【摘要】 在滨里海中区块地震时间剖面上,因高速盐丘的影响,盐丘下伏地层存在上拉现象,造成视觉上的假构造,给解释成图带来困难,也影响着钻探的效率.目前人们用变速成图和深度偏移的方法尚没能完全消除假构造的影响,主要原因是盐丘本身的速度不易精确刻画.在国内,因盐丘地质现象较少,识别盐下真假构造研究工作较少开展;而国外,也只是在最近几年叠前深度偏移技术实用之后,才有了一些研究进展.本文使用模型正演的方法,统计盐丘的平均层速度及其它各层的VSP或测井测量速度制作模型,找到了时间剖面上盐丘厚度与盐下地层向上拉伸量的变化规律.在实际应用中,识别确认了2个盐下真实构造、3个盐下假构造和2个可能真构造;其成果也已用于叠前深度偏移及构造成图分析等方面,并成为以后在类似地区的有效勘探方法之一.更多还原

【Abstract】 In the time seismic section in Middle block of Pre-Caspian basin,influenced by the high velocity salt dome,the subsalt strata reflection were pulled up caused by the upper salt dome,this phenomenon leads to visual pseudo-structure,difficult seismic interpretation and mapping and low drilling efficiency.Presently,Velocity-varying mapping technique and depth migration could not yet eliminate the effect caused by salt dome due to the difficulty to depict the velocity of salt dome accurately.In our country,as salt dome phenomenon is not common,there isn’t much study about identifying sub-salt structure;Abroad,there is some progress after the application of pre-stack depth migration in recent years.In this paper,the seismic forward modeling method was used to find the general rule dealing with the relation between the thickness of salt dome and the amount thickness of subsalt strata that have been pulled upward in time seismic section using salt dome statistical layer velocity and other VSP or logging velocity.By using this method,two real subsalt structures have been identified.Furthermore the method could also be used for analyzing of pre-stack depth migration and structure mapping and directing the next exploration methods.更多还原