Accumulation and Filling Mechanism of Lenticular Sandbody Reservoirs

Lenticular sandbody reservoir is an important subtle reservoir type for increase of reserve, but its accumulation and filling mechanism is not well understood. Driven force and resistance during lenticular sandbody reservoir-filling have been analyzed based on integrated research on the process of compaction and diagenesis in interbedded sand/mud strata. The results indicate that the driven forces resulting in the filling of reservoir include pressure due to the generation of hydrocarbon, diffusion by hydrocarbon concentration difference, capillary pressure between sand and mud. Rock absorption and adhibition are taken as resistance of reservoir-filling. Hydrocarbon and water spill into the reservoirs in the mixing pattern through pore, fracture and joint fissure. Hydrocarbon is filled in early phase of late-diagenetic stage and preserved in late phase of late-diagenetic stage.