酒东盆地热演化史与油气关系研究

摘要

Jiudong basin is formed by the stacking of two-stage differentnature and different generation basin. It was rift basin from Early-Middle jurassic to Early Creaceous and squeezed sag basin since Cenozoic. The present geothermal gradient and heat flow of Jiudong basin is very low,of which the present geothermal gradient is 3.00 ℃/100m and the heat flow value is 51 mW/m2. In later Mesozoic, the palaeothermal gradient of Yinger depression, which reached 3.50～4.20 ℃/100m,is higher than present thermal gradient. Thermal gradient of Jiudong basin has decreased since Cenozoic, Yinger depression has subsided on a large scale. The maturity of thermal evolution of source rocks in Yinger depression is controlled by present temperature. Research on the relations between geothermal history and oil-gas generation in Yinger depression indicate that Chijinbu Formation source rock of Lower Creaceous have two stage of oil generation,i. e. Late Creaceous and since Tertiary. Xiagou Formation and Zhonggou Formation source rocks of Lower Creaceous only have one main stage of oil generation, main stage of oil generation is since Pliocene. It has good prospect for exploring oil in Yinger depression.%酒东盆地是由两期不同性质、不同世代盆地叠合而成。早、中侏罗世－早白垩世为拉张盆地，第三纪以来为挤压坳陷盆地。酒东盆地现今地温梯度及大地热流值较低，分别为3.00℃/100m及51mw／m2。营尔凹陷中生代晚期地温梯度高于现今地温梯度，可达3.50～4.20℃/100m；新生代以来大幅沉降，地温梯度降低，烃源岩的热演化程度受现今地温场控制。盆地热演化史与油气关系研究表明营尔凹陷下白垩统赤金堡组烃源岩主生油期有两期，分别在早白垩世晚期及第三纪以来。下白垩统下沟组和中沟组烃源岩主生油期仅有一次，主要为上新世以来。营尔凹陷有良好的找油前景。