准噶尔盆地东部梧桐沟组岩性圈闭预测和油藏分布规律

Lithologic Trap Prediction and Reservoir Distribution of Wutonggou Formation in Eastern Junggar Basin

采用层序地层学、测井约束反演以及地震属性优选等方法,对准噶尔盆地东部Q区块梧桐沟组低位域水下扇体进行储集层和圈闭识别,进而利用预测的含油饱和度检测油藏范围。Q区块上二叠统梧桐沟组可分为低位体系域、湖侵体系域和高位体系域。其中低位体系域的水下扇扇中辫状水道是储集层最发育位置。随着湖平面反复升降,尤其是湖侵体系域沉积泥岩的封盖作用,使得原水道沉积砂体被泥岩所包围,后又经过构造抬升,形成上倾尖灭的岩性圈闭。结合测井约束反演综合识别出储集层和岩性圈闭的位置,利用遗传算法和神经网络联合优选法进行地震属性优化,结果表明含油气饱和度最优区位于研究区西部、西南部,其中以西南部储集层更好、含油气性最佳。

This paper identifies the reservoirs and traps in the submarine fan of Wutonggou formation in Q block in the eastern Junggar basin by means of stratigraphy,log-constrained inversion and seismic attributions optimization,and then detects the reservoir scopes using predicted oil saturation.The Wutonggou formation of Upper Permian in Q block can be divided into three parts: Lowstand systems tract,transgressive systems tract and highstand systems tract,among which the sand body of Lowstand systems tract is the target of this research.The braided channel in the middle fan is the best reservoir.The original sandstone was sealed by mudstone in transgressive systems tract.Therefore,updip pinchout lithologic traps were formed with tectonic uplifting.The positions of reservoirs and lithologic traps are ascertained by using the log-constrained inversion.After the seismic attributes optimizing based on genetic algorithm-neuron network optimization,the result shows that the areas of high oil saturation are located in the west and the southwest in this region,of which the southwest reservoir is much better in quality and petroliferous property than the west.