Semiquantitative Characterizations And Controlling Factors of Microscopic Pore Characteristics of The Metamorphic Rock Reservoir In The Central Paleo-Uplift Belt, Songliao Basin

Abstract

Currently, metamorphic rock is a common target for oil and gas exploration, and reservoirs are the key factors restricting hydrocarbon exploration and development in metamorphic rocks. The deep metamorphic rock gas reservoir in the central paleo-uplift of the northern Songliao Basin has good exploration and development potential. In this study, we use a combination of qualitative descriptions and quantitative analysis to comprehensively analyze the pore characteristics of the reservoir and explore the factors controlling the pore characteristics of the metamorphic rock reservoir in the central paleo-uplift belt of the Songliao Basin. The metamorphic rock reservoir in the central paleo-uplift belt contains three types of lithologies: chlorite schist, mylonite, and mica schist, each with different protoliths and metamorphic histories. The reservoir space can be divided into 4 pore types, and the reservoir space of each lithology is quite different. The results of high-pressure mercury intrusion and nitrogen adsorption indicate that the pore size distributions of the schist and mylonite differ. Compared with the schist, the mylonite has less reservoir space, stronger homogeneity, larger pore size, smaller specific surface area, more natural gas reservoir space and stronger natural gas adsorption capacity. This paper also studies the formation process of the reservoir and divides it into four stages. Finally, this article discusses in detail the factors controlling the microscopic pore characteristics of metamorphic rock reservoirs in the central paleo-uplift belt; the metamorphic rock protolith is the most important controlling factor.