东营凹陷牛庄洼陷地层压力演化及其成藏意义

东营凹陷牛庄洼陷现今的地层压力垂向分带、平面分区, 地层超压与Es₄上和Es₃下亚段成熟烃源岩分布密切相关, 并以洼陷周围的大型控洼断层为界, 洼陷内超压强烈, 洼陷外超压程度明显减弱.正演模拟表明, 洼陷内超压演化总体上经历了早期形成-下降调整-晚期再次增大3个阶段, 超压成因机制上从以欠压实为主发展到现今欠压实和生烃作用双重控制, 而控洼断层和Es3中亚段下部富泥型地层形成的侧向和垂向封闭, 控制了超压的空间分布状态.超压为Ed末期及Ng末-Nm二次重要成藏期的油气运移提供了重要的源动力; 超压演化与构造活动演化的相互耦合控制了牛庄洼陷附近断阶带上的油气成藏. 

Evolution of Geopressure Field in Niuzhuang Sag in Dongying Depression and Its Effect on Petroleum Accumulation

The present geopressure field in Niuzhuang sag in Dongying depression can be divided into dissimilar zones vertically and different areas horizontally. Overpressure is closely related to both the upper part of the fourth member and the lower part of the third member of Shahejie Formation whose source rocks matured. Large-scale faults surrounding Niuzhuang sag limit the horizontal overpressure distribution. Inside the sag it is strongly overpressured while outside it is much less overpressured. The forward modeling indicates that the overpressure evolution in the sag is divided into three stages: original-forming, meta-declining and latest-raising stages. And the main mechanism for generating overpressures evolved from undercompaction into combination of both undercompaction and hydrocarbon generation. Meanwhile, both lateral seal by large-scale faults surrounding Niuzhuang sag and vertical seal by the thick and shale-enriched bottom layer of the middle part of the third member of Shahejie Formation determined the special distribution of overpressure. The overpressure in Niuzhuang sag provided the petroleum migration with original forces in those two important accumulation periods. Coupling of overpressure evolution and tectonic activities played an active role in petroleum accumulation in the bordering faulted zone near Niuzhuang sag.