Physical Modeling of Secondary Oil Migration and Accumulation in Deltaic Sandstone Reservoir and Its Result Analysis

Physical modeling is an effective way to clarify the efficiency, process and mechanism of secondary oil migration and accumulation. Based on the deltaic front sandstone, which favors oil and gas pool forming, this paper designs and constructs a physical model of secondary oil migration and accumulation in finger-shape non-homogeneous reservoirs, which are composed of multi-layers of homogeneous reservoir, in order to research the path, efficiency and rate. The results of the experiment indicated that the path of secondary oil migration is quite limited. When oil entered into the reservoir from the tip position of finger-shape sandstone body, it mainly migrated to the trap along the middle finite path (about 5 cm wide) from its source. When the rate of migration was very fast, about 1.4 cm/min, and the saturation in the path was about 16%, and after it got to the seal layer, oil began to be accumulated. This implies that secondary oil migration and accumulation take on the characteristics along the finite path, fast and efficient migration and accumulation, and also reveals the "highway" of secondary oil migration exists and the rule of oil pool forming is synchronized with oil volume expelling.