Lithologic and Lithofacies Features of Volcanics and Their Control on Reservoir Capability in Niudong Oilfield of Santanghu Basin

To evaluate the storage performance of volcanic rocks, optimize arrangement of well sites and lay a scientific foundation for reserves upgrading and producibility construction in Niudong Oilfield, on the basis of continuous coring data, two groups (volcanic lava and volcanoclastic rock) of volcanic rock, which included 10 types, were identified through core observation, thin-section analysis, composition analysis of silicate rock, ECS composition identification and FMI rock texture and frame explanation. Meanwhile, in combination of drilling, logging data with seismic data, three groups and six types of volcanic lithofacies, including mainly effusive facies, explosive facies and volcanic sedimentary facies are found. Volcanic activities are characterized by fissure eruption. In combination with study on microscopic features of volcanic reservoirs, it is considered that volcanic lithology and lithofacies are the main factors dominating the reservoir performance of volcanic rocks.