Shale oil, a type of crude oil similar to petroleum, lies between layers of organic-rich shale. It is a highly sought after resource as it can be refined into gasoline, diesel and other products. The Qingshankou Formation at Gulong Sag, Songliao Basin, China, is a large geological body of shale deposits that formed at the bottom of an ancient lake. These deposits contain about 15.3 billion tonnes of pure shale oil. Not surprisingly, the Gulong-Qingshankou Formation is an important national reservoir for shale oil. Recent studies have revealed an interesting attribute of this large reservoir, particularly the presence of nanopores in shale layers containing solid bitumen that have not been moved for centuries.

Studying the petrological features of shale can reveal much about reservoir formation, spatial and physical properties, oil content, and development value.As a result, a new study published in earth science frontierdelving deeper into the petrological and microfabric properties of shale from the Gulong Sag to explore formation, reservoir space, and there Collection of shale oil. The study was led by Dr. He Wenyuan of Daqing Oilfield Co Ltd.Shale nanopores are considered to be important spaces for the accumulation of shale oil. Since Gulong Sag shale oil is known to have a 90% source-to-reservoir ratio, investigating the nanopores of this reservoir could reveal valuable information.“

A press release about Dr. He’s research can be read here. Watch a video explaining this study and its results here.

He used electron microscopy, energy spectrum analysis, and thermal simulations to analyze samples of the Gulong shale. He found that the Gulong shale is mainly composed of clay, with well-developed nanopores and nanocracks with diameters/widths of about 10–50 nm. Over the years, organic matter such as decomposed algal debris and kerogen (fossilized organic matter) deposited in these nanopores, forming organoclay aggregates. The organic matter content of this clay he had was as high as 91.5% (>53% on average). This organoclay then became the primary raw material for the production of hydrocarbons, primarily liquid bitumen and shale oil.

Dr. Ho’s analysis revealed that nearly 87% of the original organic matter was consumed during the formation of hydrocarbons. Moreover, the empty nanopores left by organics were occupied by liquid hydrocarbons. Given the closed geometry of the nanopores and high capillary resistance, the hydrocarbons remained inside the rocks with little movement, eventually solidifying into solid bitumen/asphalt. Thus, the Gulong shale deposit is self-generated and self-stored in shale oil, which explains the high source-to-reservoir ratio in the region.

Although preliminary, these results help paint a clearer picture of the Gulong-Qingshankou Reservoir. Regarding the possible implications of these findings, Dr. He said:The findings of this research may facilitate progress in shale oil exploration and development in the region and further in China.But for now, future research should focus on further validating and investigating these exploratory findings.“

Perhaps this is one of those rare occasions when “bottoming out” might be a good thing.

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reference

DOI: https://doi.org/10.13745/j.esf.sf.2022.8.32-en

Author: Wenyuan He

Affiliation:

Daqing Oilfield Co., Ltd. and Heilongjiang Mainland Shale Oil Key Research Institute

about earth science frontier
earth science frontier is a bimonthly, peer-reviewed academic journal co-sponsored by China University of Geosciences (Beijing) and Peking University. First published in 1994, scholar Wang Chengshan is the current editor-in-chief. Each issue of the journal is centered around a specific geoscience topic and is managed by an expert in the field as his guest editor. Each issue also contains numerous articles on self-selected subjects.Published articles earth science frontier It covers all areas of earth science with an emphasis on frontier and groundbreaking basic research. At the same time, the journal also publishes potentially controversial research findings. over the years, earth science frontier It has won several publisher awards, including “International Most Influential Chinese Journal” and “Top 100 Outstanding Chinese Academic Journals”. 2019, earth science frontier Selected among leading journals to participate in the National Action Plan for Achieving Excellence in Scientific and Technical Research Publishing in China.

Email: frontier@cugb.edu.cn
Website: http://www.earthsciencefrontiers.net.cn

About Dr. He Wenyuan
Dr. He Wenyuan is Chief Geologist, Deputy General Manager, and Commander-in-Chief of Shale Oil Exploration and Development at Daqing Oilfield Co Ltd, China’s largest oilfield. He is also a member of the Standing Committee established by PetroChina in the Daqing Oilfield. In addition, he is an adjunct professor at China Petroleum University and is affiliated with the Heilongjiang Continental Shale Oil Key Research Institute in Daqing, China. Dr. He has received several laurels and accolades, including the first prize from the National Science and Technology Progress.