A New Understanding of Channel Patterns and Facies Models of the Shallow Lake Delta Facies of Fuyu Oil Reservoir in Songliao Basin,China

In the Fuyu Reservoir of Songliao Basin,there occur a series of well-developed peculiar shallow lake delta facies,which can be divided to such three ones as the upper delta plain subfacies,the lower delta plain subfacies,and the delta front subfacies.Among them the upper delta plain subfacies mainly grows proximal distributary channels;the lower delta plain subfacies mainly grows distal ones. The entire Fuyu Reservoir has mainly developed 7 kinds of distributary channel patterns:proximal/ distal meandering type distributary channels,proximal/distal low-sinuosity type distributary channels, proximal/distal straight type distributary channels,and subaqueous distributary channels.Among these patterns,the proximal and distal meandering type distributary channels have bigger thickness of point bar and better sorting and low content of mud;moreover,they are the major reservoirs and occur in the bottom of Quan-4th member.The sandbars of the subaqueous distributary channels have higher mud content,and serve as the poorer reservoirs,and mainly occur in the top of Quan-4th member.