Mapping Sandstone Reservoir Quality – Linking 3-D Burial History and Calibrated Diagenesis Models

Thomas R. Taylor¹, Melvyn R. Giles², Gareth S. Yardley², Gino G. Birbiglia³, Rob Lander⁴, and Linda Bonnell^4
1 Shell International E&P Inc. - Technology Applications & Research, Houston, TX
² Shell International Exploration & Production, Rijswijk, Netherlands
³ Shell International Exploration & Production, New Orleans, LA
⁴ GEOCOSM, Austin, TX

A fundamental risk in exploration plays that target deeply buried sandstone reservoirs is finding sufficient porosity and permeability to support commercial development. An understanding of the three dimensional distribution of sandstone reservoir properties on a regional, prospect, or field development scale is necessary for petrophysical rock properties models, quantitative seismic interpretation, volumetric calculations, and well placement strategies. Numerical forward models (e.g. Touchstone), calibrated to petrographic and petrophysical data, can be used to forecast the effects of compaction and quartz cementation on the evolution of sandstone porosity and permeability. These models provide probabilistic predictions of reservoir quality for a specific point in the subsurface as a function of temperature and vertical effective stress histories. In order to directly link reservoir quality predictions to 3D burial histories while maintaining the rigorous standards for Touchstone model calibration, a reservoir quality module (ResQ) was created for inclusion within Cauldron, Shell's proprietary basin modeling software. Monte Carlo facilities within ResQ allow for statistical assessment of predicted values arising from the likely natural variability in sandstone composition and texture. The results of ResQ calculations are exported as 3D maps of potential porosity, permeability, and quartz cement. When coupled with depositional models, this workflow represents a major step forward in the application of burial history-based reservoir quality and rock property models. A number of integrated applications are envisioned, including; 1) evaluating the impact of alternative burial history scenarios on reservoir quality for prospect risking, 2) comparing reservoir quality trends for sands of varying composition and texture (tied to regional geology, depositional models/seismic facies, etc), and 3) assessing aquifer permeability in the absence of well control.