching geological experiment analysis project adopts industry standard or enterprise standard, the slice identification adopts industry standard rock slice identification (SY/T5368) and adopts nanometer pore structure analysis technology of unconventional reservoir layer (Q/SY DQ 1667) and adopts enterprise standard unconventional reservoir layer whole rock mineral content analysis method (Q/SY 1666 2015) and adopts dense sandstone air permeability detection method (Q/SY 1660 2015) and adopts industry standard mud (shale) rock permeability detection method (Q/SY 1663 2015) and adopts mud (shale) rock total porosity detection method (Q/SY 1662) for matrix permeability, vitrinite reflectivity adopts an industry standard 'vitrinite reflectivity determination method in sedimentary rock' (SY/T5124-2012) and the like.
2. Shale oil reservoir micro-nano pore structure full-scale field emission electron microscope analysis
(1) Automatic splicing of large-view-field images of field emission electron microscope
Compiling field emission electron microscope large-visual-field image splicing software, and automatically splicing single images of a field emission electron microscope into a large-visual-field image (the visual field area is 3X 2mm, the invention patent 201910632902. X).
(2) Pore type identification extraction
And a pore classification recognition and human-computer interaction system is established, and the automatic extraction of the pore type, the pore number, the pore size distribution and the high precision (1.8nm) is realized.
(3) Pore type quantification
And (3) normalizing and quantifying the pore types and the number and the area of the micro-nano pores to obtain the proportion (%) of the pore types, the proportion (%) of the number of the micro-nano pores and the proportion (%) of the area.
3. Shale oil reservoir pore formation and evolution evaluation
(1) Shale oil reservoir pore type
And performing centimeter-millimeter-micron three-scale precise description and evaluation on the shale by using multiple technologies such as lithology fine-drawing, rock slice, field emission electron microscope and the like to determine the lithology, mineral composition characteristics and pore type of the shale in the Qingshan-Kong group.
(2) Shale oil reservoir pore quantitative characteristics and control factors
By utilizing a full-scale field emission electron microscope analysis technology of a shale oil reservoir micro-nano pore structure, the quantitative characteristics of the quantity and the area of shale micro-nano pores in the Qingshan-Kong group are researched, and control factors of pore formation are determined.
(3) Shale oil reservoir pore evolution characterization
The shale oil reservoir pore formation and evolution at different depths and maturity are evaluated by utilizing parameters such as depth (m), Ro (%), ground temperature (DEG C), total porosity (%), organic shale seam (surface porosity,%), inorganic pore (surface porosity,%), and the like, and a shale oil reservoir pore formation and evolution mode is established.
Third, shale oil formation and evolution evaluation method
1. Shale oil reservoir stratum matching geological experimental analysis
The shale oil reservoir layer matching geological experimental analysis project adopts national standard or industry standard, the total organic carbon analysis adopts national standard 'determination of total organic carbon in sedimentary rock' (GB/T19145-2003), the rock pyrolysis adopts national standard 'rock pyrolysis analysis' (GB/T18602-2012), the chloroform bitumen 'A' adopts industry standard 'determination of chloroform bitumen in rock' (SY/T5118-, the carbon isotope analysis adopts the industry standard 'carbon and oxygen isotope analysis method of organic matter and carbonate rock' (SY/T5238-.
2. Shale oil reservoir oil content recovery
(1) Oil content loss and recovery coefficient of shale samples with different maturity
The oil content (pyrolysis S1) of the shale subjected to rock pyrolysis analysis needs to be recovered, and from the conventional coring and separation from the underground original environment of drilling and depressurization and degassing, the rock sample is crushed to 80-100 meshes and subjected to pyrolysis detection, the light hydrocarbon loss is serious in the sampling and analyzing process, and the oil content (pyrolysis S1) of the shale reservoir layer cannot truly reflect the underground real oil-containing condition. Therefore, on-site core extraction (or pressure-maintaining closed coring) is carried out, a fresh face shale sample is immediately taken and placed into a liquid nitrogen tank for freezing storage, and a massive sample (1-3 mm) is adopted for hydrocarbon fine component analysis, so that the main distribution range of light hydrocarbon loss of the shale and the relative proportions of different maturation evolution stages are determined, and the light hydrocarbon recovery coefficients of corresponding geological samples are obtained.
(2) Hydrocarbon generation kinetic characteristics and oil content recovery of hydrocarbon source rock components
And determining the chemical kinetic characteristics of the hydrocarbon components of the hydrocarbon source rock of the Qingshan group in the Songliao basin by adopting a gold tube hydrocarbon generation thermal simulation experiment method (an industry standard SY/T7035-2016). And (3) combining with the actual analysis and calibration of the shale oil field freezing pressure maintaining closed coring samples with different maturity, establishing light hydrocarbon and oil content recovery curves and coefficients of shale oil with different maturity (Ro), and accurately recovering the original oil content of the shale oil.
(3) Evaluation of oil content of shale non-coring well and interval
The method is limited by well drilling and coring, the oil content of the whole well cannot be reflected by adopting a coring sample analysis result, and the oil content evaluation technology of the shale is established through the relation between the oil content and logging parameters, so that the problem of oil content evaluation of a non-coring well section is solved. And establishing a model by using the long well section coring well, and calibrating and verifying the actually measured sample of the coring well to obtain the oil content of the shale non-coring well and the layer section.
