Abstract: Comprehensive study of global oil and gas geology and related evaluation have not yet been systematically launched in China. Overseas petroleum exploration and development has nothing to refer to, as compared to domestic petroleum exploration and development which can learn from historical experience and lessons. In order to carry out overseas petroleum exploration and development, it is required to have an all-round understanding of resource countries, to conduct a rigorous feasibility study combining different disciplines, geological and non-geological work. In addition to the rigorous appraisal of petroleum resource potential, earnest appraisal of petroleum business risk, socio-economic risk, political risk and competitive risk need to be taken into account. On the basis of risk identification and classification, a whole process of risk management and control as well as global petroleum exploration and development risk evaluation and project optimization is established. It is put forward that appraisal has risk of its own, and it is necessary to overcome the effect of seven subjective factors including seduction, overconfidence, and overly conservation, etc. Through thorough analysis of investment environment appraisal indexes, the concept and method of comprehensive investment appraisal based on considering all risk factors are proposed, which can not only help master the opportunity of risk investment, but can also aid obtaining commercial discovery and economic results

Key words: overseas, petroleum exploration and development, risk identification, risk management and control, investment appraisal, process and method