塔中西北部中1井区志留系油砂的地球化学特征

GEOCHEMICAL CHARACTERISTIC OF THE LOWER SILURIAN OIL SANDSTONES IN WELL ZHONG 1 ZONE,NORTH WESTERN TAZHONG AREA

下志留统柯坪塔格组下砂岩是塔里木盆地主要勘探层系之一。对塔中西北部中1井区的志留系油砂抽取物中的族组成、生标化合物、碳同位素等综合研究表明：中1井柯坪塔格组下砂岩中油砂抽提物中的饱和烃含量为51．31％～60．15％，饱芳比为1．68～1．94；中13井柯坪塔格组下砂岩中油砂抽提物中的饱和烃平均为30％，饱芳比平均值为1，正构烷烃分布为nC12-nC39，主峰碳为nC17-nC19，OEP介于0．91～1．08，具有一定的三、四环萜烷含量，甾烷主要显示出C27〉C28〈〈C29，族组成碳同位素组成以呈直线上升为主。中1井区柯坪塔格组油砂的油源主要来自于中下寒武统，有部分上奥陶统烃源岩的贡献。

The lower part of the Lower Silurian sandstones is one of the most important hydrocarbon exploration play in Tarim Basin Based on systematic analysis of the petroleum family composition, various biomarkers and distribution of isotope of petroleum family composition in the saturated fraction from extracts of the Lower Silurian oil sandstones in Well Zhong 1 zone, the results show that the contents of saturated hydrocarbon is from 51.31%～60.15%, the ratio for saturated and aromatics is from 1.68～1.94 in Well Zhong 1, in contrast, the contents of saturated hydrocarbon is 30%, the average ratio for saturated and aromatics is 1, the distribution for n-alkanes is nC12 to nC39 with the major contents of n-alkanes from nC17 to nC19 , OEP is from 0.91 to 1.08 in Well Zhong 13. Moreover, the latter is characteristic of a certain content of tricyclic and tetracyclic terpane, C27〉C28〈〈C29 in consist of steranen and the raising line for isotope of petroleum family composition in the saturated fraction. It therefore can be inferred that the oil for the Lower Silurian oil sandstones is mostly origined from the Middle and Lower Cambrian mixing with a certain of the Upper Ordovician source rocks.