3. Evaluation of shale formation evolution
(1) Shale occurrence state and quantification of free oil and adsorbed oil
The occurrence state of the shale oil generally comprises an adsorption state and a free state, and the adsorption oil is physically adsorbed in and on the organic matter and on the surface of the mineral matrix; the free oil mainly exists in pores and microcracks, and a small amount of the free oil exists in oleophilic organic hydrocarbon-generating residual pores in a dissolved state. The free oil is usually pyrolyzed to S1 value, and the difference between cracked hydrocarbons S2 before and after extraction is defined as adsorbed oil, which is mainly heavy polymer oil, asphalt and non-hydrocarbon substances. The adsorption oil (Δ S2) is the chloroform bitumen "a" value-pyrolysis S1 value, and the solid organic matter (kerogen) is the pyrolysis S2 value-adsorption oil amount.
(2) Shale oil formation mode
According to the analysis data of the experiment of the Qingshan Kong group in the Songliao basin, the depth (m), the maturity Ro (%), the chloroform bitumen A (%), the free oil content (mg/g), the absorbed oil content (mg/g) and the crude oil density (g/cm) are utilized3) Gas-oil ratio (m)3/m3) Isoparametric shale oil formation at different depths and maturity for the Qingshan mountain group in Songliao basinEvaluating the evolution and establishing a shale oil formation and evolution mode.
Fourth, shale oil reservoir evolution history and evolution history generation matching and enrichment relation evaluation method
1. Shale oil reservoir evolution history and evolution history generation matching relation evaluation
According to the shale oil formation and evolution mode diagram and the shale oil reservoir pore formation and evolution mode diagram, carrying out shale oil reservoir evolution history and evolution history generation matching relation evaluation, and establishing a shale oil reservoir evolution history and evolution history generation coupling relation diagram.
2. Shale oil formation and enrichment evaluation
According to the shale oil formation and enrichment theory, the evaluation of the exploration dessert layer and the dessert area is carried out, and the exploration and deployment of shale oil are guided.
The method for forming and enriching the shale oil of the continental facies mud of the large-scale fresh water lake basin is completed according to the following steps:
1) accurately describing lithology and lithofacies of the drilled core, and collecting a geological experiment matched sample according to shale oil reservoir pore formation and evolution and shale oil formation and evolution to obtain a shale oil formation and enrichment evaluation geological experiment sample;
2) forming an evolution and enrichment evaluation geological experimental sample of the shale oil obtained in the step 1), carrying out project matching analysis such as rock slice identification, a nano-pore structure, a micro-nano pore structure full-scale field emission electron microscope, a full-rock mineral, total porosity, permeability and matrix permeability according to a corresponding standard method, forming evolution evaluation on the shale reservoir pores, and obtaining a shale reservoir pore formation evolution mode and an evaluation result;
3) forming shale oil obtained in the step 1) and enriching and evaluating geological experimental samples, carrying out project matching analysis such as rock pyrolysis, organic carbon, chloroform bitumen 'A', vitrinite reflectivity, kerogen, hydrocarbon generation and discharge thermal simulation experiments, porosity, permeability, crude oil physical property and the like according to corresponding standards, carrying out oil content recovery and shale oil formation evolution evaluation, and obtaining a shale oil formation evolution mode and an evaluation result;
4) forming evolution of the shale oil obtained in the step 2)3), forming an evolution evaluation result of a shale oil reservoir pore, performing oil and storage time space matching relation research on the shale oil to form a favorable window, a favorable storage space and enrichment, and obtaining a continental facies shale oil reservoir evolution history and generated evolution history coupling relation and an evaluation result;
5) and (3) carrying out longitudinal and plane shale oil enrichment evaluation research on the north of the Songliao basin according to the evolution mode, the coupling relation and the evaluation result obtained in the step 2)3)4), and obtaining shale oil enrichment longitudinal dessert layers and plane dessert zones and control factor evaluation results for guiding shale oil exploration and deployment.
Example 1
The implementation process of the method is illustrated by taking the method for formation and enrichment evaluation of the shale oil of the continental facies of the large-scale freshwater lake basin in the north part of the Songliao basin in the Daqing exploration area as an example.
1. Background of the study
The Songliao basin is a large-scale continental fresh water lake basin, the large-scale continental lake delta sediment is developed by the Chalk system, and two large-scale lake-phase shale sediments are formed in the sedimentation periods of the green mountain group and the tender river group of the late chalk system, so that the shale oil existence layer system is formed. The Qingshan Kou group mainly comprises medium and high mature shale oil, and the tender river group mainly comprises medium and low mature shale oil. Wherein, the Qingshan mountain mouth group deposits black mudstone, oil shale and shale which are widely distributed and rich in organic matters. The organic matter type of the source rock is mainly I type, the bernaliella development is realized, the hydrocarbon generation conversion degree is high, the activation energy window is narrow, the thermal evolution degree is moderate, the hydrocarbon generation potential is high, the main target area of mature high-maturity shale oil exploration is mainly the inner front edge of an delta, the outer front edge of the delta and the shallow lake phase deposition, the plane is controlled by the development of the source rock and a reservoir stratum, and the source rock is mainly distributed in Qijiagulong pits, three Zhao pits and the like. The shale oil exploration in Daqing exploration areas obtains a series of industrial oil flows and exploration breakthroughs in key exploration wells Yx58, Yp1, Syy1, Syy2, chao21 and the like, shows good prospects and huge resource potentials of shale oil exploration in the north of Songliao basin, and becomes an important field for continuous and stable production of Daqing oil fields and hundred-year oil field establishment.
