利用余弦变换计算重力异常的向上延拓  

Calculating upward continuation of gravity anomalies using cosine transfrom

作　　者：张凤旭[1] 姜正奎[2] 张凤琴[1] 杨恕[2] 

机构地区：[1]吉林大学地球探测科学与技术学院,长春130026 [2]中国石化集团新星公司西南石油局第二物探队,德阳618000

出　　处：《地球物理学进展》2007年第1期57-62,共6页Progress in Geophysics

基　　金：大庆探区外围中新生代断陷盆地群演化与油气远景项目(XQ-2007-07-05)资助

摘　　要：利用余弦变换计算重力异常的向上延拓是一种新方法.根据余弦变换的基本性质,推导了二度、三度体异常向上延拓余弦变换谱理论公式,采用离散余弦变换实现了该法的数值计算;研究了无限长水平圆柱体的补偿因子中主频段的特性,给出了二度体的线性补偿方式;补偿后的理论模型异常向上延拓具有较高的计算精度,除边部几个数据因数据的离散和有限截断使误差较大外(最大误差为6.23%),其余数据的误差均在1%以内,理论值和计算值曲线基本重合.这说明,与Fourier变换相比,离散余弦变换在数值计算中,受非周期性深度因子的影响小,补偿方式易于选择,其计算方法优于Fourier变换.Calculating upward continuation of gravity anomalies using cosine transform is a new method. According to the essential properties of cosine transform, the paper develops theoretic formulas of cosine transform spectrum that were upward continuation of gravity anomalies for two and three-dimensional bodies and accomplished their numerical calculation using the discrete cosine transform. We studied the characteristics of dominant frequency of infinite hori- zontal cylinder in compensated factor and quve the linear compensation way of two-dimensional bodies. There ar higher computing precision in upward continuation of model gravity anomalies after compensation except that errors ol several data of boundary are bigger because of discrete and finite truncation of gravity anomaly, errors of other data are within 1 %. The theoretic and computing curve were approximately superposed. It is shown that the discrete cosine transform had lesser effect by non-periodical depth factor, and the compensated way was prone to choice compared to the Fourier transform in numerical calculation. It is that the cosine transform is superior to the Fourier transform.

关 键 词：余弦变换 向上延拓 主频段 线性补偿方式 计算精度 

分 类 号：P631[天文地球—地质矿产勘探] P312[天文地球—地质学]