北部湾盆地福山凹陷古近系流沙港组岩性油气藏勘探

Study of Lithologic Reservoir of Paleogene Liushagang Formation in Fushan Depression of Beibu Bay Basin

通过对北部湾盆地福山凹陷古近系流沙港组层序地层和沉积体系的研究,探讨岩性圈闭发育的控制因素,结合已发现岩性油气藏的研究,分析福山凹陷岩性油气藏形成的有利区域,旨在为下一步岩性油气藏的勘探提供指导。研究结果表明,福山凹陷古近系可划分为3个三级层序;主要沉积体系类型为辫状河三角洲、扇三角洲、湖底扇和湖泊;岩性油气藏主要受构造古地貌、沉积体系发育背景、储层物性以及生储盖等条件匹配关系的控制;各三级层序中湖侵体系域最易形成岩性油气藏;平面上在三角洲前缘相带易形成与河口坝、滑塌体、湖底扇等有关的岩性油气藏。

Based on study of the sequential stratigraphy and sedimentary system of Paleogene Liushagang Formation in Fushan Depression of Beibu Bay Basin, this paper focuses on the controlling factors of lithologic reservoirs and analyzes the favorable areas of lithologic oil and gas reservoirs in Fushan Depression on the basis of the research on the discovered lithologic reservoirs, aiming to guide exploration of lithologic oil and gas reservoirs at the next stage. The study indicates that the Paleogene System in Fushan Depression can be divided into three three-level sequences. The types of main sedimentary system are braided delta, fan delta, sublacustrine fan and lake. The lithologic reservoirs are mainly controlled by ancient landform of structure, development background of sedimentary system and matching relations between physical properties of reservoirs and source-reservoir-cap assemblages. In each three-level sequence, lithologic reservoirs are most easily formed in the area of lake-invaded system. On the plane, lithologic reservoirs related to channel mouth bar, slip block and sublacustrine fan are easily formed in delta frontal belts.