Reduction of potential field data to a horizontal plane

Geophysics ◽  
1990 ◽  
Vol 55 (5) ◽  
pp. 549-555 ◽  
Author(s):  
Mark Pilkington ◽  
W. E. S. Urquhart
Keyword(s):  
Potential Field ◽  
Horizontal Plane ◽  
Field Data ◽  
Synthetic Data ◽  
Mirror Image ◽  
Source Distribution ◽  
Aeromagnetic Survey ◽  
Potential Field Data ◽  
Equivalent Sources ◽  
Topographic Gradients

Most existing techniques for potential field data enhancement and interpretation require data on a horizontal plane. Hence, when observations are made on an irregular surface, reduction to a horizontal plane is necessary. To effect this reduction, an equivalent source distribution that models the observed field is computed on a mirror image of the observation surface. This irregular mirror image surface is then replaced by a horizontal plane and the effect of the equivalent sources is computed on the required horizontal level. This calculated field approximates the field reduced to a horizontal plane. The good quality of this approximation is demonstrated by two‐dimensional synthetic data examples in which the maximum errors occur in areas of steep topographic gradients and increased magnetic field intensity. The approach is also applied to a portion of a helicopter‐borne aeromagnetic survey from the Gaspé region in Quebec, Canada, where the results are a horizontal shifting of anomaly maxima of up to 150 m and changes in anomaly amplitudes of up to 100 nT.

Potential field continuation between arbitrary surfaces — Comparing methods

Geophysics ◽  
2017 ◽  
Vol 82 (3) ◽  
pp. J9-J25 ◽  
Author(s):  
Mark Pilkington ◽  
Olivier Boulanger
Keyword(s):  
Potential Field ◽  
Horizontal Plane ◽  
Real Data ◽  
Continuation Methods ◽  
Source Distribution ◽  
Potential Field Data ◽  
Low Pass ◽  
Equivalent Sources ◽  
Intermediate Surface ◽  
Field Continuation

The continuation of potential field data from one irregular surface to another, not always horizontal, is often a necessary component within the data processing and interpretation stream. The most common requirement is to reduce field values (or some related component or derivative) to a horizontal plane, to facilitate further quantitative processing. Methods available to continue data comprise two main approaches. The first (source-based) involves calculating a source distribution that produces a fit to the data and can be used to calculate the field at any other point above. The second (field-based) requires no source determinations and deals with only fields but may involve calculating the field on some intermediate surface. Nine different continuation methods were compared (four source based and five field based) through synthetic tests and on real data from a helicopter-borne survey in Yukon, Canada. The preferred methods of Guspi and Hansen are those that do not involve any theoretical or geometric approximations and involve intermediate calculations on a plane or surface close to the observation surface. The Guspi approach is faster, based on using frequency-domain processing, but the Hansen method uses equivalent sources close enough to and consistently below the observation surface so that no low-pass filtering needs to be used.

On: “Reduction of Unevenly Spaced Potential Field Data to a Horizontal Plane by Means of Finite Harmonic Series,” by R. G. Henderson and L. Cordell (GEOPHYSICS, October 1971, p. 856–866)

Geophysics ◽  
1972 ◽  
Vol 37 (6) ◽  
pp. 1046-1046
Author(s):  
K. N. Khattri ◽  
A. N. Datta
Keyword(s):  
Fourier Series ◽  
Potential Field ◽  
Horizontal Plane ◽  
Field Data ◽  
Harmonic Series ◽  
Potential Field Data ◽  
Interesting Article

We have read the interesting article by Henderson and Cordell (197l). The authors transform the observed data using the finite Fourier series and compensate for the distortion introduced in the observed potential field due to observations taken on uneven topography.

scholarly journals Geophysical tutorial: Euler deconvolution of potential-field data

2014 ◽  
Vol 33 (4) ◽  
pp. 448-450 ◽  
Author(s):  
Leonardo Uieda ◽  
Vanderlei C. Oliveira ◽  
Valéria C. F. Barbosa
Keyword(s):  
Open Source ◽  
Potential Field ◽  
Field Data ◽  
Synthetic Data ◽  
Euler Deconvolution ◽  
Potential Field Data ◽  
Python Package

In this tutorial, we will talk about a widely used method of interpretation for potential-field data called Euler de-convolution. Our goal is to demonstrate its usefulness and, most important, to call attention to some pitfalls encountered in interpretation of the results. The code and synthetic data required to reproduce our results and figures can be found in the accompanying IPython notebooks ( ipython.org/notebook ) at dx.doi.org/10.6084/m9.figshare.923450 or github.com/pinga-lab/paper-tle-euler-tutorial . The note-books also expand the analysis presented here. We encourage you to download the data and try them on your software of choice. For this tutorial, we will use the implementation in the open-source Python package Fatiando a Terra ( fatiando.org ).

