Abstract: In recent years, the volcanic rock exploration in Junggar Basin has shown that, in addition to weathered crustal reservoirs, there are still volcanic reservoirs with sound physical properties developing below 300 m from the top of the Carboniferous volcanic rock. In order to further clarify the characteristics of these primary reservoirs and provide a basis for exploration and deployment, studies were carried out on the genesis mechanism, rock type, physical characteristics, spatial distribution, rhythmical characteristics and main controlling factors of the primary volcanic reservoirs, and the concept of "primary stratified multi-stage rhyolite reservoir", which was different from the weathered crust reservoirs of volcanic rocks, was proposed, and referred to as primary rhyolite volcanic reservoir. The distribution of primary rhyolite reservoirs was characterized by large area, large span, and vertical distribution not controlled by burial depth, and the reservoir space was mainly the primary pore associated with volatile escape at the top and bottom of each multi-stage eruption cycles; magmatic evolution and volcanic activity sequence were the main controlling factors. This achievement has expanded the longitudinal exploration depth of Carboniferous volcanic rocks, and the exploration target layer has changed from single weathered crust reservoir to primary reservoir developed in multi-stage eruption cycles, guiding the discovery of multiple Carboniferous insider oil and gas reservoirs. There is much for reference to the exploration of volcanic rocks in other basins.

Key words: Junggar Basin, weathered crust, primary rhyolite volcanic reservoir, multiple eruption gyrations, main controlling factors