Print this pageAAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Capturing Interwell Scale Heterogeneity from Process-Based Modelling for Reservoir Flow Simulations: A Study of the Middle Triassic Latemar Platform, Dolomites, North Italy
(1) Earth Sciences, University of Bristol, Bristol, United Kingdom.
(2) Upstream Research Company, ExxonMobil, Houston, TX.
Many carbonate reservoirs are characterized by complex depositional and/or diagenetic facies distributions at the inter-well scale which contribute significantly to uncertainty in prediction of flow behavior. Traditional approaches to populating reservoir models often lead to under-representation of geological continuity and loss of extreme (high/low) permeability features. This study demonstrates the potential of process-based models to provide valuable 3D datasets of key reservoir properties with 100% coverage that can bridge the gap between seismic and well data. The workflow uses the forward model CARB3D+ to simulate carbonate platform architecture and porosity and permeability distribution as a function of depositional and early diagenetic processes. Single phase tracer experiments using the streamline flow simulator 3DSL are then undertaken on CARB3D+ synthetic stratigraphies and flow behaviour analysed. Thus we can compare different synthetic platforms and evaluate approaches to layer aggregation.
CARB3D+ simulations of the Latemar platform successfully replicate the 3D distribution of facies and platform geometry described from outcrop. Third order sea-level variation generates alternating sequences of cyclic carbonates with a near-complete record of sedimentation, and condensed intervals where limited accommodation gives many “missed beats” due to non-deposition and/or subaerial dissolution and greater diagenetic overprinting. At reservoir depths, contrasts in depositional texture and early diagenesis result in condensed intervals with significantly lower porosity than cyclic intervals. However cyclic intervals display much higher interior to margin differences, as well as greater systematic vertical variation within high frequency cycles. These patterns are reflected in the permeability distribution and, for simple injection/production scenarios with a fixed pressure gradient, give increased sweep efficiency of cyclic compared to condensed intervals. The effect of diagenesis is also more pronounced in the cyclic intervals, where it enhances sweep efficiency/production rate, whereas in the tighter condensed intervals diagenesis restricts fluid flow. Preliminary experiments in vertical amalgamation of high resolution synthetic stratigraphies generated using CARB3D+ suggest that significant simulation efficiency gain is possible without loss of key heterogeneities controlling flow, enabling multi-phase fluid flow experiments to be undertaken.