Resource potential and core area prediction of lacustrine tight oil: The Triassic Yanchang Formation in Ordos Basin, China

Zou, Caineng; Guo, Qiulin; Zhi, Yang; Wu, Songtao; Chen, Ningsheng; Lin, Senhu; Pan, Songqi

doi:10.1306/11211816511

Cited by 18 publications

(9 citation statements)

References 47 publications

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“…For the characteristics of different facies, marine shales in China present large thickness, wide distribution, and high TOC content together with unfavorable factors such as high degree of thermal evolution, strong late-stage tectonic deformations, and multiple hydrocarbon generation and expulsion periods. , Zones with the highest productivity, sweet spots, are constrained by both tectonic movements and sediment deposition. Continental shales have limited distribution, great buried depth, low content of brittle minerals, high clay content, and generally low thermal evolution. − Both shale oil and shale gas can be exploration targets, which is highly suggested to study as a whole. Shales of marine-continent transitional facies have thin single layers with thickness generally between 5 and 15 m .…”

Section: Distribution and Geological Characteristics Of Black Shales ...mentioning

confidence: 99%

Shale Gas Exploration and Development in China: Current Status, Geological Challenges, and Future Directions

et al. 2021

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The big success in marine shale gas exploration and production made China the third country worldwide to commercialize shale gas development. However, the Upper Ordovician Wufeng Formation and the Lower Silurian Longmaxi Formation in and around the Sichuan Basin are currently the only targets that have realized shale gas industrial development. Great challenges are emerging since tremendous shale gas resources of marine facies, continental facies, and transitional facies that are trapped in new areas and multiple other formations are yet to be successfully developed. Thus, we find it a great necessity to provide suggestions on shale gas exploration and development in China, which hopefully can be helpful for global shale gas exploitation. To meet this goal, this work provides a critical review on the history and current status of China’s shale gas exploration and development and summarizes key practical experiences. In the light of characteristic analysis of typical industrial gas fields and wells, research status, problems and challenges, along with suggestions on pivotal scientific issues are addressed including the development of organic-rich shales, reservoir types and characteristics, shale gas content, and the main controlling factors on shale gas enrichment. Further, future directions of shale gas exploration and development are nailed down, incorporating three levels: areas to improve development technology, areas to seek exploration breakthrough, and areas to conduct preliminary studies. The normal-pressure and deep shale gas retained in the Wufeng and Longmaxi Formations in and around the Sichuan Basin are the first level, which are the most realistic resources that can be commercially developed. For the normal-pressure shale gas, detailed research on the sweet spot selection, drilling–encounter ratio enhancement, and cost minimization by advanced technologies are most imperative; for the deep shale gas, state-of-the-art technology to maximize the stimulated reservoir volume of lateral wells is the key. Gas resources in other shale formations in the Sichuan Basin and its periphery such as the Cambrian marine shales, Permian transitional shales, and Jurassic continental shales are the second level, which have the greatest prospective to claim exploration breakthroughs, while shale gas resources in other basins or regions still demand grand scientific and technological tasks for exploration and development preparation. All in all, as a country with diverse shale gas types and such intricate geological and surface conditions, the summary of China’s shale gas exploration and development practices is of vital significance that will not only shed light on China’s shale gas development directions but also provide references for the shale gas industry in other countries and regions.

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Section: Distribution and Geological Characteristics Of Black Shales ...mentioning

confidence: 99%

Shale Gas Exploration and Development in China: Current Status, Geological Challenges, and Future Directions

et al. 2021

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“…With the rise of the unconventional energy revolution, unconventional resources are becoming increasingly significant in the oil industry. 1,2 In particular, shale oil and gas resources within organic mudstone have emerged as key areas for unconventional energy exploration and development. 2−5 Significant successes have been achieved in shale oil and gas exploration in North America, notably in formations such as the Mancos, Barnett, Bakken, and Woodford shales.…”

Section: Introductionmentioning

confidence: 99%

“…With the rise of the unconventional energy revolution, unconventional resources are becoming increasingly significant in the oil industry. , In particular, shale oil and gas resources within organic mudstone have emerged as key areas for unconventional energy exploration and development. − Significant successes have been achieved in shale oil and gas exploration in North America, notably in formations such as the Mancos, Barnett, Bakken, and Woodford shales. − Recently, substantial breakthroughs have been made in lacustrine shale oil exploration and development in China, including the Qingshankou Formation in the Songliao Basin, , the Shahejie Formation in the Bohai Bay Basin, and the Funing Formation in the Subei Basin. , However, lacustrine shales exhibit strong heterogeneity in reservoir characteristics and sedimentary environments, leading to significant variations in the geochemical properties and hydrocarbon generation potential of source rocks. − …”

Section: Introductionmentioning

confidence: 99%

Geological Controls on Reservoir Characteristics Influencing Shale Oil Occurrence in Lacustrine Mixed Fine-Grained Sediments of the Paleogene Funing Formation, Subei Basin

