依奇克里克油气田煤成油气的地球化学特征和库车坳陷含油气远景

GEOCHEMICAL CHARACTERISTICS OF COALIFEROUS OIL AND GAS OF YIQIKELIKE OIL AND GAS FIELD AND THE PROSPECT OF THE KUQA DEPRESSION

本文通过对依奇克里克油气田的油气地球化学特征和油气源对比的研究与分析,说明该油气田的油气确系来自上三叠统一中、下侏罗统的煤系,属煤成油气;介绍了该煤系地层形成油气的潜力,指出库车坳陷煤成油气的勘探远景。

Yiqikelike oil and gas field is on a linear folding belt of the Kuqa depression in Tarim basin.Through a geochemical study of the oil and gas of this field, it is found that the oil has following characteristics,low specific gravity and viscosity;high content of saturated hydrocarbon and aromatic hydrocarbons but low content of NSO and asphaltene;dominated with low carbon number normal paraffins and pristane in saturated hydrocarbon gas chromatography,lacking of porphyrin;containing some perylene in the aromatic hydrocarbon;it has rich oxygen-fluorene and some sulfur-fluorene and fluorene proper in three fluorene series in aromatics;and containing retene in aromatic hydrocarbon;rich in 24- ethyl—cholestane but short of C_(27)-cholestane and pregnane and homopregnane in steranes;lacking of tricyclic terpanes and gammacerane in terpane series,and containing dominantly ^(13)C in the isotopic carbon composition.It has distinct characteristics of coaliferous gas with respect to the carbon isotopes of methane, ethane and propane of gas as well as the gas composition.The geochemical fe- ature of the oil and gas described above is dearly of coaliferous origin and is ge- netically related to the evolution of coal,especially the coal-bearing rocks in the Upper Triassic-Mid-Lower Jurassic of this area.Thus,it is concluded that oil and gas in Yiqikelike oil and gas field is coaliferous.The paper is ended with a brief discussion of the potential of oil and gas generated from the coal-bearing formations and the prospect in exploration for coaliferous oil and gas in the depression.