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Evaluation of the Impact of Low-Salinity Water on Wettability Alteration and Oil Recovery in Berea Sandstones

2022; RELX Group (Netherlands); Linguagem: Inglês

10.2139/ssrn.4117075

1556-5068

Osamah Alomair, Mabkhout M. Al-Dousari, Nyeso Azubuike, Ali A. Garrouch,

Hydraulic Fracturing and Reservoir Analysis

Low-salinity water (LSW) flooding is an emerging technique to enhance oil recovery from carbonate and sandstone reservoirs. Despite growing interest in the field, significant disparities remain regarding the underlying mechanisms. While most researchers agree that wettability alterations may be the dominant mechanism, their quantitative impact on oil recovery remains elusive. This study quantitatively evaluated the effects of LSW flooding on rock wettability and oil recovery through a series of U.S. Bureau of Mines (USBM) tests and contact angle measurements on synthetic clay-free Berea samples with similar textural properties and pore structures. When water salinity was varied from 85,000 to 4,000 ppm, the USBM index increased from approximately 0.26 to 0.38, thereby confirming a change from a slightly water-wet to strongly water-wet condition. These changes were consistent with a decrease in the contact angle from approximately 55.6° to 35.3°. As water salinity decreased to approximately 5% of its original value, centrifuge data indicated a drop in the residual oil saturation from 0.247 to 0.202, corresponding to an increase (of approximately 4%) in the oil recovery factor at the end of the forced imbibition cycle. The results of wettability effects caused by LSW flooding reported in this paper are unique because they (i) are based on reproducible runs, (ii) reflect the individual effects of wettability, and (iii) are validated by two independent measurement techniques for rock wettability.