Volume 26,Issue 1,2019 Table of Contents
2019, 26(1):1-12.
DOI: 10.13673/j.cnki.cn37-1359/te.2019.01.001
Abstract:
By reviewing the exploration process of the Paleogene-Neogene shale oil in Jiyang Depression，the theoretical achievements and the technology series obtained from the previous shale oil exploration were summarized and the elements of shale oil enrichment of the Tertiary in Jiyang Depression were analyzed. Besides, the direction of shale oil deployment was pointed out considering the actual situation of drilled shale oil wells. Exploration practice shows that the continental shale oil in Jiyang Depression is different from the marine shale oil that has been drilled successfully in North America，which is characterized by strong heterogeneity，weak diagenesis and low maturity. Theoretical innovation and new exploration ideas are necessary to establish relevant supporting technologies and methods suitable for eastern continental shale oil exploration as soon as possible. The complexity of the occurrence pattern of continental shale oil requires a classified stepbystep exploration. The mixed shale oil in the interlayer，micro-crack and high-quality lithofacies should be first developed. On the basis of its effective economic production，the implementation of the matrix shale oil drilling and deployment will be carried out next, and the target optimization evaluation system suitable for eastern continental shale oil should be improved as soon as possible，in order to open up new exploration targets to increase the reserve of old oilfields.
By reviewing the exploration process of the Paleogene-Neogene shale oil in Jiyang Depression，the theoretical achievements and the technology series obtained from the previous shale oil exploration were summarized and the elements of shale oil enrichment of the Tertiary in Jiyang Depression were analyzed. Besides, the direction of shale oil deployment was pointed out considering the actual situation of drilled shale oil wells. Exploration practice shows that the continental shale oil in Jiyang Depression is different from the marine shale oil that has been drilled successfully in North America，which is characterized by strong heterogeneity，weak diagenesis and low maturity. Theoretical innovation and new exploration ideas are necessary to establish relevant supporting technologies and methods suitable for eastern continental shale oil exploration as soon as possible. The complexity of the occurrence pattern of continental shale oil requires a classified stepbystep exploration. The mixed shale oil in the interlayer，micro-crack and high-quality lithofacies should be first developed. On the basis of its effective economic production，the implementation of the matrix shale oil drilling and deployment will be carried out next, and the target optimization evaluation system suitable for eastern continental shale oil should be improved as soon as possible，in order to open up new exploration targets to increase the reserve of old oilfields.
2019, 26(1):13-28.
DOI: 10.13673/j.cnki.cn37-1359/te.2019.01.002
Abstract:
The successful development of marine shale oil and gas in North America brings great hope to the production of lacustrine shale oil in China with great potential. At present，the research and exploration of shale oil in the world is still in its infantry，and there is no consensus on the commercial production of crude oil from the shale. Practice of marine shale oil exploration and production in North America indicates that the stable and gentle tectonic setting is favorable for the enrichment of shale oil，the large-area distribution of high-quality organic rich source rocks is the resource basis for shale oil formation，the tight top/bottom formations control the distribution of shale oil prospect area，the thermal evolution of source rocks controls the distribution of shale oil core areas，while geological and engineering“sweet spots”control the largescale enrichment and stable production of shale oil. In contrast to the North American shale basins，Chinese lacustrine shale plays develop in less stable and relatively tectonically active basins. These sedimentary basins have many types being characterized by strong segmentation and strong activity. Additionally，there are many sedimentary systems such as freshwater，brackish and saline lakes，with significant variation in lithology and sedimentary facies both laterally and vertically，and with diverse reservoir-caprock association. The heterogeneity in the deposition，diagenesis and fracture development in both shale reservoir and its top and bottom seals determine the“sweet spots”and ultimate recoverable oil resources in the shale reservoir. Road map for the large scale development of shale oil resources in China includes three mportant points，a clear understanding of shale oil resource potential，an accurate estimation of core areas for shale oil enrichment，and a development of high adaptive and stable technology for shale oil production.
The successful development of marine shale oil and gas in North America brings great hope to the production of lacustrine shale oil in China with great potential. At present，the research and exploration of shale oil in the world is still in its infantry，and there is no consensus on the commercial production of crude oil from the shale. Practice of marine shale oil exploration and production in North America indicates that the stable and gentle tectonic setting is favorable for the enrichment of shale oil，the large-area distribution of high-quality organic rich source rocks is the resource basis for shale oil formation，the tight top/bottom formations control the distribution of shale oil prospect area，the thermal evolution of source rocks controls the distribution of shale oil core areas，while geological and engineering“sweet spots”control the largescale enrichment and stable production of shale oil. In contrast to the North American shale basins，Chinese lacustrine shale plays develop in less stable and relatively tectonically active basins. These sedimentary basins have many types being characterized by strong segmentation and strong activity. Additionally，there are many sedimentary systems such as freshwater，brackish and saline lakes，with significant variation in lithology and sedimentary facies both laterally and vertically，and with diverse reservoir-caprock association. The heterogeneity in the deposition，diagenesis and fracture development in both shale reservoir and its top and bottom seals determine the“sweet spots”and ultimate recoverable oil resources in the shale reservoir. Road map for the large scale development of shale oil resources in China includes three mportant points，a clear understanding of shale oil resource potential，an accurate estimation of core areas for shale oil enrichment，and a development of high adaptive and stable technology for shale oil production.
2019, 26(1):29-36.
