重力勘探中地形改正方法的研究及應(yīng)用
發(fā)布時(shí)間：2018-07-27 16:06
【摘要】：重力勘探是傳統(tǒng)的地球物理勘探方法,重力異常是地下地質(zhì)體密度變化的反映。布格重力異常的外部校正主要包括地形改正、正常場(chǎng)改正和高度改正。在地形切割較大地區(qū),各測(cè)點(diǎn)周?chē)牡匦螌?duì)各點(diǎn)的重力影響值也各異,如果忽略地形起伏對(duì)計(jì)算結(jié)果的影響,往往會(huì)給解釋工作者提供虛假異�；蚴巩惓Ｇ�(xiàn)發(fā)生明顯畸變,這樣就會(huì)影響異常的解釋精度。由于重力儀的測(cè)量精度大幅提高,精確的數(shù)字高程數(shù)據(jù)也可以容易獲得,現(xiàn)在地形改正誤差成為影響重力勘探解釋效果最主要的因素;所以已有的布格重力異常外部改正方法技術(shù)已經(jīng)不能滿(mǎn)足現(xiàn)有勘探問(wèn)題對(duì)重力異常精度的要求;故必須提高布格重力異常外部改正方法技術(shù)的精度。不同的地形改正方法有不同的精度。本文研究并分析了傳統(tǒng)方域積分(體積積分)的不足:一是方域?qū)?shí)際地形擬合(方柱擬合)不好;二是傳統(tǒng)方法采用的梯形數(shù)值積分的地形改正精度低而不能滿(mǎn)足目前高精度重力測(cè)量的要求。本文模擬研究了基于對(duì)地形表面的面積分,然后用精度比較高的高斯數(shù)值積分代替原來(lái)的梯形積分。通過(guò)模型實(shí)驗(yàn)的結(jié)果表明,一是表面積分法重力地形改正方法對(duì)于地形的擬合比傳統(tǒng)方域要好,二是地形改正計(jì)算精度有了明顯的提高。為了驗(yàn)證表面積分的應(yīng)用效果,采用兩個(gè)工區(qū)的實(shí)際地形資料,對(duì)測(cè)區(qū)分別進(jìn)行方域法地形改正和表面積分法法改正的計(jì)算,研究不同地形條件下兩種方法的計(jì)算結(jié)果。對(duì)計(jì)算地形改正后得到的總地形改正值、局部重力異常進(jìn)行誤差比較,分析兩種方法的各自特點(diǎn)。無(wú)論是計(jì)算結(jié)果和計(jì)算效率方面,都證明了基于面積積分的地形改正方法優(yōu)于傳統(tǒng)的方域地形改正方法。將表面積分法地形改正成功的應(yīng)用到了實(shí)際資料的處理中,并取得了很好的效果。為了提高獲取重力中、遠(yuǎn)區(qū)地形改正節(jié)點(diǎn)高程的精度和效率,初步討論利用Google earth系統(tǒng)軟件獲取西藏某地區(qū)節(jié)點(diǎn)高程,驗(yàn)證了利用獲取的高程進(jìn)行重力中、遠(yuǎn)區(qū)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.
【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：P631.1
本文編號(hào)：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.
【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：P631.1
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