涠西南凹陷D洼复杂地质结构成因及成藏主控因素

The Origin of Complex Geological Structure and Main Controlling Factors of Hydrocarbon Accumulation in D Sub-sag of Weixi'nan Sag

D洼是涠西南凹陷又一个被证实的富生烃次洼,但地质结构复杂,对其成因演化规律及油气成藏富集规律的认识,直接影响着对下步勘探实践的指导。该文立足对D洼地质结构的解剖,从区域构造运动、应力演化机制方面进行分析,明确了不同构造单元的断裂演化特征以及油气成藏主控与富集因素的差异,认为古隆背景、断砂输导与封堵等要素对W油田涠洲组油气成藏起主要控制作用,进而指明D洼的缓坡带与陡坡带是涠洲组与流沙港组油藏勘探的有利区,而洼槽带具备隐蔽油藏与页岩油的勘探潜力。该研究对下步研究攻关与勘探方向选择具有大的指导意义。

D sub-sag is another proven hydrocarbon-rich sub-sag in Weixi'nan Sag,but its geological structure is complex.The understanding of genetic evolution law and the enrichment regularity of oil and gas accumulation directly affect the guidance of the next exploration practice.Based on the analysis of the geological structure of D Sub-sag,this paper analyzes the regional tectonic movement and stress evolution mechanism,and clarifies the differences of fault evolution characteristics and main controlling and enrichment factors of oil and gas accumulation in different tectonic units.It is considered that the paleo-uplift background and the transporting and sealing of faults and sand bodies are the main controlling factors of oil and gas accumulation in Weizhou Formation of W oilfield.Furthermore,it is pointed out that the mild slope zone and steep slope zone of D Sub-sag are favorable areas for oil exploration in Weizhou Formation and Liushagang Formation,while the trough zone has exploration potential for subtle oil and shale oil.The study has great guiding significance for the next research and exploration direction selection.