A Streamlined Approach to Probabilistic Simulation and Robust Concept Optimization in a Highly Productive Carbonate Stringer Field in the Sultanate of Oman

Abstract Field-A Carbonate reservoir was discovered in 2006 and has been on production since 2007. It is a light sour oil carbonate reservoir with density of 45 API, Gas-Oil-Ratio (GOR) of 270 sm3/sm3 and viscosity of 0.3 cP at initial conditions (383 bar & 79 C). Three wells currently produce dry oil under strong aquifer support. Current recovery factors stand at 18%. The surface facilities are not equipped to manage water production. The main constrain is the water handling capacity at surface where only 0.1% water cut is acceptable and with the strong aquifer present, it is crucial to manage the offtake points and the rates. At the beginning of the study, a comprehensive analysis of all collected data over the years of Field development have been utilized to reach an enhancement understanding and characterization of the reservoir. Secondly, the study involved the construction of black oil model capturing the physics of aquifer interaction with the light oil in a good conductivity rock in order to perform assisted history matching using different geological static models and property distribution and ranges. Thirdly, a set of history matched models within the accepted tolerance was chosen to extract the P10, P50 and P90 models. Lastly, this effort supported the later building of robust optimization simulation models to evaluate the most promising recovery techniques for Field. This approach is beneficial as it covers full spread of uncertainty, assesses multiple subsurface realizations and surface concepts, generates a range of possible outcomes, quantifies risk, and enables better decision making. This paper covers: The multi-discipline novel data analysis to characterize the reservoir and define the uncertaintiesThe utilization of multiple geological realizations and property distributions to obtain a set of assisted history matched modelsThe methodology of obtaining a P10, P50 and P90 models and their associated forecasts for further economic evaluation and concept selectionThe robust concept optimization process using artificial intelligence (AI) techniques to obtain an optimum development scenario in terms of number of wells, production rate, well type and drive mechanismThe workflow road map for maturation of the most promising option using probabilistic simulation and robust optimization The value of streamlining the process of assessing different subsurface development realizations linked with surface concept scenarios through probabilistic method enables robust Field Development tool for teams with different experience levels. It is concluded from the conducted study work that out of the various development scenarios considered, infill drilling with a controlled rate per well is the most favorable development concept in terms of recovery and economics.