Characteristics, current exploration practices, and prospects of continental shale oil in China

Wang, Xiaoni; Li, Jiarui; Jiang, Wenqi; Zhang, Hong; Feng, Y. L.; Yang, Zhao

doi:10.46690/ager.2022.06.02

Cited by 43 publications

(18 citation statements)

References 7 publications

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“…The dip angle of the fault surface greatly impacts vertical sealing capacity. − A high-angle fault and its associated high-angle fractures may somewhat impair the self-sealing performance of shale gas reservoirs, which is unfavorable for shale gas preservation. A low-angle fault with a small throw may have limited horizons.…”

Section: Discussionmentioning

confidence: 99%

Multi-scale Fractures and Their Influence on Shale Gas Deliverability in the Longmaxi Formation of the Changning Block, Southern Sichuan Basin, China

Zhao

Zheng²,

Liu³

et al. 2023

ACS Omega

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The capacity and deliverability of shale gas are closely linked to the presence of multi-scale fractures, including fractures and faults, within organic-rich shales. This study aims to investigate the fracture system of the Longmaxi Formation shale in the Changning Block of the southern Sichuan Basin and quantify the influence of multi-scale fractures on shale gas capacity and deliverability. The fracture system was analyzed through outcrop, core observations, and 3D seismic interpretation. Criteria for fault classification were established based on the horizon, throw, azimuth (phase), extension, and dip angle. The Longmaxi Formation shale mainly comprises shear fractures that form under multi-phase tectonic stress, characterized by large dip angles, small extensions, small apertures, and high density. The high content of organic matter and brittle minerals in the Long 1-1 Member facilitates the occurrence of natural fractures, which somewhat enhance shale gas capacity. Reverse faults with a dip angle of 45−70°e xist vertically, while laterally, there are early-stage nearly E-W faults, middle-stage NE faults, and late-stage NW faults. Based on the established criteria, faults that cut upward through the strata in and above the Permian with a throw greater than 200 m and a dip angle greater than 60°have the greatest influence on shale gas preservation and deliverability. These results provide important guidance for shale gas exploration and development in the Changning Block and contribute to our understanding of the relationship between multi-scale fractures and shale gas capacity and deliverability.

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Section: Discussionmentioning

confidence: 99%

Multi-scale Fractures and Their Influence on Shale Gas Deliverability in the Longmaxi Formation of the Changning Block, Southern Sichuan Basin, China

Zhao

Zheng²,

Liu³

et al. 2023

ACS Omega

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“…Oil and gas have long been the most important primary energy in the world, playing a predominant role in the sustainable development of human society and the global economy. − It is estimated that hydrocarbon energy will continue to account for greater than 50% primary energy supply by 2040 . Shale oil resources, with global technically recoverable reserves of 1.4 × 10 12 t, are about three times the total conventional oil resources .…”

Section: Introductionmentioning

confidence: 99%

Novel Method for the Classification of Shale Oil Reservoirs Associated with Mobility: Inspiration from Gas Adsorption and Multiple Isothermal Stage Pyrolysis

Gou

Chen

et al. 2023

Energy Fuels

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The characterization and description of pores in shale oil reservoirs have long been based on the classification of micropores (<2 nm), mesopores (2–50 nm), and macropores (>50 nm) in shale gas reservoirs. However, the great difference between oil and gas molecules leads to its poor applicability, which further results in the relationship between oil properties and pores being rarely understood. To establish an individual pore division method for shale oil reservoirs, N2 adsorption, Soxhlet extraction, and programmed pyrolysis were performed on the Paleogene Xin’gouzui lacustrine shale in the Jianghan Basin. With the results, a new classification method, i.e., adsorption pores (pore diameter <20 nm), restricted pores (20–100 nm), and movable pores (>100 nm), was proposed. A fractal theory and scanning electron microscopy (SEM) images confirm the rationality of this method. Hydrocarbons in movable pores determine the initial productivity of a shale oil well, while those in restricted pores are closely related to the production time of a well to some extent. Compared to the previous division methods, this novel method reveals the correlation between shale oil attributes as well as movability and pore spaces for the first time. Our work can provide more accurate evaluation results for shale oil recoverable resource potential and is of great significance for optimizing favorable areas and reducing exploration risks.

