245 / 2019-06-29 23:07:09

Characteristics and significance of blomarker compounds of Xiamaling Formation hydrocarbon source rocks along Xiaozhuanghu section in Lingyuan-ningcheng basin

Lingyuan-ningcheng basin; Xiamaling Formation; hydrocarbon source rocks; biological marker compound

Abstract: Based on gas chromatography and gas chromatography mass spectrometry techniques, the authors studied the characteristies of biomarker compounds of Xiamaling Fomation hydrocarbon source rocks along Xiaozhuanghu section in Lingyuan-ningcheng basin,and analyzed the information and geological and geochemical significance indicated by sources of organic matter, sedimentary environment,the degree of the thermil evolution of organic matter and some other factors. Gas chromatogaphy peaks of saturated hydrocarbons from Xiamaling Fomation source rocks show "the frontal peak type" of the single peak distribution and the C18-dominant main peak of carbon. This indicates that the main sources of organic matter were mixed organic matter; Pr/Ph ratios range from 0.28 to 0.62, suggesting a strongly reducing sedimentary enviroment. Molecular fossil assemblages of Xiamaling Fomation source rocks have abundant tricyclic terpane with long side chains and high level of gammacerane,and show dominant distibution of C27 steranes. Gammacerane ratios range from 0.10 to 0.31, with an average of 0.24, implying that Xiamaling Fomation hydrocarbon source rocks were formed in an environment of half-salewater water; the hopane/sterines ratios are mainly berween 0.75 and 0.89, with an average of 0.85, implying that bacteria and algae had almost the same contribution to organic matter, and the maturity of hydrocarbon source rocks was high. The abundance of C27 steranes is high, and the ratio of C27 steranes/C28 steranes is 1.13, showing that alga was the main source of hydrocarbon percursors.