2. Shale oil reservoir pore formation evolution evaluation
(1) Mud shale reservoir pore type of the Mount Qingshan group
The rock core shale of the tongliao basin north mountain mouth group is accurately described and analyzed and evaluated in a centimeter-millimeter-micron scale three-dimension mode by using lithologic fine-drawing, thin-sheet and field emission electron microscope analysis technologies and the like, and by taking the main viewpoint of shale reservoir pore classification in domestic and foreign research into the mode of three-level classification, the pore types of the rock of the tonglian mouth group are divided into 2 major classes and 6 classes and 13 subclasses of matrix pores and cracks (the pore types and the characteristics of the shale reservoir pore types of the tonglian mouth group are shown in table 1), the main development types are interparticle pores, clay mineral intercrystalline pores, erosion pores, organic matter pores, shale cracks and microcracks (figure 1), and the tonglian group mainly develops streak layered shale, oil shale, siltstone, mesolite limestone and marlite and 5 mud shale lithofacies (figure 2).
TABLE 1
(2) Quantitative characteristics and control factors of mud shale reservoir pores in Qingshan Kou group
1) Mud shale reservoir pore quantitative characteristics of Qingshan Kou group
The quantitative characteristic research of the 5-type lithofacies pores of the shale oil reservoir of the Qingshan mountain group is carried out by utilizing a full-scale field emission electron microscope analysis technology of the micro-nano pore structure of the shale oil reservoir.
Lamellar shale phase: the pores are distributed unevenly (fig. 3), the types of the pores are mainly intergranular pores (61%), and the deposition conditions are reflected to have a control effect on the formation of primary pores; the shale fissures (26%) develop, increasing the horizontal permeability of the shale reservoir; the inner holes (8%) are relatively developed and mainly distributed in the inner part and the edge of the silty-sand-grade feldspar particles with relatively coarse granularity, so that the storage layer is reflected to have a certain corrosion action; other pore types such as intercrystalline pores (4%), organic pores (< 1%) did not develop. The lamellar shale phase pores are relatively developed, the number of the nanopores accounts for 94.3 percent of the total pore amount, and the pore diameter is more than 500 nm; the micro-pore face porosity fraction was 80.9% (fig. 4), reflecting the large contribution of the micro-pores to the reservoir space.
Oil shale phase: compared with the lamellar shale phase, the pore distribution is relatively uniform, the pore type is mainly intergranular pores (72%), the lamellar seams (22%) develop, and other pore types such as intergranular pores (4%), intragranular pores (1%), and organic pores (< 1%) do not develop. The oil shale phase pores are relatively developed, the number of the nano pores accounts for 95.6 percent of the total amount of the pores, and the pore diameter is more than 500 nm; the micro-pore face porosity was 43.7%, and the micro-pores contributed slightly less to the reservoir space than the lamellar shale phase.
Silty sandstone phase: the shale bed series is distributed in the shale bed series in the form of thin layers, strips and lumps, and the pore types mainly develop inter-granular pores, inter-granular solution pores, intra-granular pores and inter-granular pores, and organic matter pores are rarely seen. The silty rock phase pores are poor in development, mainly comprise nanopores in number, account for 90.9% of the total amount of the pores, and the pore diameter is mainly distributed between 100nm and 500 nm; the silty-sandstone-phase micron-pore surface porosity accounts for 47.4%, and micron-sized pores slightly contribute to a reservoir space.
Intermediate debris limestone phase: the shale is mostly distributed in a lamellar manner in the shale layer system, the pore type mainly develops the mesoscale body cavity pores, and a small amount of micropores among the mesoscales. The mesoscale limestone phase pores are poor in development, mainly comprise nanopores in number, accounting for 86.7% of the total pore amount, the pore diameter is mainly distributed in the range of 100 nm-500 nm, and the pore diameter of partial mesoscale body cavities can reach more than 10 mu m; the porosity of the mesoscale limestone phase micron pore surface accounts for 71.2%, and the contribution of micron pores to the storage space is larger than that of nanometer pores.
Argillaceous crystal cloud lithofacies: the clay minerals are often filled in dolomite particles to form a small amount of tiny clay mineral intercrystalline pores. The marbled rock has compact lithology and poor pore development, mainly comprises nanometer pores accounting for 88.7 percent of the total pore amount in terms of number, and the pore diameter is mainly distributed between 10nm and 100 nm; the porosity of the mudstone cloud phase micron pore surface is 63.1%, and the contribution of the micron pores to the storage space is larger than that of the nanometer pores.
2) Factors controlling pore formation of mud shale reservoirs in the Qingshan Kou group
Mineral composition is the material basis for shale oil reservoir space formation
In the shale forming process, the development of a shale oil reservoir space is determined by complex interaction between diagenetic minerals or between diagenetic minerals and organic matters, the microscopic pore characteristics of the shale oil reservoir layer are determined by mineral components, forms, arrangement positions, contact modes, distribution and the like among mineral particles (crystal grains), and various pores of different types are formed among mineral particles, inside minerals, among crystal grains and between organic matters and inorganic minerals. The shale oil reservoir rock mineral of the Qingshan mountain group mainly comprises quartz, feldspar minerals (plagioclase feldspar and potash feldspar), carbonate minerals (calcite, iron dolomite, dolomite and siderite), pyrite and clay minerals (the shale oil reservoir rock mineral of the Qingshan mountain group in the north of Songliaopelvic area is shown in a table 2), mainly comprises quartz (the average content of each layer is 32-34%) and clay minerals (the average content of each layer is 19-31%), and is feldspar and carbonate minerals.
