等时格架及地震反演双重约束的精细砂体对比研究

Research on fine sandbody correlation method under the double constraints of isochronous framework and seismic inversion

为了对相变迅速、砂体横向变化大的陆相地层进行等时砂体对比,并对有利砂体的展布规律进行较为精确的评价和预测,以川西坳陷新场-丰谷地区上三叠统须家河组四段为例,提出了等时格架及地震反演双重约束的精细砂体对比方法.通过建立砂体对比的等时地层格架,利用单井岩性、沉积特征及测井、三维地震资料,进行砂组划分与对比,结合等时地层格架约束的地震反演进行精细砂体对比.结果表明：沿辨状主河道的FG21—CF125井一带可识别出19套砂体,多呈透镜状分布,其两侧可识别的砂体为11套或更少,有多套砂体的缺失.相比较传统的＂砂对砂,泥对泥＂的对比方式,能确保5~8 m的砂体对比不串层,有效性分析表明砂体对比的结果是可信的.

To study the isochronous sandbody correlation of continental environment strata with rapid changes of facies and sandbody distribution vertically and laterally,and evaluate and predict the favourable sandbodies,a new method for the double constraints of isochronous framework and seismic inversion was proposed taking the 4th member of Upper Triassic Xujiahe formation in Xinchang-Fenggu area as an example.Based on the isochronous sequence stratigraphic framework,sandstone groups were divided and correlated using the lithologic,sedimentary,logging and tridimensional seismic data.By means of seismic inversion under the constraint of isochronous framework,the sandbodies were correlated finely.The results show that nineteen sets of lenticular sandbodies along the FG21—CF125 zone and eleven sets or less sandbodies deposited along the both sides outward can be recognized.Comparing with the traditional correlating means of ＂from sandstone to sandstone and from mudstone to mudstone＂,the distinguishable thickness of sandbodies for correlation can reach to 5-8 m.The availability analysis shows that the effects of sandbody correlation are believable.