Laboratory measurement of oil viscosity reduction due to CO<SUB align="right">2 injection at high-pressure, high-temperature conditions

Abstract

This work presents the use of rolling-ball viscometer to measure viscosity reduction of two dead oil samples injected with CO2 at a temperature of 168°F and a pressure range of 1,114.7 psi-3,514.7 psi. First, a new digital control unit was designed to replace the analogue unit. Afterwards, viscometer was calibrated with Cannon S-6 and S-60 viscosity standards. Next, validation was conducted by measuring the viscosity of n-decane at a temperature range of 77°F-266°F and a pressure range of 514.7 psi-2,014.7 psi. Next step was the investigation of CO2 effect in reducing n-decane viscosity at 130°F-266°F temperature range and 1,014.7 psi-2,014.7 psi pressure range. Results showed significantly reduced viscosities of the CO2 mixture compared to n-decane viscosities, especially at lower temperatures. Afterwards, viscosity of two distinct crude samples was measured at 168°F and 14.7 psi-3,514.7 psi pressure interval. Next, CO2 was injected to respective oil samples and system viscosity was measured at the same temperature and at pressures between 1,114.7 psi and 3,514.7 psi. [Received: September 20, 2021; Accepted: January 30, 2022]