Reservoir heterogeneities mainly include interformational

intraformational and areal heterogeneities. The following understandings are achieved from study of the Gaoshangpu deep reservoir and other reservoirs in Jidong and Shengli oilfields. The interformational heterogeneity may result in monolayer breakthrough in the main sublayer

early watered out the main layer

low recovery percent in the non-major reservoirs and low oil displacement efficiency during waterflood development. The intraformational heterogeneity controls and affects the swept volume of the injectant in single sand layer

directly determines the waterflood efficiency

and is the key factor influencing the distribution of the remaining oil. The areal heterogeneity directly influences the swept area and sweep efficiency of the injected water

and thus controls the areal distribution of the remaining oil. Based on these understandings

several geological and developmental measures

including subdivision of layer series for development

separate zone water injection and detailed study of flow unit

are presented to effectively lower the influences of various heterogeneities on the ultimate recovery factor of oil reservoirs.