Forward modeling for 2D-body gravity anomaly in[JP2]the space-wavenumber mixed domain
DAI Shikun1,2, WANG Xulong1,2, ZHAO Dongdong1,2, LIU Zhiwei3, ZHANG Qianjiang4, SUN Jinfei5
1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring, Ministry of Education, Changsha, Hunan 410083, China; 2. School of Geosciences and Info-physics, Central South University, Changsha, Hunan 410083, China; 3. Guangdong Electric Power Design Institute, China Energy Engineering Group CO., Guangzhou, Guangdong 510663, China; 4. College of Earth Sciences, Guilin University of Technology, Guilin, Guangxi 541004, China; 5. No. 1 Daqing Geophysical Exploration Company of BGP, CNPC, Daqing, Heilongjiang 163357, China
Abstract：An efficient and high-precision forward modeling of 2D-body gravity anomaly in a space-wavenumber mixed domain is proposed to calculate the gravity anomaly in the case of arbitrary density distribution.By performing 1D Fourier transform,2D partial differential equation governing gravity potential in the spatial domain is transformed into a group of independent 1D differential equations engaged with different wavenumbers.The method preserves the vertical direction in the spatial domain,thus shallow and deep meshes for modeling can be fine and coarse respectively.By this way,both the accuracy and the efficiency of calculation are taken into account.1D finite element method is used to solve the transformed differential equations with different wave numbers.Moreover,the efficiency of solving linear equations with a fixed bandwidth assembled by the finite element analysis is further improved by a chasing method.To test the proposed algorithm,a constant-density 2D model and a variable-density 2D model are designed.Numerical test results show that the proposed algorithm not only guarantees the calculation accuracy,but also improves the calculation efficiency compared with the conventional methods.
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