Petroleum accumulation mode and potential in the eastern section of the southern slope of Dongying Sag

The Dongying Sag is a rich reservoir, but the distribution of oil and gas is very uneven. The characteristics of oil accumulation and distribution in the eastern section of the southern slope of Dongying Sag are studied in detail. Results indicate that the uplift zone, slope zone, and gentle slope zone of the study area have diverse sedimentary environments and geological structures, thus different hydrocarbon accumulation modes exist. The uplift zone is dominated by stratigraphic oil pools overlain by unconformities; the slope zone dominated by structural pools with a small amount of stratigraphic oil pools onlapping on unconformities; and the gentle slope zone dominated by lithological oil pools. The faults in the study area have a key impact on the migration, accumulation, and distribution of petroleum pools. In the areas of dense faults, oil migrates over long distances to form structural and stratigraphic oil pools through 3-D conduit systems of faults, unconformities, and sand bodies. In the areas of sparse faults, oil migrates over very short distances to form lithological oil pools close to the source area. The preliminary exploration and development show that the lithological oil pools undergo high pressures, showing good production potential and direction of exploration for additional reserve and yield in a mature field.