南苏门答腊盆地北部新生代层序地层格架及有利储层分布

Phanerozoic sequence stratigraphic framework and reservoir distribution in the north of South Sumatra Basin

南苏门答腊盆地是在欧亚、印度洋-澳大利亚、太平洋三大板块交汇处发育起来的新生代弧后裂谷沉积盆地,经历了一次完整的海进—海退旋回。应用层序地层学的原理和方法,综合研究盆地北部钻井、测井及地震资料,确定4种层序界面识别标志,在盆地北部新生代始新世—中新世识别出2种类型层序界面:不整合面和沉积作用转换面。南苏门答腊盆地北部新生代始新世—中新世发育8个具有等时意义的层序界面,将其划分为7个三级层序。分析层序格架内基准面上升期与下降期地层叠加样式及沉积相构成特征,认为冲积扇、河流、三角洲和盆底低位扇等沉积体系是南苏门答腊盆地北部最重要的勘探目标,有利的岩性储集相带主要分布在基准面上升期,为后期盆地勘探的潜在领域,特别要重视对邻近不整合面或沉积作用转换面位置的储集层精细描述,选择有利相带进行钻探与评价。

South Sumatra Basin is located in the combination region of Eurasian-Asian, Indian -Australian and Pacific plates. It is a Phanerozoic back-arc tiffed basin and undergoes an integral cyclic succession of the transgression-regression. According to drilling, logging and seismic data in the north of the basin, four types of identification signs were determined to the Phanerozoic sequence boundary. And two kinds of sequence boundaries （unconformity and shift surface of deposition） were identified. Stratigraphic superimposed style and sediment feature inside the base level cycles were studied. The results show that eight isochronous sequence boundaries develop in the Phanerozoic stratigraphy, which divides into seven third-order sequences in the north of South Sumatra Basin further. A｜luvial fan system, fluvial system, delta system and basin floor fan are the key target series for exploration in the north of South Sumatra Basin. The distribution of advantaged lithologic reservoir facies is mainly developed in the half cycle of increasing A/S conditions, which is potential exploitation resource in the region.