鄂尔多斯盆地大牛地气田山1段储层与沉积微相的关系

鄂尔多斯盆地大牛地气田二叠系山1段主要发育河床滞留、分流河道、河道砂坝、心滩、天然堤、决口扇、河间洼地和河漫沼泽8种沉积微相,储层主要发育在分流河道和心滩沉积微相。储层综合特征和沉积微相研究表明,影响气层产能的最敏感的参数是储层中值半径。储层喉道中值半径的大小、分布和连通性以及碎屑颗粒粒度和石英含量等地质特征决定于沉积微相展布特征。通过对区内山1段储层沉积微相和中值半径等参数的对比分析发现,天然气主要赋存于分流河道沉积微相,平面上分流河道沉积微相分布在研究区西南部河流交汇处。

Relationship of sedimentary microfacies with reservoirs in the Shan-1 member of the Daniudi gas field,Ordos Basin

Eight sedimentary micro-facies,including channel floor lag,distributary channel,channel sand,channel bar,natural barrier,crevasse splay,interchannel low-lying land,and flood swamp,occur in the Shan-1 member (the first member of Shanxi Formation) of the Daniudi gas field in Ordos Basin.Reservoirs are mainly developed in the distributary channels and channel bars.Research on reservoir features and sedimentary micro-facies shows that the median throat radius of the reservoir has the strongest influence upon gas production capacity.The size of median radius,distribution and connectivity of throats as well as the debris particle size and content of quartz,and other geological features of the reservoir,depend on the microfacies distribution.Correlation of sedimentary microfacies with various parameters such as median throat radius of the reservoirs in Shan-1 member indicate that natural gas is mainly accumulated in distributary channels,which are distributed in areas where the rivers meet in the southwest part of the study area.