Abstract
Enhanced oil recovery (EOR) from heavy oil reservoirs is challenging. High oil viscosity, high mobility ratio, inadequate sweep, and reservoir heterogeneity adds more challenges and severe difficulties during any EOR method. Foam injection showed potential as an EOR method for challenging and heterogeneous reservoirs containing light oil. However, the foams and especially polymer enhanced foams (PEF) for heavy oil recovery have been less studied. This study aims to evaluate the performance of CO2 foam and CO2 PEF for heavy oil recovery and CO2 storage by analyzing flow through porous media pressure profile, oil recovery, and CO2 gas production. Foam bulk stability tests showed higher stability of PEF compared to that of surfactant-based foam both in the absence and presence of heavy crude oil. The addition of polymer to surfactant-based foam significantly improved its dynamic stability during foam flow experiments. CO2 PEF propagated faster with higher apparent viscosity and resulted in more oil recovery compared to that of CO2 foam injection. The visual observation of glass column demonstrated stable frontal displacement and higher sweep efficiency of PEF compared to that of conventional foam. In the fractured rock sample, additional heavy oil recovery was obtained by liquid diversion into the matrix area rather than gas diversion. Aside from oil production, the higher stability of PEF resulted in more gas storage compared to conventional foam. This study shows that CO2 PEF could significantly improve heavy oil recovery and CO2 storage.
Highlights
With growing concerns about climate change and CO2 emissions, the storage of CO2 in Enhanced oil recovery (EOR) operations has been recognized as one of the most practical means of reducing CO2 emissions
Foam/polymer enhanced foams (PEF) performance for heavy oil recovery was investigated in tertiary mode
Pressure along the length of the rock sample, liquid production, and CO2 gas production were recorded to investigate the potential of CO2 foam for heavy oil recovery and CO2 storage, which will be analyzed in the discussion section
Summary
With growing concerns about climate change and CO2 emissions, the storage of CO2 in EOR operations has been recognized as one of the most practical means of reducing CO2 emissions. CO2 EOR and storage has been studied for fractured reservoirs in the form of immiscible or miscible gas injections [1,2,3,4,5,6]. Haugen et al (2014) investigated the foam performance on mobility control and EOR in fractured oil-wet carbonate rocks [21]. As per their experimental results, the miscible injection of CO2 foam significantly increased the oil sweep efficiency more than that of the immiscible injection of N2 foam. This work presents the experimental results on the potential of CO2 foam and CO2 PEF for relatively viscous oil recovery from unconsolidated and consolidate porous media, focusing on the effect of heterogeneity and polymer addition
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