Pore-scale processes in tertiary low salinity waterflooding in a carbonate rock: Micro-dispersions, water film growth, and wettability change
File(s)
Published version
Author(s)
Selem, Ahmed M
Agenet, Nicolas
Blunt, Martin J
Bijeljic, Branko
Type
Journal Article
Abstract
HYPOTHESIS: The wettability change from oil-wet towards more water-wet conditions by injecting diluted brine can improve oil recovery from reservoir rocks, known as low salinity waterflooding. We investigated the underlying pore-scale mechanisms of this process to determine if improved recovery was associated with a change in local contact angle, and if additional displacement was facilitated by the formation of micro-dispersions of water in oil and water film swelling. EXPERIMENTS: X-ray imaging and high-pressure and temperature flow apparatus were used to investigate and compare high and low salinity waterflooding in a carbonate rock sample. The sample was placed in contact with crude oil to obtain an initial wetting state found in hydrocarbon reservoirs. High salinity brine was then injected at increasing flow rates followed by low salinity brine injection using the same procedure. FINDINGS: Development of water micro-droplets within the oil phase and detachment of oil layers from the rock surface were observed after low salinity waterflooding. During high salinity waterflooding, contact angles showed insignificant changes from the initial value of 115°, while the mean curvature and local capillary pressure values remained negative, consistent with oil-wet conditions. However, with low salinity, the decrease in contact angle to 102° and the shift in the mean curvature and capillary pressure to positive values indicate a wettability change. Overall, our analysis captured the in situ mechanisms and processes associated with the low salinity effect and ultimate increase in oil recovery.
Date Issued
2022-12-15
Date Acceptance
2022-06-14
Citation
Journal of Colloid and Interface Science, 2022, 628 (Pt A), pp.486-498
ISSN
0021-9797
Publisher
Elsevier
Start Page
486
End Page
498
Journal / Book Title
Journal of Colloid and Interface Science
Volume
628
Issue
Pt A
Copyright Statement
© 2022 The Authors. Published by Elsevier Inc. This is an open access article under a CC-BY 4.0 License (https://creativecommons.org/licenses/by/4.0/)
License URL
Sponsor
Total E&P UK Limited
Total E&P UK Limited
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/35940140
PII: S0021-9797(22)01042-6
Grant Number
4200016668
4200009805
Subjects
Enhanced oil recovery
Low salinity waterflooding
Micro-dispersions
Pore-scale mechanisms
Wettability change
X-ray micro-CT coreflooding
Publication Status
Published
Coverage Spatial
United States
Date Publish Online
2022-06-18