Full-field production forecasting is a key requirement for facilities design and economic analysis during development of a Field Development Plan (FDP). However, forecasting using relatively fine-grid thermal simulation models with over one million grid blocks can require days or weeks to complete a run. Within the timeframe of a typical FDP project, teams must often evaluate multiple geologic and reservoir engineering scenarios, development concepts, and uncertainty ranges in high- sensitivity variables in terms of their impact on production streams, costs, and overall project economics. During this evaluation process, fast and flexible forecasting methods are favored over slower but perhaps more accurate methods.
Mukhaizna field is a giant heavy oil field in South Sultanate of Oman and is presently under steamflood. Following a period of cold production development involving the drilling of 75 horizontal producers and resulting in very low recovery, a steamflood FDP was developed over a period of six months. Based on this FDP, drilling of hundreds of horizontal producers and thousands of vertical injectors is planned for the next 20 years. Mukhaizna is the first large-scale commercial steamflood to use horizontal producers and vertical injectors.
Full field production forecasting for Mukhaizna was performed using a novel, fit-for-purpose workflow. Pattern-scale, fine- grid geologic models representing areas of distinctive flow unit and permeability architecture were built and simulated to develop pattern production type curves. Full-field production forecasts were obtained by scaling up production streams from type-curve simulation using a scale-up tool prototyped in Excel. Inputs to the scale-up tool included pattern STOOIP, drilling sequence/schedule, production targets, and facilities constraints. Once type curve simulation was completed, any field development scenario could be forecasted within a few hours. This paper 1) describes how the type-curve models were defined, generated, and simulated; 2) how the detailed scale-up methodology was developed and applied in the Mukhaizna FDP.