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Systematic uncertainty reduction for petroleum reservoirs combining reservoir simulation and Bayesian emulation techniques

Nandi Formentin, Helena; Vernon, Ian; Avansi, Guilherme Daniel; Caiado, Camila; Maschio, Celio; Goldstein, Michael; Schiozer, Denis Jose


Helena Nandi Formentin

Guilherme Daniel Avansi

Camila Caiado

Celio Maschio

Michael Goldstein

Denis Jose Schiozer


Reservoir simulation models incorporate physical laws and reservoir characteristics. They represent our understanding of sub-surface structures based on the available information. Emulators are statistical representations of simulation models, offering fast evaluations of a sufficiently large number of reservoir scenarios, to enable a full uncertainty analysis. Bayesian History Matching (BHM) aims to find the range of reservoir scenarios that are consistent with the historical data, in order to provide comprehensive evaluation of reservoir performance and consistent, unbiased predictions incorporating realistic levels of uncertainty, required for full asset management. We describe a systematic approach for uncertainty quantification that combines reservoir simulation and emulation techniques within a coherent Bayesian framework for uncertainty quantification. Our systematic procedure is an alternative and more rigorous tool for reservoir studies dealing with probabilistic uncertainty reduction. It comprises the design of sets of simulation scenarios to facilitate the construction of emulators, capable of accurately mimicking the simulator with known levels of uncertainty. Emulators can be used to accelerate the steps requiring large numbers of evaluations of the input space in order to be valid from a statistical perspective. Via implausibility measures, we compare emulated outputs with historical data incorporating major process uncertainties. Then, we iteratively identify regions of input parameter space unlikely to provide acceptable matches, performing more runs and reconstructing more accurate emulators at each wave, an approach that benefits from several efficiency improvements. We provide a workflow covering each stage of this procedure. The procedure was applied to reduce uncertainty in a complex reservoir case study with 25 injection and production wells. The case study contains 26 uncertain attributes representing petrophysical, rock-fluid and fluid properties. We selected phases of evaluation considering specific events during the reservoir management, improving the efficiency of simulation resources use. We identified and addressed data patterns untracked in previous studies: simulator targets, e.g. liquid production, and water breakthrough lead to discontinuities in relationships between outputs and inputs. With 15 waves and 115 valid emulators, we ruled out regions of the searching space identified as implausible, and what remained was only a small proportion of the initial space judged as non-implausible (~10−11%). The systematic procedure showed that uncertainty reduction using iterative Bayesian History Matching has the potential to be used in a large class of reservoir studies with a high number of uncertain parameters. We advance the applicability of Bayesian History Matching for reservoir studies with four deliveries: (a) a general workflow for systematic BHM, (b) the use of phases to progressively evaluate the historical data; and (c) the integration of two-class emulators in the BHM formulation. Finally, we demonstrate the internal discrepancy as a source of error in the reservoir model.


Nandi Formentin, H., Vernon, I., Avansi, G. D., Caiado, C., Maschio, C., Goldstein, M., & Schiozer, D. J. (2019). Systematic uncertainty reduction for petroleum reservoirs combining reservoir simulation and Bayesian emulation techniques. In SPE Europec featured at 81st EAGE Conference and Exhibition, 3-6 June, London, England, UK (SPE-195478).

Conference Name SPE Europec featured at 81st EAGE Annual Conference 2019
Conference Location London
Start Date Jun 3, 2019
End Date Jun 6, 2019
Acceptance Date Feb 15, 2019
Publication Date Jan 1, 2019
Deposit Date Feb 20, 2019
Publisher Society of Petroleum Engineers (SPE)
Pages SPE-195478
Book Title SPE Europec featured at 81st EAGE Conference and Exhibition, 3-6 June, London, England, UK.