DOI: 10.13673/j.cnki.cn37-1359/te.2019.01.003
Abstract:
Through the analysis of the geological conditions of shale oil and gas reservoirs in Western Canadian Basin，it is found that the oil and gas enrichment conditions in Jiyang Depression have three comparable characteristics. First，the sedimentary environment of shale oil and gas reservoirs in Western Canadian Basin is mostly marine facies，in which the homogeneous shale distributes widely and forms a large accumulation in the whole foreland basin which tilts eastward in the Rocky Mountains（north to south direction）. However，the shale reservoirs in Jiyang Depression are mostly form in continental lacustrine environment，which is the typical separated-isolated basin with complete sedimentary layers，and with high source-sink symmetry coincidence. Second，there are two types of hydrocarbon generating parent material in the marine shale of the Western Canadian Basin. TypeⅠand Type Ⅰ-Ⅱ kerogens are mostly from marine plankton and algae，TypeⅡ-Ⅲ kerogens are mostly from spore pollen deposited in surface marine environment. While Type Ⅰ-Ⅱ kerogens are the major hydrocarbon-generating parent materials of continental shale in Jiyang Depression，and they are mostly from phytoplankton，dinoflagellates，coccolites，etc. Third，organic pores from thermal evolution is commonly developed in low-density Devonian sediments of Western Canadian Basin，while they are rarely found in shale of Jiyang Depression because the shale is in the middle-late stage of diagenesis and develops compact structure. In addition，the development conditions of shale oil and gas in West Canadian Basin and Jiyang Depression are quite different. The shale strata in Western Canadian Basin contain a large proportion of rigid felsic quartz particles，and the brittleness and compressibility of rocks are better，while the shale components in Jiyang Depression is comprised of more carbonate minerals with lower hardness. The content of rigid particles in Jiyang Depression is extremely low，and therefore it is difficult to establish the necessary supporting structure for later fracturing operation. The“sweet spots”of continental shale oil and gas should distributes in rhythmic bedding fracture zone，irregular cracks caused by curvature change，micro-nanopores caused by mineral crystallization and pyrolysis of organic matter in Jiyang Depression.
Through the analysis of the geological conditions of shale oil and gas reservoirs in Western Canadian Basin，it is found that the oil and gas enrichment conditions in Jiyang Depression have three comparable characteristics. First，the sedimentary environment of shale oil and gas reservoirs in Western Canadian Basin is mostly marine facies，in which the homogeneous shale distributes widely and forms a large accumulation in the whole foreland basin which tilts eastward in the Rocky Mountains（north to south direction）. However，the shale reservoirs in Jiyang Depression are mostly form in continental lacustrine environment，which is the typical separated-isolated basin with complete sedimentary layers，and with high source-sink symmetry coincidence. Second，there are two types of hydrocarbon generating parent material in the marine shale of the Western Canadian Basin. TypeⅠand Type Ⅰ-Ⅱ kerogens are mostly from marine plankton and algae，TypeⅡ-Ⅲ kerogens are mostly from spore pollen deposited in surface marine environment. While Type Ⅰ-Ⅱ kerogens are the major hydrocarbon-generating parent materials of continental shale in Jiyang Depression，and they are mostly from phytoplankton，dinoflagellates，coccolites，etc. Third，organic pores from thermal evolution is commonly developed in low-density Devonian sediments of Western Canadian Basin，while they are rarely found in shale of Jiyang Depression because the shale is in the middle-late stage of diagenesis and develops compact structure. In addition，the development conditions of shale oil and gas in West Canadian Basin and Jiyang Depression are quite different. The shale strata in Western Canadian Basin contain a large proportion of rigid felsic quartz particles，and the brittleness and compressibility of rocks are better，while the shale components in Jiyang Depression is comprised of more carbonate minerals with lower hardness. The content of rigid particles in Jiyang Depression is extremely low，and therefore it is difficult to establish the necessary supporting structure for later fracturing operation. The“sweet spots”of continental shale oil and gas should distributes in rhythmic bedding fracture zone，irregular cracks caused by curvature change，micro-nanopores caused by mineral crystallization and pyrolysis of organic matter in Jiyang Depression.
2019, 26(1):37-45.
DOI: 10.13673/j.cnki.cn37-1359/te.2019.01.004
Abstract:
In order to gain a further understanding of shale gas/oil resource，and to learn from successful overseas development experience，the geological characteristics of shale in Ohio，Marcellus，Barnett，Wolfcamp in North America and the shale in Longmaxi and Shahejie in China were compared in detail. The similarities and differences of typical shales in organic geochemistry and reservoir characteristics in both China and America were deeply clarified，at the same time，the development trends of oil and gas resources in China and the United States were also presented，and the referential values were given. The results show that the oil/gas-bearing shales developed successfully are characterized by simple structure，thick layer，small thickness change，moderate TOC content and organic maturity，rich typeⅡkerogen，rich brittle mineral content and overpressure. North American shale oil developers use large amount of fracturing fluid，large amount of sand， short fracture cluster distance and stage distance to improve the fracturing technique，and use multi-well pad mode to reduce the land occupancy area，and apply the“chain”fracturing to reduce the overall engineering time. By using the big data to analyses the influence weight of different production parameters on oil or gas output，the production increases with the well configured parameters. The development experiences of shale oil or gas that China can learn from U.S. include combining transport pipelines，introducing private capital，and rewarding innovation.
In order to gain a further understanding of shale gas/oil resource，and to learn from successful overseas development experience，the geological characteristics of shale in Ohio，Marcellus，Barnett，Wolfcamp in North America and the shale in Longmaxi and Shahejie in China were compared in detail. The similarities and differences of typical shales in organic geochemistry and reservoir characteristics in both China and America were deeply clarified，at the same time，the development trends of oil and gas resources in China and the United States were also presented，and the referential values were given. The results show that the oil/gas-bearing shales developed successfully are characterized by simple structure，thick layer，small thickness change，moderate TOC content and organic maturity，rich typeⅡkerogen，rich brittle mineral content and overpressure. North American shale oil developers use large amount of fracturing fluid，large amount of sand， short fracture cluster distance and stage distance to improve the fracturing technique，and use multi-well pad mode to reduce the land occupancy area，and apply the“chain”fracturing to reduce the overall engineering time. By using the big data to analyses the influence weight of different production parameters on oil or gas output，the production increases with the well configured parameters. The development experiences of shale oil or gas that China can learn from U.S. include combining transport pipelines，introducing private capital，and rewarding innovation.
2019, 26(1):46-58.
