复杂山前带基于层序地层格架的油气成藏规律

HYDROCARBON ACCUMULATING RULES BASED ON THE SEQUENCE STRTIGRAPHIC FRAMEWORK FOR COMPLEX MOUNTAIN FRONT

应用层序地层学理论,对准噶尔盆地哈拉阿拉特山(哈山)南缘山前带油气成藏规律进行研究。结果表明:哈山南缘山前带浅层可划分为2个二级层序、5个三级层序和13个体系域;层序旋回控制了油气聚集层位,低位域砂体更容易聚集油气成藏;山前带受沉积构造背景影响,油气藏主要发育在层序界面附近;山前带除了可以形成受层序地层格架控制的典型地层岩性油气藏外,还易形成断块等构造油气藏;良好的输导条件和不整合封堵也可让湖侵体系域成为油气聚集的有利层位;在输导体发育的复杂山前带,封堵油气的盖层发育和圈闭形成与油气成藏期次的匹配是油气成藏应考虑的因素。

By means of the theory of sequence stratigraphy, the oil and gas accumulation rules are studied for the southern margin of Hala＇alat Mountain （ Ha Mountain} in Junggar Basin. The results show that the sequences in the shallow formations can be divided into two second-order sequences, five third-order sequences and thirteen system tracts; the sequence cycles control the horizons of the oil and gas accumulation, the oil and gas is prone to accumulate and enrich in the lower system tracts; the mountain front belt is influenced by the sedimentary tectonic back-ground, the hydrocarbon is mainly developed near the sequence interfaces; besides the typical lithologic petroleum reservoirs controlled by sequence stratigraphic framework in the mountain front belt, the structural reservoirs i. e. fault blocks are easy to form; the lake-encroached system tract can become the favorable oil accumulation horizon with the help of the much better transporting conditions and unconformity blockade; in the complex mountain front belt with well-developed transporting bodies, the factors should be considered for the hydrocarbon-reservoir accumulation are the well-developed plugging cap rocks and the match between the trap generation and hydrocarbon-reservoir formation period-times.