On: “Reduction of Unevenly Spaced Potential Field Data to a Horizontal Plane by Means of Finite Harmonic Series” by Roland G. Henderson and Lindrith Cordell (GEOPHYSICS, October 1971, p. 856–866)

Geophysics ◽  
1972 ◽  
Vol 37 (4) ◽  
pp. 703-703
Author(s):  
Alan T. Herring
Keyword(s):  
Gravity Field ◽  
Potential Field ◽  
Horizontal Plane ◽  
Field Data ◽  
Bouguer Anomaly ◽  
Harmonic Series ◽  
Potential Field Data ◽  
Topographic Relief ◽  
Vertical Gradients

The authors recommend on page 864, that their technique for correcting for anomalous vertical gradients in the gravity field be applied only in “cases where high topographic relief produces large corrections to the station Bouguer anomaly.” The correction applied by the authors amounts to the continuation of the observed gravity field onto a single‐elevation plane from the varying elevations of the observation points. The authors should therefore caution the reader against choosing the datum plane such that the gravity field is continued through sources of interest lying above the datum plane—an easily made mistake in areas of high topographic relief.

scholarly journals OpenMP Implementation of a Novel Potential-Field-Data Source-Growth-Based Inversion Approach for 3D Salt Imaging in Deepwater Gulf of Mexico

2020 ◽  
Vol 10 (14) ◽  
pp. 4798
Author(s):  
Naín Vera ◽  
Carlos Couder-Castañeda ◽  
Jorge Hernández ◽  
Alfredo Trujillo-Alcántara ◽  
Mauricio Orozco-del-Castillo ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Potential Field ◽  
Field Data ◽  
Three Dimensional ◽  
Synthetic Data ◽  
Complex Salt ◽  
Research Field ◽  
Inversion Method ◽  
Potential Field Data ◽  
Simultaneous Inversion

Potential-field-data imaging of complex geological features in deepwater salt-tectonic regions in the Gulf of Mexico remains an open active research field. There is still a lack of resolution in seismic imaging methods below and in the surroundings of allochthonous salt bodies. In this work, we present a novel three-dimensional potential-field-data simultaneous inversion method for imaging of salt features. This new approach incorporates a growth algorithm for source estimation, which progressively recovers geological structures by exploring a constrained parameter space; restrictions are posed from a priori geological knowledge of the study area. The algorithm is tested with synthetic data corresponding to a real complex salt-tectonic geological setting commonly found in exploration areas of deepwater Gulf of Mexico. Due to the huge amount of data involved in three-dimensional inversion of potential field data, the use of parallel computing techniques becomes mandatory. In this sense, to alleviate computational burden, an easy to implement parallelization strategy for the inversion scheme through OpenMP directives is presented. The methodology was applied to invert and integrate gravity, magnetic and full tensor gradient data of the study area.

An adaptive iterative method for downward continuation of potential-field data from a horizontal plane

Geophysics ◽  
2013 ◽  
Vol 78 (4) ◽  
pp. J43-J52 ◽  
Author(s):  
Xiaoniu Zeng ◽  
Xihai Li ◽  
Juan Su ◽  
Daizhi Liu ◽  
Hongxing Zou
Keyword(s):  
Iterative Method ◽  
Tikhonov Regularization ◽  
Potential Field ◽  
Horizontal Plane ◽  
Field Data ◽  
Regularization Parameter ◽  
Downward Continuation ◽  
Tikhonov Regularization Method ◽  
Potential Field Data ◽  
Wavenumber Domain

We have developed an improved adaptive iterative method based on the nonstationary iterative Tikhonov regularization method for performing a downward continuation of the potential-field data from a horizontal plane. Our method uses the Tikhonov regularization result as initial value and has an incremental geometric choice of the regularization parameter. We compared our method with previous methods (Tikhonov regularization, Landweber iteration, and integral-iteration method). The downward-continuation performance of these methods in spatial and wavenumber domains were compared with the aspects of their iterative schemes, filter functions, and downward-continuation operators. Applications to synthetic gravity and real aeromagnetic data showed that our iterative method yields a better downward continuation of the data than other methods. Our method shows fast computation times and a stable convergence. In addition, the [Formula: see text]-curve criterion for choosing the regularization parameter is expressed here in the wavenumber domain and used to speed up computations and to adapt the wavenumber-domain iterative method.

