The overseas oil and gas investment evaluation is one of the core tasks in overseas investment of oil and gas companies, among which risk evaluation and benefit evaluation are the most important. This paper sets forth transmission paths of risk factors to the investment benefit by identifying 14 overseas oil and gas investment risks in four categories. On the basis of the concept of risk compensation, different compensation mechanisms specific to each risk are designed. The risk and benefit are integrated objectively to develop a comprehensive evaluation model by correcting the recoverable reserve, adjusting benefit evaluation parameters such as investments on exploration and development, and compensating for the changes in risk factors with time through dynamic discount rate. Moreover, two cases studies, namely the evaluations of Project A in Sudan and comparison among Blocks A–G, are used to describe usage method and applicable scope of such evaluation model, respectively. According to the results, oil price is a key influencing factor for enterprise internal risk and industrial risk. Risk compensation reduces comprehensive benefit of overseas oil and gas investment and undermines the investment feasibility and priority of blocks. The research findings of this paper are free from the effects of some subject factors and avoid multi-objective decision making, and also avoid the undesired repeated calculation of risk factors.