鄂尔多斯盆地大牛地气田上古生界储层特征

Upper Paleozoic Reservoir Characteristics of Daniudi Gas Field In Ordos Basin

大牛地气田位于鄂尔多斯盆地伊陕斜坡北部,主要含气层位为上古生界石炭系太原组、二叠系山本组和下石盒子组。气田具有石炭系太原组障壁沙坝、二叠系山西组三角洲平原分流河道砂和下石盒子组河流相河道砂3套储集体,储集体为低孔、低渗、致密性储层;下石盒子组、山西组和太原组储层孔隙特征基本相同;下石盒子组和太原组储层孔隙结构相对较好,山西组储层孔隙结构相对较差;上古生界储层共划分为4类,下石盒子组和太原组Ⅰ、Ⅱ类储层较为发育,而山西组Ⅲ类储层较发育。

Daniudi Gas Field lies in the north of Yishan Slope in Ordos Basin. Its mainly gassy formations are Carboniferous Taiyuan Formation, Permian Shanxi Formation and Lower Shihezi Formation. It has three reservoir sands: the barrier bar of Carboniferous Taiyuan Formation, delta-plain distributary channel sand of Permian Shanxi Formation and fluvial facies channel sand of Lower Shihezi Formation. The reservoir sands are low porous, low permeable and tight. The characteristics of Lower Shihezi Formation, Shanxi Formation and Taiyuan Formation are same basically. The porous structures of the Lower Shihezi Formation and Taiyuan Formation are better than Shanxi Formation’s. There are four types in the Upper Paleozoic reservoir. Reservoir typeⅠand Ⅱ show a more development in Lower Shihezi Formation and Taiyuan Formation, and reservoir type Ⅲ presents a more development in Shanxi Formation. The reservoirs of Lower Shihezi Formation and Taiyuan Formation are better than Shanxi Formation’s.