Abstract:

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.

Key words: distributary channel, sedimentary microfacies, tight sand, Daniudi gas field, Ordos Basin