Abstract:

During Paleozoic and Mesozoic,Jianghan plain had experienced multicycle sedimentary tectonic evolution,including Caledonian,Hercynian-Early Indosinian,Late Indosinian-Early Yanshanian,and Late Yan-(shan)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 tectoclases 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 experienced an evolution process of formation-reconstruction,destruction-survival or re-formation 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.Xiantao-Daijiachang 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.

Key words: petroleum system, tectonic evolution, reservoiring, Meso-Paleozoic, Jianghan plain