地层切片技术在水下分流河道砂体解释中的应用

Application of Stratigraphic Slicing in Sandbody Interpretation of Underwater Distributary Channel

三角洲前缘沉积中,水下分流河道非常发育。水下分流河道砂体在横向上迁移摆动,垂向上相互叠合:在远离物源方向叠合不严重,上下2套砂体对应2套地震同相轴;在物源方向叠合很严重,上下2套砂体对应1套地震同相轴。因此,在地震剖面上进行人工解释很困难,往往会出现"串轴"问题。地层切片技术能使地震解释地质化,有助于找出有利砂体:应用单个地层切片,在平面上能很好地识别出多套砂体在横向上的迁移摆动情况,以便分析沉积相;应用相互关联的多张地层切片,在垂向上能判断每个砂体发育时间,刻画出砂体发育的期次。利用该方法在惠州X构造进行砂体解释,识别出A、B、C、D共4套砂体,经钻探证实,惠州X构造B砂体为有商业价值的岩性地层圈闭。

Underwater distributary channels were well developed in the delta front deposits.They migrated back and forth laterally and overlapped with each other vertically during the process of sedimentation.The overlapping of sandstone away from the source was not serious,the two sets of sandbodies upper and down were equals to 2 sets of seismic axis and they were equal to only one seismic axis when overlapping of sandstone was serious.Therefore,seismic interpretation was difficult to be done manually and mistakes would take place sometimes.The application of single stratum slicing makes it easy to recognize the migration and swing of several sets of sandbodies in the horizontal direction and analyze the sedimentary facies on the plane.Several strata slicing which correlated with each other in the vertical direction could be used to identify the times of sandstone developed and characterize the periods of sandstone development.Strata slicing which brings geological significance to the seismic interpretation can help us find the favorable sandstone.The 4 sets of sand A,B,C and D can be recognized by using the method to interpret Sand B in Structure A of Huizhou Sag.The sand B of the prospect A in Huizhou was drilled and proven to be a lithological trap,it obtains the commercial value.