CHARACTERISTICS AND ACCUMULATION OF MIDDLE JURASSIC OIL SHALE IN THE YUQIA AREA, NORTHERN QAIDAM BASIN, NORTHWEST CHINA

QINGTAO MENG ； ZHAOJUN LIU ； PINGCHANG SUN ； YINBO XU ； FENG LI ； YUEYUE BAI ； WENQUAN XIE ； SHUO DENG ； SHUO SONG ； KEBING WANG ； CHUAN XU

《Oil Shale》 35卷1期 (2018/03) Pp. 1-25

https://doi.org/10.3176/oil.2018.1.01

摘要

Two oil shale sequences in the Middle Jurassic Shimengou Formation in the Yuqia area, northern Qaidam Basin in Northwest China were evaluated based on geochemical and proximate analyses. The characteristics and accumulation conditions of oil shale in the Lower Coal-bearing Member (J_2sh^1) and Upper Shale Member (J_2sh^2) are different. The oil shale in J_2sh^1 with a high, terrigenous organic matter (OM)-derived total organic carbon (TOC) content is of medium-high oil yield, low ash and moisture contents, and low-medium calorific value and sulfur content. The oil shale in J_2sh^2 having a medium, alginite and bituminite-originated TOC content is characterized by a low-medium oil yield, high ash content, and low calorific value and moisture and sulfur contents. The oil shale in J_2sh^1 was deposited in a limnic environment under a varied climate from hot-humid to warm-humid, whereas that in J_2sh^2 was deposited in a semi-deep and deep lake environment under a stable warm-humid climate. Climatic conditions may have controlled the quality, distribution and thickness of oil shale by influencing the origin of organic matter and sedimentary environment. High paleoproductivity in J_2sh^2 (or high terrigenous detrital matter input in J_2sh^1) and strong water salinity stratification are responsible for the accumulation of high-quality oil shale.

關鍵字

oil shale geochemical characteristics ； industrial quality ； accumulation conditions ； Middle Jurassic ； Qaidam Basin