DOI: 10.13673/j.cnki.cn37-1359/te.2019.01.005
Abstract:
According to the traditional view，the semi-deep lake-deep lake area in the lacustrine basin is mainly dominated by relatively homogeneous mudstone shale with high clay and low terrigenous clast，which is a forbidden area for hydrocarbon exploration. But in recent years，the exploration and discovery of shale oil and gas in China and abroad has completely broken through the traditional understanding of the past. In order to research the basic geological characteristics of shale system in fine-grained sedimentary area of the lacustrine basin，based on 635 m cores of Well G108-8，Well GD14 and Well GD12，more than 8 000 analytical laboratory data and matching logging data，the lithologic characteristics，reservoir characteristics，organic geochemical characteristics and their influence on the reservoir stimulation of Kong2 Member in Cangdong Sag，Huanghua Depression were studied. It’s found that the mineral composition of shale system in Kong2 Member is complex and the rock types are diverse. According to the X-ray diffraction（XRD）mineral composition，the shale system can be divided into three categories and seven sub-categories，such as felsic shale，limy dolomite and hybrid shale.Shale system not only has ability to generate oil but also has a certain storage capacity，in which there are many kinds of pores and fractures，such as organic pore，intergranular pore，micro-crack，etc. The shale can be easily stimulated as well.The abundance of organic matter and the maturity of thermal evolution have obvious effects on the porosity development，oil content and carbonate crystallization of shale oil reservoirs. The differences in mineral composition and structure of shale result in differences in petroleum geology among different rocks. Hydrocarbon of short-distance migration should be look for in limy dolomite，while the hydrocarbons of in-situ retention should mainly be look for in felsic shale and hybrid shale. All the three types of shale are beneficial for shale oil storage，but different types of shale should be stimulated by different engineering measures to maximize the exploration and development of shale oil.
According to the traditional view，the semi-deep lake-deep lake area in the lacustrine basin is mainly dominated by relatively homogeneous mudstone shale with high clay and low terrigenous clast，which is a forbidden area for hydrocarbon exploration. But in recent years，the exploration and discovery of shale oil and gas in China and abroad has completely broken through the traditional understanding of the past. In order to research the basic geological characteristics of shale system in fine-grained sedimentary area of the lacustrine basin，based on 635 m cores of Well G108-8，Well GD14 and Well GD12，more than 8 000 analytical laboratory data and matching logging data，the lithologic characteristics，reservoir characteristics，organic geochemical characteristics and their influence on the reservoir stimulation of Kong2 Member in Cangdong Sag，Huanghua Depression were studied. It’s found that the mineral composition of shale system in Kong2 Member is complex and the rock types are diverse. According to the X-ray diffraction（XRD）mineral composition，the shale system can be divided into three categories and seven sub-categories，such as felsic shale，limy dolomite and hybrid shale.Shale system not only has ability to generate oil but also has a certain storage capacity，in which there are many kinds of pores and fractures，such as organic pore，intergranular pore，micro-crack，etc. The shale can be easily stimulated as well.The abundance of organic matter and the maturity of thermal evolution have obvious effects on the porosity development，oil content and carbonate crystallization of shale oil reservoirs. The differences in mineral composition and structure of shale result in differences in petroleum geology among different rocks. Hydrocarbon of short-distance migration should be look for in limy dolomite，while the hydrocarbons of in-situ retention should mainly be look for in felsic shale and hybrid shale. All the three types of shale are beneficial for shale oil storage，but different types of shale should be stimulated by different engineering measures to maximize the exploration and development of shale oil.
2019, 26(1):59-64.
DOI: 10.13673/j.cnki.cn37-1359/te.2019.01.006
Abstract:
The samples of shale oil reservoirs from the Qian34 formation of Qianjiang Sag in Jianghan Basin were collected for a series of experimental studies including core description，thin section analysis，Argon Ionization-Field Emission Scanning Electron Microscopy（AIP-FESEM）analysis，low-temperature nitrogen adsorption，high-pressure mercury injection，etc. to analyze the characteristics of lithologic facies，reservoir storage space types，reservoir physical properties and their influencing factors. The results indicate that the inter-salt shale oil reservoirs in Qian34 are characterized by complex mineral composition. There are six types of lithofacies in the study area，which includes layered dolomite（argillaceous）calcium mangerite lithofacies，laminated argillaceous dolomite lithofacies，laminated dolomite mudstone lithofacies，laminated argillaceous limestone lithofacies，laminated lime mudstone lithofacies and massive dolomite lithofacies. The main reservoir storage space of inter-salt shale oil are interlayer fractures，intercrystalline pores，intercrystalline dissolved pores and clay intracrystalline pores. The average porosity is 11.4%-18.9% and the average permeability is 2.635-4.827 mD. The formation belongs to mid-porosity and extra-low permeable formation. Laminated argillaceous dolomite lithofacies and massive dolomite lithofacies are the most favorable facies types with good physical properties and high oil-bearing characteristics. Compaction and authigenic sulfate minerals filling are the main reasons for the poor physical properties of the reservoir.
The samples of shale oil reservoirs from the Qian34 formation of Qianjiang Sag in Jianghan Basin were collected for a series of experimental studies including core description，thin section analysis，Argon Ionization-Field Emission Scanning Electron Microscopy（AIP-FESEM）analysis，low-temperature nitrogen adsorption，high-pressure mercury injection，etc. to analyze the characteristics of lithologic facies，reservoir storage space types，reservoir physical properties and their influencing factors. The results indicate that the inter-salt shale oil reservoirs in Qian34 are characterized by complex mineral composition. There are six types of lithofacies in the study area，which includes layered dolomite（argillaceous）calcium mangerite lithofacies，laminated argillaceous dolomite lithofacies，laminated dolomite mudstone lithofacies，laminated argillaceous limestone lithofacies，laminated lime mudstone lithofacies and massive dolomite lithofacies. The main reservoir storage space of inter-salt shale oil are interlayer fractures，intercrystalline pores，intercrystalline dissolved pores and clay intracrystalline pores. The average porosity is 11.4%-18.9% and the average permeability is 2.635-4.827 mD. The formation belongs to mid-porosity and extra-low permeable formation. Laminated argillaceous dolomite lithofacies and massive dolomite lithofacies are the most favorable facies types with good physical properties and high oil-bearing characteristics. Compaction and authigenic sulfate minerals filling are the main reasons for the poor physical properties of the reservoir.
LI Tingwei
,
JIANG Zhenxue
,
SONG Guoqi
,
LI Zheng
,
ZHU Rifang
,
SU Siyuan
,
CHEN Weitao
,
NING Chuanxiang
,
WANG Zhi
,
XUE Zixin
2019, 26(1):65-71.
