江汉平原区构造演化对中、古生界油气系统的影响

Impact of tectonic evolution on Paleozoic and Mesozoic petroleum systems in Jianghan plain

江汉平原区中、古生界经历了加里东、海西—早印支、晚印支—早燕山、晚燕山—喜山期等多旋回沉积构造发展阶段,纵向上构成了震旦系—志留系及志留系—侏罗系两套油气系统。每一个构造运动期都是一次油气的大规模运聚期。构造运动所产生的构造裂缝对区内储层的储集性能具有明显的改善作用,构造运动形成的风化壳是储层发育的有利层段。加里东、海西—早印支、晚印支—早燕山以及晚燕山—喜山期4次主要构造活动,使得4套油气保存单元经历了形成-改造、破坏-残存或重铸的演变过程。印支期以来的构造运动是江汉平原区中、古生界油气系统形成和演化的主要动力和影响因素。印支期区内构造格局以大隆大坳为特征,是区内烃源岩的生烃高峰期,形成了隆起区早期的油气富集。早燕山期是区内中、古生界内幕构造的主要形成期,同时,也是油气运聚和油气藏形成的主要时期。晚燕山—喜山期则是油气藏改造和调整期,不同类型的油气藏最终定型于喜山期。区内仙桃-戴家场和当阳次级深坳陷是原生改造型油气藏勘探的有利地区,沉湖-土地堂复向斜北部麻洋潭构造带是晚期生烃型油气藏勘探的有利地区,丫新和万城潜山带是次生多源型油气藏勘探的最有利地区。

During Paleozoie and Mesozoic, Jianghan plain had experienced muhicycle sedimentary tectonic evolution, including Caledonian, Hereynian-Early Indosinian, Late Indosinian-Early Yanshanian, and Late Yanshan ian-Himalayan movements, leading to the formation of Sinian-Silurian and Silurian-Jurassic petroleum systems. Large scale hydrocarbon migration and accumulation has occurred in every tectonic movement stage. The tectoelases resulting from tectonic movement can remarkably improve the poroperm characteristics of reservoirs. The weathering crusts resulting from tectonic movement are favorable reservoir intervals. The 4 hydrocarbon preservation units have experieneed an evolution process of formation-reconstruction, destruction-survival or reformation during these 4 major tectonic movements. The tectonic movements developed since Indosinian are the main driving force and influential factors of the formation and evolution of Meso-Paleozoic petroleum systems. In Indosinian, tectonic framework in this area is characterized by large uplift and large depression and the source rocks have entered the peak hydrocarbon generation stage, resulting in the early enrichment of hydrocarbons in the uplifted area. Early Yanshanian is the main period of the formation of Meso- Paleozoic intrasequence-structures and hydrocarbon migration and accumulation. While Late Yanshanian-Himalayan is the period of reservoir reconstruction and adjustment, leading to the finalization of various types of reservoirs in Himalayan. XiantaoDaijiachang and Dangyang secondary deep depressions are the favorable areas for exploration of reconstruction type reservoirs. Mayangtan structural belt in the northern part of Chenhu-Tuditang synclinorium is the favorable area for exploring the late hydrocarbon-generation type reservoirs. Yaxin and Wancheng buried-hill belts are the most favorable area for exploration of secondary and multiple source types oil/gas reservoirs.