Abstract: The economic evaluation and investment decision analysis methods of exploration and development projects play a very critical role in the investment decision-making and investment quality of oil and gas companies. Economic evaluation based on deterministic models cannot evaluate a project from the whole picture, which will result in certain valuation bias and consequently lead to higher risk of investment. Therefore, non-deterministic models have been introduced into the economic evaluation and decision analysis, including decision tree, VOI method based on Bayes theorem, Monte Carlo simulation, etc., to solve specific types of investment decision problems. However, these traditional non-deterministic models and methods are not universal, and each of them has certain limitations, and cannot quantify and analyze the project technical and economic risks very well. The S-curve non-deterministic economic evaluation method (hereinafter referred to as the S-curve analysis method) provides a set of universal evaluation method and decision analysis mechanism, which can well accomplish the quantitative analysis for project economic risks, calculate the breakeven probability, and provide various comparative analysis needed for decision-making. The authors in-depth analyzed the theory, features and advantages of the S-curve analysis method, introduced the implementation experience and understanding, and demonstrated its application in exploration and development projects through case study. In recent years, many international oil companies have established their project economic evaluation and investment decision analysis systems based on the S-curve analysis method, continuously improved the level of economic evaluation and decision analysis, this has reference significance for China's major oil and gas companies, and will help to improve the scientific and effective investment decision-making.

Key words: S-curve analysis method, economic evaluation, decision analysis (DA), non-deterministic model, risk analysis, breakeven probability, exploration and development

摘要： 勘探开发项目经济评价和投资决策分析方法对石油天然气公司的投资决策和投资质量起到非常关键的作用。基于确定性模型的经济评价不能从全貌来评估项目,会产生一定的估值偏差,进而导致较大的投资风险。非确定性模型因此被引入到经济评价和决策分析中,包括决策树、基于贝叶斯定理的VOI方法、蒙特卡洛模拟等,用以解决特定类型的投资决策问题。但是这些传统的非确定性模型和方法不具有通用性,各自存在一定的应用局限性,且不能很好地对项目技术经济风险进行量化和分析。S曲线非确定性经济评价方法(简称S曲线分析方法)提供了一套具有一定通用性的评价方法和决策分析机制,能够较好地完成项目经济风险量化分析、计算盈亏平衡概率,并提供决策所需要的各种比较分析。通过深入分析S曲线分析方法的理论、特点和优势,介绍了实施经验和认识,并通过案例分析展示其在勘探开发项目上的应用。近年很多国际石油公司构建了基于S曲线分析方法的项目经济评价和投资决策分析体系,持续提升经济评价和决策分析水平,这对中国大型石油天然气公司具有借鉴意义,有助于提高投资决策的科学性和有效性。

关键词: S曲线分析方法, 经济评价, 决策分析, 非确定性模型, 风险分析, 盈亏平衡概率, 勘探开发