辽西凸起南段斜坡带油气地质新认识与勘探突破

New geological understandings and prospecting breakthrough in slope zone of southern Liaoxi uplift

斜坡带是油气勘探发现的重要领域,辽西凸起南段斜坡带却历经多年油气勘探一直未获商业性发现。近年来利用大量岩心、测井、地震、分析化验资料,对制约辽西凸起斜坡带油气勘探关键问题进行系统分析。研究表明,根据隐性走滑断裂解释新模式,重新落实了辽西凸起南段一批大型构造圈闭群;沙河街组厚层混积滩坝砂优质储层发育突破了传统薄层认识,奠定了沙河街组规模性油气储量的发现;构造-岩性双重作用控制中生界优质储层发育,形成了LD25-A构造区孔隙-裂缝型优质储层;超压封盖、高效输导通道联合控制斜坡带油气优势汇聚成藏。这些创新地质认识指导了LD25-A构造高丰度高产轻质油田的发现,实现了辽西凸起斜坡带油气勘探的突破,对渤海湾盆地斜坡带勘探具有重要指导意义。

Slope zone is a significant area for prospecting oil and gas, whereas there is no commercial discovery in the slope zone of southern Liaoxi uplift through many years of exploration. Using a large number of core, well logging, seismic as well as laboratory data, critical questions constricting the oil and gas exploration in the slope zone of the Liaoxi uplift are systematically analyzed. The study result reveals that:(1) According to the concealed strike-slip fault interpretation model, many large-scale structural trap groups were reconfirmed in southern Liaoxi uplift.(2) The thick high-quality reservoir of the mixed beach bar in the Shahejie Formation breaks through the traditional understanding of thin-layer reservoir, laying a foundation for large-scale oil and gas reserves discovery in this formation.(3) Structural-lithological process controlled the development of high-quality reservoir in Mesozoic and formed the porous-fractured reservoir in LD25-A structure.(4) The over-pressure sealing and efficient transporting pathway both decide the convergence and accumulation of oil and gas in the slope zone. These innovative geological understandings have guided the discovery of LD25-A light oil field with high yield and high abundance, contributed to the breakthrough in the slope zone of the Liaoxi uplift, and have important guiding significance for prospecting the slope zone in the Bohai Bay Basin.