Organic Geochemical Characteristics of the Bilong Co Oil Shale (China): Implications for Paleoenvironment and Petroleum Prospects

Abstract

The Bilong Co oil shale is located in the southern part of the Qiangtang basin. This oil shale zone, together with the Shengli River-Changshe Mountain oil shale zone in the northern part of the Qiangtang basin, represents a large marine oil shale resource in China. An organic geochemical investigation of the oil shale was performed to reconstruct paleoenvironment during deposition and to assess petroleum prospects. The TOC content (6.75-19.2 wt.%) and S 2 values (5.96-70.2 mg HC/g rock) of oil shale samples from the Bilong Co area are relatively high indicating that the oil shale from the Bilong Co area has shale oil producing potential. The thermal maturity assessed from T max and other maturity-related parameters (Ts/(Ts+Tm), C 32 Hop S/(S+R), C 29 St S/(S+R), and C 29 St ββ/(αα+ββ)) shows a mature stage of the organic matter. Analyzed oil shale samples from the Bilong Co area are characterized by a dominance of low carbon number molecular compositions with relatively high C 21-/C 21+ (0.82-1.95), low Pr/Ph (0.13-0.80), high concentrations of homohopanes (C 31-C 35), and a slight predominance of C 29 steranes, indicating reducing environments, highly saline conditions, a strong contribution of inferior aquatic organisms, and some influence of terrestrial organic matter. Highly similar biomarker characteristics between the Bilong Co oil shale and nearby Zharen-Longeni crude oil in the southern Qiangtang depression suggest that the oil shale from the Bilong Co area has made a strong contribution to the generation of Zharen-Longeni crude oil.

Characteristics of Source Rocks and Genetic Origins of Natural Gas in Deep Formations, Gudian Depression, Songliao Basin, NE China

“…Steranes are derived from sterols in higher plants and algae. ,, C 28 steranes have been commonly found in green algae and higher plants, whereas C 27 steranes are typical for zooplankton and red algae in marine/lacustrine settings, and C 29 steranes occur in higher plants and some strains of brown or green algae. , According to ternary plots of C 27 , C 28 , and C 29 steranes (Figure a) and their distribution patterns on m / z 217 mass chromatograms (Figure ), the OMs of the Huoshiling–Yingcheng shales mainly originate from plankton, bacteria, and algae, consistent with the dominant input of phytoplankton and algae illustrated in the cross-plots of C 27 /C 29 and Pr/Ph (Figure b). The ratios of C 27 /C 29 are 0.89–1.99 (Avg.…”

A Micro-Ct Study of Changes in the Internal Structure of Daqing and Yan’an Oil Shales at High Temperatures

“…China has abundant oil shale resources. According to the latest assessment of national oil shale resources conducted by Jilin University, China, these total 720 billion tons of oil shale, or 48 billion tons of shale oil, ranking second in the world [3][4][5][6][7][8]. The exploitation and utilization of oil shale have been the focus of numerous scientific studies, and can bring considerable economic benefits.…”