Ranking of multiple realizations is an important step when the processing time for a realization is large. This is the case in reservoir flow simulation and in other areas of geology, environmental and even medical applications. Significant uncertainty exists in all reservoirs especially at unsampled locations where the geological heterogeneity and connectivity are impossible to exactly predict between wells. Geostatistical techniques are used to construct models of static properties such as lithofacies, porosity, permeability and residual fluid saturations and provide multiple equally probable realizations of these properties. The number of realizations that is required for modeling the uncertainty may be large; usually 100 realizations are considered enough to quantify uncertainty. However, this number of realizations is still too high for processing by a flow simulator. This thesis aims at developing a robust and reliable ranking methodology to rank the realizations using a static ranking measure. The outcome is the identification of the high, low, and intermediate ranking realizations for further detailed simulations. The methodology was developed for the steam assisted gravity drainage (SAGD) reservoir application. This thesis will consider the cumulative oil produced (COPrate) and cumulative steam-oil-ratio (CSOR) as the ranking parameters in the flow simulations, hereafter called performance parameter. Connected hydrocarbon volume (CHV) was the parameter that was used in the ranking methodology as the static ranking measure. High calibration between the performance parameters and the CHV would indicate the success of the proposed ranking methodology. The ranking methodology was validated against the results of the flow simulations. The results indicate a mediocre correlation between the SAGD performance parameters and CHV. The ranking methodology was modified by incorporating the average reservoir permeability. Significant improvement in the correlation between the static ranking measure and the SAGD performance parameters resulted. / Petroleum Engineering

Well testing has long been used to determine the dynamic characteristics of a reservoir. However due to the increase in interest in exploring deep offshore reservoirs and the expense associated with performing well tests of sufficient duration, alternative methods for retrieving reservoir specific information from tests of limited duration are necessary. This thesis presents analysis of derivative plots from well tests in different locations along a heterogeneous channelized environment and the information that can be derived the shape of these plots. The viability of calibrating a multiple point proxy that captures the reservoir flow connectivity information contained in well test data is explored. Such a proxy can provide useful insight into the nature of reservoir heterogeneity in the vicinity of the well. The behavior of the log-log derivative plot gives invaluable information about the nature of the reservoir surrounding the penetrating wells. Based on the change in slope of the derivative plot one can tell if a flow conduit or a low permeability zone is close to the well. Proximity to these features is also indicated in the curvature of the derivative plot with the test plot showing increasing symmetry as flow boundaries are approached. This was found to be true in both systematic simulations as well as in real build up test data. The calibration of the multiple point permeability proxy also provides information about the connectivity of the reservoir. Single point statistics provide the best estimate for wells either inside a channel or very close to the channel boundary. This is because of the relative homogeneity of permeability values within the spatial template used for averaging. The further the well gets from the channel fewer high permeability blocks will be picked up by the template and thus multiple point models provide the best estimate for effective permeability, Keff. Three point models were found to be the most accurate when the template exhibited complex permeability transition from the mudstone to the channel facies. / text

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