1. Harbin Institute of Technology, School of Mathematics and Center of Geophysics, Harbin, China.
2. Harbin Institute of Technology, School of Mathematics and Center of Geophysics, Harbin, China. (corresponding author)
3. BGP, CNPC, Zhuozhou, China. .
4. Peking University, School of Earth and Space Sciences, Beijing, China and Harbin Institute of Technology, School of Mathematics, Harbin, China.