Reactive Transport Modeling of Carbonate Diagenesis: Linking Fundamental Geochemical Processes to Reservoir Quality Prediction

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

Diagenesis is a critical control on carbonate reservoir quality. Reactive transport models have the capability to simulate coupled fluid flow and diagenetic reactions to predict spatial and temporal variations in porosity and permeability. We used a reactive transport model to investigate three styles of carbonate 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; and 3) Geothermal con­vection and burial diagenesis in a salt buried isolated platform. Adopting a sensitivity analy­ses approach, we examined how key natural variables, such as climate, sea level, tempera­ture, salinity and fluid 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 results suggest 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 reservoir quality, especially in data poor environments.