The mineral components and contents have important control effects on the porosity and physical characteristics of the shale reservoir. The contents of quartz and clay minerals in the green shale oil reservoir layer have positive correlation with the total porosity, which shows that the contents of quartz and clay minerals have positive effects on the formation and the preservation of a reservoir space; the contents of carbonate minerals and feldspar have negative correlation with the total porosity, which indicates that a certain amount of feldspar or carbonate intra-granular pores exist in the feldspar and the carbonate minerals in the shale, but the development degree of the erosion effect is strong in heterogeneity, the local erosion pores are relatively developed (the inner part and the edge of silt-grade long stone particles with relatively coarse granularity in the grained shale phase), and the carbonate minerals are used for filling primary pores mainly for cementing and blocking the pores, so that the development of the shale pores is inhibited to a certain degree.
TABLE 2
Second, the lithofacies type has important influence on the storage space and physical property characteristics of the shale oil reservoir
The Qingshan mountain mouth group mainly develops 5 lithofacies types of striated lamellar shale, oil shale, siltstone, mesocratic limestone and marjoram, which respectively account for 84.6%, 6.1%, 5.8%, 1.0% and 2.5%, and the main lithofacies is striated lamellar shale. 94.3% of lamellar shale phase nanopores, 80.9% of micron-sized pore surface porosity, 95.6% of oil shale nanopores, 43.7% of micron-sized pore surface porosity, 90.9% of siltstone nanopores, 47.4% of micron-sized pore surface porosity, 86.7% of mesolite nanopores, 71.2% of micron-sized pore surface porosity, 88.7% of marlite nanopores and 63.1% of micron-sized pore surface porosity, so that the contribution of the pores of different lithofacies to the storage space is different. The total and effective porosities of the different facies vary greatly (fig. 5), with the average 11.6% and 6.2% for oil shale, 7.9% and 5.2% for the lamellar shale facies being the most favorable reservoir facies, followed by siltstones 5.3% and 4.6%, interbedded limestone 4.1% and 2.6%, and worst marmite 3.3% and 1.2%.
(3) Mud shale reservoir pore evolution characteristics of Qingshan Kou group
The intergranular pores of the shale in the Qingshan-Kong group account for 31-72% of the total surface porosity, and the shale seams account for 22-79%, which shows that the shale seams have important contribution to a reservoir space. The formation and evolution characteristics of shale pores in the Qingshan-Kou group are obviously controlled by different diagenesis stages, lamellar algae are combined with minerals in the low evolution stage of the evolution process of the shale oil reservoir space, the maturity of the algae increases hydrocarbon generation shrinkage to form organic shale cracks (figure 6), and the porosity of the organic shale cracks can reach 3.8% in the hydrocarbon generation peak period; the organic matter type of the North American shale (Woodford) is a marine phase II type, and the generated hydrocarbon mainly forms honeycomb organic matter pores which are different from organic shale oil shale seams of continental facies of Songliao Qingshan Kong; after the formation A2 stage (temperature >105 deg.C), clay mineral is converted into illite/montmorillonite mixture layer, and lamellar clay mineral shrinks along the page to form inorganic page-seam.
The depth (m), the maturity (Ro) and the total porosity (%) of shale in the diagenesis stage, organic shale seam (surface porosity,%), inorganic pore (surface porosity,%) parameter indexes and the like are utilized to establish a shale oil reservoir pore evolution diagram (figure 7) in different diagenesis evolution stages of the Qingshan mountain mouth composition in Songliao basin. In the early diagenesis stage (the depth is less than 1400m, Ro is less than 0.7%), inorganic pores develop, and the pore cause is mainly deposition; in the A1 stage of medium diagenesis rock (the depth is 1400-2050 m and Ro0.7% -1.1%), the pores are not developed under the influence of compaction; in the period A2 (the depth is 2050-2600 m and Ro1.1% -1.6%), because the lamellar algae generates hydrocarbon and shrinks to form organic lamellar gaps, and simultaneously a clay mineral illite/montmorillonite mixed layer and illite are converted, the lamellar clay mineral shrinks along the lamellar gaps to form inorganic lamellar gaps, so that the storage space (the maximum accounts for 65% of the total pore space) is increased, the maximum total porosity is 15%, and a secondary pore development zone is formed; in the middle diagenesis stage B (depth >2600m, Ro > 1.6%), clay mineral transformation occurs due to temperature and pressure rise (temperature >117 ℃), and inorganic interparticle pores and inorganic lamellar gaps develop in large quantities (66% and 33% of total pores, respectively).
