Wettability of oil-producing reservoir rocks as determined from X-ray photoelectron spectroscopy
- Univ. of Concepcion (Chile)
- Intevep, S.A., Caracas (Venezuela)
Wettability has a dominant effect in oil recovery by water-flooding and in many other processes of industrial and environmental interest. Recently, the suggestion has been made the surface science analytical techniques (SSAT) could be used to rapidly determine the wettability of reservoir materials. Here, the authors bring the capability of X-ray photoelectron spectroscopy (XPS) to bear on the wettability evaluation of producing reservoir rocks. For a suite of freshly exposed fracture surfaces of rocks they investigate the relationship between wettability and surface composition as determined from XPS. The classical wettability index as measured with the Amott-Harvey tests is used here as an indicator of the wettability of natural sandstones. The XPS spectra of oil-wet surfaces of rocks reveal the existence of organic carbon and also of an organic silicon species, of the kind Si-CH relevant to silanes, having a well-defined binding energy which differs from that of the Si-O species of mineral grains. The authors provide quantifiable evidence that chemisorbed organic material on the pore surfaces defines the oil-wetting character of various reservoir sandstones studied here which on a mineralogic basis are expected to be water-wet. This view is supported by a strong correlation between C content of pore surfaces and rock wettability. The results also suggest a correlation between organic silicon content on the pore surfaces and rock hydrophobicity.
- OSTI ID:
- 404599
- Journal Information:
- Journal of Colloid and Interface Science, Journal Name: Journal of Colloid and Interface Science Journal Issue: 2 Vol. 183; ISSN 0021-9797; ISSN JCISA5
- Country of Publication:
- United States
- Language:
- English
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