大地电磁测深拟地震时间剖面解释法研究

【作者】 杨晓弘；

【导师】 席振铢；

【作者基本信息】 中南大学 ， 地球探测与信息技术， 2005， 硕士

【摘要】 大地电磁测深拟地震解释法是依据电磁波和弹性波在数学表达形式上和物理意义上都有一定的相似性原则,把地震法中行之有效的方法来用运到电磁法中的一种电磁解释方法。大地电磁测深拟地震时间剖面解释方法,在一维水平均匀层状介质条件下能有效地划分反射界面和电性层位,较之常规解释方法具有自己的特点,但是拟地震解释法和其它地球物理勘探方法的反演方法一样,都存在解的非唯一性。因此,如何缩小和判断解的非唯一性、提高解的精度和可靠性,取得更接近真实的地球物理模型,就成了拟地震解释法一项亟待研究的课题。 本文首先概述了大地电磁测深的发展概况及其数据处理的方法技术,重点阐述了大地电磁测深和地震勘探法的相关技术,论述了拟地震解释法的基本原理;推导了一维断面模型下拟地震法的反演计算公式,编写出了计算拟地震反射系数的程序;论文计算了一维两层、三层和四层不同模型参数的反射系数,说明在一维水平均匀层状介质条件下,大地电磁测深拟地震时间剖面解释方法能有效地划分反射界面和电性层位。 论文又从拟地震法中“微层”入手,探讨“微层”对反演结果的影响规律,以一维两层、三层和四层为模型,通过取不同厚度“微层”,反演计算反射系数,总结了不同厚度“微层”,对反演结果影响的基本规律是:1、相同模型不同厚度“微层”参数,其反演结果不尽相同;2、“微层”厚度划分越细,反演的结果与实际越接近;3、“微层”厚度越细,反演计算时间越长,成本增高;4、第一层电性层至少划分为两个“微层”,这样才能保证反演结果的正确性。 论文通过计算不同模型参数的反射系数的变化规律,论证在一维水平均匀层状介质条件下,大地电磁测深拟地震时间剖面解释方法能有效地划分反射界面和电性层位。同时,论文又通过“微层”厚度对反演计算结果的影响规律探讨,论证了“微层”厚度是影响拟地震解释法解的非唯一性的关键技术之一,科学合理选择“微层”厚度参数是提高解的精度和可靠性,实现反演更接近真实的地球物理模型的基础。更多还原

【Abstract】 The pseudo - seismic interpretation is the method of to draw up the earthquake to explain the method deeply according to the similar to flexible wave express the formality and the physics meanings in mathematics top certainly all have principle of electromagnetic wave, valid method go in the earthquake method to use to carry the electromagnetism method of a kind of electromagnetism explain the method. The pseudo - seismic interpretation , can divide the line to reflect the interface availably under the condition of 1D , compared with the normal regulations that it have its own characteristics , but the pseudo - seismic interpretation like other Earths physics methods all exist fault. Therefore, how contract and judge the fault and raise the accuracy and credibility of the solution, becoming a urgent task.First, the article explain the general development of the Magnetotell-uric and its data processing ,and explain the method of the explores and the techniques of the earthquake explore , and discuss the basic principles of the pseudo - seismic interpretation;Deduced the formula under the 1D section model write out the calculation procedure of the pseudo - seismic , We computed the two-layer, three-layer and four-layer of 1D of the differ- rent model parameter.It is obvious that the pseudo - seismic interpretation can divide the line of the reflection and electricity layers,under the condition of lD,The inversion of the influence regulation of result from drawing up the earthquake method to commence in" tiny layer", inquiry into" tiny layer" to, with two layers of 1D, three" tiny layer" of different from four layers for model, pass to take thickness of layers, the inversion to compute the glint coefficient, tally up" tiny layer" of different thickness, to anti- play basic regulation of the result influence is: 1) the same model,with different thickness" tiny layer" parameter,which is anti- to play the not exhausted ho-mology of result;2) the " tiny layer" thickness was divided more thin, the inversion result wad more precious;3) " tiny layer" thickness is more thin, the inversion to compute time more long, the cost increase high;4) the first floor electricity layer divides the line to two" tiny layer" at least,then can guarantee thus the inversion accuracy of result.The article argument that under the condition of lD,the earth elect-romagnetism measure and draw up the earthquake time section to explain the method and can divide the line to reflect the interface and electricity layers availably . At the same time , the " tiny layer" thickness to inversion the influence regulation study of compute the result, argument" tiny layer" thickness is one of the key techniques that the influence draws up not unique that the earthquake explains the solution, reasonably choice the " tiny layer" thickness and parameter is an accuracy and credibility, carry out the inversion of more prcious physics model.更多还原