The development of the shale oil transverse seepage capability is effectively improved through the development of the shale seams in the diagenetic evolution process, the horizontal permeability is 10-100 of the vertical permeability (the analysis results of the horizontal permeability and the vertical permeability at the same depth are compared in a table 3), and the analysis of a bidirectional argon ion profile light field emission electron microscope proves that the horizontal shale seams are obviously more than the vertical shale seams (fig. 8); the development of the shale jointing effectively improves the pore structure of the reservoir layer, so that the micron-sized pores are increased, the total porosity (7.9-11.6%) of lamellar and striation lamellar shale and the effective porosity (5.2-6.2%) are higher than those of other lithofacies, a secondary pore development zone is formed in the advanced shale evolution stage (Ro1.1-1.6%), and a reservoir space is provided for the large-scale accumulation of shale oil.
According to the pore evolution mode of the shale oil reservoir, a Gy1 well preferably selects a green section of a type I reservoir 2 section (2530-2600 m), the lower part of the green section of the reservoir is preferably selected to be a type II reservoir 1 section, the daily oil production is performed in a 2.04 direction and the gas production is performed in a 2016 direction after the pressure, and the oil exploration depth of the Songliao basin is favorably expanded to 2600 meters.
TABLE 3
3. Evaluation of shale oil formation evolution
(1) Shale reservoir oil content and oiliness characteristics
The organic carbon abundance (TOC) of shale in the Qingshan Kou group of the Songliao basin tends to increase from shallow to deep and has the highest bottom (figure 9), wherein the organic carbon in the development section of the oil shale at the middle lower part of the Qingshan Kou section can reach 13.2% at most (the geochemical chemical parameters of the shale in the Qingshan Kou group are shown in Table 4); from the oil-bearing index of the shale, the change trend of the shale is basically consistent with that of organic carbon, the oil content of the middle lower part of the green section is highest, particularly the oil content of the oil shale (with the thickness of 40m) of the lower part of the green section is 10.1mg/g at the highest and 2.31 mg/g on average, and the obvious control effect of the abundance of organic matters on the oil content is reflected; from the view of the carbon isotope of the kerogen, the weight of the carbon isotope of the kerogen tends to change from shallow to deep, the middle lower part of the green section is the heaviest, particularly in the well section of 2450-2455 m, the carbon isotope of the kerogen rapidly changes from-27.14 per thousand to-24.14 per thousand, the maximum positive deviation is 3.0 per thousand, which is the result of heavy carbon enrichment in an atmosphere-water system due to the massive burying of organic matters rich in light carbon in sediments, and is consistent with the trend of the change of the carbon isotope of the organic matters deposited in the ancient ocean anoxic event period in the later Cenomanian-Turonian period of the New Chapter worldwide, which shows that the middle lower part of the green section and the green section has undergone massive organic matter enrichment and burying, and the shale oil enrichment is formed in Ro1.5% -1.6%.
TABLE 4
(2) Shale oil formation evolution mode and evaluation
According to the analysis data of the 40 wells of the Qingshan group in the Songliao basin, the depth (m), Ro (%), kerogen (HI, mg/g), chloroform bitumen "A" (%), free oil (mg/g), adsorbed oil (mg/g), crude oil density (g/cm)3) Gas-oil ratio (cm)3/cm3) And establishing a shale oil formation and evolution mode (figure 10) according to the parameter index relation. Shale oil initial formation stage: ro<1.1 percent of kerogen crude oil, free oil and adsorbed oil are increased, and the quantity of shale oil is not large; in the stage of bulk formation of shale oil, Ro1.1% -1.6%, the adsorbed oil is converted into free oil, the shale oil is generated in large quantity, and the shale oil window is lagged behind that of conventional oil; cracking of shale oil to gas stage, Ro>1.6%, shale oil begins to crack into gas, but shale oil quantity is much higher than conventional crude oil mode.
Kerogen cracking occurs at Ro of about 1.1 percent, corresponding to hydrocarbon generation peak, the total residual oil (free oil + adsorption oil) of the shale after entering a hydrocarbon discharge threshold is more than 100mg/gC, and the fact that lake-phase shale has good oil content in a maturation-high maturation evolution stage is reflected. The shale oil content in the high maturity stage is increased by 1.5-3.5 times, and the problem that the error of the traditional crude oil model is larger along with the higher maturity is solved. The shale oil content recovery analysis shows that the amount of free oil of the shale with Ro > 1.1% reaches 200mg/gC, while the conventional pyrolysis analysis is about 100 mg/gC. From the oil content of the shales with different maturity, the oiliness of the shales from maturity to high maturity is better, and from the ratio of free oil/total retained oil, when Ro is more than 1.1%, the proportion of the free oil is obviously increased, which reflects that the mobility of the shale oil is better, and is beneficial to mining.
4. Shale oil reservoir evolution history and evolution history generation matching and enrichment relation evaluation
According to the evolution formed by the shale oil reservoir pores and the evolution evaluation result formed by shale oil, a matching relation graph (figure 11) of shale oil reservoir evolution history and generated evolution history is established by utilizing the parameter relations of depth (m), Ro (%), diagenesis stage, reservoir evolution mode, shale oil formation mode, oil gas property and the like, and a continental facies shale oil formation and enrichment theory is established, so that in the Ro1.1% -1.6% stage, a secondary favorable storage zone (the total porosity is 15% at most) is formed in the shale development, the reservoir property is improved, a large amount of shale adsorption oil is converted to free oil, a large amount of shale oil is formed, and the two are highly coupled in space and time to form continental facies shale oil scale aggregation.
