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石炭系火山岩是我国西部深部油气勘探新领域,在准噶尔盆地显示出广阔油气远景。针对盆地陆东地区火山岩储层岩心及露头样品地球化学分析、显微观察、扫描电镜和包裹体等综合研究,阐述了研究区火山岩储层特征及主控因素。陆东地区石炭系发育一套低钾富钠碱性—亚碱性系火山岩,主要为爆发相火山角砾岩和凝灰岩、溢流相玄武岩和安山岩。火山岩储集空间主要为次生溶蚀孔缝型、孔隙—裂缝复合型,爆发相火山角砾岩、溢流相玄武岩和安山岩物性最好。有利储层区带主要为风化体淋滤带,其次为崩解带。淋滤带以风化淋滤作用、构造破裂作用和热液蚀变作用为主,特别是热液蚀变形成沸石或方解石充填对储层演化具有重要意义。陆东地区石炭系火山岩储层发育的主控因素可以归结为断裂—火山岩风化体结构—岩性/岩相三级因素控制。
Carboniferous volcanic rocks are the new field of deep oil and gas exploration in the western part of China, showing a broad oil and gas prospect in the Junggar Basin. In view of the geochemical analysis, microscopic observation, scanning electron microscopy and fluid inclusions of volcanic reservoir core and outcrop in the Luodong Basin, the volcanic reservoir characteristics and main controlling factors in the study area are expounded. In the Carboniferous of the Luodong area, a set of low-kalium-rich alkaline-alkaline-alkaline volcanic rocks are developed, which are mainly volcanic breccias and tuffs, and overflow basalts and andesites. The volcanic reservoirs are mostly secondary dissolution pore fractures, pore-fracture complexes, eruptive volcanic breccias, overflow-phase basalts and andesites. The favorable reservoir zone is mainly the leaching zone of weathered body, followed by the disintegration zone. The leaching zone is dominated by weathering and leaching, tectonic rupture and hydrothermal alteration. In particular, hydrothermal alteration into zeolite or calcite filling plays an important role in reservoir evolution. The main controlling factors for the development of Carboniferous volcanic reservoirs in the Ludong area can be attributed to the control of fault-volcanic weathering body structure-lithology / lithofacies.