Characteristics and main controlling factors of igneous reservoirs in Chepaizi uplift, Junggar Basin

The lithofacies distribution, reservoir characteristics and main controlling factors of igneous rocks in the eastern Chepaizi uplift of Junggar Basin are studied, by means of core observation, thin section identification, physical property testing and logging data analysis. It is considered that volcanic lithofacies can be divided into near Crater facies, explosive facies, eruptive facies and volcanic sedimentary facies, and that reservoir lithology includes tuffaceous sandstone, volcanic breccia, tuff, andesite and basalt; volcanic breccia reservoir with near-crater facies has the highest porosity and tuff reservoir with explosive facies has the highest permeability; reservoir space includes primary pore, secondary pore and fracture; micro-fracture and intragranular solution pore account for 77.4% of the total pore type; near-crater facies and explosive facies are superior to other lithofacies, and reservoirs in seepage and subsurface are eroded. Fractures play an important role in connecting all kinds of pores, and they are important factors affecting the development of dissolution pores.