Selection of Best Reserves Estimation Methodology to Quantify and Reduce the Uncertainty – Accompanied by Çayirdere Gas Field Case Study

Abstract

Abstract Uncertainty in reserves estimation plays a critical role at all-time steps of production/development plans and determines the financial strength of the project and the company. In this study, the importance of probabilistic approach to reserves estimation is emphasized by showing change in the estimated values of reserves with producing time. An analytic uncertainty propagation method (AUPM), a simple, yet quite accurate alternative uncertainty quantification method to the well-known Monte Carlo method, is used to assess the uncertainty in gas reserves estimations. In addition to the theory, as a case study, one of the largest Turkish Petroleum Corporation (TPAO) gas field, Çayırdere Field, reserves is estimated, and uncertainties for this field reserve are presented at all-time steps. As a result, the estimated value of the most likely reserve (P50) by utilization of AUPM in conjunction with probabilistic methodology prior to production period, matches quite well with the value estimated at the abandonment of the reservoir by using performance-based methods. The Çayırdere Gas Field Case Study supports the glorious success of the approach promised in this study.