Pore Connectivity Characteristics and Controlling Factors for Black Shales in the Wufeng-Longmaxi Formation, Southeastern Sichuan Basin, China

Fei Zhao, Zaitian Dong, Chaoyong Wang, Wenli Zhang and Rui Yu
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Fei Zhao: Xuzhou Datun Engineering Consulting Co., Ltd., Xuzhou 221618, China
Zaitian Dong: School of Resources and Earth Sciences, China University of Mining and Technology, Xuzhou 221008, China
Chaoyong Wang: School of Resources and Earth Sciences, China University of Mining and Technology, Xuzhou 221008, China
Wenli Zhang: School of Management, Xi’an University of Science and Technology, Xi’an 710054, China
Rui Yu: School of Mines, China University of Mining and Technology, Xuzhou 221008, China

Energies, 2022, vol. 15, issue 8, 1-16

Abstract: Investigations into the connectivity and complexity of pore systems in shales are essential for understanding the flow of shale gas and the capacities of the associated reservoirs. In the present study, eight shale samples from the Wufeng-Longmaxi (WF-LMX) Formation that were collected from Well Yucan-6 in the southeast of the Sichuan Basin were analyzed for microstructural, pore network, and pore connectivity characteristics. The measurement results of low-pressure nitrogen adsorption illustrated that all shale samples contain micropores, mesopores, and macropores. Micropores and mesopores account for a high proportion of the total pores, and the dominant pore throat size is in the range of 2–6 nm. High-pressure mercury injection tests reveal that the porosity, total pore volume, and total specific surface area of pores for samples from the WF Formation are higher than those for samples from the LMX Formation. In spontaneous absorption experiments, the slopes of the absorption curves of n -decane (oil-wetting) and deionized water (water-wetting) in the WF and LMX Formations varied from 0.254 to 0.428 and from 0.258 to 0.317, respectively. These results indicate that shales in both formations exhibit mixed wettability characteristics, but lipophilic pores are better connected relative to hydrophilic pores. The total organic carbon and silica contents are the main factors controlling the pore connectivity in these shales, while the effects of other minerals are not significant. The findings of this work can improve our understanding of the pore structure characteristics of black shale.

Keywords: pore size distribution; pore connectivity; marine shale; Wufeng–Longmaxi Formation; Sichuan Basin (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2022
References: View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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