The Experiment of Burial Dissolution Kinetics for Dolomitized Limestone

Abstract

Carbonate rocks dissolution kinetics, under burial condition, is crucial to carbonate petroleum reservoirs exploration. The experiment investigates dolomitic limestone dissolution kinetics in acetic acid solution with pH 4.4 at temperatures of 75℃ to 200℃, P=30MPa using the continuous flow column pressure vessel reactor, to model the dolomitized limestone dissolve under burial condition. The result indicates the component of MgCO3 is more sensitive than CaCO3 as environment change. The rates increase with as the temperature goes up and the flow velocity speeds up. From the lowest, 7.981×10-12 mol • cm-2 • s-1, at 75℃, to the highest 7.310×10-11 mol • cm-2 • s-1, the dissolution rates rise by a factor of ten. The dissolution mechanisms above 175℃ are extremely different from the below. Moreover, the distance from equilibrium could influence on the mechanism. The switch concentrations Cs vary with temperature yet. The activity energy Ea is 15.195 kJ• mol-1, showing the diffusion control at T=75～125℃; The reaction lacks sufficient data at T=150~200℃, needing further research.