Characterized by complex lithology and strong
heterogeneity, volcanic reservoirs in China developed three
reservoir space types: primary pores, secondary pores and
fractures. The formation of reservoir space went through
the cooling and solidification stage (including blast fragmentation,
crystallization differentiation and solidification)
and the epidiagenesis stage (including metasomatism, filling,
weathering and leaching, formation fluid dissolution
and tectonism). Primary pores were formed at the solidification
stage, which laid the foundation for the development
and transformation of effective reservoirs. Secondary
pores were formed at the epidiagenesis stage, with key
factors as weathering and leaching, formation fluid dissolution
and tectonism. In China, Mesozoic–Cenozoic
volcanic rocks developed in the Songliao Basin and Bohai
Bay Basin in the east and Late Paleozoic volcanic rocks
developed in the Junggar Basin, Santanghu Basin and Tarim
Basin in the west. There are primary volcanic reservoirs
and secondary volcanic reservoirs in these volcanic
rocks, which have good accumulation conditions and great
exploration potential.