湖盆洼槽区沉积充填模式与演化规律——以饶阳凹陷马西洼陷沙河街组为例

DEPOSITIONAL FILLING MODEL AND EVOLUTION OF THE SAG IN LACUSTRINE BASIN: A CASE STUDY FROM SHAHEJIE FORMATION IN MAXI SAG, RAOYANG DEPRESSION

洼槽区是断陷湖盆的重要组成部分,是烃源岩的主要富集区域,但由于其独特的沉积充填特征、埋深及储集层发育程度方面的影响,洼槽区的油气勘探程度通常较低。以冀中坳陷饶阳凹陷中的马西洼槽为研究对象,针对主力油气勘探层段沙河街组开展沉积充填模式与演化规律研究,明确了洼槽区陡坡、缓坡沉积类型与沉积模式的差异,再现了沙河街组沙三段、沙二段及沙一段沉积展布特征,建立了洼槽不同构造演化期的沉积充填模式。研究表明,断陷湖盆洼槽区具有储集层发育的沉积条件,因此是岩性地层油气藏发育的有利区带,应该成为今后油气勘探走向深层的一个重要领域。

Sag is an important part of the rift lacustrine basin and is the main occurrence area of hydrocarbon source rocks. But in terms of its unique characteristics of sedimentary filling, the buried depth and the reservoir development, the exploratory degree of petroleum in a sag is usually low. Maxi sag is located at Raoyang depression, Jizhong sub-basin and this paper is to discuss the sedimentary filling model and evolution law of Shahejie Formation which is one of the main petroleum exploration intervals. The differences of sedimentary facies type and the depositional model between the steep slope and gentle slope of the sag area were delineated. Furthermore, the depositional characteristics of the Shahejie Formation, the depositional filling models of different tectonic evolution periods of the sag area were analyzed. The sag area of rift basin had the depositional conditions of the reservoir existence, and it＇s the favorable area for the stratigraphic reservoirs. Therefore, the sag area could be an important area for future petroleum exploration of deep strata in the rift basin.