江汉盆地印支—喜马拉雅期构造演化与海相地层油气成藏模式及勘探方向

江汉盆地自晚元古代统一的变质基底形成后,先后经历了加里东、海西—早印支,晚印支—早燕山以及晚燕山—喜马拉雅期四次大的构造运动,从而形成前印支期的地台型广海盆地、印支期间的前陆湖沼盆地和晚燕山以来的内陆断陷盐湖盆地叠置的“三层楼”构造格局。江汉盆地构造的复杂演化过程表明,江汉盆地具有改造盆地的特点,同时也决定了该区的成藏基本地质要素动态演化的复杂性。构造演化对油气的运移、聚集与保存起到了至关重要的控制作用,从而赋予江汉盆地平原海相地层油气运聚时间长、跨度大而且聚集规律复杂的特点。根据构造对油气运聚的控制,推测具有早期生烃早期成藏、早期生烃晚期成藏、晚期生烃晚期成藏和次生混源成藏4种成藏模式。同时,油气勘探的难易程度也受控于构造演化,早期生烃早期成藏模式油藏的有利发育区是油气勘探的首选勘探领域。

Indosinian-Himalayian Tectonic Evolution, Marine Reservoir-forming Pattern and Exploration Field in Jianghan Basin

After an entire metamorphic basement was formed during the Late Proterozoic era, 4 large tectonic cycles have happened in Jianghan Basin, i.e. Caledonian, Hercian-Early Indosinian, Late Indosinian-Early Yanshanian and Late Yanshanian-Himalayian cycles, which resulted in a three-storey-type tectonic framework, which was superimposed by the open-sea basin of platform type before the Indosinian, the foreland lake basin during Indosinian and the intracontinental fault-depression salt lake since Yanshanian. The complexity of the tectonic-evolutionary process of Jianghan Basin demonstrates this basin is a reformed basin. This tectonic-evolutionary process also resulted in a complexity of active evolution for the essential geological elements of reservoir formation in the study area. Therefore, the complex tectonic evolution controls oil-gas migration and accumulation; and this process endow marine strata of Jianghan Basin with several characteristics, i.e. the long time and large scan feature for the oil/gas migration and accumulation, and the complexity of the law of oil-gas migration and accumulation. The reformed basin has a variety of reservoir-forming patterns including the earlier hydrocarbon generation-earlier reservoir formation, the early hydrocarbon-generating and late reservoir-forming, the late hydrocarbon- generating and late reservoir-forming , and secondary mixed-source patterns. Meanwhile,the structural evolution controls the exploration direction and target. The region marked by the earlier hydrocarbon-generating and earlier reservoir-forming is the promising exploration target for choice.