鄂尔多斯盆地西南部上古生界油气成藏条件分析

THE ANALYSIS OF HYDROCARBON ACCUMULATION CONDITION OF UPPER PALAEOZOIC OF THE SOUTHWEST ORDOS BASIN

陈全红 李文厚 姜培海 胡孝林 强芳青 崔军平 高永祥

Chen Quanhong Li Wenhou Jiang Peihai Hu Xiaolin Qiang Fangqing Cui Junping Gao Yongxiang

中海石油有限公司 北京研究中心, 北京 100027 2. 西北大学地质学系, 西安 710069

CNOOC Research Center, Beijing 100027, China 2. Department of Geology, Northwest University, Xi'an, Shaanxi 710069, China

鄂尔多斯盆地西南部上古生界烃源岩主要为太原组、山西组的煤层及暗色泥岩,有机碳含量为0.2%~7.95%,干酪根类型为Ⅱ和Ⅲ型,Ro平均为2.34%,烃源岩普遍进入高成熟—过成熟阶段;储集层主要为三角洲平原分流河道砂体、水下分流河道砂体,属Ⅱ—Ⅲ类储集层;区域性盖层主要为二叠系下部的水进和高位体系域的滨浅湖相泥岩,连续性好,封闭性好;天然气主要通过微裂缝及扩散排烃的方式向庆阳一带一直持续运聚,赋存于二叠纪形成的地层—岩性圈闭中。油气成藏主要受储层及区域构造控制。惠安堡—沙井子断裂向东的天环向斜东翼区,局部背、向斜构造相对发育,保存条件相对变好,成为天然气主要富集区。主要的有利勘探目标分布在泾川—宁县缓坡区及环县—镇原向斜区的有利储集体的构造高点上。

The source rocks in the Southwest Ordos Basin are mainly the coalbed and melanomudstone of Taiyuan Fm and Shanxi Fm,and the content of organic carbon is 0.2%～7.95%,its kerogen is Ⅱ-Ⅲ type and the mean value of Ro is 2.34%,and the rocks are generally of hige-or-super maturation.The reservoir are mostly the distributary channel sand of delta plain and subaquatic distributary channel sand,belonging to the Ⅱ-Ⅲ type.The caprocks are primarily the mud of littoral and shallow lake facies with good continuity and is well Closed.The gas continuously migrates to Qingyang area by means of diffusion through crevice and collects in litho-stratigraphic traps formed in Permian.The Hydrocarbon migration is generally controled by reservoir bed and regional tectonic.To the east of Huianbao-Shajingzi Fault is the Tianhuan SynCline in whose east slope there is comparatively developed regional tectonic of synCline and antiCline,and with the fairly good reservoir condition,it has the primary enrichment of gas.The main preffered exploration areas are the Jingchuan-Ningxian's mild slope and the top point of the tectonic of the good reservoir in the Huanxian-Zhenyuan synCline.

国家重点基础研究发展计划(973计划)项目(2003CB214602);陕西省自然科学基金项目(2003D14)

https://doi.org/10.11781/sysydz200706554