Limestone dissolution rates in 0.6 M NaCl solution at 50°to 300 °Cand 25 MPa

摘要

Limestone dissolution in geofluids can become undersaturated as a result of fluid migration. This study measured limestone dissolution rates in 0.6 M NaCl solution with flow velocity varying from 0.25 to 4mL·min-1 at 50° to 300 °C and 25MPa. The dissolution rate can be described by the rate equation: R=kc-n, where the rate constant k=a0· Exp(a1/T) and the reaction order n=-(a2T +a3),ai represent fitting parameters, which can be estimated from a multiple regression model of the form ln R = ln a0 + a1/T + a2 T ln c + a3 ln c. The reaction order, varying from 2.16 to 1.94, decreased linearly with the increasing of temperature, and the activity energy of the limestone dissolution reaction is 24 kJ· Mol-1.