胜二区沙二段7砂组地层基准面旋回与沉积微相研究

Stratigraphic base-level cycles and sedimentary microfacies of Es_2-7 Formation in the Shengtuo Oilfield

应用油田开发区岩心、测井及地震等资料,对胜坨油田二区7砂组高分辨率层序发育特征以及不同级次基准面旋回内部沉积微相空间展布规律进行研究。研究表明,该区7砂组发育多级基准面旋回,包括1个长期基准面旋回、2个中期基准面旋回和9个短期基准面旋回,反映了可容空间与沉积物补给速率比值(A/S比值)在纵向上的多级变化发育模式,即在A/S比值总体向上变小的背景上,有多个次级A/S比值向上变小再变大的旋回。随着基准面的下降-波动-下降,沉积微相从7砂组底部的河口坝过度为地层中部的席状砂背景下残存的分流河道沉积,再到7砂组上部的河口坝沉积。A/S比值控制着研究区沉积微相的发育类型、展布模式。弄清楚研究区地层沉积特征与基准面旋回之间的关系对于精细储层表征和油田开发中后期井网调整具有重要指导意义。

Combining borehole data with dynamic data from the oil development area of Es_2-7 Formation in the Shengtuo Oilfield,the authors studied the features of the high resolution sequence stratigraphy and the sedimentary microfacies in different base-level cycles.The results show that the hierarchical base-level cycles are well developed and composed of one long-term cycle,two middle-term cycles and nine short-term cycles,indicating the hierarchical change of the accommodation space to sediment supply ratios（A/S） in a vertical direction.Several smaller cycles with decreasing-increasing A/S ratios were observed on a general decreasing A/S background.With the descending-fluctuating-ascending of base-level cycles,the microfacies change from the sheet pattern of relict distributary channel at the bottom to the combined pattern of mouth bar at the top of the 7th Formation.A/S ratios control the sedimentary microfacies types and distribution pattern,suggesting that the relationship between the sedimentation characteristics and the base-level cycles has a very important guiding significance in precise reservoir characterization and well pattern optimization.