博兴洼陷西部沙三段有利储集砂体分布探讨

Distribution of reservoir sandbodies of the 3rd member of shahejie formation,western of boxing sub-depression

博兴洼陷油气勘探已进入隐蔽油气藏为主的勘探阶段,储集砂体的分布,尤其是能够形成地层岩性油藏的有利储集砂体的分布,是油气勘探的关键.研究区主要发育有浊积扇、辫状三角洲前缘和近岸水下扇三种类型的储集砂体,其中浊积扇扇体是岩性圈闭勘探的最有利砂体.通过已发现油气藏的地层位置分析,发现MSC8、MSC7、MSC6、MSC5、MSC2旋回的上升半旋回是有利储集砂体发育的主要层段,浊积扇砂体发育,且具有有利的油气成藏条件.平面上,MSC8旋回的有利储集砂体主要发育在高青断层东南侧的狭长区域内,MSC5、MSC6、MSC7旋回的有利储集砂体发育在坡折带之下的洼陷区.综合上述分析,预测了坡折带下部洼陷区、高青断裂下降盘和高24—高27井间区域3个岩性和构造-岩性圈闭勘探有利区.

Lithologic traps are the main plays for the further exploration of Boxing Sub-depression. The distribution of reservoir sandbodies is the key factor for the exploration of lithologic traps. This paper focused on the analysis of reservoir sandbodies, including the types, the stratigraphic position and distribution of the sandbodies of the 3rd Member of Shahejie Formation, Western of Boxing Sub-depression. Three kinds of reservoir sandbodies are recognized in studied area, which are turbidite fan, braided-delta front and near-bank subaqueous fan. The turbidite fan is the most favorable reservoir to lithologic traps. The favorable members for lithologic traps are the rising hemi-cycles of MSCS, MSC6, MSC7, MSC8 in light of analysis on the stratigraphic position of discovered oil and gas, in which the turbidite fan occurs and the petroleum - forming conditions are better. South-east area of Gaoqing fault is the favorable area for reservoirs in MSC8 and the depression area under the slope break of south slope is the favorable area for reservoirs in MSCS, MSC6, MSC7. Based on compressive analysis, three favorable areas are predicated, which are the depression area under the slope break of south slope, the thrown wall of Gaoqing fault and the region between Well Gao24 and Well Gao 27.