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鄂尔多斯盆地深层寒武系海相沉积是重要的勘探领域。从基础地质研究入手,通过系统研究盆地周边露头剖面及盆地内钻遇寒武系的探井资料、重点分析寒武系岩性岩相特征及分布特点、采集寒武系暗色岩石样品并进行TOC、氯仿沥青“A”等分析测试。结果表明,鄂尔多斯盆地深层寒武系分布稳定,厚度约为50~800m,主要由缓坡—台地相碳酸盐岩及混积缓坡—深水相泥岩、碳酸盐岩组成;盆地南中部寒武系馒头组黑色泥岩及三山子组深灰色、灰黑色纹层状白云岩形成于还原环境,有机质含量相对较高(TOC最高值为0.34%),具有一定的生烃潜力。寒武系及其暗色岩类在贺兰奥拉谷和歧山—延安奥拉谷厚度明显增大,TOC值也明显增高,在环县、定边地区也有TOC高值区出现,表明了奥拉谷是鄂尔多斯盆地寒武系主要烃源岩发育区,预测可与中央古陆隆起带及其斜坡区形成有效的生烃—聚集成藏组合,鄂尔多斯盆地寒武系是值得进一步研究和勘探的重要层系。
The deep Cambrian marine sediments in the Ordos Basin are important exploration areas. Based on the study of basic geology, focusing on the lithofacies and lithofacies characteristics and distribution characteristics of Cambrian by systematically studying the outcrop profile around the basin and the exploration drilling data of the Cambrian within the basin, Cambrian black rock samples were collected and subjected to TOC, Chloroform bitumen “A ” analysis test. The results show that the deep Cambrian in the Ordos Basin has a stable distribution with a thickness of about 50 ~ 800m and is mainly composed of gentle slope - platform facies carbonate rock and mixed sedimentary slope - deepwater mudstone and carbonate rock. The Cambrian Steatite black mudstone and the Sanshanzi formation of dark gray and gray-black layered lava dolomite formed in a reducing environment with a relatively high organic matter content (the highest value of TOC is 0.34%) and a certain potential for hydrocarbon generation. The thickness of Cambrian and its dark-colored rocks in Helanlao Valley and Qishan-Yan’an Ola Valley increased obviously, and the TOC value also increased obviously. In the Central and Dingbian areas, the areas with high TOC value also appeared, Ladaogu is the main source rock development area of the Cambrian in the Ordos Basin. It is predicted that it will form an effective hydrocarbon generation-accumulation assemblage with the central Gulu Uplift and its slope. The Cambrian of the Ordos Basin is worth further exploration and exploration Important layers.