Experimental measurement of diffusivity of carbon dioxide in lan krabue crude

Abstract

Measurement of diffusivity of carbon dioxide (99.99% purity CO2) in Lan Krabue crude was carried out by using Parr reactor with a pressure decay method to estimate the decay of pressure over time. The diffusivity was done with two different APIs of 14.1, and 21.3 at 30 ℃ and 40 ℃, and at initial pressure 300 psi and 700 psi. The non-linear regression function with a curve fitting tool in MATLAB was used to fit curves from the obtained data. The diffusivity of CO2 in the two crudes was then calculated. As the initial pressure was increased and the temperature at 30 ℃ the diffusivity of CO2 into crude API 14.1 was increased from 1.2779x10-9 m2/s at 300 psi to 3.2533x10-9 m2/s at 700 psi. Moreover, for crude API 21.3, the diffusivity of carbon dioxide increased from 9.7956x1 O-9 m2/s at 300 psi to 1.1729x10-8 m2/s at 700 psi. The diffusivity of CO2 increased when initial pressure increased because higher initial pressure produced a higher driving force: And when temperature increased, the diffusion coefficient of CO2 increased due to the decreasing of viscosity of Lan Krabue crude. In addition, the diffusivity of CO2 increased dramatically with increasing API gravity of the crude because higher API gravity causes lower viscosity.