1. School of Geosciences; China University of Petroleum; Qingdao 266580 China
2. Department of Earth Sciences; Durham University; Durham DH1 3LE UK
3. Shengli Oilfield Company, SINOPEC; Dongying Shandong 257015 China
4. Shengli Geophysical Research Institute of SINOPEC; Dongying Shandong 257000 China