苏丹Muglad盆地Moga地区Abu Gabra组二段层序及沉积微相

Sequence and Sedimentary Microfacies of the Second Member of Abu Gabra Formation in Moga Area of Muglad Basin,Sudan

为了探究Muglad盆地Fula凹陷Moga地区岩性-地层圈闭的勘探潜力,利用11口钻井资料,参考地震资料,运用层序地层学、沉积学理论和方法,将AbuGabra组二段自下而上划分为ag2-3、ag2-2、ag2-1四级层序,每个层序均以最大湖泛面为界划分为湖泊扩张体系域(ESTa2-3、ESTa2-2、ESTa2-1)和湖泊萎缩体系域(SSTa2-3、SSTa2-2、SSTa2-1)。AbuGabra组二段发育的沉积相类型为辫状河三角洲、湖泊相和湖底扇;各四级层序体系域地层厚度分布特征均反映了东北高西南低的总体古地貌特征;古地貌控制了沉积相带的分布:ESTa2-3体系域,东部和北部发育辫状河三角洲,向西、南相变为较深湖,Moga-8井附近还发育湖底扇;SSTa2-3和ESTa2-2体系域,东北部发育辫状河三角洲,西南部发育滨浅湖砂质滩坝;SSTa2-2、ESTa2-1、SSTa2-1体系域,东北部和东南部均有辫状河三角洲发育,SSTa2-2、ESTa2-1体系域Moga-8井附近发育湖底扇,SSTa2-1体系域Moga-8井附近发育砂质滩坝。

In order to explore the exploration potential of lithologic-stratigraphic traps in Moga area of Fula Sag,Muglad Basin,based on the drilling data of 11 wells and seismic data,by means of theory and method of sequence stratigraphy and sedimentology,the second member of Abu Gabra Formation was divided into three 4th-order sequences of ag2-3,ag2-2 and ag2-1from bottom to top,and each 4th-order sequence can be further subdivided into lake expanding system tract (ESTa2-3,ESTa2-2,ESTa2-1) and lake shrinking system tract (SSTa2-3,SSTa2-2,SSTa2-1) by the maximum flooding surface.The sedimentary facies of the second member of Abu Gabra Formation are braided river delta,lacustrine facies and sublacustrine fans.The stratum thickness distribution characteristics of each 4th-order sequence system tract reflect the general paleogeomorphic feature which is high in the northeast and low in the southwest of Moga area.Palaeogeomorphology controls the distribution of sedimentary facies zones:in the ESTa2-3 system tract,the braided river delta developed in the east and north parts,and changed into deeper lacustrine facies toward west and south,and the sublacustrine fan developed near the Well Moga-8;In the SSTa2-3 and ESTa2-2 system tracts,the braided river delta developed in the northeast part,and the shore-shallow lacustrine sandy beach bars developed in the southwest part;In the SSTa2-2,ESTa2-1 and SSTa2-1 system tracts,the braided river delta developed in the northeast and southeast parts,and the sublacustrine fans developed near well Moga-8 in SSTa2-2 and ESTa2-1 system tracts,and the sandy beach bars developed near well Moga-8 in SSTa2-1 system tract.