--> ABSTRACT: The Impact of Subgrid Heterogeneities on Flow Prediction in Carbonates: From Pore-to-Outcrop Scale, by Geiger, Sebastian; Al-Dhahli, Adnan; Annewandter, Robert; Butler, Ian; Chandra, Shanti; van Dijke, Marinus; Fricke, Claudia; Maier, Christine ; Schmid, Karen; Sorbie, Ken; Zaretskiy, Yan; #90135 (2011)

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The Impact of Subgrid Heterogeneities on Flow Prediction in Carbonates: From Pore-to-Outcrop Scale

Geiger, Sebastian 1; Al-Dhahli, Adnan 1; Annewandter, Robert 1; Butler, Ian 2; Chandra, Shanti 1; van Dijke, Marinus 1; Fricke, Claudia 1; Maier, Christine 1; Schmid, Karen 1; Sorbie, Ken 1; Zaretskiy, Yan 1
(1)Institute of Petroleum Engineering, Heriot-Watt University, Edinburgh, United Kingdom. (2) School of GeoSciences, University of Edinburgh, Edinburgh, United Kingdom.

Carbonate reservoirs host a substantial amount of the world’s remaining oil reserves yet face major challenges during production and a small increase in recovery would have a major impact on global hydrocarbon recovery. One key challenge is related to the numerical simulation of flow processes, including IOR and EOR methods, because traditional reservoir simulators have difficulties to resolve the complex geological structures which prevail across all scales in carbonate reservoirs and control flow and transport processes. For example, small-scale variations in lithology result in different (micro and macro) pore geometries, which not only cause spatial variations in permeability and porosity but equally important spatial variations in wettability. Fractures can overprint carbonate lithologies and create localised high-permeability zones such that major quantities of oil are bypassed or held back in the low-permeability matrix. Ideally, these small-scale processes are upscaled in a physically consistent way in reservoir simulations to provide reliable production forecasts.

In this paper we present a new finite element - finite volume method that allows us to simulate multiphase fluid flow problems, including chemical reactions, in real 3D carbonate geometries at scales that are commonly not resolved adequately in a reservoir simulation, that is at the pore-, core-, and outcrop scale. Our numerical simulations are complemented by computerised X-Ray tomography (X-Ray CT) experiments, which allow us to visualise the in-situ flow processes in carbonates in real time and ensure that our simulations model the correct physics, and by analytical solutions, which allow us to analyse the scaling relations of the physical processes occurring during emergent IOR and EOR methods such as controlled-salinity waterflooding. The combination of pore- to outcrop-scale simulations with X-Ray CT flow experiments and analytical solutions is crucial to understand the fundamental controls of flow in carbonates at production and geological time scales. It is an important building block in our wider research effort that aims to develop a consistent and rigorous upscaling method which accounts for structural, lithological, and wettability heterogeneity across all scales in a carbonate reservoir.

 

AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.