Geochemical modeling of diagenetic reactions in Snorre Field reservoir sandstones: a comparative study of computer codes

ABSTRACTDiagenetic reactions, characterized by the dissolution and precipitation of minerals at low temperatures, control the quality of sedimentary rocks as hydrocarbon reservoirs. Geochemical modeling, a tool used to understand diagenetic processes, is performed through computer codes based on thermodynamic and kinetic parameters. In a comparative study, we reproduced the diagenetic reactions observed in Snorre Field reservoir sandstones, Norwegian North Sea. These reactions had been previously modeled in the literature using DISSOL-THERMAL code. In this study, we modeled the diagenetic reactions in the reservoirs using Geochemist's Workbench (GWB) and TOUGHREACT software, based on a convective-diffusive-reactive model and on the thermodynamic and kinetic parameters compiled for each reaction. TOUGHREACT and DISSOL-THERMAL modeling showed dissolution of quartz, K-feldspar and plagioclase in a similar temperature range from 25 to 80°C. In contrast, GWB modeling showed dissolution of albite, plagioclase and illite, as well as precipitation of quartz, K-feldspar and kaolinite in the same temperature range. The modeling generated by the different software for temperatures of 100, 120 and 140°C showed similarly the dissolution of quartz, K-feldspar, plagioclase and kaolinite, but differed in the precipitation of albite and illite. At temperatures of 150 and 160°C, GWB and TOUGHREACT produced different results from the DISSOL-THERMAL, except for the dissolution of quartz, plagioclase and kaolinite. The comparative study allows choosing the numerical modeling software whose results are closer to the diagenetic reactions observed in the petrographic analysis of the modeled reservoirs. RESUMOReações diagenéticas, caracterizadas pela dissolução e precipitação de minerais a baixas temperaturas, controlam a qualidade de rochas sedimentares como reservatórios de hidrocarbonetos. A modelagem geoquímica, ferramenta utilizada para compreender os processos diagenéticos, é feita através de códigos computacionais com base em parâmetros termodinâmicos e cinéticos. Em um estudo comparativo, foram reproduzidas as reações diagenéticas observadas nos arenitos-reservatório do Campo de Snorre, Mar do Norte Norueguês. Essas reações já haviam sido previamente modeladas na literatura com uso do código DISSOL-THERMAL. Neste estudo, modelamos reações diagenéticas de reservatórios usando os códigos Geochemist's Workbench (GWB) e TOUGHREACT, com base em um modelo de convecção-difusão-re