柴达木盆地德令哈地区下古生界成藏地质条件研究

德令哈地区位于柴达木盆地东北部，油气勘探和研究程度较低。文章在野外地质调查基础上，结合钻井和地震资料解释成果，主要开展下古生界烃源岩、储盖层、储盖组合和输导条件等成藏条件研究，根据构造条件和周边油气发现，对研究区下古生界含油气系统进行推测。研究结果表明，德令哈地区下古生界发育两套烃源岩，即震旦系全吉群红藻山组滨岸潮坪相灰黑色-黑色泥页岩，奥陶系石灰沟组浅海半深海相灰黑色黑色泥页岩。其中，震旦系烃源岩46%达到有效烃源岩标准，有效烃源岩有机质丰度平均为0.72%，奥陶系烃源岩38%达到有效烃源岩标准，且分布于石灰沟组底部，有效烃源岩有机质平均为0.77%；两套烃源岩有机质类型以Ⅰ型为主，热演化程度已进入高成熟-过成熟阶段。研究区发育碎屑岩和碳酸盐岩两类储层，三角洲前缘和台缘礁滩相是优势储集相，碳酸盐岩储层的储集空间主要为裂缝和溶蚀孔隙。根据烃源岩特征和周边油气发现，将研究区划分为推测的Z∈(?)油气系统和OO(?)油气系统。

A study of the Lower Paleozoic accumulation condition in Delingha region in Qaidam Basin

Delingha region is located in the northeastern of Qaidam Basin, where oil and gas exploration and research level is low. Based on field geological investigation drilling and seismic interpretation, this paper analyzes Lower Paleozoic petroleum accumulation conditions, including source rock, reservoir caprock conditions, source reservoir caprock combination and transporting condition. According to the structural conditions and surrounding discoveries, we have defined the Lower Paleozoic petroleum systems in the research area. In Delingha region, there are two sets of source rocks, including Sinian Quanji Group mudstone formed in coastal tidal flat facies and Ordovician Shihuigou Formation shale formed in shallow bathyal facies. 46% of Sinian source rocks achieved effective source rocks standards, with the average TOC of 0.72%, and 38% of Ordovician source rocks achieved effective source rocks standards, with the average TOC of 0.77%. Organic matter types mainly belong to typeⅠ. Thermal evolution has entered into the high and over mature stages. There are clastic and carbonate reservoirs in the study area, whose dominant reservoir facies are delta front and platform margin reef, while carbonate reservoir space are mainly made up of fractures and solution pores. Based on the analysis of source rock characteristic and surrounding discoveries, Delingha region is divided into Z∈(?) and OO(?) suppositional petroleum systems.