摘要
大间距深度-时间约束高精度合成地震记录制作技术是在VSP速度校正人工合成地震记录基础上发展起来的,VSP速度校正人工合成地震记录的方法一般要求井下检波器的深度间距不大于20m,如果检波器深度间距逐渐增加"校正"的误差就要逐渐增大.大间距深度-时间约束合成地震记录制作技术弥补了前者的不足,利用各深度间隔顶、底的深度-时间和深度间隔内的声波时差,采用正文中描述的二分法双向计算时间序列的方法计算时间-反射系数序列,最大限度消除了只用声波时差数据计算时间序列产生的"累积误差",把深度-时间间隔的变化对人工合成地震记录"约束"精度产生负面影响的程度降低到最小,再用人工合成地震记录与井旁地面地震记录作相关,消除二者存在的"系统时间差",使人工合成地震记录与井旁地面地震记录达到最佳匹配.
The development of high-precision synthetic seismic record constrained by large spacing depth-time is based on the synthetic seismogram correcting by VSP speed, which generally requires that the depth interval of well seismometer is no more than 20 m, and in which the depth-time transforming of synthetic seismogram is completely calculated by the average velocity obtained from VSP data. With the increasing of detector spacing, the ＂correction＂ error also increases gradually. In order to make up for the deficiency of the traditional method, the technology of high-precision synthetic seismic record constrained by large spacing depth-time is introduced in this paper. Assuming that the acoustic log is divided into N-1 intervals by N down-hole detectors, for the acoustic data and the one-way travel time in top and bottom of corresponding interval obtained from VSP data in each interval, the bidirectional calculating time series with bisection method described in this paper is applied to calculate the time-reflection coefficient series in corresponding depth interval. At last, the full-interval time-reflection coefficient series is made up of N-1 time-reflection coefficient. And this method eliminates utmost the ＂accumulated error＂ in calculating the time series of full interval only by acoustic data, minimizes the negative effect on the constrained precision of synthetic record resulting from the spacing variation. At the same time, the ＂system time difference＂ between the synthetic seismogram and the well-nearby seismic records is eliminated by correlation so that the synthetic seismogram and the well-nearby seismic records can achieve a best matching.
出处
《地球物理学进展》
CSCD
北大核心
2013年第2期808-814,共7页
Progress in Geophysics
关键词
累积误差
全井段VSP速度校正
局部合成地震记录
二分法双向计算时间序列
系统时间差
accumulated error, VSP speed Correction of full-length well, local synthetic seismogram, bidirectional calculating times series with dichotomy method, system time difference