5. Shale oil distribution and enrichment and control factors thereof
(1) Beneficial to controlling the longitudinal distribution of shale oil by overlapping the reservoir development zone and the shale oil window
The shale oil undergoes evolution stages of early diagenesis, diagenesis A1, diagenesis A2, diagenesis B and the like, organic shale seams and favorable reservoir development zones are formed in the diagenesis A2 stage (Ro1.1-1.6 percent), and the total porosity is mainly distributed in the range of 5-11 percent, 15 percent at the maximum and 9.6 percent on average. Meanwhile, in the period of medium lithogenesis A2 (Ro1.1% -1.6%), a large amount of organic matters evolve and are enriched to form shale oil, the shale oil is located at the best storage part favorable for a reservoir development zone, the shale oil reservoir evolution is coupled with a shale oil generation window (Ro1.1% -1.6%) (figure 11) to control the longitudinal distribution of the shale oil, and the shale oil is mainly enriched in the first green section and the second green section in scale.
(2) Shale oil deposition background, organic matter abundance and maturity determine shale oil plane enrichment area
Multiple influences of deposition, organic matter abundance and maturity in the northern part of the Songliao basin control the shale oil level enrichment region (FIG. 12). The organic matter abundance (Toc) of the green section in Qijia-Gulong region is generally more than 2%, the green section is mainly more than 1.5%, the maturity (Ro) green section is 1.0-2.0%, and the green section is 0.9-1.7%; the organic matter abundance (Toc) of the three-hit pit (cha21 well) is more than 1.5 percent of the first green section, the second green section is mainly between 0.5 and 2.6 percent, the maturity (Ro) first green section is 0.80 to 0.86 percent, and the second green section is 0.8 to 0.68 percent. The oil content of the green shale in the Qijia-Gulong area is the highest, and is mostly in the range of 2-11 mg/g, and the highest value areas are mainly distributed in the Qijia south-Gulong area (5-11 mg/g) and the three Zhao pits (5-7 mg/g); the shale in the second green stage has the second oil content, the highest area is mainly distributed in the Qijianan-Gulong area (3-6 mg/g), and the dessert area is 5800km2Extended to 13000km2。
The hydrocarbon source lithogenesis oil discharge is a process of mass conservation, namely, oil discharge amount is oil production amount-residual oil amount, the residual oil amount is free oil amount + oil absorption amount, the free oil amount is shale oil amount, pyrolysis S1, and oil absorption amount is chloroform asphalt A' -S1; the residual oil before oil drainage of the source rocks is gradually increased along with the thermal evolution degree, the residual oil after oil drainage of the source rocks is saturated, the saturated residual oil is related to the abundance of residual organic carbon, and the average residual oil is generally 100 mg/gC. According to the data results (figure 13) of the pyrolysis and organic carbon of the rock in the green section, the shale oil mass (S1) and the organic carbon abundance in different thermal evolution stages all present positive correlation, the higher the organic carbon abundance is, the higher the oil content is, the higher the maturity and the oil content of the same organic carbon abundance are; in the low maturity evolution stage (Ro < 0.75%, S1/(S1+ S2) <0.1), the oil content per organic carbon gradually increases, and in the maturity-high maturity evolution stage (Ro > 0.75%, S1/(S1+ S2) >0.1), the oil content per organic carbon averages about 100 mg. The shale oil quantity is controlled by the abundance and maturity of organic substances at the same time, mainly controlled by the abundance of organic carbon in the low maturity evolution stage, and mainly controlled by the maturity in the maturity-high maturity evolution stage.
(3) Shale maturation evolution stage affecting shale oil properties
In the mature-high mature evolution stage of the diagenesis A2 (Ro1.1% -1.6%) which is the most favorable exploration stage of the shale oil, the thermal evolution influences the property of the shale oil. Cracking kerogen under the further action of heat at Ro1.1-1.3% (2050-2300 m), converting adsorbed oil into free oil, and largely generating light oil and condensate oil, wherein the shale oil mainly comprises heavy oil and light oil; in Ro1.3% -1.5% (2300-2500 m), kerogen cracking is slowed down, an oil C-C bond is broken to generate moisture, and shale oil mainly comprises light oil, heavy oil and condensate oil; at Ro1.5% -1.6% (2500-2600 m), the shale oil mainly comprises light oil, condensate oil and heavy oil, a certain amount of moisture is formed, and shale oil exploitation is facilitated; ro is more than 1.6% (>2600m), the quantity of shale oil tends to be reduced, the quantity of moisture generated by cracking the shale oil is obviously increased, and Ro1.6% -1.9% of shale oil should have exploration potential from the trend of change of history coupling relation between shale reservoir evolution and shale oil generation evolution mode.
The whole process of the method for evaluating the formation and enrichment of the shale oil of the continental facies of the large-scale fresh water lake basin is specifically described by the examples, and the shale oil formation and enrichment evaluation result of the method can be used for the exploration and production of the shale oil. The invention has the following characteristics:
(1) a land facies shale oil formation and enrichment evaluation method of a large freshwater lake basin is provided and established, which is mainly characterized in that a land facies shale oil formation and enrichment evaluation method is established by utilizing shale oil exploration drilling coring, lithology and lithofacies accurate description and a matched geological experimental analysis method, and the land facies shale oil formation and enrichment evaluation method is established by adopting parameter indexes such as depth (m), Ro (%), ground temperature (DEG C), total porosity (%), organic shale seam (face porosity,%), inorganic pore%), kerogen (HI, mg/g), chloroform bitumen 'A' (%), free oil content (mg/g), adsorbed oil content (mg/g) and oil content (mg/g), the requirements of unconventional oil and gas exploration and development are met.
