This paper presents the rheological behaviour of supercritical CO2 （sCO2） foam at reser- voir conditions of I 500 psi and 80 ℃. Different commercial surfactants were screened and utilized in or- der to generate a f...This paper presents the rheological behaviour of supercritical CO2 （sCO2） foam at reser- voir conditions of I 500 psi and 80 ℃. Different commercial surfactants were screened and utilized in or- der to generate a fairly stable CO2 foam. Mixed surfactant system was also introduced to generate strong foam. Foam rheology was studied for some specific foam qualities using a high pressure high tempera- ture （HPHT） foam loop rheometer. A typical shear thinning behaviour of the foam was observed and a significant increase in the foam viscosity was noticed with the increase of foam quality until 85%. A de- sired high apparent viscosity with coarse texture was found at 85% foam quality. Foam visualization above 85% showed an unstable foam due to extremely thin lamella which collapsed and totally disap- peared in the loop rheometer. Below 52%, a non-homogenous and unstable foam was found having low viscosity with some liquid accumulation at the bottom of the circulation loop. This research has demon- strated rheology of sCO2 foams at different qualities at HPHT to obtain optimal foam quality region for immiscible CO2 foam co-injection process.展开更多
A hybrid enhanced oil recovery(EOR)method by combining low salinity water(LSW)and low salinity surfactant(LSS)flooding techniques was designed.Different experiments were done to screen the Caspian seawater(SW)with alt...A hybrid enhanced oil recovery(EOR)method by combining low salinity water(LSW)and low salinity surfactant(LSS)flooding techniques was designed.Different experiments were done to screen the Caspian seawater(SW)with altered ionic composition and surfactant,for the optimized performance in Kazakhstani carbonate oil fields.Changing to a more water-wet state and creating the middle phase were studied as the main criteria to select the best-engineered brine and anionic surfactant.The largest alteration towards the water-wet condition was recorded at 10 times dilution of the SW with 3-and 6-times spiked calcium and sulfate ions,respectively(10xSW-6SO4,Mg,3Ca).This combination of anionic surfactants with carbonate formations is considered as a new approach in hybrid EOR methods.Among the anionic surfactants screened,Soloterra-113H(alkyl benzenesulfonic acid)showed the best solubilization ratio,aqueous stability and Winsor type 3 microemulsions.The wettability alteration by the combination of optimized brine and screened surfactant was greater compared to the standalone LSW,which was confirmed by the 10difference in contact angle measurement.The microemulsion phase constituted nearly 40%of the total height of the oil/brine column by the hybrid method.The recovery factor after injecting formation water was 52%,and it increased to 61%after optimized LSW injection.After switching to the engineered brine/surfactant,the recovery factor reached 70%,which proves the effectiveness of the hybrid method.The proposed combined method works better than either standalone EOR method due to the higher alteration in capillary number by changing wettability and reducing IFT,which leads to higher oil recovery.展开更多
基金financial support by Universiti Teknologi PETRONAS (No. YUTP-0153AA-E70)
文摘This paper presents the rheological behaviour of supercritical CO2 （sCO2） foam at reser- voir conditions of I 500 psi and 80 ℃. Different commercial surfactants were screened and utilized in or- der to generate a fairly stable CO2 foam. Mixed surfactant system was also introduced to generate strong foam. Foam rheology was studied for some specific foam qualities using a high pressure high tempera- ture （HPHT） foam loop rheometer. A typical shear thinning behaviour of the foam was observed and a significant increase in the foam viscosity was noticed with the increase of foam quality until 85%. A de- sired high apparent viscosity with coarse texture was found at 85% foam quality. Foam visualization above 85% showed an unstable foam due to extremely thin lamella which collapsed and totally disap- peared in the loop rheometer. Below 52%, a non-homogenous and unstable foam was found having low viscosity with some liquid accumulation at the bottom of the circulation loop. This research has demon- strated rheology of sCO2 foams at different qualities at HPHT to obtain optimal foam quality region for immiscible CO2 foam co-injection process.
基金The authors would like to thank Nazarbayev University for supporting this research through the NU Faculty Development Competitive Research Grants program(grant number:110119FD4541)。
文摘A hybrid enhanced oil recovery(EOR)method by combining low salinity water(LSW)and low salinity surfactant(LSS)flooding techniques was designed.Different experiments were done to screen the Caspian seawater(SW)with altered ionic composition and surfactant,for the optimized performance in Kazakhstani carbonate oil fields.Changing to a more water-wet state and creating the middle phase were studied as the main criteria to select the best-engineered brine and anionic surfactant.The largest alteration towards the water-wet condition was recorded at 10 times dilution of the SW with 3-and 6-times spiked calcium and sulfate ions,respectively(10xSW-6SO4,Mg,3Ca).This combination of anionic surfactants with carbonate formations is considered as a new approach in hybrid EOR methods.Among the anionic surfactants screened,Soloterra-113H(alkyl benzenesulfonic acid)showed the best solubilization ratio,aqueous stability and Winsor type 3 microemulsions.The wettability alteration by the combination of optimized brine and screened surfactant was greater compared to the standalone LSW,which was confirmed by the 10difference in contact angle measurement.The microemulsion phase constituted nearly 40%of the total height of the oil/brine column by the hybrid method.The recovery factor after injecting formation water was 52%,and it increased to 61%after optimized LSW injection.After switching to the engineered brine/surfactant,the recovery factor reached 70%,which proves the effectiveness of the hybrid method.The proposed combined method works better than either standalone EOR method due to the higher alteration in capillary number by changing wettability and reducing IFT,which leads to higher oil recovery.
