Physics:USBM wettability index
The U.S. Bureau of Mines (USBM), developed by Donaldson et al. in 1969, is a method to measure wettability of petroleum reservoir rocks. In this method, the areas under the forced displacement Capillary pressure curves of oil and water drive processes are denoted as [math]\displaystyle{ A1 }[/math] and [math]\displaystyle{ A2 }[/math] to calculate the USBM index.[1][2]
- [math]\displaystyle{ USBM = log\frac{A_{\mathit{1}}} {\ A_{\mathit{2}}} }[/math]
USBM index is positive for water-wet rocks, and negative for oil-wet systems.
Bounded USBM (or USBM*)
The USBM index is theoretically unbounded and can vary from negative infinity to positive infinity. Since other wettability indices such as Amott-Harvey, Lak wettability index and modified Lak are bounded in the range of -1 to 1, Abouzar Mirzaei-Paiaman highlighted the bounded form of USBM (called USBM*) as a replacement of the traditional USBM as [3]
- [math]\displaystyle{ USBM* = \frac{A_{\mathit{1}}-A_{\mathit{2}}} {\ A_{\mathit{1}}+A_{\mathit{2}}} }[/math]
USBM* varies from -1 to 1 for strongly oil-wet and strongly water-wet rocks, respectively.
See also
- Wetting
- Amott test
- Lak wettability index
References
- ↑ Donaldson, E.C.; Thomas, R.D.; Lorenz, P.B. (1969). "Wettability determination and its effect on recovery efficiency". SPE Journal 9 (1): 13–20.
- ↑ Sharma, M.M.; Wunderlich, R.W. (1987). "The alteration of rock properties due to interactions with drilling fluid components". J. Petrol. Sci. Technol. 1: 127–143.
- ↑ Mirzaei-Paiaman, A. (2022). "Analysis of the bounded and unbounded forms of USBM wettability index". Energy Geoscience 3 (1): 94–102. doi:10.1016/j.engeos.2021.12.001.
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