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Graph-Based Simulator for Steam-Assisted Gravity Drainage Reservoir Management
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- Author / Creator
- Gallardo Vizcaino, Enrique
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Petroleum reservoir managers must make decisions about projects (e.g. infill drilling and/or operational strategies) with uncertain economic results due to imperfect knowledge of the reservoir geometry and properties. Their decision-making workflows should actively manage the geological uncertainty. This requires transferring the geological uncertainty to probability distributions of a response variable suitable for decision-making and use of a decision criterion that considers the reservoir manager’s preferences toward the project’s return-risk trade-off. This is challenging in petroleum reservoir management because transferring the geological uncertainty is time and computationally expensive. Moreover, common decision-making criteria do not consider preferences toward the geological risk of the projects.This dissertation improves reservoir management decision-making practices in steam-assisted gravity drainage (SAGD) projects by introducing: 1) A novel graph-based simplified physics simulator, called APDS, that efficiently transfers the geological uncertainty into steam-chamber evolution paths that can directly support SAGD reservoir management or be converted to a monetary response variable, and 2) A decision-making criterion consistent with the utility theory framework that combines Mean-Variance Criterion (MVC) and Stochastic Dominance Rules (SDR) to guide the decision process. APDS is formulated and implemented using graph theory, simplified porous media flow equations, heat transfer concepts and ideas from discrete simulation. It works on homogeneous and heterogeneous reservoirs and is computationally efficient enough to be applied over multiple geostatistical realizations. A case study performed with a realistic multi-realization geological model validates the predictive capabilities of APDS. Visual and numerical comparisons with the results obtained from a conventional full physics thermal flow simulation are satisfactory. APDS was 3 orders of magnitude faster than the conventional simulator to model the steam-chamber expansion and to provide predictions of reservoir response. The reduction in the precision of the results is deemed acceptable. Another case study demonstrates that APDS can complement methodologies for assimilation of 4D-seismic dynamic data to improve reservoir characterization. This thesis also demonstrates that MVC-SDR is a viable criterion for decision making under geological uncertainty. MVC-SDR does not rely on a specific utility function and leads to decisions that are considered rational to risk-averse reservoir managers. The shortcoming is a reduced ability to rank projects with very similar value. Two examples illustrate the use of MVC-SDR, the first one relates to the selection of a SAGD well-pad to be drilled from a set of several possible options, and the second one considers the problem of finding the best vertical location for a SAGD well-pair project in a target volume.
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- Graduation date
- Spring 2019
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- Type of Item
- Thesis
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- Degree
- Doctor of Philosophy
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- License
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.