DOI: 10.13673/j.cnki.cn37-1359/te.2019.01.007
Abstract:
Since shale oil and gas occur in micro-to nano-pores and fractures，researches on pore structure characteristics of shale reservoirs are important to understand the accumulation mechanism of shale oil and gas. There are great differences in pore structure between continental and marine shale reservoirs. In order to analyze their differences in pore structure，several methods including field emission-scanning electron microscopy，CO2 adsorption，N2 adsorption，high-pressure mercury injection，and Soxhlet Extraction，etc. were applied to analyze samples from the lower submember of 3rd member of Eocene Shahejie Formation（Es3l）continental shale in Zhanhua Sag and Longmaxi Formation marine shale in Sichuan Basin.The results show that interconnected honeycomb-shape pores are not developed within organic matter for Es3l shale in Zhanhua Sag. In addition，macro-pores with great pore volume are well-developed，providing good spaces for free hydrocarbon storage and controlling shale oil accumulation. In contrast，interconnected honeycomb-shape pores are well-developed within organic matter for Longmaxi Formation marine shale in Sichuan Basin. Micropores with great specific surface area provide sufficient spaces for absorbed hydrocarbon and control shale gas accumulation.
Since shale oil and gas occur in micro-to nano-pores and fractures，researches on pore structure characteristics of shale reservoirs are important to understand the accumulation mechanism of shale oil and gas. There are great differences in pore structure between continental and marine shale reservoirs. In order to analyze their differences in pore structure，several methods including field emission-scanning electron microscopy，CO2 adsorption，N2 adsorption，high-pressure mercury injection，and Soxhlet Extraction，etc. were applied to analyze samples from the lower submember of 3rd member of Eocene Shahejie Formation（Es3l）continental shale in Zhanhua Sag and Longmaxi Formation marine shale in Sichuan Basin.The results show that interconnected honeycomb-shape pores are not developed within organic matter for Es3l shale in Zhanhua Sag. In addition，macro-pores with great pore volume are well-developed，providing good spaces for free hydrocarbon storage and controlling shale oil accumulation. In contrast，interconnected honeycomb-shape pores are well-developed within organic matter for Longmaxi Formation marine shale in Sichuan Basin. Micropores with great specific surface area provide sufficient spaces for absorbed hydrocarbon and control shale gas accumulation.
WANG Min
,
JIAO Chenxue
,
LI Chuanming
,
LI Zheng
,
ZHOU Nengwu
,
LI Jinbu
,
LU Shuangfang
,
TIAN Fuchun
,
HAO Guixian
,
SHI Jin
2019, 26(1):72-79.
DOI: 10.13673/j.cnki.cn37-1359/te.2019.01.008
Abstract:
Characterizing the heterogeneity of pore volume，pore size distribution，and specific surface area is an important task in the evaluation of shale oil exploration. In this study，the multifractal theory was adopted to study the experimental data of low temperature N2 adsorption of Shahejie Formation shale in Dongying Sag. Relationships among multifractal characteristics，fractal parameters，pore parameters and shale mineral composition were discussed. Results show that：the pore size distribution of Shahejie Formation shale in Dongying Sag is characterized by multiple fractal features，and the heterogeneity of the pore size distribution is mainly related to the specific surface area of the pore. The larger the Hurst index indicates the greater penetration rate. There are strong positive or negative correlations among the multifractal parameters except the difference between the right semi-biased parameter and the left semi-biased parameter of multifractal spectrum.Information dimension and correlation dimension are positively related to Hurst index and negatively to Hausdorff dimension，left semi-biased parameter and multifractal spectral peak width，while multi-fractal parameters，such as information dimension and correlation dimension，are positively correlated with the specific surface area and pore volume，and the other multifractal parameters are negatively correlated with the specific surface area and pore volume（except for the right semibias parameter）. There is no obvious correlation between multi-fractal parameters and rock mineral composition.
Characterizing the heterogeneity of pore volume，pore size distribution，and specific surface area is an important task in the evaluation of shale oil exploration. In this study，the multifractal theory was adopted to study the experimental data of low temperature N2 adsorption of Shahejie Formation shale in Dongying Sag. Relationships among multifractal characteristics，fractal parameters，pore parameters and shale mineral composition were discussed. Results show that：the pore size distribution of Shahejie Formation shale in Dongying Sag is characterized by multiple fractal features，and the heterogeneity of the pore size distribution is mainly related to the specific surface area of the pore. The larger the Hurst index indicates the greater penetration rate. There are strong positive or negative correlations among the multifractal parameters except the difference between the right semi-biased parameter and the left semi-biased parameter of multifractal spectrum.Information dimension and correlation dimension are positively related to Hurst index and negatively to Hausdorff dimension，left semi-biased parameter and multifractal spectral peak width，while multi-fractal parameters，such as information dimension and correlation dimension，are positively correlated with the specific surface area and pore volume，and the other multifractal parameters are negatively correlated with the specific surface area and pore volume（except for the right semibias parameter）. There is no obvious correlation between multi-fractal parameters and rock mineral composition.
TENG Jianbin
,
LIU Huimin
,
QIU Longwei
,
ZHANG Shoupeng
,
HAO Yunqing
,
TIAN Fang
,
ZHU Lipeng
,
FANG Zhengwei
2019, 26(1):80-87.
DOI: 10.13673/j.cnki.cn37-1359/te.2019.01.009
Abstract:
By means of petrology and geochemical analysis，the oil-bearing properties and material components of shale oil reservoirs in Upper Es4 and Lower Es3 Members in Jiyang Depression were analyzed. Fluorescence characteristics analysis results show that the resident and free asphaltene selectively occur in argillaceous laminates，gray carbonate laminates and fractures. Argillaceous lamina，as the parent material storage for oil-generated，is easy to enrich carbon asphaltene and bituminiferous asphaltene. Carbonate laminates have superior storage space compared with argillaceous laminates，which are suitable to accumulate gum asphaltene and crude oil asphaltene，and crude oil asphaltene can easily flow into microcracks.It is found that the calcite vein is essentially a kind of fully filled fracture. Four identification marks of recognition calcite vein are summarized，among which the calcite intercrystalline pore and the non healing crack near the shaft healing line can be regarded as the percolation path for the oil asphaltene. The spatial development and oil content of shale oil reservoir are mainly controlled by the rock texture，structure types and material components. Mineral composition differences and thermal evolution of organic matter are two main factors that influence shale oil storage space and oil content. As a result，the storage of shale oil has following characteristics：shale with argillaceous laminates and gray carbonate laminates has high porosity，shale with high carbonate content has high porosity，and the higher thermal evolution degree of organic matter corresponds to the higher porosity.
