苏里格大气田成藏地质特征

苏里格大气田位于我国鄂尔多斯盆地中部,是我国陆上目前已发现的最大的天然气气田。自2000年开展系统评价勘探以来,目前已在上古生界二叠系碎屑岩地层中获得天然气三级储量8606.67×10⁸m³。该区具有良好的天然气成藏地质条件,广泛沉积的海陆交互相煤系地层形成了广覆式的烃源岩,有机质在热演化作用下已达到成熟至高成熟阶段,在盆地内形成了丰富的气源。二叠系由北向南展布的河流三角洲砂体在平缓的西倾单斜背景下,与侧向的河流间湾泥质岩遮挡及北部上倾方向的致密岩性遮挡一起,构成了大面积的岩性圈闭。陆相砂岩储层中的高石英含量和火山组构的溶蚀是形成高孔渗储层的主要因素。生、储、盖、圈闭以及保存条件的有机配置,为气藏的形成与保存提供了保障。

Geological features of reservoir formation of Sulige gas field

Sulige gas field in Ordos Basin is the largest natural gas field in China.At present,the gas reserves in Carboniferous_Permian have been proven since the beginning of systematic evaluation and exploration in 2000.Sulige gas field is located in the central part of the basin,where there is the favorable geological conditions for forming natural gas.The source rock widely distributed in Ordos Basin was deposited widely in the paralic environment during the Paleozoic.With the deepening and thermal evolution,organic matters were matured or highly matured,which provides the abundant gas sources.The superimposed fluvial_delta sandstones distributed approximately from north to south have constituted the complex sandstone reservoir body in a large area.Under the background of the gentle west_dip monocline,the fluvial_bay pelitic rocks to the east acted as the barriers laterally,and the various deposition face belt to north part as lithologic tight barrier,and the lacustrine pelitic rocks of the Upper Permian as a good regional seal.As a result,a large_area lithologic trap was formed in Sulige area.High content of quarts in continental facies as well as the dissolution and erosion of volcanic matters were favorable for forming the high_porosity and high_permeability reservoirs.The perfect timing of sources,reservoirs,seals,traps and the conditions of preservation provided a fundamental guarantee for forming and preserving the Sulige gas field.