试论火山岩油气藏成藏机理

全球100多个国家/地区在火山岩内或其周围发现了油气藏或油气显示,展示了火山岩油气藏勘探的广阔前景。火山岩已从油气勘探的"禁区"转变为了"靶区",成为油气勘探的新目标。火山岩储集物性较好,其本身可直接作为储层,各类侵入体与围岩相互作用还可形成与火成岩有关的圈闭。火山岩油气藏的烃源包括有机成因和无机成因两种。火山作用可以明显提高烃源岩内有机质的成熟度,加快烃的产生,促进油气运移,并为无机成因烃提供合成原料(CO_2和H_2等)和运移通道。虽然火山岩在盆地早期尤为发育,约占盆地充填体积的1/4,但是目前火山岩油气储量仅占世界油气探明储量的1%左右,勘探潜力巨大。中国沉积盆地内发育不同时代火山岩,火山岩储层与烃源岩匹配较好,无机成因气来源丰富,火山岩油气藏正在成为我国油气勘探的重要领域之一。

Discussion on the formation mechanism of volcanic oil and gas reservoirs

Hydrocarbons in or around volcanic rocks have been found over 100 countries or areas. Volcanic rocks can form petroleum trap because of its good porosity in deeper formation. The traps can also be formed by reciprocity between volcanic structures and sedimentary layers. Igneous rocks have been changed from "forbidden area" to "target area" and become new object for petroleum exploration. Hydrocarbons in volcanic rock reservoirs are both biogenic and abiogenic. Volcanism can efficiently enhance the maturity, speed in the hydrocarbon-generation, afford materials of abiogenic hydrocarbon-formation and make migration pathway. Liquid and gas of volcanism positively influence on the migration of petroleum. Although the volume of volcanic rocks accounts for one quarter of the basin filling body in depression stage, the reserves of petroleum in volcanic rocks only occupy one percent of proven oil all over the world. There are volcanic rocks with different ages which have good relationship with source rocks in sedimentary basins in China. The abiogenic hydrocarbons are quite abundant. In a word, the volcanic rock reservoir is becoming an important area for petroleum exploration.