The reservoir rocks of the subaqueous fans in the western segment of the steep slope zone of northern Dongying depression, Shandong

A variety of sandstone and conglomerate fans occur along the steep slope zone of northern Dongying depression, Shandong, a prospective area for the concealed oil and gas pools. These sandstone- and conglomerate-dominated nearshore fans were formed during the deposition of the fourth member of the Paleogene Shahejie Formation in the western segment of the slope zone. The reservoir rocks have lower textural maturity and compositional maturity and display bimodal or polymodal structures. The study of the porosity types and structures of the sandstone and conglomerate reservoirs on the basis of rock type, deposition, planar distribution and diagenesis shows that the reservoir rocks in the study area have moderate to low porosity and low permeability.