龙门山中段上三叠统须家河组三、四段砂体研究

Study of third and fourth sandstones of upper Triassic Xujiahe Formation in middle Segment of Longmen Mountain area

利用野外岩石露头、钻井岩心、镜下薄片和测井曲线等地质资料,研究龙门山中段逆冲推覆体带上三叠统须家河组三、四段砂体类型及特征,分析了砂体沉积古环境以及砂体发育过程,还原了古地理条件在砂体的沉积过程中的控制作用。结果表明,须家河三、四段主要发育辫状河三角洲以及扇三角洲2类沉积砂岩,且煤矿富集层位,高品位烃源岩也较为发育。因此,对这一区域须家河组砂体的研究,不仅是对龙门山前陆盆地古沉积环境的恢复,也是对该区域煤藏和油气资源的远景探索,具有重大的现实意义。

Based on the outcrop, drilling core, microscopic thin section analysis, and logging geology data, the Longmen Mountain overthrust nappe type and characteristics of Xujiahe Formation at third and fourth sandstones of the upper Triassic were analyzed,and the sedimentary environment and sandstone formation process were researched. The result shows that the sedimentary sandstone in the study area is mainly composed of braided river delta sandstone and the fan delta sandstone, disclosing the control effect of paleogeographic conditions in the process of deposition and sandstone. In addition, in the study area developed coal enrichment horizon and high grade hydrocarbon source rocks. Therefore, the study of Xujiahe sandstone body in this area not only shows the ancient sedimentary environment of Longmen Mountain foreland basin but also prospects the region coal reserves and oil and gas resources exploration, which has a great practical significance.