By means of petrology and geochemical analysis，the oil-bearing properties and material components of shale oil reservoirs in Upper Es4 and Lower Es3 Members in Jiyang Depression were analyzed. Fluorescence characteristics analysis results show that the resident and free asphaltene selectively occur in argillaceous laminates，gray carbonate laminates and fractures. Argillaceous lamina，as the parent material storage for oil-generated，is easy to enrich carbon asphaltene and bituminiferous asphaltene. Carbonate laminates have superior storage space compared with argillaceous laminates，which are suitable to accumulate gum asphaltene and crude oil asphaltene，and crude oil asphaltene can easily flow into microcracks.It is found that the calcite vein is essentially a kind of fully filled fracture. Four identification marks of recognition calcite vein are summarized，among which the calcite intercrystalline pore and the non healing crack near the shaft healing line can be regarded as the percolation path for the oil asphaltene. The spatial development and oil content of shale oil reservoir are mainly controlled by the rock texture，structure types and material components. Mineral composition differences and thermal evolution of organic matter are two main factors that influence shale oil storage space and oil content. As a result，the storage of shale oil has following characteristics：shale with argillaceous laminates and gray carbonate laminates has high porosity，shale with high carbonate content has high porosity，and the higher thermal evolution degree of organic matter corresponds to the higher porosity.
2019, 26(1):88-100.
DOI: 10.13673/j.cnki.cn37-1359/te.2019.01.010
Abstract:
Mud shale material composition is variable and its pore structure is complex，thus，clarifying the characteristics，the influence factors and the evolution of nano-pores in shale is of great significance to predict the oil/gas enrichment intervals. Shale from Well S in Dongying Sag was studied with the combination of N2 adsorption and mercury intrusion methods，to obtain the pore size distribution，the volume of different type of pore，and other quantitative parameters. The results show that the argillaceous siltstone is dominated of macropore，and the silty mudstone and mudstone are mainly characterized by mesopore and micropore. By analysing the relationships among mineral composition，organic composition and pore structure，it is found that clay content and clay mineral type in mud shale have the most strong effect on micropore and mesopore.And the influence of carbonate minerals on the pore structure is controlled by its genesis. Furthermore，the total organic carbon（TOC），and organic matter type affect more strongly the pore structure of mud shale. By analyzing the evolution characteristics of pore structure，mineral composition and organic composition，it is found that mineral transformation，hydrocarbon generation of organic matter and burial compaction together lead to the multiple stages pore evolution during burial evolution.
Mud shale material composition is variable and its pore structure is complex，thus，clarifying the characteristics，the influence factors and the evolution of nano-pores in shale is of great significance to predict the oil/gas enrichment intervals. Shale from Well S in Dongying Sag was studied with the combination of N2 adsorption and mercury intrusion methods，to obtain the pore size distribution，the volume of different type of pore，and other quantitative parameters. The results show that the argillaceous siltstone is dominated of macropore，and the silty mudstone and mudstone are mainly characterized by mesopore and micropore. By analysing the relationships among mineral composition，organic composition and pore structure，it is found that clay content and clay mineral type in mud shale have the most strong effect on micropore and mesopore.And the influence of carbonate minerals on the pore structure is controlled by its genesis. Furthermore，the total organic carbon（TOC），and organic matter type affect more strongly the pore structure of mud shale. By analyzing the evolution characteristics of pore structure，mineral composition and organic composition，it is found that mineral transformation，hydrocarbon generation of organic matter and burial compaction together lead to the multiple stages pore evolution during burial evolution.
2019, 26(1):101-108.
DOI: 10.13673/j.cnki.cn37-1359/te.2019.01.011
Abstract:
Mud shale in Upper Es4 to Lower Es3 Members of Jiyang Depression has complicate composition and structural heterogeneity，and controlling factors of reservoir property difference are unclear，restricting the progress of shale oil exploration. Bedding structures in mud shale characterized by rich carbonate in Upper Es4 to Lower Es3 Members of Jiyang Depression can be divided into 10 types by using thin slice analysis data. Results show that types of B，C and D are the most developed in mud shale，which proportion can reach 80%. By analyzing and observing pore types of mud shale matrix through thin section and argon ion polishing-scanning electron microscopy，the main pore types in the study area are considered to be rigid intergranular pore，organic matter and clay shrinkage pore，and carbonate intergranular pore. According to the bedding structure type，G，H，B and D have the best reservoir property，followed by E and F，A and C，and other types are the worst. By analyzing the controlling factors of mud shale reservoir property of different types of bedding structure，the mineral composition plays a leading role in controlling the degree of pore development in mud shale with muddy crystal structure carbonate. Bedding structure strongly affects the degree of pore development in mud shale with carbonate grain structure（including columnar fiber structure）. According to the analysis of mud shale oil production section，it is clear that the further main exploration direction should be to turn to mud shale of G，H，B and D types with 30%-50% carbonate content，and it is preferable to consider shale sections with more concentrated G and H types with carbonate content meeting the above conditions.
Mud shale in Upper Es4 to Lower Es3 Members of Jiyang Depression has complicate composition and structural heterogeneity，and controlling factors of reservoir property difference are unclear，restricting the progress of shale oil exploration. Bedding structures in mud shale characterized by rich carbonate in Upper Es4 to Lower Es3 Members of Jiyang Depression can be divided into 10 types by using thin slice analysis data. Results show that types of B，C and D are the most developed in mud shale，which proportion can reach 80%. By analyzing and observing pore types of mud shale matrix through thin section and argon ion polishing-scanning electron microscopy，the main pore types in the study area are considered to be rigid intergranular pore，organic matter and clay shrinkage pore，and carbonate intergranular pore. According to the bedding structure type，G，H，B and D have the best reservoir property，followed by E and F，A and C，and other types are the worst. By analyzing the controlling factors of mud shale reservoir property of different types of bedding structure，the mineral composition plays a leading role in controlling the degree of pore development in mud shale with muddy crystal structure carbonate. Bedding structure strongly affects the degree of pore development in mud shale with carbonate grain structure（including columnar fiber structure）. According to the analysis of mud shale oil production section，it is clear that the further main exploration direction should be to turn to mud shale of G，H，B and D types with 30%-50% carbonate content，and it is preferable to consider shale sections with more concentrated G and H types with carbonate content meeting the above conditions.
