Characteristics of Permian-Carboniferous volcanic reservoir in Zhongguai-Wuba area in northwestern margin of Junggar Basin

Volcanic reservoir in Zhongguai-Wuba area in the northwestern margin of Junggar Basin mainly developed in Carboniferous and Jiamuhe Formation of Lower Permian. The volcanic rocks are mainly composed of basalt, andesite, eruptive tuff, volcanic breccia, volcanic breccia lava, rhyolite and a small quantity of intrusive rocks such as granite. The reservoir spaces are made up of primary and secondary spaces. The primary space has poor connectivity, while the secondary space developed reservoir with good connectivity, owing to weathering, denudation and leaching. The reservoir rocks have two types of pore texture. The typeⅠhas poor sorting, while the typeⅡ has good sorting and better properties. The volcanic reservoir in the study area belongs to low porosity and low permeability reservoir. Because of the deep buries, the exploration of volcanic reservoir is different. The properties of volcanic reservoir become better while its age becomes younger.