Deng,

Lu,

et al. 2024

Energy Fuels

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Unconventional lacustrine shale formations exhibit significant heterogeneity, with substantial variations in vertical shale oil content vertically. However, most research focuses on the reservoir characteristics of shales, analyzing the impact of organic matter and pore structure on shale storage while overlooking the material foundation of shale hydrocarbon generation capacity. This study adopts petrophysical and geochemical experiments to systematically analyze the total organic content (TOC), free hydrocarbon (S1), thermal maturity (Ro), OM type, mineral content, and overall pore system of the second member of the Funing Formation in Qintong Sag, the Subei Basin. Additionally, statistical methods were employed to analyze the data correlations. The results indicate that the TOC content, thermal maturity, mineral composition, and pore network structure significantly influence the enrichment of lacustrine shale oil. Fluorescence observations reveal that shale oil primarily occurs within the interparticle pores, and its migration is influenced by microfractures. The maturity level is low (within the oil window), with organic matter significantly reducing the pore volume and specific surface area while enhancing the pore throat size. As the TOC content increases, the concentration of free hydrocarbons (S1) also rises. Oil occurrence is influenced by both the mineral composition and pore network structure. Clay minerals positively impact the pore volume and specific surface area but negatively affect the pore throat size. The critical threshold for clay minerals is 28%. Free oil initially increases with the clay mineral content but decreases when the clay mineral content surpasses the critical threshold. Carbonate minerals undergo alteration due to organic acids formed during hydrocarbon generation. The critical threshold for carbonate minerals is 30%. Furthermore, the predominant mineral combination was identified. Free oil increases with increasing carbonate mineral content and then gradually declines. When the ratio of clay minerals to siliceous minerals to carbonate minerals ranged from 1:1:1 to 1:2:1, free oil increased with a higher siliceous mineral content. Additionally, based on qualitative and quantitative pore analysis, a microscopic pore network structure model of reservoirs was developed. It was elucidated that a network structure comprising brittle minerals and mixed pore types facilitates the storage and migration of shale oil.

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“…However, because most of the previous explorations that regarded the Chang 7 member as a source rock, the geochemical characteristics of the Chang 7 member source rock were mainly analyzed through geochemical and other experimental methods. Consequently, it was not regarded as a shale oil exploration layer, resulting in an incomplete shale reservoir evaluation of the formation [23][24][25]. The reservoir is the direct target layer of oil and gas exploration and research, and it is the main object of the oilfield's development.…”

Section: Introductionmentioning

confidence: 99%

Pore Structure Change in the Continental Shale Oil Reservoir and Its Main Influencing Factors: A Case Study of the Chang 7 Member in the Ordos Basin

Chen

et al. 2023

Processes

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Shale oil in the Chang 7 member is the main target for further exploration in the Ordos Basin. However, the lack of research on the characteristics of the Chang 7 member’s mudstone and shale reservoir has seriously affected the next stage of exploration for shale oil in the Chang 7 member. This study analyzed in detail the changes in the pore structure of different types of reservoirs and their influencing factors in detail through experiments such as gas adsorption, nuclear magnetic resonance, and high-pressure mercury intrusion. The results showed that black shale is mainly composed of micropores, with a micropore ratio of up to 79.88%. Dark mudstone and silty mudstone are mainly composed of mesopores, with a mesopore ratio greater than 30%. Argillaceous sandstone is mainly composed of large pores, accounting for 78.57%. From black shale to muddy sandstone, the proportion of micropores decreases, while the proportion of macropores increases. The micropore volume is mainly controlled by the organic matter content and the inorganic mineral content related to the organic matter content. Inorganic minerals such as quartz and feldspar mainly control the degree of development of mesopores and macropores. For rocks with a strong hydrocarbon-generating ability (black shale and dark mudstone), the ratio between the total pore volume and micropore volume is the main factor restricting their oil content. For rocks with a weak hydrocarbon-generating capacity (silty mudstone and argillaceous sandstone), the macropore volume and total pore volume are the main controlling factors for oil content. The results of this study have important guiding significance for the next step of exploration and development for shale oil in the Chang 7 member and, to a certain degree, for the exploration of continental shale oil in other basins.

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Resource potential and core area prediction of lacustrine tight oil: The Triassic Yanchang Formation in Ordos Basin, China

Cited by 18 publications

References 47 publications

Shale Gas Exploration and Development in China: Current Status, Geological Challenges, and Future Directions

Shale Gas Exploration and Development in China: Current Status, Geological Challenges, and Future Directions

Geological Controls on Reservoir Characteristics Influencing Shale Oil Occurrence in Lacustrine Mixed Fine-Grained Sediments of the Paleogene Funing Formation, Subei Basin

Pore Structure Change in the Continental Shale Oil Reservoir and Its Main Influencing Factors: A Case Study of the Chang 7 Member in the Ordos Basin

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