白云凹陷恩平组沉积晚期大型三角洲发育特征及其意义

发布时间：2019-05-06 09:21

【摘要】：白云凹陷恩平组沉积晚期发育大型的辫状河三角洲,但该三角洲的沉积过程、内部发育期次及平面分布规律尚不明确.基于9口钻遇恩三段的钻井资料,开展了砂岩碎屑锆石U-Pb定年及全区覆盖的三维、二维地震资料分析.结果表明恩平组不同沉积时期的主要物源供给方式:恩平组早-中期以白云凹陷四周隆起提供短程物源碎屑为主(母岩类型以中生代火成岩为主),恩平组沉积晚期白云凹陷与北部珠一坳陷开始连通,盆外大型水系携带华南褶皱带物源碎屑沿NW-SE方向进入白云凹陷沉积(母岩类型以古生代-前寒武系变质岩为主),大型三角洲开始发育.地震相及能量半衰时属性分析揭示了白云凹陷恩平组沉积晚期大型三角洲的沉积构成特征,即发育3期不断向东南方向进积的楔状体,其沉积规模由小到大,然后再变小,直至断陷消亡.恩平组沉积晚期三角洲煤系烃源岩及陆源海相烃源岩广泛发育,大型三角洲具备优越的生储盖组合,有利于形成三角洲前缘上倾尖灭油气藏,是白云凹陷深水区古近系油气勘探重要目标.
[Abstract]:Large braided river deltas developed in the late depositional stage of the Enping formation in Baiyun Sag, but the depositional process, the internal developmental stages and the plane distribution of the delta are still unclear. Based on the drilling data of the third member of 9 drilling wells, the three-dimensional and two-dimensional seismic data analysis of sandstone clastic zircon U-Pb dating and coverage in the whole area has been carried out. The results show that the main provenance supply modes of the Enping formation at different sedimentary stages are as follows: the early-middle stage of the Enping formation is dominated by the uplift around Baiyun depression to provide short-range provenance clastic (the mother rock type is mainly Mesozoic igneous rocks). In the late sedimentary stage of the Enping formation, the Baiyun depression began to connect with the northern Zhuyi depression, and the large water system outside the basin carried the source debris from the South China fold belt into the Baiyun depression along the direction of NW-SE (the parent rock type was mainly Paleozoic-Precambrian metamorphic rocks). Large deltas begin to develop. The analysis of seismic facies and half-life time of energy reveals the sedimentary characteristics of the large delta in the late stage of the Enping formation in Baiyun Sag, that is, the wedges developed in the third stage, which continuously advance to the southeast, and their sedimentary scale increases from small to large and then decreases. Until the collapse dies. The delta coal measure source rocks and continental source marine hydrocarbon source rocks are widely developed in the late depositional stage of the Enping formation. The large delta has superior source reservoir cap assemblage, which is conducive to the formation of the updip pointed out oil and gas reservoirs in the delta front. It is an important target for Paleogene oil and gas exploration in deep water area of Baiyun Sag.
【作者单位】：中国地质大学构造与油气资源教育部重点实验室;中国地质大学资源学院;中海油研究总院;
【基金】：国家科技重大油气专项项目(Nos.2011ZX05023-001-015,2011ZX05023-001-001)
【分类号】：P618.13

【参考文献】