摘要
通过岩心、测井、地震资料的综合研究及其层序界面的划分,歧南洼陷西斜坡,发育沙河街组滩坝砂、近岸水下扇及重力流水道等多种类型砂体。沙河街组底超、顶剥、中间相变明显,易形成多个层系、多种类型非构造圈闭。歧口凹陷西斜坡为继承性发育构造斜坡,是歧口凹陷油气运移的主要指向区,供油条件优越。广泛分布其间的的沙河街组三段滩、坝砂体平均孔隙度24.8%。平均渗透率175.5×10μm,具有高孔高渗特征。而且,滩、坝砂体沉积后没有遭受大规模构造运动破坏,油气保存条件有利。多年来的勘探成果,区内发现以歧647井油藏为代表的不整合油藏、以联盟为代表的上翘尖灭型油藏,以歧南9-1井为代表的构造-岩性油气藏等多种类型的油气藏,具备形成一定规模隐蔽油气藏的成藏条件。根据岩心相、测井相和地震相研究,预测歧南西斜坡沙三段低水位水下扇砂体及歧北斜坡的坡折带是下一步勘探的有利地区。其中,扣50南岩性圈闭及庄43井断块是最有利地区。
Abstract
Comprehensive study of core, logging and seismic data, and classification of stratigraphic sequence interfaces show that various types of sandbodies, including beach and bar sands, coastal subaqueous fan and gravitational flow channel sands in Shahejie Formation, are developed on the western slope of Qinan sag. Basal overlapping, top denudation, and facies variation between them are evident in Shahejie Formation, thus multiple layer systems and various types of non-structural traps can be formed.The western slope in Qikou depression,an inherent structural slope,is the main directional area of hydrocarbon migration in the depression, and has excellent hydrocarbon supplying conditions. The beach and bar sandbodies in the 3 member of Shahejie Formation are widely distributed, and have an average porosity of 24.8% and average permeability of 175.5×10μm,thus belong to high porosity and high permeability reservoirs.Moreover, these sandbodies have never been disrupted by large tectonic movement since their sedimentation, thus the area would have favorable hydrocarbon preservation conditions. Various types of reservoirs have been discovered during previous exploration, including unconformity reservoirs, upwarping pinch-out reservoirs, and structural-lithologic reservoirs represented by Qi674 well reservoir, Lianmeng reservoir and Qinan 9-1 well reservoir, respectively, indicating that the area possesses the condition of forming certain size subtle reservoirs. According to the study of core, log and seismic facies, it is predicted that the low stand subaqueous fan sandbodies in the 3 member of Shahejie Formation on the western slope of Qinan sag and the slope break zone of the slope in Qibei sag would be the favorable areas in the later exploration; among which, the lithologic traps to the south of Kou 50 well and Zhuang 43 well fault block would firstly be selected as the exploration targets.
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