渤海海域辽中南洼渐新统湖平面变化及其油气勘探意义

Lake-Level Changes of Oligocene of Liaozhong Southern Sag in Bohai Sea Region and Its Significance in Petroleum Exploration

湖平面变化研究是陆相层序地层学研究的难点,针对陆相断陷湖盆湖平面变化研究难点,选择渤海海域辽中南洼渐新统为研究对象,采用古生物含量变化定性评价等多种方法对该区湖平面变化规律开展研究。研究结果表明:研究区渐新世时期湖平面变化总体表现为完整的上升到下降的旋回趋势,内部发育多个次级湖平面升降旋回,其总体变化规律与区域地质规律相吻合。通过研究区构造活动史及古气候研究认为,湖平面整体变化趋势受古气候影响,而构造活动控制其阶段性升降旋回。该研究对渤海海域渐新统浊积扇体的储层评价可以起积极的作用,同时可以指导处于不同湖平面升降时期三角洲沉积体的形成机制及储层发育程度的评价,对拓展渤海海域油气勘探具有较好的启示作用。

Lake-level changes research is the difficulty of sequence stratigraphy.Aiming at the difficulty,this paper studies the lake-level variation by using the paleontological content change qualitative evaluation methods with example from Liaozhong southern sag of Bohai Sea in China.The results indicate that the lake-level changes for the study area experienced the integrated cycle of rising and dropping during the deposition of Oligocene,in which multiple sub-cycles of rising and dropping were also developed,and the whole changing trend was consistent with regional geology.The study of regional tectonic history and paleoclimate has come to a conclusion that the change of lake-level was mainly dominated by the tectonic movement,while the development of sub-cycles was controlled by the palaoclimate.Based on the results,the reservoir evaluation of turbidite fan bodies deposited in Oligocene have been accomplished,delta body depositing mechanism has been analyzed and its reservoir development of different lake-level rising and dropping stages has been evaluated,and significant effectiveness has been achieved in guiding subtle reservoir exploration in Bohai sea area.