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| |+ {{table number|1}}Approximate relationship among wettability, contact angle, and the USBM and Amott wettability indexes | | |+ {{table number|1}}Approximate relationship among wettability, contact angle, and the USBM and Amott wettability indexes |
| |- | | |- |
− | ! | + | ! || Water Wet || Neutrally Wet || Oil Wet |
− | ! Water Wet
| |
− | ! Neutrally Wet
| |
− | ! Oil Wet
| |
| |- | | |- |
− | | Contact angle | + | | Contact angle || || || |
− | | | |
− | | |
− | | | |
− | | |
− | | | |
− | | |
| |- | | |- |
− | | Minimum | + | | Minimum || 0° || 60 to 75° || 105 to 120° |
− | | 0° | |
− | | 60 to 75° | |
− | | 105 to 120° | |
| |- | | |- |
− | | Maximum | + | | Maximum || 60 to 75° || 105 to 120° || 180° |
− | | 60 to 75° | |
− | | 105 to 120° | |
− | | 180° | |
| |- | | |- |
− | | USBM wettability index | + | | USBM wettability index || W near 1 || W near 0 || W near -1 |
− | | W near 1 | |
− | | W near 0 | |
− | | W near -1 | |
| |- | | |- |
− | | Amott wettability index | + | | Amott wettability index || || || |
− | | | |
− | | |
− | | | |
− | | |
− | | | |
− | | |
| |- | | |- |
− | | Displacement by water ratio | + | | Displacement by water ratio || Positive || Zero || Zero |
− | | Positive | |
− | | Zero | |
− | | Zero | |
| |- | | |- |
− | | Displacement by oil ratio | + | | Displacement by oil ratio || Zero || Zero || Positive |
− | | Zero | |
− | | Zero | |
− | | Positive | |
| |- | | |- |
− | | Amott-Harvey wettability index | + | | Amott-Harvey wettability index || 0.3 to 1.0 || –0.3 to 0.3 || –1.0 to –0.3 |
− | | 0.3 to 1.0 | |
− | | –0.3 to 0.3 | |
− | | –1.0 to –0.3 | |
| |} | | |} |
− |
| |
− | [[file:wettability_fig2.png|thumb|{{figure number|2}}Combined Amott and USBM method. (After Anderson;<ref name=pt05r14>Anderson, W. G., 1986b, Wettability literature survey—Part 2, Wettability measurements: Journal of Petroleum Technology, v. 38, p. 1246–1262., 10., 2118/13933-PA</ref> from Shamra and Wunderlich.<ref name=pt05r143>Shamra, M. M., Wundlerlich, R. W., 1985, The alteration of rock properties due to interactions with [[drilling fluid]] components: Annual Technical Conference and Exhibition of the Society of Petroleum Engineers, Las Vegas, NV, Sept. 22–25, SPE 14302.</ref>)]]
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| ===USBM method=== | | ===USBM method=== |