(2) The shale pore types of the Qingshan-Kou group are divided into a matrix pore and a crack 2, a large class, 6 classes and 13 subclasses, and 5 lithofacies types of mainly developed striated lamellar shale, oil shale, siltstone, cutting limestone and marmite of the Qingshan-Kou group are defined and respectively account for 84.6%, 6.1%, 5.8%, 1.0% and 2.5%; the quantitative characteristics of 5 types of lithofacies pores of mud shale reservoirs of the mountain jaw group are determined, the number of the striated lamellar shale facies nanopores accounts for 94.3%, the proportion of the micron-sized pore surface porosity accounts for 80.9%, the number of the oil shale nanopores accounts for 95.6%, the proportion of the micron-sized pore surface porosity accounts for 43.7%, the number of the siltstone nanopores accounts for 90.9%, the proportion of the micron-sized pore surface porosity accounts for 47.4%, the number of the mesocratic limestone nanopores accounts for 86.7%, the proportion of the micron-sized pore surface porosity accounts for 71.2%, the number of the argillite cloud nanopores accounts for 88.7%, and the proportion of the micron-sized pore surface porosity accounts for 63.1%. Therefore, the number of the nanometer pores is large, and the micron pores are the main contribution of the shale oil storage space; the inorganic shale joint and the organic shale joint are put forward for the first time, and play an important control role in the formation of the land shale storage space, and the view that the shale pores of foreign scholars are mainly cellular organic matter pores is broken through; continental shale oil forms a secondary pore development zone in late diagenesis Ro1.1-1.6% and has a large-scale gathering storage space.
(3) The stage of forming a large amount of mud shale oil of the mud shale group is middle-diagenesis late Ro1.1% -1.6%, mud shale adsorbed oil is converted into free oil in a large amount, and the shale oil at the high maturity stage is clarified for the first timeThe quantity is 1.5-3.5 times of that of a classical crude oil mode, and the method has a resource foundation of large-scale aggregation; the formation of a large number of windows of shale oil is highly coupled with the development of secondary favorable storage zones of shale in space and time, and necessary conditions for large-scale accumulation of continental shale oil are formed. By utilizing the theory of formation and enrichment of continental facies shale oil, the shale oil dessert layer at the north of the Songliao basin is determined to be mainly a green section and a green section, which is favorable for expanding the lower limit of exploration depth to 2600 m; the sweet spot with shale oil content is mainly distributed in regions of Qijia south-gulong and Sanzhao (green section), the favorable exploration area of the green section of shale oil is increased to 2.24 times than that of the classical crude oil mode, and the sweet spot area is increased from 5800km2Extended to 13000km2The method guides the optimization and exploration of the continental facies shale oil dessert to make a new breakthrough, and enriches the unconventional oil and gas geological connotation and shale oil exploration basic theory.
Claims (3)
1. A large-scale fresh water lake basin continental facies mud shale oil formation and enrichment evaluation method comprises the following steps:
1) accurately describing lithology and lithofacies of a core drilled by shale oil exploration, and collecting geological experiment matched samples according to the formation and evolution of shale oil reservoir pores and the formation and evolution of shale oil to obtain shale oil formation and enrichment evaluation geological experiment samples;
2) forming and enriching evaluation geological experimental samples of the shale oil obtained in the step 1), carrying out rock slice identification, nano-pore structure, micro-nano-pore structure full-scale field emission electron microscope, whole rock mineral, total porosity, permeability and matrix permeability geological experimental project matching analysis according to a corresponding standard method, and carrying out evolution evaluation on shale oil reservoir pore formation to obtain a shale reservoir pore formation evolution mode and an evaluation result;
the geological experimental project comprises rock slice identification, a nano pore structure, a micro-nano pore structure full-scale field emission electron microscope, full-rock minerals, total porosity, permeability and matrix permeability projects; carrying out quantitative evaluation on the evolution evaluation of the pore formation of the shale oil reservoir according to the pore type, the pore area, the distribution, the evolution characteristics, the control factors and different shale lithofacies; the shale reservoir pore formation evolution mode and the evaluation result adopt depth m, Ro%, ground temperature, diagenesis stage, total porosity, organic shale seam, inorganic shale seam and inorganic pore, the evaluation adopts algae hydrocarbon generation shrinkage to form organic shale seam at the late diagenesis stage and Ro1.1% -1.6% evolution stage, clay mineral illite/montmorillonite mixed layer and illite conversion at the temperature of more than 105 ℃, layered clay mineral shrinks along the shale to form inorganic shale seam and inorganic pore combination to form a secondary pore development zone mainly, and the shale oil reservoir pore formation evolution mode has a reservoir space with large scale shale oil aggregation; the unit of the organic page seams, the inorganic page seams and the inorganic holes is the surface porosity;
3) carrying out rock pyrolysis, organic carbon, chloroform bitumen 'A', vitrinite reflectivity, kerogen, hydrocarbon generation and discharge thermal simulation experiments, rock pyrolysis gas chromatography, porosity, permeability and crude oil physical property geological experimental project matching analysis on shale oil formation and enrichment evaluation geological experimental samples obtained in the step 1) according to corresponding standards, and carrying out oil content recovery and formation evolution evaluation on a shale oil reservoir to obtain a shale oil formation evolution mode and an evaluation result;
