Calibration of facies proportions through a history-matching process

The facies-proportion calibration method is a new history-matching technique, which modifies facies proportions within a fine geological -- geostatistical model until a good match of the field data is reached. The initial facies proportions in the model are usually locally constrained by well data, for example, but their spatial tendencies may be unreliable in some parts of the reservoir. The algorithm presented in this paper introduces average proportion ratios between facies groups in order to calculate new facies proportions while taking into account their initial values. It can be applied locally on specific regions or globally on the whole reservoir for stationary or non-stationary facies distributions. The proportion ratios can be manually adjusted or iteratively computed through an optimization process. The method has been successfully applied to a real field case.