Abstarct: Due to existence of huge oil and gas reserves in Iran, petroleum industry has a major importance in all economics, politics, social and scientific aspects of country. In order to maximize value in this industry precise identification and analysis of value chain is critical. The oil and gas industry encompasses a range of different activities and processes that jointly contribute to the transformation of underlying petroleum resources into useable end-products. These different activities are inherently lixnked with each other (conceptually, contractually, and physically). The value chain starts with the exploration for potential reserves, after that petroleum fields are appraised, developed, and produced. These activities are generally called exploration and production (E&P) or referred to as “upstream” oil and gas. After human, natural, financial resources and market, technology is considered as the most important element in value creation and core competency. Upstream oil and gas industry as the main part of petroleum value chain encompasses a vast range of technologies. As developing all the technologies requires great cost and time, it is essential to prioritize technologies for investment. As technology appraisal is considered as one of technology strategy development steps and according to the importance of understanding value creation process in upstream oil and gas industries; Porter’s technology strategy model has been considered as the baxse of this research. First of all a survey on the literature and previous researches about technology strategy, technology appraisal and prioritizing and petroleum value chain has been carried out to identify initial technology appraisal indicators (Attractiveness-Ability) and petroleum value chain in upstream and to plan research executive model. In this research, with identification of related experts, upstream value chain has been analyzed and the technology tree under each chain has been identified according to references and experts’ opinion. Then through experts’ panel, technology appraisal indicators has been defined and nationalized. A questionnaire has been prepared to examine each indicator’s quantity for each technology, then by implementing a TOPSIS - a Multi Criteria Decision Making method- these technologies has been prioritized. Enhanced Oil Recovery (EOR) technologies has been identified as the first priority with significant difference. Regarding the fact that Iran’s most major reservoirs are experiencing the end of their mature life phase, this rank shows the importance of enhancing recovery factor baxsed on expert’s opinion. This prioritizing can be assumed as an appropriate reference for investment and new technology development policies in upstream oil and gas.