固体物理模型井间数据层析成像

TOMOGRAPHY FOR CROSSWELL DATA FROM SOLID MODELS

近年来已发表的用层析方法重建图象的物理模型井间数据都是在水槽内采集的,异常体与背景介质速度差都比较小.反投影重建采用直射线方法.本文介绍固体模型模拟井间采集方式.异常体与背景介质的速度差达46％,采用了弯曲射线成象方法.文中给出了楔形模型和断层模型用SIRT和LSQR联合层析成象的结果,并讨论了影响图象重建质量的各种因素.

Until recently, applied examples of tomography have worked with crosshole data which were collected from physical models with water as medium, in which the velocity contrast between the background and anomalous body is so low that the straight ray hypothesis appear to be acceptable in back projection reconstruction process. This paper will study the tomography for crosswell data from a model with solid medium, in which the velocity contrast goes up to 46%. In this case, the straight ray hypothesis is no longer valid and the fact of curved rays has to be honoured in reconstruction process. Some results obtained as a consequence of incorperating both SIRT and LSQR techniques for the reconstruction of a tapered and a fault models are given in the paper as well. In addition, the paper further discusses a number of factors that have influence on the quality of image reconstruction in tomography.