Waterflooding of Channel Sandstone Reservoirs

Channel sandstones are described which occupy a particularly important place among the main oilfields in China. Within a depositional system the channel sandstones are always deposited in a intermediate position and they have moderate grain size and sorting to become main reservoirs with highest permeability. The inner sequence of grain size of channel sandbodies is characterized by normal rhythm, which leads to in-layer heterogeneity, less conformance factor in thickness and rapid rising of water cut. Channel sandbodies exhibit significant directional permeability. Injected water rapidly tongues along the ancient channels and preferentially flows toward the downstream direction. Various channel sandstones are different in in-layer heterogeneity, and therefore in production performance. 11 refs.