1. Key Laboratory of Tectonics and Petroleum Resources, Ministry of Education, China University of Geosciences, Wuhan 430074, China
2. Department of Geology, University of Jos, P. M. B 2084 Jos, Plateau State, Nigeria
3. Wuhan Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
4. Nnamdi Azikiwe University, Awka, Anambra State 420110, Nigeria
5. Department of Petroleum Chemistry, American University of Nigeria, P. M. B. 2250 Yola, Adamawa State, Nigeria