Abstract: The study on volcanic rocks from Luxi area in Junggar basin shows that the dissolution of the alkaline volcanic rocks of overflow facies is a key factor to form high-quality reservoir. The discussion of the origin of acidic fluids and mechanism of dissolution suggests that there are different dissolution mechanisms between inorganic acids and organic acids. The inorganic acids mainly take K+, Na+ and other ions away to have a dissolution, however, the organic acids largely depend on increasing the activity of Al3+ for it. The acidic fluids for dissolution were derived from volcanic degasification, fluids overflowed upwards along the deep faults and organic matter. It is concluded that the adjacent to craters, lateral of deep faults and hydrocarbon-generation sags would be the favorable zone for petroleum prospecting. In Luxi area, the most potential zones could be found in line from Well Xiayan-2 to Well Da-1 and Shixi area. In addition, the more potential zones place in line from Well Xiayan-1 to Well Shinan-4 and from Well Madong-2 to Well Lu-2.

Key words: dissolution, alkaline volcanic rock, premium reservoir, Luxi area