墨西哥湾北部深水区Wilcox沉积特征及沉积模式研究

墨西哥湾北部盆地的始新—古新统Wilcox是深水区重要的储集层和产油层,埋深大,分布广.前人对Wilcox的沉积类型认识存在不同的观点,本文通过岩芯观察、薄片分析,结合测井、录井资料和地震资料,对深水区的Wilcox砂岩的沉积环境和沉积特征进行了深入研究.研究表明,Wilcox砂岩为深水扇沉积,中等到好分选,细粒—极细粒,以岩屑砂岩和长石质岩屑砂岩为主.结合沉积物源分析和盐岩演化形变形成的微盆地对Wilcox沉积的影响,建立了Wilcox深水沉积模式,下陆坡区为受盐岩微盆控制的水道沉积,盆地区为深水扇沉积.

Study on Depositional Characteristics and Model of Wilcox in the Deep Waters of Northern Gulf of Mexico

Paleocene to Eocene-age Wilcox Group which is deeply buried and distributed extensively is the significant oil-bearing reservoir in the deep waters of the northern Gulf of Mexico Basin. The different recognition of Wilcox sedimentary facies existed. In this article, by means of observing cores, analyzing sections and well logging data, we studied on the sedimentary environment and characteristics of the Wilcox group. The result shows that Wilcox group in the deep waters of the northern Gulf of Mexico pertained to deepwater basin-floor fan deposits. The sandstone is very fine to fine-grained arkostic and lithic sandstones. And, we analyzed the provenance of Wilcox and discussed the effect of salt related mini-basin controlling the deposition in deepwater setting. Based on this study, we propose a model for Wilcox deposition, in which the lower slope is defined as channel and there is deepwater fan in basin floor.