Grading evaluation of deep reservoir in Xihu Depression, East China Sea Basin

Xihu Depression is a sedimentary basin with the most oil and gas potential and exploration difficulty in the East China Sea Basin. The existing reservoir evaluation standard cannot fully take into account the characteristics of reservoir diversity, so the reservoir evaluation relies on the conventional standard, and the systematic reservoir classification and grading evaluation are constrained. This paper, on the basis of discussion reservoir control factors, takes the "Microfacies-Diagenesis-Temperature" as the main evaluation parameters of reservoir classification and evaluates the main reservoirs on this basis. The results show that the Huagang Formation is mainly composed of low-permeability and super-low permeability reservoirs, accounting for more than 35% of the total reservoir, and thus is the main exploration type in the future. The Pinghu Formation is mainly composed of conventional and low-permeability reservoirs. The research results establish a foundation for the later stage of resource quantity grading evaluation and, also to provide some help for same type reservoir in others basin.