History-Matched Reservoir Model Validation Based on Wavelets Methods

摘要

Many predictive methods based on numerical simulation generate undesired changes on the distribution of their parameters that depend mainly on the numerical method or the grid orientation (artifacts). On the other hand, it is common to find an appropriate match of the production history through the use of reservoir properties as calibration parameters, even when this procedure generates in many cases geological inconsistencies. Also, as real time data acquisition is becoming a powerful and popular technique, it is important to achieve a methodology that allows the input of new sources of information without disturbing the history matching previously validated. In this paper a new methodology to integrate a historymatched reservoir model with other geological data is presented. It is based on the methodology proposed by Sahni and Horne1, that based on the Haar wavelet transform allows for the improvement of the history-matched geological model through the inclusion of additional geological constraints without needing to perform the history matching every time the reservoir model is updated. The first step of the method presented in this study is to match the production history of the reservoir that will be modeled by means of numerical simulation. Then, the wavelet function that better fits the distribution of the considered properties, keeping the highest Energy Compaction Ratio (ECR), is chosen. After performing the wavelet transform, the most sensitive coefficients to the production data are determined. Those that are not significant for the model validation can be modified and geostatistical interpolation algorithms can be applied (e.g. Sequential Gaussian Simulation). Finally, when the inverse transform is performed, the data set is not only validated by the production history but also by the geological properties. If the wavelet transform is not Haar, an additional benefit is obtained. It is possible to interpolate the geological information in the different regions where the data acquisition is difficult or doubtful. This new heuristic methodology has been tested in different reservoir configurations. In this paper, we validate the results achieved for a test case reservoir with patterns of 4 producers and 2 injectors. This procedure is very helpful in numerical simulation of reservoirs and it has a direct impact on its management, risk analysis and the development of depletion plans.