--> Abstract: Organic Petrological Characteristics and Hydrocarbon Generation of Jurassic Source Rocks in the Northwest of China, by F. Wang, P. He, C. Zhao, and S. Zhang; #90939 (1997)

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Abstract: Organic Petrological Characteristics and Hydrocarbon Generation of Jurassic Source Rocks in the Northwest of China


The Lower and Middle Jurassic coal-bearing strata occurring as oil source rocks widely throughout the northwest of China. About 1800 Jurassic coals, carbonaceous mudstone and mudstones from Tarim, Junggar, Turpan-Hami, Santanghu, Yaji, Yili six basins have been petrologically analyzed in the past five years to assess their petroleum source character. The organic petrological procedures used include incident microscopy, fluorescence microscopy, confocal scanning laser microscopy (CLSM) and transmission electron microscopy (TEM), Analytical scales range from maceral group, maceral, submaceral to submicromaceral. The maturity of Jurassic source rocks are mainly ranging from 0.50% to 0.80%VRo, and exceed 1.0%Ro in the sag areas of foreland basins such as Baichen and Yanxia sag in Kuqa depression, Kashi and Yechen sag of southwest depression in Tarim basin, Changji depression in Junggar basin. Maceral compositions of Jurassic source rocks appear similarity in the whole northwest of China. Oil-prone constituents are characteristics of small , fine and filmy in shape. Microscopically, oil-prone constituents are perhydrous desmocolliniteexinite (mainly tenuicutinite tenuisporinite and suberinite) and minor sapropelinite (mainly alginite and bituminite), relatively lack of resinite crassicutinite crassisporinite. Submicroscopically, oil-prone constituents are submicroliptinites which disseminated in desmocollinitemineral-bituminous matrixsemifusinite and macrinite. Abundant liptodetrinite are existed between microscopical and submicroscopical levels. According to the amount composition and evolution of oil-prone constitutes, Jurassic coal-bearing strata can be a source for liquid hydrocarbons, and its oil windows are located in the range of vitrinite reflectance from 0.50% to 1.30%VRo, especially significant oils are generated in the stage of 0.50% to 0.90%VRo. The petroleum potential of lower Jurassic Badaowan Formation are higher than that of middle Jurassic Xishanyao Formation.

AAPG Search and Discovery Article #90939©1997 AAPG Eastern Section and TSOP, Lexington, Kentucky