Improved Potential Field Correlation Imaging Method
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摘要: 位场相关成像是根据实测异常与地下不同位置地质体所产生异常之间的相关系数来快速获得地质体的空间位置.现有的相关成像方法是利用球体模型来模拟地下地质体的形状，当场源体的实际形状与球体相差较大时，计算结果势必出现较大误差.为了解决这一问题，对该方法进行改进，以不同模型来模拟地下地质体形状，计算其产生异常与实测数据的相关系数，理论上使相关系数取得最大值的模型与实际地质体情况一致.因此，改进后的方法不仅可以获得地质体的位置参数，还可以对地质体的类型(构造指数)进行估计.磁异常的相关成像计算采用异常的解析信号来完成，这样可有效地避免磁化方向的干扰，且计算公式相对简单.通过理论模型试验，证明此方法可以成功地完成位场数据的反演工作，且稳定性较高.最后将其应用于上海实测磁异常数据的解释中，获得了地下未爆炸物的分布情况.Abstract: Potential correlation imaging method uses the correlation coefficient of the anomaly generated by the different location of geologic bodies and the observed data to rapidly obtain the location of the causative sources. The existing correlation imaging methods only use the sphere to simulate the shape of the geologic bodies, when the real shape of the source is different from sphere, and the inversion results suffer large errors. To solve this problem, we present improved correlation imaging method, which computes the correlation coefficients of the observed anomaly and the anomalies generated by different types of the model, respectively, and the larger one of the maxima of the correlation coefficients calculated by different models corresponds to the true model. The improved method can both obtain the depth and the nature (structural index) of the source. We use the analytic signal to compute the correlation coefficient of magnetic anomaly, which can avoid the interference of magnetization direction, and the calculation equation is simpler. We try the method on synthetic potential field data, and the inversion results indicate that the method can successfully finish the inversion of potential field data, and produce more stable results. We have also applied it to measured magnetic data, and we obtain the distribution of the unexploited body.
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Key words:
- geologic models /
- potential field /
- correlation imaging /
- nature /
- analytic signal /
- data processing
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图 4 板状体磁异常相关成像结果
a.埋深为5 m的板状体产生的磁异常；b.磁异常的解析信号；c.构造指数为1的结构函数与解析信号的相关系数；d.构造指数为2的结构函数与解析信号的相关系数
Fig. 4. Correlation imaging of magnetic anomaly generated by the dike
图 6 上海某工地实测磁异常(a)和磁异常的解析信号(b)
a.实测磁异常；b.磁异常解析信号
Fig. 6. Measured magnetic anomaly in Shanghai (a) and analytic signal of the data in 6a (b)
图 7 实测磁异常相关成像结果
a.y=147处剖面的相关成像结果；b.相关系数结果的三维显示
Fig. 7. Correlation imaging of real magnetic anomaly
表 1 构造指数与地质模型之间的关系
Table 1. Correlation between structural indices and geological models
构造指数 磁场反映的构造 重力场反映的构造 0.0 无限薄板盖层 岩墙，台阶 0.5 垂直接触带 薄板 1.0 板状体、岩墙 水平圆柱体 2.0 水平圆柱体 球体 3.0 球体 无 
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表 2 构造指数与相关系数最大值之间的对应关系
Table 2. The corresponding relationship between the structural indices and the maxima of correlation coefficients
构造指数 相关系数最大值 2.0 0.856 5 2.2 0.877 1 2.4 0.910 5 2.6 0.939 6 2.7 0.978 2 2.8 0.981 3 2.9 0.975 4 3.0 0.942 7
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