ES-MDA applied to estimate skin zone properties from injectivity tests data in multilayer reservoirs

Estimating reservoir properties, such as the skin factor, is an essential role of injectivity tests. Nevertheless, determining individual layer properties in multilayer systems remains a difficult task. Some techniques have been proposed to compute layer permeabilities and skin factors based on the pressure response of reservoirs under single-phase flow. Regardless, determining layer skin zone permeability and radius remains challenging. Ensemble-based techniques are optimization methods known for its easy implementation and good data match when estimating model parameters. Notably, the ensemble smoother with multiple data assimilation (ES-MDA) has proven to be a powerful parameter estimation tool. Thereby, this work attempts to apply the ES-MDA to determine individual layer skin zone properties. To the best of the authors' knowledge, this is the first time that ES-MDA is applied to this problem. In all tested cases, the resulting histogram contains the reference parameters. We also presented a sensitivity study regarding the performance of ES-MDA when different number of assimilations and ensemble sizes are used.

Automated summary

This study attempts to utilize the ES-MDA method to determine individual layer skin zone properties and finds that in all tested cases, the resulting histogram contains reference parameters. Through a sensitivity study on the performance of ES-MDA with different assimilations and ensemble sizes, the advantages of this method in evaluating model parameters are discovered.