The Impact of Sandstone's Geometry Form on Water Flooding Efficiency in Heterogeneous Reservoirs

Abstract

Due to the sedimentary environment, diagenesis effect, and tectogenesis effect, the geometry form of sandstone shows heterogeneity, which affects the water flooding efficiency, especially in continental sedimentary reservoir. First, according to distribution characters of sandstone, an idealized mode can be obtained. The 2-D and two-phase mathematical mode at certain inlet and outlet pressure was established. By applying discrete and differential numerical methods, the cumulative oil production under two conditions can be calculated. It is higher when the inlet end is wider part of the sandstone. Second, using streamline numerical simulation to build similar injection and production horizontal well model, the authors obtained analog and study sweep efficiency of different displacement directions. Last, by adopting reservoir numerical simulation method, the influence of geometric form of sandstone on water flooding efficiency of well pattern was further studied. The conclusion was drawn that when injector was deployed in narrow part of sandstone and oil well in the wide part, the speed of water flood front was fast, and water breakthrough times were shorter, which led to rapid water cut rises. Under certain bottomhole flowing pressure, formation pressure surrounding injector was a little higher, water injection rate dropped, and cumulative oil production decreased.