井间地震资料层位标定方法研究

Stratigraphic calibration method for seismic crosshole data

制作高精度的深度域合成地震记录是实现井间地震资料层位标定的关键。介绍了采用深度域不对称子波算子求取合成地震记录的方法,即对已有的测井曲线,利用有效地震地质模型分析方法进行层位划分并建立深时关系;根据由波动方程导出的反射系数计算公式,求取频率域的反射系数;把井旁道记录转换到时间域.利用相关分析方法提取实际资料的地震子波,进而得到频率域的子波谱;利用频率域褶积模型计算合成记录,经傅里叶反变换、时深转换和重采样后得到深度域合成地震记录。实际应用表明,采用深度域方法制作的合成记录与井旁地震道吻合程度较高,可以用于井间地震资料的层位标定。

To calibrate strata of seismic crosshole data, what is crucial is to making high precision synthetic seismogram. And there is great difference in making methods of depth domain and time domain. The making procedure in depth domain consists of the following steps: Firstly, classify horizons by the log data, and build up depth-time relationship, and calculate reflectivity coefficients through the reflectivity formula derived from elastic wave propagation e-quation of multiple horizontal media. Secondly, extract seismic wavelet from borehole side seismic trace with autocorrelation method to get wavelet spectrum. Thirdly, calculate synthetic seismogram by convolution model formula, and get synthetic seismogram in time domain by anti-Fourier transform, and then request the corresponding depth one of every sample in time domain, and resample according to needed sample interval in depth domain to get synthetic seismogram in depth domain. The synthetic seismogram made by those methods fit greatly borehole side trace, and may use reliably in horizon identification of cross-well data by the practical application.