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“…In addition, the characteristics of these three reservoir types are quite different in terms of the total organic carbon (TOC) content, thermal maturity, gas–oil ratio, and dominant pore type. ,− Furthermore, there could be more than one shale oil reservoir type in the same block. For example, Chang 7 3 member in Ordos Basin is a pure shale type, whereas Chang 7 1 and Chang 7 2 members are sandwich-type shales . Meanwhile, the vertical lithology of the Fengcheng Formation in the Mahu Sag changes rapidly, containing multiple types of source–reservoir configuration relationships.…”

Section: Introductionmentioning

confidence: 99%

“…For example, Chang 7 3 member in Ordos Basin is a pure shale type, whereas Chang 7 1 and Chang 7 2 members are sandwich-type shales. 18 reservoir configuration relationships. However, there is still a lack of systematic and targeted comparative studies among different types of reservoirs in the Fengcheng Formation, hindering the in-depth understanding of hydrocarbon accumulation mechanisms of shale oil therein and restricting the effective exploration of the Fengcheng Formation shale oil.…”

Section: Introductionmentioning

confidence: 99%

Occurrence Mechanisms of Laminated-Type and Sandwich-Type Shale Oil in the Fengcheng Formation of Mahu Sag, Junggar Basin

Gong,

Bai,

Gao

et al. 2023

Energy Fuels

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The shale oil resources of the Permian Fengcheng Formation in the Mahu Sag are abundant, and the types of shale oil reservoirs therein are diverse. However, differences in the reservoir spaces, occurrence states, and source−reservoir configurations of different types of shale oil reservoirs restrict the in-depth understanding of the enrichment and accumulation mechanisms of shale oil in this formation. Thus, using multiple complementary experiments, this study systematically compared laminated-type and sandwich-type shale oil reservoirs (LTSOR and STSOR), in terms of hydrocarbon generation potential, physical characteristics, and oil-bearing properties. These two types of shale oil reservoirs had distinct differences in total organic carbon (TOC), porosity, oil saturation index, and S 1 , demonstrating differences in accumulation mechanisms. These two types of reservoirs were mainly dominated by inorganic intergranular pores and dissolution pores, and the storage capability of STSOR was much better than that of LTSOR. Specifically, STSOR mainly developed macropores, whereas LTSOR developed macropores and mesopores. The free oil content in the STSOR was found to be higher than that of the adsorbed oil, whereas the free and adsorbed oil contents in the LTSOR were similar. Furthermore, the shale oil occurrence in the STSOR was mainly affected by pore structure and mineral composition, whereas the shale oil occurrence in the LTSOR was affected by pore structure, mineral composition, TOC content, and sedimentary structure. The source−reservoir configuration relationship of STSOR was one where the upper and lower shale layers were source rocks, whereas the intercalated siltstone layers were reservoirs. The source−reservoir configuration of the LTSOR involved bright laminae as reservoirs and dark laminae as source rocks (i.e., integrated source and reservoir). Hydrocarbon accumulation models were established for the STSOR and LTSOR that involved source−reservoir configurations, occurrence states, and migration directions.

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Characteristics, current exploration practices, and prospects of continental shale oil in China

Cited by 43 publications

References 7 publications

Multi-scale Fractures and Their Influence on Shale Gas Deliverability in the Longmaxi Formation of the Changning Block, Southern Sichuan Basin, China

Multi-scale Fractures and Their Influence on Shale Gas Deliverability in the Longmaxi Formation of the Changning Block, Southern Sichuan Basin, China

Novel Method for the Classification of Shale Oil Reservoirs Associated with Mobility: Inspiration from Gas Adsorption and Multiple Isothermal Stage Pyrolysis

Occurrence Mechanisms of Laminated-Type and Sandwich-Type Shale Oil in the Fengcheng Formation of Mahu Sag, Junggar Basin

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