重力勘探中地形改正方法的研究及应用
发布时间：2018-07-27 16:06
【摘要】：重力勘探是传统的地球物理勘探方法,重力异常是地下地质体密度变化的反映。布格重力异常的外部校正主要包括地形改正、正常场改正和高度改正。在地形切割较大地区,各测点周围的地形对各点的重力影响值也各异,如果忽略地形起伏对计算结果的影响,往往会给解释工作者提供虚假异常或使异常曲线发生明显畸变,这样就会影响异常的解释精度。由于重力仪的测量精度大幅提高,精确的数字高程数据也可以容易获得,现在地形改正误差成为影响重力勘探解释效果最主要的因素;所以已有的布格重力异常外部改正方法技术已经不能满足现有勘探问题对重力异常精度的要求;故必须提高布格重力异常外部改正方法技术的精度。不同的地形改正方法有不同的精度。本文研究并分析了传统方域积分(体积积分)的不足:一是方域对实际地形拟合(方柱拟合)不好;二是传统方法采用的梯形数值积分的地形改正精度低而不能满足目前高精度重力测量的要求。本文模拟研究了基于对地形表面的面积分,然后用精度比较高的高斯数值积分代替原来的梯形积分。通过模型实验的结果表明,一是表面积分法重力地形改正方法对于地形的拟合比传统方域要好,二是地形改正计算精度有了明显的提高。为了验证表面积分的应用效果,采用两个工区的实际地形资料,对测区分别进行方域法地形改正和表面积分法法改正的计算,研究不同地形条件下两种方法的计算结果。对计算地形改正后得到的总地形改正值、局部重力异常进行误差比较,分析两种方法的各自特点。无论是计算结果和计算效率方面,都证明了基于面积积分的地形改正方法优于传统的方域地形改正方法。将表面积分法地形改正成功的应用到了实际资料的处理中,并取得了很好的效果。为了提高获取重力中、远区地形改正节点高程的精度和效率,初步讨论利用Google earth系统软件获取西藏某地区节点高程,验证了利用获取的高程进行重力中、远区地形改正的可行性。
[Abstract]:Gravity exploration is a traditional geophysical exploration method and gravity anomaly is the reflection of the density change of underground geological body. The external correction of Bouguer gravity anomaly mainly includes terrain correction, normal field correction and height correction. In the larger area of terrain cutting, the gravity influence values of the topography around each survey point are different. If the influence of topographic fluctuation on the calculation result is ignored, it will often provide false anomalies to the interpreter or make the abnormal curve appear obvious distortion. This will affect the interpretation accuracy of the anomaly. As the precision of gravimeter is greatly improved, the accurate digital elevation data can be easily obtained. Now the error of terrain correction has become the most important factor affecting the interpretation effect of gravity exploration. Therefore, the existing external correction techniques for Bouguer gravity anomalies cannot meet the requirements of the existing exploration problems for the accuracy of gravity anomalies, so the precision of the external correction methods for Bouguer gravity anomalies must be improved. Different terrain correction methods have different accuracy. This paper studies and analyzes the shortcomings of the traditional square domain integral (volume integral): first, the square domain is not good for the actual terrain fitting (square column fitting); Second, the traditional method of trapezoidal numerical integration has low accuracy of terrain correction and can not meet the requirement of high precision gravity survey. In this paper, the area fraction of terrain surface is simulated and the Gao Si numerical integral with high precision is used to replace the original trapezoidal integral. The results of model experiments show that one is that the surface integration method is better than the traditional square domain, and the other is that the accuracy of terrain correction is obviously improved. In order to verify the application effect of surface integration, the actual topographic data of two working areas are used to calculate the topographic correction by square domain method and surface integral method, respectively. The results of the two methods under different terrain conditions are studied. The errors of the total terrain correction and the local gravity anomaly are compared and the respective characteristics of the two methods are analyzed. It is proved that the area integral based terrain correction method is superior to the traditional square domain terrain correction method in terms of calculation results and computational efficiency. The topographic correction of surface integration method has been successfully applied to the processing of practical data, and good results have been obtained. In order to improve the accuracy and efficiency of obtaining the elevation of the node in the remote area of gravity, the paper preliminarily discusses the use of the software of Google earth system to obtain the elevation of a node in a certain area of Tibet, and verifies that the obtained elevation is used in gravity. Feasibility of remote terrain correction.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P631.1
本文编号：2148366
[Abstract]:Gravity exploration is a traditional geophysical exploration method and gravity anomaly is the reflection of the density change of underground geological body. The external correction of Bouguer gravity anomaly mainly includes terrain correction, normal field correction and height correction. In the larger area of terrain cutting, the gravity influence values of the topography around each survey point are different. If the influence of topographic fluctuation on the calculation result is ignored, it will often provide false anomalies to the interpreter or make the abnormal curve appear obvious distortion. This will affect the interpretation accuracy of the anomaly. As the precision of gravimeter is greatly improved, the accurate digital elevation data can be easily obtained. Now the error of terrain correction has become the most important factor affecting the interpretation effect of gravity exploration. Therefore, the existing external correction techniques for Bouguer gravity anomalies cannot meet the requirements of the existing exploration problems for the accuracy of gravity anomalies, so the precision of the external correction methods for Bouguer gravity anomalies must be improved. Different terrain correction methods have different accuracy. This paper studies and analyzes the shortcomings of the traditional square domain integral (volume integral): first, the square domain is not good for the actual terrain fitting (square column fitting); Second, the traditional method of trapezoidal numerical integration has low accuracy of terrain correction and can not meet the requirement of high precision gravity survey. In this paper, the area fraction of terrain surface is simulated and the Gao Si numerical integral with high precision is used to replace the original trapezoidal integral. The results of model experiments show that one is that the surface integration method is better than the traditional square domain, and the other is that the accuracy of terrain correction is obviously improved. In order to verify the application effect of surface integration, the actual topographic data of two working areas are used to calculate the topographic correction by square domain method and surface integral method, respectively. The results of the two methods under different terrain conditions are studied. The errors of the total terrain correction and the local gravity anomaly are compared and the respective characteristics of the two methods are analyzed. It is proved that the area integral based terrain correction method is superior to the traditional square domain terrain correction method in terms of calculation results and computational efficiency. The topographic correction of surface integration method has been successfully applied to the processing of practical data, and good results have been obtained. In order to improve the accuracy and efficiency of obtaining the elevation of the node in the remote area of gravity, the paper preliminarily discusses the use of the software of Google earth system to obtain the elevation of a node in a certain area of Tibet, and verifies that the obtained elevation is used in gravity. Feasibility of remote terrain correction.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P631.1
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