冀中坳陷隐蔽型潜山油气藏主控因素与勘探实践

渤海湾盆地冀中坳陷具有形成碳酸盐岩潜山油气藏的地质条件。随着勘探程度的不断深入,勘探方向逐步转向埋藏深、识别难度大、成藏条件复杂的隐蔽型深潜山、潜山内幕等隐蔽型潜山目标。研究表明,埋藏深度大于3 500m的隐蔽型深潜山以沙河街组三段—四段为主要烃源层,油气资源比较丰富,其储集空间以孔洞、裂缝为主,物性受埋深影响小,具有较好的储集能力;潜山内幕成藏受控于潜山内幕储盖组合的有效性、潜山内幕储层物性与油气运移通道输导能力的耦合关系,具有良好封堵能力的内幕盖层、良好储集物性的内幕储层以及优势的油气运移通道是潜山内幕成藏的关键。牛东潜山带、长洋淀潜山带、肃宁潜山带等多个隐蔽型潜山油气成藏区带的发现,展现了冀中坳陷该领域良好的勘探前景。

Main controlling factors and exploration practice of subtle buried-hill hydrocarbon reservoir in Jizhong depression

Jizhong depression in Bohai Bay Basin has the geological conditions to form carbonate buried-hill hydrocarbon reservoir.With continuous deepening of the degree of exploration,the exploration gradually shifts to subtle deep buried-hill,buried-hill inside and other subtle buried-hill targets with large buried depth,great identification difficulty and complex accumulation conditions.Studies have shown that the subtle deep buried-hill with burial depth greater than 3 500m takes the 3rd member-4th member of Shahejie Foramtion as the major source rock with relatively rich oil and gas resources.The reservoir space is dominant by holes and cracks and presents better accumulation capacity because the reservoir physical properties are less affected by buried depth.As for buried-hill inside,the reservoir formation is controlled by the coupling relationship among the effectiveness of internal buried-hill reservoir and caprock assemblage,the physical properties of internal buried-hill reservoir and transporting capacity of oil-gas migration channel.The internal caprocks with better sealing capacity,internal reservoirs with better reservoir physical properties and preferential hydrocarbon migration channels are the key for internal buried-hill accumulation.In practice,multiple subtle buried-hill hydrocarbon accumulation belts have been discovered,such as Niudong buried-hill belt,Changyangdian buried-hill belt,Suning buried-hill belt,etc,presenting good exploration prospects in Jizhong depression.