西藏东北部比如盆地中生界油气苗的发现与意义

比如盆地位于西藏的东北部。野外石油地质考察期间,在比如盆地发现了大量的地表油气苗。油气苗均为干沥青,出露层位集中在中-上侏罗统拉贡塘组与下白垩统多尼组中,其他层位未发现油气苗。镜下观察结果显示,拉贡塘组与多尼组碎屑岩骨架颗粒之间发育有油气包体与不发光沥青。从地表出露形态与特点看,干沥青主要分布于断裂带、裂缝等构造强变形的部位。与青藏高原腹地同类残留盆地对比,比如盆地新生代构造变形更强烈,盆地抬升并遭受剥蚀的幅度更大。由此,提出高原找油可能面临的诸多难题,应该重点关注新生代构造与构造地貌演化对油气藏的影响。

Discovery and significance of Mesozoic oil and gas seepages in Biru basin, northeastern Tibet, China.

During field geological survey, many oil and gas seepages had been found in Biru basin, which is located in the central-east part of Tibet Plateau. All oil and gas seepages outcropped can be classified as solid asphalt, and target horizons are in Middle-Upper Jurassic Series Lagongtang Formation and Lower Cretaceous Series Duoni Formation. Under microscope, oil & gas inclusions and nonluminous asphalt appear among framework grains of clastic rock in those two formations. By analysis of the shapes and the characteristics from outcrops, solid asphalt distributes near intensive deformation area, such as fault zone and fracture zone. Cenozoic structure in Biru basin had been undergone more intensive deformation and bigger uplift or much more denudation than the rest basins of the same kinds properties in the central of Tibet Plateau. Therefore, many problems would be faced during plateau oil-prospecting in the future, and impact of structural evolution and tectonic landform action on hydrocarbon-bearing pool should be stressed.