苏北盆地高邮凹陷古近系岩性油藏形成特征及分布规律

Formation of Paleogene Lithologic Reservoir and Distribution in Gaoyou Sag,Subei Basin

近年来,苏北盆地高邮凹陷岩性油藏的勘探取得重大突破。通过对高邮凹陷岩性油藏成藏过程动态解剖研究,高邮凹陷岩性油藏成藏期处于有利的充注动力窗口,储层物性普遍高于充注临界物性,岩性圈闭早期开始持续发育,因此,高邮凹陷整体具有形成岩性油藏的有利条件。高邮凹陷上含油气系统岩性油藏成藏的关键因素是运移通道和圈闭条件。主控断层早期开启,晚期封闭是研究区岩性油藏成藏的必要条件,同时,砂地比较低,砂体欠发育,泥岩发育有利于形成岩性圈闭,也是成藏不可或缺的条件。岩性油藏在陡坡带和缓坡带均有分布,戴南组岩性油藏的分布具有明显的分带性,靠近凹陷两侧断裂带向深洼带依次发育有断层—岩性油藏、上倾尖灭岩性油藏、砂岩透镜体油藏。

In recent years,the lithologic reservoir exploration in the Gaoyou sag has achieved major breakthroughs. By taking key factors controlling hydrocarbon accumulation of lithologic reservoirs,it is concluded that the geological conditions in the Gaoyou sag are favorable for forming lithologic reservoirs, since the time oil entrapment is at the strong filling dynamic window, the physical property of reservoirs is more profitable than that of filling critical physical property, and the lithologic traps is early developed. The lithologic reservoir accumulation was controlled by two key factors, migration pathways and trap condition in the Gaoyou sag. It is required that the main fault opened early and closed later for oil accumulation in this study. In addition,the moderate content of sandstone is available to form lithologic reservoirs. Lithologic reservoirs as a belt shape are widely distributed in the steep slope as well as gentle slope. The slope belts mainly consist of structurallithologic and updip pinchout reservoirs,the depressed belts mainly consist of lenticular lithologic reservoirs.