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Influence factor analysis of quantitative interpretation for gravity anomaly and its gradient tensor by DEXP |
Feng QIU1,2, Jin-Song DU1,2,3( ), Chao CHEN1,2 |
1. Institute of Geophysics and Geomatics, China University of Geosciences, Wuhan 430074, China 2. Hubei Subsurface Multi-scale Imaging Key Laboratory, China University of Geosciences, Wuhan 430074, China 3. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China |
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Abstract Fast imaging inversion method has been a hotspot in quantitative interpretation of gravity and magnetic exploration in recent years. Because it does not need to add prior information in the calculation, it can quickly estimate the source depth, density and other related parameters. DEXP (Depth from Extreme point) imaging method adds the corresponding structural index to the depth scaling function in the calculation, making the imaging results more accurate. Based on the basic theory of the DEXP rapid imaging method, firstly, transformation formulas for gravity field and gravity gradient tensor regarding depth from the extreme point method were calculated and applied to the causative source interpretation in this paper. Then, through different synthetic models tests, the effects of sampling interval, data error, computing range and background field on the imaging results were analyzed, respectively. Finally, the imaging method was applied to the full gravity tensor gradient field data, and the results were compared with those provided by previous researchers in the literature. Both the synthetic tests and the field example show that the DEXP imaging method not only has good suppression on the noise in the observation data but also shows the characteristics of computing stability and accuracy. In addition, the data sampling interval, calculation range and background field all have certain influences on DEXP imaging results. Therefore, when actual field data are interpreted, it is necessary to comprehensively consider their influences on the imaging results and perform the corresponding pre-processing to improve the accuracy of the quantitative interpretation.
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Received: 15 July 2019
Published: 24 June 2020
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Corresponding Authors:
Jin-Song DU
E-mail: jinsongdu@cug.edu.cn
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Gravity anomaly (a) of the rectangular prism model and its DEXP transform results (b)
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Gravity gradient tensor components of the rectangular prism model (a) and its DEXP transform results (b)
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Tzz component anomaly of the rectangular prism model with different Gauss noise (a) Tzz component with 0% Gauss noise; (b) Tzz component with 1% Gauss noise; (c) Tzz component with 2% Gauss noise;(d) Tzz component with 5% Gauss noise; (e) Tzz component with 10% Gauss noise
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Fig. 3. ">
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DEXP transform results of Tzz component corresponding to Fig. 3.
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DEXP transform results of Tzz component with data spaces of 1 m (a), 2 m (b) and 5 m (c)
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DEXP transform results of Tzz component with data spatial ranges of -50~50 m (a), -60~60 m (b),-70~70 m (c), -80~80 m (d) and -100~100 m (e)
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DEXP transform results of Tzz component with background fields of -1E(a)、-0.5E(b)、-0.2E(c)、0E(d)、0.2E(e) 和 0.5E(f)
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Gravity anomaly (a) in Vinton Salt Dome region and its DEXP transform results (b)
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The full gravity gradient tensor fields in Vinton Salt Dome region
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DEXP transform results of the full gravity gradient tensor field data in Vinton Salt Dome region
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The residual fields of ΔTxx, ΔTyy and ΔTzz components after anomaly separation in Vinton Salt Dome region
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DEXP transform results of the residual fields of ΔTxx, ΔTyy and ΔTzz components after anomaly separation in Vinton Salt Dome region
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The results of the corresponding structural index Np
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