层间速度差分析在伦坡拉盆地圈闭评价中的应用

APPLICATION OF DIFFERENTIAL INTERFORMATION VELOCITY ANALYSIS TO TRAP EVALUATION IN LUNPOLA BASIN

讨论了伦坡拉盆地叠加速度的基本特征,以及由其导出的层间速度差分析(DIVA)在圈闭评价中的应用.其叠加速度资料有两个显著特点:(1)叠加速度并不随地层的埋藏深度增加而变差,其各个反射层的叠加速度曲线形态从浅到深没有多大变化;(2)叠加速度随地层的埋藏深度增加而递增的趋势不明显,尤其是在同一套地层中,叠加速度的这种自然递增更小.层间速度差分析结果表明,伦坡拉盆地的东部 DIVA 异常好于西部地区,这或许表明东部含油气情况优于西部地区;从 DIVA 异常的纵向分布来看,深部的 DIVA 异常好于浅层,牛堡组好于丁青湖组.以上特征基本与现有钻井勘探情况相符.此外,LJ-93-16Z1测线在坳陷内部还显示出一个较好的 DIVA 异常,它可能揭示了一个新的有利勘探区.

Seismic velocity characteristics resulted from the analysis of the stacking velocity spectrums and application of differential interformation velocity analysis(DIVA)to trap evaluation are discussed.The results show that:(1)the quality of stacking velocity data does not change worse with the increase of me- dium burial depth;(2)the quantity or numberation of stacking velocity data does not have much change (or enlargement)with the increase of medium burial depth.As a result of DIVA study of 10 seismic lines,DIVA anomaly in the eastern part of Lunpola Basin is better than that in the western part.There are some better DIVA anomalies in deeper Niubao Formation than those in shallower Dingqinghu Forma- tion.It is assumed that there is a better hydrocarbon existence in the east than in the west,and in deeper Niubao Formation than in shallower Dingqinghu Formation,which is in correspondence with the results of well-drilling of the basin.The DIVA profile of seismic line LJ-93-16Z1 indicates a better DIVA anomaly in the inner part of central depression.It is suggested the DIVA anomaly may reveal a very good potential hydrocarbon-bearing area.