Correction of topographic distortions in potential‐field data: A fast and accurate approach

Geophysics ◽  
1993 ◽  
Vol 58 (4) ◽  
pp. 515-523 ◽  
Author(s):  
Jianghai Xia ◽  
Donald R. Sprowl ◽  
Dana Adkins‐Heljeson
Keyword(s):  
Potential Field ◽  
Field Data ◽  
Gravity Data ◽  
Source Distribution ◽  
Potential Field Data ◽  
Equivalent Source ◽  
Horizontal Shift ◽  
Maximum Elevation ◽  
Rms Error ◽  
Forward Calculation

The equivalent source concept is used in the wavenumber domain to correct distortions in potential‐field data caused by topographic relief. The equivalent source distribution on a horizontal surface is determined iteratively through forward calculation of the anomaly on the topographic surface. Convergence of the solution is stable and rapid. The accuracy of the Fourier‐based approach is demonstrated by two synthetic examples. For the gravity example, the rms error between the corrected anomaly and the desired anomaly is 0.01 mGal, which is less than 0.5 percent of the maximum synthetic anomaly. For the magnetic example, the rms error is 0.7 nT, which is less than 1 percent of the maximum synthetic anomaly. The efficiency of the approach is shown by application to the gravity and aeromagnetic grids for Kansas. For gravity data, with a maximum elevation change of 500 m reducing to a horizontal datum results in a maximum correction in gravity anomaly amplitude of up to 2.6 mGal. For aeromagnetic data, the method results in a maximum horizontal shift of anomalies of 470 m with a maximum correction in aeromagnetic anomaly amplitudes up to 270 nT.

scholarly journals A computation scheme based on field attenuation rate for improving regional-residual separation of potential field data set

2019 ◽  
Author(s):  
Jun Wang ◽  
Xiaohong Meng ◽  
Fang Li
Keyword(s):  
Potential Field ◽  
Field Data ◽  
Synthetic Data ◽  
Regional Trend ◽  
Data Set ◽  
Potential Field Data ◽  
Attenuation Rate ◽  
Original Field ◽  
Computation Scheme ◽  
The Difference

Abstract To further improve the accuracy of regional-residual separation of potential field data set, this paper presents a novel computation scheme based on different attenuation rate of the fields induced from deep and shallow sources respectively. For the new scheme, the observations are first upward continued to a plane above it to get an updated field. Then, the difference between the original field and the updated field is calculated. Next, a controlling parameter is set to select those data points whose amplitudes have been much reduced. The adverse effects from the residual anomalies on the fitting of the regional trend can be reduced by removing the identified local points from the original field. Finally, a low-order polynomial is utilised for approximating the regional trend, and the corresponding residual field can be obtained by simple subtraction. Compared with gradient-based methods, the proposed new scheme has better noise adaptability for distinguishing different anomalies. The accuracy of the presented scheme was tested on synthetic data with and without noise. All tests showed that the new scheme reduces subjectivity and inaccuracy of the conventional methods significantly. In addition, the scheme was applied to Bouguer gravity anomaly of the Dida orebodies in Jilin Province, northeast China. This application also verified the superiority of the proposed scheme.

scholarly journals Backus-Gilbert inversion of potential field data in the frequency domain and its application to real and synthetic data

1994 ◽  
Vol 33 (4) ◽  
pp. 531-539
Author(s):  
Uwe Koppelt ◽  
Javier Rojas
Keyword(s):  
Frequency Domain ◽  
Potential Field ◽  
Field Data ◽  
Synthetic Data ◽  
Potential Field Data

Se presenta un algoritmo para la inversión de datos del campo potencial en el dominio de las frecuencias utilizando la transformación de Backus-Gilbert. Se describe uno de los problemas fundamentales en todo proceso de interpretación geofísica como es la solución del problema directo y del problema inverso. La comparación de los resultados en el domino del espacio y de las frecuencias muestra las ventajas del algoritmo aquí presentado. Se demuestra la efectividad del algoritmo solucionado tareas de geofísica ambiental como la detección de depósitos antiguos de desechos industriales. Esta técnica interpretativa es aplicable también a la interpretación de investigaciones geofísicas en sitios arqueológicos.

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