中国南方中、古生界古今油气藏形成演化控制因素及勘探方向

FACTORS CONTROLLING THE FORMATION AND EVOLUTION OF MESOZOIC AND PALEOZOIC OIL/GAS RESERVOIRS AND THEIR EXPLORATION TARGETS IN SOUTH CHINA

根据南方多期构造改造及油气演化复杂性的特点 ,将南方中、古生界古今油气藏分成原生、次生及再生烃油气藏 3类。原生及次生油气藏的分布主要受生烃凹陷邻近的古隆起及古斜坡控制 ,再生烃油气藏分布主要受“二次生烃”或晚期生烃中心控制。南方现存的中、古生界工业性油气藏特别是天然气藏的成藏期均较晚 ,以第三纪为主 ;南方中、古生界烃源岩存在早期—晚期的多期生烃、多期成藏 ,而勘探的重点应该是晚期生烃及晚期成藏的油气藏。晚侏罗世—早白垩世燕山运动对南方中、古生界原生油气藏的保存与破坏起到了决定性的作用 ,它控制了现今南方中、古生界主要油气藏成因类型———次生型及再生烃型油气藏的分布。上扬子地区主要考虑次生气藏的勘探 ,中、下扬子地区主要考虑再生烃油气藏的勘探。

According to the characteristics of multi stage tectonic reconstruction and the complexity of hydrocarbon evolution, Mesozoic and Paleozoic oil and gas reservoirs in South China can be divided into three types: the primary, the secondary and the regenerated hydrocarbon reservoirs. The distribution of the primary and the secondary reservoirs is mainly controlled by paleouplift and paleoslope near the source rock sedimentary sag, and the distribution of the regenerated reservoirs is by the secondary or later stage hydrocarbon generating center. Those existent industrial reservoirs of Paleozoic and Mesozoic in South China were formed especially in late periods, significantly in Tertiary. There the source rocks were found with multi stage generating hydrocarbon and multi stage forming reservoirs. The oil and gas exploration should be concentrated on the reservoirs generated and formed at the later periods. Yanshan Movement which occurred from Late Jurassic to Early Cretaceous played a decisive role in conservation and destruction of the primary reservoirs, controlling the distribution of the secondary and the regenerated reservoirs-the significant genetic models of the existent Mesozoic and Paleozoic oil/gas reservoirs. The exploration of the secondary gas reservoirs will be in upper Yangtze area while the exploration of the regenerated reservoirs in middle and lower Yangtze area. The beneficial areas of oil and gas exploration have already been certified by those exploration results discovered from Zhujiadun gas field in Yancheng sag of North Jiangsu Basin and Kaixiantaixi oil bearing trap in the southern Chenhu area of Jianghan Basin.