There are two basic principles of economic evaluation of medium-long term exploration & development plan.One is to obey relevant rules and policies and to be in accordance with national macro-economic polices

and another is to give priority to benefits and to be favorable for sustainable development of enterprises.Economic evaluation includes specifically collecting basic data correlated with the plan and estimating investment

calculating various economic indicators in the exploration and development

calculating various dynamic and static indicators and analyzing the profitability of the project

as well as making risk analysis aimed at the characteristics of petroleum industry.Special attentions should be given to selection and optimization of some key parameters such as planned reserves

planned production and costs of oil and gas.Static medium-long term plan should be changed into dynamic and progressive plan through combining with annual plan.In the economic evaluation

limits of various technical and economic indicators should be defined rationally and dimension of investment should be controlled appropriately according to the existing technical conditions.