the geological experimental project comprises rock pyrolysis, organic carbon, chloroform bitumen A, vitrinite reflectivity, kerogen, hydrocarbon generation and discharge thermal simulation experiment, rock pyrolysis gas chromatography, porosity, permeability and crude oil physical property; the oil content recovery of the shale oil reservoir is carried out by two methods, one is that the shale hydrocarbon generation and discharge thermal simulation hydrocarbon generation dynamics experiment analysis is utilized, and the pyrolysis gas chromatography analysis and calibration are carried out by on-site pressure maintaining closed coring frozen samples to obtain the light hydrocarbon recovery curves and coefficients of the shale oil with different maturity Ro; secondly, the oil content of the shale non-cored well or the oil content of the interval are calculated and recovered by adopting a logging delta logR method and establishing a relation model of the oil content and logging parameters by utilizing the cored well or the interval, calibrating and verifying an actual measurement sample of the cored well, and calculating and recovering the oil content of the shale non-cored well or the interval; the shale oil formation evolution mode and the evaluation result adopt depth m, Ro%, kerogen mg/g, chloroform bitumen A% in the traditional crude oil mode, free oil mg/g, adsorbed oil mg/g, crude oil density g/cm3Gas-oil ratio cm3/cm3Shale oil forming windowDetermining the relationship of indexes, namely determining that the shale oil is the most favorable stage for the formation of the shale oil when the amount of adsorbed oil is converted into free oil in Ro1.1-1.6 percent, wherein the shale oil is 1.5-3.5 times of the shale oil in the mature and high-mature stages in a classical crude oil mode;
4) forming the shale oil reservoir pores obtained in the steps 2) and 3) into evolution and forming the shale oil into evolution evaluation results, and carrying out oil and storage time space matching relation research on the shale oil forming favorable windows, favorable reservoir spaces and enrichment to obtain the shale oil reservoir evolution history, the generated evolution history coupling relation and the evaluation results;
the shale oil reservoir evolution history and generated evolution history coupling relation and evaluation result adopt the indexes of depth m, Ro%, diagenesis stage, porosity in a reservoir evolution mode, S1 mg/g in the shale oil evolution mode and oil gas property, a window formed by a large amount of shale oil is determined to be highly coupled with a secondary reservoir zone favorable for shale development in space and time, and necessary conditions for large-scale gathering of continental facies shale oil are formed;
5) and (4) carrying out longitudinal and plane shale oil enrichment evaluation research on the northern part of the Songliao basin on the evolution mode, the coupling relation and the evaluation result obtained in the steps 2), 3) and 4) to obtain a shale oil enrichment longitudinal dessert layer, a plane dessert area and a control factor evaluation result.
2. The method for evaluating the formation and enrichment of land-phase mud shale oil of large-scale fresh water lakes according to claim 1, which is characterized in that: the geological experimental sample for shale oil formation and enrichment evaluation in the step 1) comprises a shale oil reservoir pore formation and evolution experimental sample matched with shale oil formation and evolution.
3. The method for evaluating the formation and enrichment of land-phase mud shale oil of large-scale fresh water lakes according to claim 1, which is characterized in that: in the step 5), the shale oil enriched longitudinal dessert layer, the plane dessert region and the control factor evaluation result are determined to be mainly a green section and a green section by utilizing the theory of continental shale oil formation and enrichment, so that the shale oil dessert layer in the north of the Songliaopelvic area is favorable for exploration depthThe limit is expanded to 2600 m; the sweet spot area with oil content of shale is mainly distributed in the green section of the regions of Qijianan-Gulong and Sanzhao, the favorable exploration area of the green section of shale oil is increased to 2.24 times than that of the classical crude oil mode, and the sweet spot area is increased from 5800km2Extended to 13000km2And guides the optimization and exploration of the land shale oil dessert in the Songliao basin to make a new breakthrough.
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| CN112903737A (en) * | 2021-01-21 | 2021-06-04 | 西南石油大学 | Method for evaluating oil content of shale by utilizing pyrolysis before and after extraction |
| CN112922591B (en) * | 2021-03-01 | 2021-11-26 | 中国地质大学（北京） | Shale reservoir lithofacies dessert prediction method and system |
| CN113049471B (en) | 2021-03-23 | 2021-10-08 | 中国石油大学(北京) | Recovery method for porosity evolution process of carbonate rock sequence stratum |
| CN114280090B (en) * | 2021-11-23 | 2023-06-06 | 中国地质大学（武汉） | Evaluation method for hydrocarbon discharge efficiency and shale oil enrichment degree of continental shale |
| CN115598736B (en) * | 2022-12-14 | 2023-03-10 | 克拉玛依禾鑫石油科技有限公司 | Method for determining desserts of shale and compact oil-gas horizontal well based on rock debris |
| CN116168172B (en) * | 2023-04-19 | 2023-07-11 | 武汉中旺亿能科技发展有限公司 | Shale oil gas dessert prediction method, device, equipment and storage medium |
| CN117233357B (en) * | 2023-11-13 | 2024-01-09 | 东北石油大学三亚海洋油气研究院 | Evaluation method for shale reservoir pore evolution in-situ heating process |
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