Integrating reservoir characterization: 3D dynamic, petrophysical and geological description of reservoir facies

Abstract

Integrating conventional geologic, petrophysical and reservoir engineering rock typing methods requires studies which incorporate 3D imaging of rock material, 2D petrographic studies, fluid:fluid and fluid:solid interactions (e.g., wettability), and geological facies descriptions. This paper illustrates a new integrated methodology for the multidisciplinary study of reservoir core material. Petrophysical units define zones of a reservoir with similar flow and storage capacity. Geological facies are based on depositional and diagenetic criteria, which are tied to poro-perm data. Empirical relationships are often used to tie the petrophysical to the geological models, to estimate initial hydrocarbons in place. Reservoir engineers also wish to define rock types based on their recovery characteristics (e.g., relative permeability). In this case fluid properties (e.g., fluid components and wettability) can be a major factor controlling the flow and distribution of fluids in porous rocks, which in turn greatly impacts ultimate recovery of hydrocarbons. QEMSCAN®, automated Scanning Electron Microscopy with fully integrated x-ray microanalysis and image analysis, enables one to obtain spatial and numeric 2D mineralogical information from geologic samples. This analysis allows high quality 2D mapping of key parameters used in characterizing rocks: mineralogy, modal mineral proportions, mineral relationships and associations. Micro-CT (μ-CT) imaging enables one to enumerate the porosity, pore geometrical and topological complexities in reservoir rock and visualize fluids within the pore structure of core material in 3D; this enhances the estimation of both fluid flow and recovery properties of core. Results show how the integration of these techniques allows one to more accurately map the mineralogy and wettability characteristics of reservoir rocks in three dimensions, and therefore better couple relevant information from petrologists, petrophysicists and reservoir engineers. A number of case studies illustrate the application of this integrated approach to enhance prediction of petrophysical and multiphase flow characteristics in complex core.