鄂尔多斯盆地天然气成藏特征

CHARACTERISTICS OF NATURAL GAS RESERVOIR FORMATION IN E’ERDUOSI BASIN

鄂尔多斯盆地天然气资源丰富,含气层系多,具有上、下古生界复合含气的特征,已发现4 个储量达到1×1011 m3 以上的大型气田。通过对生烃、沉积、储层、圈闭保存条件等的综合研究,认为上古生界具有煤系地层“广覆式”生气特色,三角洲分流河道中粗粒石英砂岩是上古生界高效储层的主要岩石类型,圈闭以大型岩性圈闭为主,天然气成藏条件优越,勘探领域广阔,仍具有发现大型气田的地质条件;下古生界具有混源气特征,白云岩风化壳岩溶储层是主要储集岩类型,圈闭以古地貌—岩性复合圈闭为主,勘探潜力较大。

E'erduosi Basin is rich in natural gas resources and it possesses the characteristics as multiple gas-bearing layer series, Upper-Lower Palaeozoic complex gas-bearing strata and so on. Four giant gas fields with reserves of more than 100 × 109 m3 have been found out in the basin. Through a comprehensive research on hydrocarbon generation, sedimentation, reservoir, trap and preservation conditions, it was considered that, in Upper Palaeozoic, the conditions of forming gas reservoirs are excellent, the area for gas exploration is wide and the geological conditions of finding out giant gas fields are still in existence, because a 'widely-covered' gas-generation character is evident, the reservoir rocks are mainly composed of the medium-coarse quartzose sandstones of delta distributary channel and the large-sized lithologic traps are in the majority; and, in Lower Palaeozoic, the potential for gas exploration is relatively great, because the natural gas is of the features of source-mixed gas, the reservoirs are mainly composed of karst reservoirs of dolomite weathering crust and the paleogeomorphologic-lithologic traps are in the majority.