Recent Advances in Reactive Transport Modeling of Carbonate and Clastics Diagenesis and Reservoir Quality Prediction

Yitian Xiao and Gareth Jones
ExxonMobil Upstream Research Company, Houston, TX

Diagenesis is a critical control on carbonate and clastics reservoir quality. Reactive transport modeling is an emerging technology with the capability to simulate coupled fluid flow and diagenetic reactions to predict spatial and temporal variations in porosity and permeability. We applied reactive transport modeling to investigate several styles of carbonate and clastics diagenesis:

1. Early diagenesis in four hydrological zones (vadose, freshwater, mixing, and saline) in an isolated carbonate platform;
2. Dolomitization and anhydrite cementation in a brine reflux system;
3. Geothermal convection and burial diagenesis in a salt-buried isolated platform;
4. Fault-induced hydrothermal fluid flow and illitization; and
5. Formation damage associated with water injection and artificial diagenesis.

Adopting a sensitivity analyses approach, we examined how key natural variables, such as climate, sea level, temperature, fluid salinity and composition, and porosity/permeability heterogeneity impact different styles of diagenesis. By linking fundamental geochemical processes to predict reservoir quality we have significantly improved our understanding of previous conceptual diagenetic models and paradigms. Our novel approach suggests that reactive transport models, if sufficiently integrated with traditional methods and calibrated with field data, have the potential to significantly improve our ability to predict carbonate and clastics reservoir quality.