ZHANG Shun
,
LIU Huimin
,
WANG Yongshi
,
ZHANG Shoupeng
,
ZHANG Kuihua
,
WANG Min
,
WANG Yong
,
FU Aibing
,
BAO Youshu
2019, 26(1):109-118.
DOI: 10.13673/j.cnki.cn37-1359/te.2019.01.012
Abstract:
The shale of Paleogene Shahejie Formation in Dongying Sag was studied，according to the data of core，thin section，scanning electron microscopy（SEM），electron probe micro element scanning and carbon-oxygen isopiestic，etc. The effect of diagenetic events on shale pore space was analyzed. The results show that：①The shale in Dongying Sag develops obvious laminated layers，and the mineral types in shale is complicated. The content of carbonate minerals，especially calcite，is generally high. Organic matter is abundant with medium vitrinite reflectance. The porosity of laminar argillaceous limestone is relatively high，and free oil mainly distributes in micro-pores and fractures. ②The major shale is at the middle stage of diagenesis，and 3 000-3 600 m is the key interval of pore development and evolution. The key diagenetic events during shale diagenesis include shrinkage and transformation of clay minerals，recrystallization of carbonate minerals，organic matter persistent hydrocarbon generation and acid dissolution. ③Recrystallization could form cleavage slits and intercrystalline pores，and the dissolution during the hydrocarbon generation and discharge process could generate internal dissolution pores in carbonate minerals，these pores form the effective pore space combination and increase the reservoir porosity. ④The inter-laminar cracks are not rigorous fractures，which is related to the seepage force induced by overpressure and high overpressure. Below 3 000 m，the fluid overpressure alone could not overcome the overburden pressure to open the crack. The inheritance and matching of diagenetic events such as acid dissolution，induced overpressure of hydrocarbon generation from organic matter and clay mineral syneresis，forming the pore spaces（combination）that is easier for fluid flow，thus becoming an effective seepage channel and oil pore space.
The shale of Paleogene Shahejie Formation in Dongying Sag was studied，according to the data of core，thin section，scanning electron microscopy（SEM），electron probe micro element scanning and carbon-oxygen isopiestic，etc. The effect of diagenetic events on shale pore space was analyzed. The results show that：①The shale in Dongying Sag develops obvious laminated layers，and the mineral types in shale is complicated. The content of carbonate minerals，especially calcite，is generally high. Organic matter is abundant with medium vitrinite reflectance. The porosity of laminar argillaceous limestone is relatively high，and free oil mainly distributes in micro-pores and fractures. ②The major shale is at the middle stage of diagenesis，and 3 000-3 600 m is the key interval of pore development and evolution. The key diagenetic events during shale diagenesis include shrinkage and transformation of clay minerals，recrystallization of carbonate minerals，organic matter persistent hydrocarbon generation and acid dissolution. ③Recrystallization could form cleavage slits and intercrystalline pores，and the dissolution during the hydrocarbon generation and discharge process could generate internal dissolution pores in carbonate minerals，these pores form the effective pore space combination and increase the reservoir porosity. ④The inter-laminar cracks are not rigorous fractures，which is related to the seepage force induced by overpressure and high overpressure. Below 3 000 m，the fluid overpressure alone could not overcome the overburden pressure to open the crack. The inheritance and matching of diagenetic events such as acid dissolution，induced overpressure of hydrocarbon generation from organic matter and clay mineral syneresis，forming the pore spaces（combination）that is easier for fluid flow，thus becoming an effective seepage channel and oil pore space.
2019, 26(1):119-128.
DOI: 10.13673/j.cnki.cn37-1359/te.2019.01.013
Abstract:
In order to clarify the diagenetic types of shale and their effects on shale reservoir development，the shale of Upper Es4 to Lower Es3 Members in Dongying Sag is taken as the research object. The diagenetic type was studied through core and thin section observation，SEM，EDS，XRD，and elemental analysis. The diagenetic stages were divided in combination with analyses on vitrinite reflectance，rock pyrolysis and I/S mixed-layer ratio. Meanwhile，the diagenetic evolution characteristics were also determined and the effects of diagenesis on the spatial development of reservoirs were clarified.The results show that the diagenesis types of the shale of Upper Es4 to Lower Es3 Members in Dongying Sag include formation of pyrite，dolomitization，compaction，cementation，dissolution，recrystallization，clay mineral transformation and rupturing，etc. The diagenetic evolution had been in the middle diagenetic stage A. The formation of pyrite，dolomitization，recrystallization，clay mineral transformation are beneficial to the formation of intercrystalline pores，dissolution is favorable for the formation of grain inner pores，and rupturing can form fractures.
In order to clarify the diagenetic types of shale and their effects on shale reservoir development，the shale of Upper Es4 to Lower Es3 Members in Dongying Sag is taken as the research object. The diagenetic type was studied through core and thin section observation，SEM，EDS，XRD，and elemental analysis. The diagenetic stages were divided in combination with analyses on vitrinite reflectance，rock pyrolysis and I/S mixed-layer ratio. Meanwhile，the diagenetic evolution characteristics were also determined and the effects of diagenesis on the spatial development of reservoirs were clarified.The results show that the diagenesis types of the shale of Upper Es4 to Lower Es3 Members in Dongying Sag include formation of pyrite，dolomitization，compaction，cementation，dissolution，recrystallization，clay mineral transformation and rupturing，etc. The diagenetic evolution had been in the middle diagenetic stage A. The formation of pyrite，dolomitization，recrystallization，clay mineral transformation are beneficial to the formation of intercrystalline pores，dissolution is favorable for the formation of grain inner pores，and rupturing can form fractures.
2019, 26(1):129-136.
