Using near wellbore upscaling to improve reservoir characterization and simulation in highly heterogeneous carbonate reservoirs

V. Chandra, Sebastian Geiger, Patrick William Michael Corbett, Richard Steele, Paul Milroy, Andrew Barnett, Paul Victor Wright, P. Jain

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Carbonate reservoirs host a major portion of the world's remaining conventional and unconventional hydrocarbon reserves, typically containing multi-scale geological heterogeneities varying over many orders of magnitude in size. Characterizing and representing them robustly in reservoir models is a prime challenge in carbonate reservoir simulation. One of the key aims of this paper is, hence, to present a novel near wellbore upscaling (NWU) workflow that addresses the challenges associated with conventional carbonate modelling workflows. The NWU workflow provides a systematic geostatistical approach to obtain more realistic representation of multi-scale geological-petrophysical heterogeneities in complex carbonate reservoir simulation models. Using well log and core data, near wellbore regions were recreated to represent the core scale heterogeneities via high resolution geostatistical models. These core/centimeter scale permeability models were then upscaled into wireline/decametre scale using flow-based upscaling. The results, coupled with wireline data were used to generate global porosity-permeability and vertical-horizontal permeability relationships for reservoir simulation. Importantly, the workflow mitigates sample bias, which is frequently observed in the core data for carbonate reservoirs. We have applied our approach to a mature carbonate field, to model and upscale crucial multi-scale heterogeneities ubiquitous in the reservoir. These heterogeneities, such as mechanically weak zones of enhanced micro- and macro-porosity, leached stylolites and associated tension gashes, were caused by diagenetic corrosion. Core plugs representivity is always an issue in carbonates and these highly corroded features were very difficult, if not impossible, to sample due to their fragility. As a result, the field suffers from inherent sample biasing and insufficiency of Routine Core Analysis (RCA) data, consequently underestimating the permeability in the simulation model. The workflow presented here has enabled the authors to re-evaluate the reservoir permeability model by accounting for as yet under-sampled geological heterogeneities. The paper represents a focused individual study addressing this specific issue and doesn't necessarily reflect the operator's full understanding of this multifaceted field. Our new permeability model has addressed the need for artificial permeability multipliers and provided insight on the potential causes of the original mismatch. As a result, a new alternative model scenario has been built to help guide the on-going development plans and forecasting incremental oil recovery.
Original languageEnglish
Title of host publicationSPE Reservoir Characterisation and Simulation Conference and Exhibition (RCSC 2013)
Subtitle of host publicationnew approaches in characterisation and modelling of complex reservoirs
Place of PublicationRichardson, Texas
PublisherSociety of Petroleum Engineers
Pages943-956
Number of pages14
ISBN (Electronic)9781613992685
ISBN (Print)9781629931449
DOIs
Publication statusPublished - Sep 2013
EventSPE Reservoir Characterisation and Simulation Conference and Exhibition 2013 - Abu Dhabi, United Arab Emirates
Duration: 16 Sep 201318 Sep 2013

Conference

ConferenceSPE Reservoir Characterisation and Simulation Conference and Exhibition 2013
Abbreviated titleRCSC 2013
CountryUnited Arab Emirates
CityAbu Dhabi
Period16/09/1318/09/13

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    Chandra, V., Geiger, S., Corbett, P. W. M., Steele, R., Milroy, P., Barnett, A., Wright, P. V., & Jain, P. (2013). Using near wellbore upscaling to improve reservoir characterization and simulation in highly heterogeneous carbonate reservoirs. In SPE Reservoir Characterisation and Simulation Conference and Exhibition (RCSC 2013): new approaches in characterisation and modelling of complex reservoirs (pp. 943-956). Society of Petroleum Engineers . https://doi.org/10.2118/166033-MS