TY - JOUR
T1 - Experimental analysis of hybrid low salinity water alternating gas injection and the underlying mechanisms in carbonates
AU - Moradpour, Nikoo
AU - Pourafshary, Peyman
AU - Zivar, Davood
N1 - Funding Information:
The authors would like to thank Nazarbayev University for supporting this research through the NU Faculty Development Competitive Research Grants program (grant number: 110119FD4541 ).
Publisher Copyright:
© 2021 Elsevier B.V.
Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.
PY - 2021/7
Y1 - 2021/7
N2 - Enhanced oil recovery methods have been widely used around the world to improve ultimate hydrocarbon recovery. Among them, low salinity water flooding has gained attention as a practical enhanced oil recovery method which modifies the rock wettability to a more hydrophilic state. Besides, gas, mainly CO2, injection by means of water alternating gas process is proved to improve un-swept oil recovery due to the mobility control of displacing fluids. Hence, the mutual application of these two enhanced oil recovery techniques, as low salinity water alternating gas) injection, benefits the driving mechanisms subjected by both methods resulting in higher oil production. In this study, a series of experiments including contact angle measurements, gas solubility in brine, emulsion formation, and coreflooding were conducted. Wettability alteration of the carbonate samples towards the more water wet state was observed by the contact angle measurements for diluted sea waters which shows salinity of the injected water can play a significant role in the enhancement of ultimate oil recovery. 10 times diluted brine was found to be the optimum one which changed the contact angle for 52°. It shows that there is an optimum concentration for different CBR systems under which the available PDIs are not sufficient to alter the rock wettability to a greater extent. The presence of gas phases favorably improved the wettability modification. The successful performance of 10 times diluted brine was also confirmed by emulsion formation tests. For this case, the number of the generated water in oil emulsion droplets was 1.54 times that of SW. Stable emulsions enhance the oil displacement through provoking wettability alteration by low salinity water and mobilizing the residual oil via the osmotic effect. Finally, a 10.8% incremental oil recovery by low salinity water alternating gas flooding verified the synergistic effects of this method regarding enhanced oil recovery.
AB - Enhanced oil recovery methods have been widely used around the world to improve ultimate hydrocarbon recovery. Among them, low salinity water flooding has gained attention as a practical enhanced oil recovery method which modifies the rock wettability to a more hydrophilic state. Besides, gas, mainly CO2, injection by means of water alternating gas process is proved to improve un-swept oil recovery due to the mobility control of displacing fluids. Hence, the mutual application of these two enhanced oil recovery techniques, as low salinity water alternating gas) injection, benefits the driving mechanisms subjected by both methods resulting in higher oil production. In this study, a series of experiments including contact angle measurements, gas solubility in brine, emulsion formation, and coreflooding were conducted. Wettability alteration of the carbonate samples towards the more water wet state was observed by the contact angle measurements for diluted sea waters which shows salinity of the injected water can play a significant role in the enhancement of ultimate oil recovery. 10 times diluted brine was found to be the optimum one which changed the contact angle for 52°. It shows that there is an optimum concentration for different CBR systems under which the available PDIs are not sufficient to alter the rock wettability to a greater extent. The presence of gas phases favorably improved the wettability modification. The successful performance of 10 times diluted brine was also confirmed by emulsion formation tests. For this case, the number of the generated water in oil emulsion droplets was 1.54 times that of SW. Stable emulsions enhance the oil displacement through provoking wettability alteration by low salinity water and mobilizing the residual oil via the osmotic effect. Finally, a 10.8% incremental oil recovery by low salinity water alternating gas flooding verified the synergistic effects of this method regarding enhanced oil recovery.
KW - CO
KW - CO solubility
KW - Emulsion
KW - Low salinity water
KW - WAG
KW - Wettability alteration
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U2 - 10.1016/j.petrol.2021.108562
DO - 10.1016/j.petrol.2021.108562
M3 - Article
AN - SCOPUS:85101633960
SN - 0920-4105
VL - 202
JO - Journal of Petroleum Science and Engineering
JF - Journal of Petroleum Science and Engineering
M1 - 108562
ER -