基于地质统计学的沙漠地区逐点时深曲线静校正方法

A point-by-point time-depth curve static correction method based on geostatistics

在我国西部沙漠地区,起伏剧烈的沙丘造成了严重的静校正问题。在沙丘成因单一、物性变化不大的沙漠区,通常应用时深曲线静校正方法来解决静校正问题,但在沙丘成因多样化或者沙漠边缘区域,应用常规的时深曲线静校正技术误差较大。基于微测井测量数据的地质统计学分析结果,提出了一种逐点时深曲线静校正方法。基于数据正态分布检验、变异函数分析等地质统计学手段,明确了沙漠地区沙层厚度与地震波垂直传播到地表的时间之间具有空间分布相关性,在此基础上利用克里金插值方法对微测井测量数据进行插值,得到各炮点和检波点处的时间深度散点数据,再利用最小二乘法对所有散点进行拟合,获得炮点和检波点的时深曲线量板,计算静校正量。以准噶尔盆地S1X工区野外64口微测井的测量数据为控制点,采用上述方法计算得到各个炮点和检波点的静校正量,并对计算结果进行了交叉验证,该方法获得的静校正量与微测井获得的静校正量基本一致。应用该静校正量进行了叠加成像,并与常规静校正方法处理后的共炮点道集和叠加剖面进行了对比,结果显示,逐点时深曲线静校正方法的应用效果明显优于常规时深曲线静校正方法。

In the desert areas of Western China,the rolling sand dunes cause substantial static correction problems.Although conventional time-depth curve static correction technology can resolve static correction when the dune has a single cause and homogenous physical properties,it produces significant errors when applied to areas where the dune has diverse causes or desert edges.Based on the geostatistical analysis of microlog data,a point-by-point time-depth curve static correction method is proposed.First,this method reveals a clear spatial distribution related correlation between the sand dune thickness and the seismic wave vertical transmission time,based on a normal distribution test and variance function analysis.The depth-time scatter data of shot and receiving points are obtained using the Kriging interpolation method.Next,all discrete points are fitted using the least squares method to achieve a time-depth curve measuring board of each shot point and detection point.Finally,the static correction values are calculated and cross-validated.By taking micro logging data from 64 wells from the S1X work area as the control point,the application results showed that the static correction values obtained by the proposed method are consistent with those obtained by micro logging.The stacked imaging with these static correction values was superior to that obtained with the conventional time-depth curve static correction method.