莺歌海盆地中新统黄流组一段重力流沉积特征

Sedimentary characteristics of gravity flow deposits in the first member of Miocene Huangliu formation,Yinggehai basin

为揭示莺歌海盆地中新统黄一段的有利储集相,运用沉积学及层序地层学的理论和方法,基于岩心、钻测井、分析化验及三维地震资料对区内重力流沉积特征、演化规律及主控因素开展了综合分析,认为重力流沉积影响因素主要为地形、相对海平面升降、物源及构造运动等,重力流沉积可进一步识别出水道、朵叶、堤岸/溢流及泥质沉积单元.结果表明:黄一段可划分为3个三级层序(SQ1-SQ3),自下而上总体呈相对海平面上升的退积特征;各层序具明显的"二分"特征,下部发育水道、堤岸/溢流及朵叶,上部多发育泥质沉积;水道以砂岩为主,堤岸/溢流为细砂-粉砂岩,朵叶为砂泥互层;陆架区重力流的发育主要受地形控制;此外,相对海平面升降、物源及构造运动等因素也起着重要作用;海底扇中扇分支水道和朵叶为有利的储集相,复合水道及堤岸/溢流沉积为潜在的储集类型.

In order to reveal the favorable reservoir facies in the Huang 1 Member in the Mio- cene, Yinggehai basin, this study used the principles of sedimentology and sequence stratigra- phy, an integrated dataset containing core, drilling, logging, analysis assay and 3-D seismic data to investigate the gravity flow sedimentary characteristics, evolution and the main control- ling factors. Based on above analysis, this study concluded that the main influence factors of gravity flow deposits were morphology, relative sea-level change, sediment source, tectonic movement, etc. What＇s more, channel, lobe, levee/overbank, and muddy deposit had been further identified. The results show that： Huang 1 Member can be divided into three third or- der sequences （SQ1-SQ3）, which displays relative sea level rising retrogradation from bottom up; each sequence displays ＂bipartite＂ feature, and channel, levee/overbank and lobe well de- velop in lower, but muddy deposits were mostly in the upper; Channel was mainly sandstone- rich while levee/overbank was dominantly fine-siltstone-rich, and lobes were interbeded sandstone and mudstone. Gravity flow deposits were mainly controlled by morphology on continen- tal shelf. In addition, relative sea level change, sediment supply and tectonic movement were probably important factors. Bifurcated channel and lobe in middle fan of submarine fan are fa- vorable reservoir facies. Channel complex and levee/overbank are potential reservoir facies.