In Situ CO₂ Enhanced Oil Recovery: Parameters Affecting Reaction Kinetics and Recovery Performance

Abstract

In situ CO2 enhanced oil recovery (ICE) shows great potential for increasing oil field tertiary recovery. Instead of injecting liquid CO2 directly into the oil reservoir, a solution of a CO2-generating agent is injected to deliver CO2 to the targeted zone. Urea is an attractive gas-generating agent for ICE because it has both low price and exceptional stability in brine with elevated divalent cation concentrations. Besides CO2, urea thermal hydrolysis releases NH3(aq). Both molecules have positive impacts on the tertiary recovery, such as oil swelling, oil viscosity reduction, brine alkalinity increase, and sand surface wettability reversal. Thermal hydrolysis of urea is rapid at 120 °C, but the reaction rate decreases exponentially at lower temperatures. This work compares tertiary recovery from urea hydrolysis at 120 and 80 °C with and without a homogeneous catalyst (NaOH) for the purpose of examining the feasibility of urea-ICE for low-temperature reservoirs. The tertiary recovery was studied and optim...