西北沙巴盆地油气成藏模式及勘探方向

摘要

Guided by hydrocarbon geological theory, through typical reservoir dissecting, it identifies the features of Northwest Sabah Basin reservoir. The result shows that three different hydrocarbon accumulation patterns can be built based on the research for characteristic of structure, sedimentary formation and petroleum geology. They are lithologic, stratigraphic and rollover anticline type, respectively. The basin tectonic evolution involved rift, compression and inverse stage, depression stages and it developed four Cenozoic formations: Stage I, StageⅡ, StageⅢ, StageⅣ. Mudstones and shales in the StageⅣ are the main source rocks. The pretty reservoir is provided by the Stage IVA Lower Sandstone Unit, Stage ⅣC, ⅣD and ⅣE Upper Sandstone Unit and Stage ⅣC/ⅣD slump turbidite fan. Three reservoir⁃seal combinations, called lower, upper, deep⁃water turbidite fan combinations, are identified in basin. It builds three hydrocarbon accumulation models, named Updip sandstone pinchout, Unconformity and Rolling anticline type which distribute in different tectonic area in this basin. The fundamental conditions of hydrocarbon accumulation are analyzed. It shows that hydrocarbon source rocks and reservoir contacting each other in the plane and superimposing in the space provides favorable conditions for hydrocarbon migration and accumulation. Based on the above analysis, it suggests that stratigraphic reservoir in Inboard belt and lithologic reservoir in Outboard belt will be the future exploration targets for basin.%以油气地质理论为指导，在构造、沉积、石油地质特征分析基础上，从典型油气藏解剖入手，构建了西北沙巴盆地3种类型的油气成藏模式，即岩性型、地层型和滚动背斜型油气成藏模式。盆地经历了裂谷期、挤压反转期和拗陷期3个演化阶段，发育Stage I、 StageⅡ、 StageⅢ、 StageⅣ等4套新生代沉积地层。盆地以StageⅣ泥／页岩为主要烃源岩；有利储集层为由StageⅣC、 StageⅣD、 StageⅣE砂岩构成的上砂岩单元、由StageⅣA砂岩构成的下砂岩单元及StageⅣC／ⅣD地层滑塌形成的深水浊积砂体；空间配置方面，烃源岩与储集体平面相接、空间叠置，为油气运移成藏提供了有利条件。通过油气富集条件及分布规律的综合分析，认为“内带”构造区的地层油气藏及“外带”构造区的岩性油气藏是盆地未来的油气勘探重点。