Diagenetic Albitization of K-Feldspar and Plagioclase in Sandstone Reservoirs: Thermodynamic and Kinetic Modeling

Abstract

ABSTRACT Diagenetic albitization of K-feldspar and plagioclase is a common diagenetic phenomenon in numerous sedimentary basins. Three geochemical codes (DISSOL, THERMAL, and KINDIS) are used to simulate these albitization reactions in terms of fluid chemistry and temperature. The geochemical codes show that albitization of K-feldspar is enhanced by increasing temperature, and is most likely to occur at 120-150°C. Kinetic modeling of this reaction predicts the instability of quartz, which is generally considered a K-feldspar albitization product. Albitization of plagioclase is shown to decrease with increasing temperature. For low pCO2 conditions it probably occurs between temperatures of 60°C and 100°C, while for higher values of pCO2 it continues at temperat res greater than 100°C.