Using seismic sedimentology in delineating a distributary channel type shallow-water lacustrine delta: first member of the Cretaceous Yaojia Formation in Changling area, South of Songliao Basin

Shallow-water delta sandstones in lacustrine basin are widely a concern due to their petroleum exploration potential. However, characteristics such as small thickness, multi-genesis, and multi-stage limit their successful exploration. Here, we present a comprehensive seismic sedimentological research on shallow-water delta in the first member of the Cretaceous Yaojia Formation of Changling area in southern Songliao Basin. The target strata can be divided into 1 third-order sequence and three system tracts. Interpretations of typical stratal slices which were extracted from each system tract indicate that the distributary channel type shallow-water delta is mainly developed in Changling area, two subfacies such as shallow-water delta plain and shallow-water delta front; five main sand bodies such as distributary channel, abandon distributary channel, subaqueous distributary channel, mouth bar, and distal bar are further identified. The type and shape of the sand body are closely related to the degree of sheet modification. Meandering distributary channel, multilevel branching dendritic channel, and lobate subaqueous distributary channel develop at the delta plain, the proximal and distal of the delta front respectively. The study shows that sedimentary characteristics and sedimentary model study based on seismic sedimentology theory provide a powerful theoretical support for lateral reservoir prediction of thin distributary channel type shallow-water lacustrine delta sandstones.