DOI: 10.13673/j.cnki.cn37-1359/te.2019.01.014
Abstract:
Shale oil resource potential analysis is one of the most important basic works in shale oil exploration practice. Recoverable oil resource is the most direct index of resource potential evaluation. Based on the existing research results of shale oil resources evaluation and the recovery of shale oil，the total resources and recoverable resources of the shale oil in Lower Es3 Member in Dongying Sag were calculated by the chloroform asphalt“A”method and the pyrolysis parameter method respectively. The calculation results show that the calculation results obtained by the two methods are basically consistent，which are 1 139 million tons and 1 157 million tons respectively. The shale oil resources are mainly distributed horizontally in the central zone of the subsags，which the abundance of the resources is between1 million and 2.5 million t/km2.Vertically，the shale oil resources are mainly occurred at the depth from 3 000 m to 3 500 m with 701 million tons shale oil resources，followed occurred at the depth from 3 500 to 4 000 m，which is 437 million tons shale oil resources. However，the amount of recoverable resources of shale oil are roughly equivalent at those two deep segments，which is 75 million tons and 73 million tons respectively. Shale oil located deeply has a higher recoverable rate. Lijin Subsag has high shale oil resource abundance and recovery mobility，high shale oil resource potential，and is a favorable area for shale oil exploration.
Shale oil resource potential analysis is one of the most important basic works in shale oil exploration practice. Recoverable oil resource is the most direct index of resource potential evaluation. Based on the existing research results of shale oil resources evaluation and the recovery of shale oil，the total resources and recoverable resources of the shale oil in Lower Es3 Member in Dongying Sag were calculated by the chloroform asphalt“A”method and the pyrolysis parameter method respectively. The calculation results show that the calculation results obtained by the two methods are basically consistent，which are 1 139 million tons and 1 157 million tons respectively. The shale oil resources are mainly distributed horizontally in the central zone of the subsags，which the abundance of the resources is between1 million and 2.5 million t/km2.Vertically，the shale oil resources are mainly occurred at the depth from 3 000 m to 3 500 m with 701 million tons shale oil resources，followed occurred at the depth from 3 500 to 4 000 m，which is 437 million tons shale oil resources. However，the amount of recoverable resources of shale oil are roughly equivalent at those two deep segments，which is 75 million tons and 73 million tons respectively. Shale oil located deeply has a higher recoverable rate. Lijin Subsag has high shale oil resource abundance and recovery mobility，high shale oil resource potential，and is a favorable area for shale oil exploration.
2019, 26(1):137-152.
DOI: 10.13673/j.cnki.cn37-1359/te.2019.01.015
Abstract:
Quantitative assessment of oil-bearing properties and oil mobility in fine-grained rocks was a prerequisite for the shale play selection and drilling target evaluation. In conventional exploration，laboratory-based open pyrolysis technique was commonly used to evaluate source rock quality and resource potential. Shale oil exploration and development focused on movable resources in shale reservoirs. Routine parameters obtained by Rock-Eval pyrolysis could not be applied directly to shale resource assessment. Through the improvement of conventional pyrolysis analysis methods and the optimization of data processing flow，a series of new evaluation methods of oil-bearing and movability of shale were proposed. The methods included chemical kinetic parameters of hydrocarbon generation in heterogeneous shale system obtained by using pyrolysis data of a single heating rate，identifying and quantitatively deducting hydrocarbon migration in organic-rich shale using pyrolysis data，“one-step”pyrolysis method of total oil content in shale and its comparison with two-step pyrolysis，and determining composition of free hydrocarbons by using conventional pyrolysis curve information. These methods have been applied to shale oil-bearing analysis and hydrocarbon migration identification in Jiyang Depression and Qianjiang Sag and the pertinence of quantitative evaluation results of shale oil-bearing is obviously improved，which are conducive to accurately delineating in-situ shale oil resources and associated conventional trap resources.
Quantitative assessment of oil-bearing properties and oil mobility in fine-grained rocks was a prerequisite for the shale play selection and drilling target evaluation. In conventional exploration，laboratory-based open pyrolysis technique was commonly used to evaluate source rock quality and resource potential. Shale oil exploration and development focused on movable resources in shale reservoirs. Routine parameters obtained by Rock-Eval pyrolysis could not be applied directly to shale resource assessment. Through the improvement of conventional pyrolysis analysis methods and the optimization of data processing flow，a series of new evaluation methods of oil-bearing and movability of shale were proposed. The methods included chemical kinetic parameters of hydrocarbon generation in heterogeneous shale system obtained by using pyrolysis data of a single heating rate，identifying and quantitatively deducting hydrocarbon migration in organic-rich shale using pyrolysis data，“one-step”pyrolysis method of total oil content in shale and its comparison with two-step pyrolysis，and determining composition of free hydrocarbons by using conventional pyrolysis curve information. These methods have been applied to shale oil-bearing analysis and hydrocarbon migration identification in Jiyang Depression and Qianjiang Sag and the pertinence of quantitative evaluation results of shale oil-bearing is obviously improved，which are conducive to accurately delineating in-situ shale oil resources and associated conventional trap resources.
2019, 26(1):153-164.
DOI: 10.13673/j.cnki.cn37-1359/te.2019.01.016
Abstract:
Shale oil is an important component of unconventional hydrocarbon. It mainly exists in different types of pores and fractures of shale. Unlike the shale at high maturity stage which generate shale gas，hydrocarbon pore space in organic shale at oil-generating window is often filled completely or partially by early hydrocarbon-generating materials，thus affecting the structure characterization and geometry description of shale oil pore spaces. Through the microscopic observation of a large number of shale samples，the pores of shale oil reservoir could be divided totally into intergranular mineral pore，intragranular mineral pore and organic pore. The former two types of pores include intergranular pore among different mineral particles，dissolution pore，clay mineral interlaminar pore，etc. The organic pores are composed by marginal shrinkage pore （fracture）and a small amount of pyrolysis pore. Based on the requirement for characterization of shale oil pores，solvent extraction was carried out on the samples，and the suitable pore characterization techniques for crushed and blocked samples were discussed respectively. Different shale oil characterization methods have certain differences in principle and application，and have certain limitations as well. In order to avoid the influence of this factor on pore characterization，a variety of characterization methods could be combined to characterize pore through comparative analysis and unified dimension，so as to improve the accuracy of pore characterization results of shale oil reservoir.
