巴兰三角洲地区构造特征及其成藏控制因素

Tectonic Characteristics and Hydrocarbon Accumulation Controlling Factors in the Baram Delta Province

巴兰三角洲地区位于西北婆罗洲活动大陆边缘,其构造格局具有南北分带的特征,即北部挤压应力下叠瓦状逆冲推覆带、中部拉张应力下伸展沉降带、南部压扭作用下挤压反转带。与位于被动大陆边缘三角洲发育的地区不同,其北部三角洲前端收缩量大于中部三角洲末端伸展量的1.8%左右,而这无法用理想的被动大陆边缘三角洲体模型来进行解释。在研究区区域构造背景、应力特征分析的基础上,认为这种现象是区域压应力远距离效应与三角洲发育过程重力驱动综合作用的结果。受构造南北分带的影响,研究区发育的上部、中部和下部油气成藏组合分布于不同构造带内;各构造带不同应力背景形成了各自内部独特的构造圈闭类型,而作为油气运移通道的长期继承性发育的断层则控制了研究区内油气的垂向运移。这些研究结果对巴兰三角洲地区油气地质研究、油气勘探部署及优选有利勘探新领域具有一定的借鉴和指导意义。

Baram Delta Province is located at the NW Borneo active margin. It has the features of different zones in north and south： the overlap-thrusting belt under compression in north, extensive subsiding belt generated by extension in middle and compressive inverting belt in south. Different from the area developing Cenozoic deltas located on the passive-margin,its total shortening in compression province goes beyond 1.8 % compared with the stretching in extension province and this can not be explained by the ideal delta system. Based on the regional tectonic setting analysis and stress features in the study area, it regards the far-field compression and the function driven by gravity during delta growing process as the mechanism for this phenomenon. For the effection of tetonic division,the upper,middle and lower oil-gas reservoir-forming assemblages distributed in different tectonic zone; different stress background generated unique structural trap in various tectonic belt and the fault with long-term activity provided major pathways for hydrocarbon migration. Thus,the conclusion will be helpful for the research of hydrocarbon for- mation and further hydrocarbon exploration in Baram Delta area.