TY - JOUR
T1 - Response of crude oil deposited organic layers to brines of different salinity
T2 - An atomic force microscopy study on carbonate surfaces
AU - Kumar, Saravana
AU - Rao, Ashit
AU - Alotaibi, Mohammed B.
AU - Ayirala, Subhash C.
AU - Yousef, Ali A.
AU - Siretanu, Igor
AU - Mugele, Frieder
N1 - Funding Information:
We thank Carla Annink for her help in the preparation of aged samples used for AFM topography imaging and mechanical characterization experiments reported in this study. Funding from the Saudi Arabian Oil Company (Saudi Aramco) under the contract no. 6600041100 is gratefully acknowledged.
Publisher Copyright:
© 2021 The Authors
PY - 2021/10/15
Y1 - 2021/10/15
N2 - The various microscopic processes that take place during enhanced oil-recovery upon injecting low salinity brines are quite complex, particularly for carbonate reservoirs. In this study, we characterize the in-situ microscopic responses of the organic layers deposited on flat Iceland spar calcite surface to brines of different salinity using Atomic force Microscopy (AFM). Organic layers were deposited from crude oil at the end of a two-step aging procedure. AFM topography images reveal that the organic layers remain stable in high-salinity brines and desorb upon exposure to low-salinity brines. In addition, the organic layers swell in low-salinity brines, and the stiffness of the organic layers is found to directly proportional to the brine salinity. These observations are explained in terms of ‘salting-out’ effects, where the affinity of organic layers to solvent molecules increases upon reducing the brine salinity. The swelling and desorption of organic materials provide access for the brine to mineral surface causing dissolution and change in wetting properties of the surface. Our results show the significance of de-stabilizing the organic layer on rock surfaces in order to design any successful improved oil recovery (IOR) strategy.
AB - The various microscopic processes that take place during enhanced oil-recovery upon injecting low salinity brines are quite complex, particularly for carbonate reservoirs. In this study, we characterize the in-situ microscopic responses of the organic layers deposited on flat Iceland spar calcite surface to brines of different salinity using Atomic force Microscopy (AFM). Organic layers were deposited from crude oil at the end of a two-step aging procedure. AFM topography images reveal that the organic layers remain stable in high-salinity brines and desorb upon exposure to low-salinity brines. In addition, the organic layers swell in low-salinity brines, and the stiffness of the organic layers is found to directly proportional to the brine salinity. These observations are explained in terms of ‘salting-out’ effects, where the affinity of organic layers to solvent molecules increases upon reducing the brine salinity. The swelling and desorption of organic materials provide access for the brine to mineral surface causing dissolution and change in wetting properties of the surface. Our results show the significance of de-stabilizing the organic layer on rock surfaces in order to design any successful improved oil recovery (IOR) strategy.
KW - Atomic force microscopy
KW - Improved oil recovery
KW - Low-salinity effect
KW - Polyaromatic hydrocarbons
KW - Salting-out effects
UR - http://www.scopus.com/inward/record.url?scp=85107597927&partnerID=8YFLogxK
U2 - 10.1016/j.fuel.2021.121129
DO - 10.1016/j.fuel.2021.121129
M3 - Article
AN - SCOPUS:85107597927
SN - 0016-2361
VL - 302
JO - Fuel
JF - Fuel
M1 - 121129
ER -
