尼日尔三角洲Stubb Creek油田阿格巴达组层序地层学研究

Study on sequence stratigraphy in Stubb Creek Oilfield of Niger delta

根据测井、岩屑录井及地震资料,尼日尔三角洲Stubb Creek油田阿格巴达组可划分为SQ1、SQ2、SQ33个层序。每个层序均由低位体系域、海侵体系域和高位体系域组成,符合Vail经典的层序地层学模式。各层序低位体系域底部在地震剖面上表现为一系列的削截面,高位体系域由下超面组成。层序界面还表现为沉积相的突变面。最大海泛面位于自然伽玛最大值处。低位体系域砂体在研究区北部最发育,向南部逐渐减薄,这与研究区的物源位于北部有关。研究区沉积体系包括下切谷充填、浅海陆棚和三角洲沉积体系。下切谷沉积体系分布在各层序低位体系域,浅海陆棚沉积体系分布在海侵体系域和高位体系域,而三角洲沉积体系仅分布在高位体系域。

Based on logging , sieve residue log and seismic Stubb Creek of Niger delta can be identified, including SQ1, SQ2 data, three sequences of Agebada Formation in and SQ3. Every sequence can be subdivided into Lower Stand Tract （LST）, Transgressive Stand Tract （TST） and High Stand Tract （HST）, which is correspondent to the classic sequence model advocated by Vail. The bottom of LST in each sequence presents a series of truncation surfaces, and HST consists of downlap surfaces. On the other hand, the sequence bounders also present surface of facies discontinuity. The maximal flooding surface locates at maximal value of GR. The LST presents very well in northern studied area, and becomes thinner northward, and this trend is relative with provenance that is located at northern area. The sedimentary systems include incised valley, shelf and delta. Incised valley distributes in LST of every sequence, and shelf in TST and HST, but delta only distributes in HST.