北部湾盆地涠西南凹陷西南缘油气成藏条件及模式

Hydrocarbon accumulation conditions and patterns in the southwestern margin of Weixinan Sag, Beibuwan Basin

张萍 郑军 席敏红 王文军 黄建军 王修平

Zhang Ping Zheng Jun Xi Minhong Wang Wenjun Huang Jianjun Wang Xiuping

中国石化 上海海洋油气分公司研究院, 上海 200120

Institute of SINOPEC Shanghai Offshore Oil & Gas Company, Shanghai 200120, China

结合近两年勘探成果,应用现代油气成藏、地球物理学、地球化学等理论和方法,对北部湾盆地涠西南凹陷西南缘开展了油气成藏条件和成藏模式研究。结果表明,该区发育流沙港组半深湖—深湖相优质烃源岩,古近系发育4套有利的储盖组合,断鼻、断块、构造—地层复合圈闭发育,成藏要素时空配置良好,油气成藏地质条件有利。鉴于以上成藏条件研究及对本区超压的认识,提出以超压面为界的上、下2种油气成藏模式:超压界面以下油气以自生自储—侧向运移、上生下储—垂向运移的方式汇聚成藏;超压界面以上油气以下生上储—垂向运移方式为主汇聚成藏。研究区近洼陷生烃中心的陡坡带和缓坡带为有利勘探区带。

The hydrocarbon accumulation conditions and patterns in the southwestern margin of the Weixinan Sag of the Beibuwan Basin were studied based on modern reservoir theory, geophysics and geochemistry. Favorable hydrocarbon source rocks of semi-deep or deep facies developed in the Paleogene Liushagang Formation. Four sets of favorable reservoir and cap rock assemblages were deposited in the Paleogene. Faulted nose, faulted block and structure-formation complex traps formed. The good configuration of time and space was favorable for hydrocarbon accumulation. Two accumulation patterns, an upper one and a lower one, were determined, which were separated by an overpressure interface. For the lower system, hydrocarbon was self-generated, self-reservoir and migrated laterally, or upper-generated, lower-reservoir and migrated vertically. For the upper system, hydrocarbon was lower-generated, upper-reserved and migrated vertically. The steep and gentle slopes close to the deep depression were favorable exploration targets.

https://doi.org/10.11781/sysydz201502157