Robust integrated optimization of well placement and control under field production constraints

Field development and control optimization aim to maximize the economic profit of oil and gas production while respecting various constraints such as production limits imposed by the available fluid processing capacity and/ or reservoir management strategies. The limitations of the existing optimization workflows are 1) well locations or production/injection controls are optimized independently despite the fact that one affects another, and 2) forthcoming field production limits are ignored during at least one of these optimization stages. This paper presents a robust, multi-level framework for field development and control optimization under fluid processing capacity constraints while considering reservoir description uncertainty. The developed framework is based on sequential iterative optimization of control variables at different levels, where the loop of well placement followed by control optimization continues until no significant improvement is observed in the expected objective value. Simultaneous perturbation stochastic approximation (SPSA) algorithm is employed as the optimizer at all optimization levels. Field production constraints are imposed on the reservoir model using a simplified production network. Smart clustering techniques are applied to systematically select an ensemble of reservoir model realizations as the representative of all available realizations at each optimization level. The developed framework is tested on the Brugge benchmark field case study with a maximum field liquid production limit imposed via the production network. A comparative analysis is performed for each case to investigate the impact of field liquid production constraints on optimal well placement and control strategy. Results demonstrate that ignoring fluid processing capacity constraints, in one or multiple levels of optimization, results in a sub-optimal scenario, highlighting the significance of the proposed optimization framework in robust field development and management.