Robust ensemble-based multi-objective optimization

Robust ensemble-based multi-objective optimization

Fonseca, R.M.
Stordahl, A.
Leeuwenburgh, O.
Van den Hof, P.M.J.
Jansen, J.D.

Civil Engineering and Geosciences

Geoscience and Engineering

2014-09-08

We consider robust ensemble-based multi-objective optimization using a hierarchical switching algorithm for combined long-term and short term water flooding optimization. We apply a modified formulation of the ensemble gradient which results in improved performance compared to earlier formulations. We also apply multi-dimensional scaling to visualize projections of the high-dimensional search space, to aid in understanding the complex nature of the objective function surface and the performance of the optimization algorithm. This provides insights into the quality of the gradient, and confirms the presence of ridges in the objective function surface which can be exploited for multi-objective optimization. We used a 18553-gridblock reservoir model of a channelized reservoir with 4 producers and 8 injectors. The controls were the flow rates in the injectors, and the long-term and short-term objective functions were undiscounted net present value (NPV) and highly discounted (25%) NPV respectively. We achieved an increase of 15.2% in the secondary objective for a decrease of 0.5% in the primary objective, averaged over 100 geological realizations. The total number of reservoir simulations was around 20000, which indicates the potential to use the ensemble optimization method for robust multi-objective optimization of medium-sized reservoir models.

EnOpt
robust optimization
production optimization
oil and gas
energy

http://resolver.tudelft.nl/uuid:5c0b81d2-34f6-4daf-bfe3-eb65c6069104

EAGE

ECMOR XIV: Proceedings 14th European Conference on Mathematics in Oil Recovery, Catania, Italy, 8-11 September 2014

Institutional Repository

conference paper

(c) 2014 The Author(s)