摘要:
静态效应是深部探测噪声之一. 为深入认识静态效应,以均匀大地为背景,卡尼亚视电阻率为解释参数,分别模拟旁侧和轴侧两种观测方式中含有静态效应的地表响应,得到以下结论:( 1) 两种观测方式中的静态效应特征表现一致. (2)异常体正上方的测点受干扰程度最大,测点离异常体越远,受干扰程度越小. (3)低阻异常体引起干扰区域的等值线下凹,电阻率越低下凹越明显,高阻异常体引起干扰区域的等值线上凸,但增大异常体的电阻率,等值线上凸的变化并不明显;无论是低阻异常还是高阻异常都会引起干扰区域的中高频段等值线近乎直立.( 4)低阻体的静态效应使低频段的标准曲线平行下移,但在中高频段标准曲线平行下移程度与低阻体的电阻率有关,电阻率越低,标准曲线平行下移程度越差,这是由于电阻率较低的异常体在中高频段有较强的电磁感应异常,这种异常被叠加到了静态效应中;而高阻体的静态效应使标准曲线在整个频段上平行上移. 研究结果可为静态效应的识别及校正算法的改进提供参考,具有一定的理论和应用价值.
Abstract:
Uneven electric body near the ground surface interferes the target field, which is called static effect that is regarded as one of the noises of deep exploration. In order to deeply understand the static effect, the authors simulated respectively the ground surface re-sponses of axial and asides observation methods on the conditions of taking homogeneous earth as model background and Cagniard ap-parent resistivity as explanation parameter. Some conclusions have been reached:( 1) The effects of static characteristics of the two ob-servation methods are consistent. ( 2) The interference is maximum for measuring points above the anomaly body. On the contrary, the interference is minimum for the points which stay away from the anomaly body. ( 3) Low resistivity abnormal body causes the contours of the interference area to become concave. The resistivity is lower. High resistivity abnormal body causes the contours of the interfer-ence area to become convex. However, changes of contours into convexity are not obvious although the resistivity of anomaly body is en-larged. Both low resistivity abnormal body and high one cause the mid-low frequency contours to become nearly erect in the interference area;( 4) The static effect of low resistivity causes the standard curve to be parallel downward in mid-low frequency, but in high fre-quency the extent of the standard curve paralleling downward depends on low resistivity value, the lower the resistivity is, the less par-allel the standard curve downward is, because of stronger electromagnetic induction for lower abnormal body which is superimposed up-on the static effect. However, the static effect of high resistivity causes the standard curve parallel upward in full frequency, which is consistent with previous conclusions. The results can provide a reference for the identification and improvement of static effect correction algorithm and hence has a certain theoretical and practical value.
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