ABSTRACT
Channel sandstones occupy a particularly important place among the sandstone reservoirs deposited in lake basin. According to statistics of fourteen main oilfields in China, the oil reserves in channel sandstones are more than half of total ones. Within a depositional system the channel sand stones 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 serious in-layer heterogeneity, less conformance factor in thickness and rapid rising of water cut. Channel sandbodies exhibit significant directional permeability. Injected water rapidly tongue along the ancient channels and preferentially flow toward the down stream direction. Various channel sandstones are different in-layer heterogeneity, and so in production performance.
