Influence of Sandstone Architecture on Waterflooding Characteristics in Common Heavy Oil Reservoir

Taking common heavy oil reservoir as an example, we characterized spatial structure characteristics of delta front and analyzed waterflooding characteristics of underwater distributary channel sand, mouth bar sand, and beach bar sand, finally cleared the fact that sandstone architecture has influence on waterflooding characteristics in common heavy oil reservoir. The research results show that spatial structure characteristics of delta front are complicated: vertically, single sand bodies have independent, superposed, and cutting-stacked contacts with each other. Sandstone architecture has great influence on waterflooding development: Underwater distributary channel sand has positive rhythm characteristics, and mouth bar sand has weak inverted rhythm characteristics with low permeability contrast value as well as beach bar sand has homogeneous rhythm characteristics. Therefore, at the process of waterflooding development, because of the influence of gravity and high viscosity of heavy oil, the bottom part of underwater distributary channel and the bottom part of most mouth bar sands are priorly waterflooded, while beach bar sand is waterflooded uniformly; long-term waterflooding and high viscosity characteristics of heavy oil will lead to formation of dominant water flowing channel in sand inside and cause remaining oil accumulate at the top of sands, which are the main target for late tapping.