A hierarchical process-approach to reservoir heterogeneity: Examples from outcrop analogues

Characterisation and prediction of reservoir heterogeneities require a proc ess understanding of the sedimentary architecture. We propose a simple, pro cess-based methodology to analyse heterogeneities in a rigorously hierarchi cal way. moving from the smallest to the largest sedimentary units (particl es to basins): 1) Microscale heterogeneities: caused by particle and pore properties (size , composition, texture etc.). which are determined by depositional and diag enetic fluid dynamics; 2) Mesoscale heterogeneities: caused by Various stratification styles, whic h are controlled by the major depositional/erosional processes; 3) Macroscale heterogeneities: caused by facies and architectural elements, which record the differing dynamics and preservation of facies tracts; 4) Megascale heterogeneities: caused by fundamental sedimentary cycles and sequences, which reflect the stratigraphic dynamics of small-scale baseleve l fluctuations; 5) Gigascale heterogeneities: caused by the stacking of fundamental cycles within a cycle hierarchy, which is controlled by long-term baselevel dynami cs. Understanding the formative processes of each scale allows to deduce "rules " and predictions on the distribution of heterogeneities. This approach of "dynamic stratigraphy" is illustrated by two case studies using outcrop analogues for subsurface reservoirs. A combination with petro physical (porosity, permeability, gamma-ray logs) and geophysical tools (3- D georadar in outcrop) should lead to an integrated data set for reservoir modelling from microscopic to seismic scale.