Characterization of sedimentary and flow characteristics of shallow water delta front sand bodies: Xingshugang Oil Field, Daqing placanticline, Songliao Basin

The low degree of integration between relative permeability research and the sedimentary characteristics of sand bodies was studied. The sedimentary and flow characteristics of distributary channel microfacies and sheet sand microfacies in shallow water delta front subfacies in the Daqing placanticline of the Songliao Basin were characterized by using core and logging data of continuously cored wells, relative permeability test data, grain size analysis, scanning electron microscopy and mercury injection data under reservoir conditions. The vertical variation of distributary channels and the difference of the positions of the outer edge, middle and inner edge of sheet sand were analyzed. The factors controlling the development degree of distributary channel sand body and sheet sand are the difference of vertical oil-water fluidity and the heterogeneity of horizontal flow capacity, respectively. In the distributary channel microfacies of shallow water delta, the relative permeability varies little; however, the vertical oil-water fluidity makes the bottom more prone to flooding, which is the main factor causing the formation of residual oil between wells. The planar difference of sheet sand sedimentary characteristics makes it easier for the injected water to advance along the outer edge, which is the main factor causing the low recovery of the reserves in the inner edge and the middle.