鄂尔多斯大型含煤盆地岩性气藏成藏规律与勘探技术

鄂尔多斯盆地为—大型含煤盆地,天然气资源丰富。已发现了榆林、苏里格、乌审旗和米脂4大 气田,资源探明率lO．6％,勘探潜力较大。上古生界广泛发育的煤系地层为主要的烃源岩层,在晚侏罗 世至早白垩世末期盆地含煤烃源岩大面积成熟,表现为“广覆型”生烃模式。在大面积的低渗背景下, 天然气以近距离运移为主,生气强度控制气田的形成和分布;相对高孔高渗的三角洲平原分流河道砂体 为主要的储集体,是天然气富集的主要场所;由多个岩性圈闭组成的大型岩性圈闭是天然气成藏的主要圈闭类 型。针对上古生界的天然气地质特征,在勘探中,形成了一套适合长庆低渗透岩性气藏的勘探技术方法。

Law of Reservoir Formulation and Exploration Techniques of Natural Gas Lithologic Reservoir in Ordos Basin

Ordos basin is rich in natural gas resources,which is a large coal-bearing basin. Four giant gas fields, such as Yulin, Sulige. Wushenqi. Mizhi Fields are found out in the basin. Only 10. 6% of the natural gas resources are found out, potential for gas exploration is relatively high. In upper Palaeozoic system, the strata including coal bed main contain hydrocarbon source rocks. From late Jurassic to early Cretaceous, the hydrocarbon source rocks are mature at large scale, and showing the character of "widely-covered" gas-generation. The relatively high-porosity and high-permeability sandstone of delta distributary channel are mainly reservoir rock, on the background of low-porosity and low-permeability. The large-sized lithologic traps made up of many lithologic traps are in the majority. The gas migration is mainly close quarters, so the forming and distributing of gas field are controlled by the intensity of hydrocarbon generation. To the exploration of upper Palaeozoic strata, a series of techniques suit of Changqing Oilfield are established. With the advancement of exploration theory and techniques, a set of method suitable for low permeability lithologic gas reservoirs are established in Changqing Oilfield.