Abstract: The residual oil of small complex fault block reservoirs is extremely complex in the late stage of development.
There are many factors controlling it. And the residual oil controlled by a single factor is dispersed and limited. Considering
the main controlling factors of the residual oil，the form of the fault block reservoirs，the adequacy of natural energy and energy
provider，we divide the edge-water fault block reservoirs into three categories. They are open-type edge-water fault block
reservoir，semi-closed edge-water fault block reservoir and closed edge-water fault block reservoir. Based on the studies on the
distribution features of the residual oil and the exploiting potential of each reservoir type we find that the open-type edge-water
fault block reservoir is of the highest degree of recovery percent and the residual oil is few and dispersed，that the closed edgewater
fault block reservoir is the lowest degree of recovery percent and the residual oil is much and contiguous，and that the
semi-closed edge-water fault block reservoir is between the above two. On the basis of the above study we propose the technical
countermeasures for farther development according to the characteristics of each reservoir type.

Key words: residual oil, edge water, the faulted block reservoir, the type of reservoir, natural energy, the Geo Qiannan area