Shale oil is an important component of unconventional hydrocarbon. It mainly exists in different types of pores and fractures of shale. Unlike the shale at high maturity stage which generate shale gas，hydrocarbon pore space in organic shale at oil-generating window is often filled completely or partially by early hydrocarbon-generating materials，thus affecting the structure characterization and geometry description of shale oil pore spaces. Through the microscopic observation of a large number of shale samples，the pores of shale oil reservoir could be divided totally into intergranular mineral pore，intragranular mineral pore and organic pore. The former two types of pores include intergranular pore among different mineral particles，dissolution pore，clay mineral interlaminar pore，etc. The organic pores are composed by marginal shrinkage pore （fracture）and a small amount of pyrolysis pore. Based on the requirement for characterization of shale oil pores，solvent extraction was carried out on the samples，and the suitable pore characterization techniques for crushed and blocked samples were discussed respectively. Different shale oil characterization methods have certain differences in principle and application，and have certain limitations as well. In order to avoid the influence of this factor on pore characterization，a variety of characterization methods could be combined to characterize pore through comparative analysis and unified dimension，so as to improve the accuracy of pore characterization results of shale oil reservoir.
2019, 26(1):165-173.
DOI: 10.13673/j.cnki.cn37-1359/te.2019.01.017
Abstract:
With the continuous improvement of conventional oil and gas exploration，the eastern old oilfields，especially Shengli Oilfield，are facing a new situation and new task of expanding exploration field and opening up situation of unconventional oil and gas exploration. Compared with North American marine shale oil，continental shale oil has its own particularity of complex reservoir-forming conditions and being lack of corresponding quantitative evaluation technology. Therefore，taking the Lower Es3 Member of Luojia area in Jiyang Depression as an example，on the basis of definition of the logging response characteristics of shale oil“sweet spot”，the logging quantitative identification model of shale oil“sweet spot”in Luojia area was established，by which the logging quantitative identification of shale oil“sweet spot”is realized.Meanwhile，the relationship between key geological and engineering factors，including TOC，lithofacies，fracture and brittleness，and pre-stack and post-stack seismic information was discussed. Four categories of unique seismic prediction technologies were generated，including the inversion prediction of TOC under multi-logging curves constraint，the sedimentary parameter based shale lithofacies prediction，post stack seismic data based gentle angle fracture density quantitative characterization，pre-stack elastic parameters based shale brittleness characterization. Finally，based on the seismic prediction results of four key geological and engineering factors and constrained by logging quantitative identification，a“sweet spot” seismic characterization model is constructed，which realizes quantitative evaluation of“sweet spot”in continental shale oil with the well-seismic joint technology，and achieves good application results.
With the continuous improvement of conventional oil and gas exploration，the eastern old oilfields，especially Shengli Oilfield，are facing a new situation and new task of expanding exploration field and opening up situation of unconventional oil and gas exploration. Compared with North American marine shale oil，continental shale oil has its own particularity of complex reservoir-forming conditions and being lack of corresponding quantitative evaluation technology. Therefore，taking the Lower Es3 Member of Luojia area in Jiyang Depression as an example，on the basis of definition of the logging response characteristics of shale oil“sweet spot”，the logging quantitative identification model of shale oil“sweet spot”in Luojia area was established，by which the logging quantitative identification of shale oil“sweet spot”is realized.Meanwhile，the relationship between key geological and engineering factors，including TOC，lithofacies，fracture and brittleness，and pre-stack and post-stack seismic information was discussed. Four categories of unique seismic prediction technologies were generated，including the inversion prediction of TOC under multi-logging curves constraint，the sedimentary parameter based shale lithofacies prediction，post stack seismic data based gentle angle fracture density quantitative characterization，pre-stack elastic parameters based shale brittleness characterization. Finally，based on the seismic prediction results of four key geological and engineering factors and constrained by logging quantitative identification，a“sweet spot” seismic characterization model is constructed，which realizes quantitative evaluation of“sweet spot”in continental shale oil with the well-seismic joint technology，and achieves good application results.
2019, 26(1):174-182.
DOI: 10.13673/j.cnki.cn37-1359/te.2019.01.018
Abstract:
As an important carrier of shale oil，soluble organic matter contains abundant information which is of great significance to the prediction of shale oil“sweet spots”. Shale samples drilled from Lower Es4 Member，Upper Es4 Member，Lower Es3 Member and Middle Es3 Member in Dongying Sag were selected to analyze the group component of soluble organic matter and saturated hydrocarbon chromatography. According to the characteristics of soluble organic matter content，group composition and light hydrocarbon content，indicators including the total amount of soluble organic matter and the amount of saturated hydrocarbon were established to identify the abundance of shale oil，as well as indicators including the MI parameter，light hydrocarbon content and loss of light hydrocarbon to characterize the mobility capacity of shale oil. The results indicate that the content of soluble organic matter and saturated hydrocarbon of Upper Es4 Member and Lower Es3 Member was significantly larger than that of Lower Es4 Member and Middle Es3 Member，and that of Upper Es4 Member were the highest among the four layers. Shale oil MI of Upper Es4 Member and Lower Es3 Member was higher than that of Lower Es4 Member and Middle Es3 Member. Meanwhile，the original light hydrocarbon content and loss of Upper Es4 Member were higher. According to the comprehensive analysis，Lower Es3 Member and Upper Es4 Member are favorable development formations of shale oil. Further more，Upper Es4 Member is the preferred target area of Paleogene shale oil“sweet spots”in Dongying Sag.
As an important carrier of shale oil，soluble organic matter contains abundant information which is of great significance to the prediction of shale oil“sweet spots”. Shale samples drilled from Lower Es4 Member，Upper Es4 Member，Lower Es3 Member and Middle Es3 Member in Dongying Sag were selected to analyze the group component of soluble organic matter and saturated hydrocarbon chromatography. According to the characteristics of soluble organic matter content，group composition and light hydrocarbon content，indicators including the total amount of soluble organic matter and the amount of saturated hydrocarbon were established to identify the abundance of shale oil，as well as indicators including the MI parameter，light hydrocarbon content and loss of light hydrocarbon to characterize the mobility capacity of shale oil. The results indicate that the content of soluble organic matter and saturated hydrocarbon of Upper Es4 Member and Lower Es3 Member was significantly larger than that of Lower Es4 Member and Middle Es3 Member，and that of Upper Es4 Member were the highest among the four layers. Shale oil MI of Upper Es4 Member and Lower Es3 Member was higher than that of Lower Es4 Member and Middle Es3 Member. Meanwhile，the original light hydrocarbon content and loss of Upper Es4 Member were higher. According to the comprehensive analysis，Lower Es3 Member and Upper Es4 Member are favorable development formations of shale oil. Further more，Upper Es4 Member is the preferred target area of Paleogene shale oil“sweet spots”in Dongying Sag.
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