义北油田大43块沙四上亚段沉积微相研究

义北油田大43块位于济阳坳陷义和庄凸起东北部的斜坡带,东邻四扣洼陷,北邻郭局子洼陷。受区域构造运动的影响,研究区发育多期区域不整合,地层超覆、剥蚀现象普遍,是被断层复杂化的岩性断块及构造岩性油藏,具有较高的开发潜力。本研究旨在针对目前制约大43块勘探开发面临的沉积微相和储层分布问题,依据区内已有的和邻近地区的地震、钻测井、分析化验等资料,研究该区的构造演化,对沙四段地层进行精细划分,采用点-线-面的思路,逐步进行单井相分析、连井剖面对比以及沉积微相展布恢复。通过研究地震剖面确定了西南方向古隆起的存在,确定了近物源来自于西南方向,对沙四上亚段进行了统层,并建立了扇三角洲前缘-滨浅湖滩坝沉积体系。沉积微相研究结果表明,在横向上,沙四上亚段以扇三角洲相的扇三角洲前缘亚相和滨浅湖滩坝亚相为主;在纵向上,沙四段为扇三角洲沉积经湖盆扩大过程发育为滨浅湖滩坝沉积体系的过程,砂体主要发育在沙四上的三砂组和二砂组的下部,碳酸盐岩沉积主要发育在一砂组。

Sedimentary microfacies in the upper submember of the fourth member of the Shahejie Formation in the Yibei Oil Field, Shandong

The D43 block in the Yibei Oil Field lies in the slope zone of the northeastern Yihezhuang uplift in the Jiyang depression. Controlled by the regional tectonic movement, the multiphase regional unconformity, widespread stratigraphic overlap and erosion are observed in the study area. The fault-block and lithologic oil reservoirs formed in the complex fault-thrust anticline are believed to have great petroleum exploration potential. The present paper focuses on the tectonic evolution, sedimentary microfacies and stratigraphic division of the upper submember of the fourth member of the Shahejie Formation in the D43 block, Yibei Oil Field in the light of well logs, seismic and analytical data. The results of research show that the principal source of detritus lay to the ancient uplift in the southwest. Horizontally, the upper submember of the fourth member of the Shahejie Formation is mostly built up the fan delta facies include the fan delta front and littoral-shallow lake beach/bar subfacies. Vertically, there are gradations from the fan delta to the littoral-shallow lake beech-bar depositional systems. The sedimentary microfacies in the upper submember of the fourth member of the Shahejie Formation including the subaqueous distributary channel, channel-mouth bar, sandbar and carbonate shoal microfacies, which are interpreted as the good oil reservoirs. The bathyal lake oil mudstones and oil shales in the third member of the Shahejie Formation occur as good source rocks and cap rocks of the fourth member of the Shahejie Formation.