RESERVOIR CHARACTERISTICS AND PORE STRUCTURE CLASSIFICATIONS OF CHANG 6 MEMBER OF YANCHANG FORMATION OF TRIASSIC IN JIYUAN OILFIELD OF ORDOS BASIN, CHINA

摘要

Methods such as conventional physical property, casting thin-section, scanning electron microscope (SEM), conventional mercury injection, nuclear magnetic resonance (NMR), etc. are used to analyze the classification of the microscopic pore structure and its influence on moveable fluid saturation in Chang 6 member of Yachang formation in Ji-yuan area. The research shows that the accumulation space in this area are mainly primary interparticle pores followed by feldspar dissolution pore. According to capillary pressure curve and its corresponding parameters, the reservoir pore structure is classified into four types: Type I , H , H and ^ corresponding to different accumulation spaces, and the accumulation properties and permeability ability of these four types are turning worse from type I to W". It is tested from NMR that the distribution of T2 spectrum is analogous to the distribution of the mercury saturation of its corresponding pore throat radius; the T2 value is positively correlated with pore throat radius; pore throat radius is the main factor affecting the moveable fluid saturation; moveable fluid distribution is positively correlated with permeability which is the direct parameter characterizing the permeability ability of different pore structures.