| 摘要 |
The invention discloses a method for determining the wettability of an underground formation traversed by u borehole, the method comprising: determining the critical water fraction of the underground formation; determining the critical water fraction of the underground formation taken entirely oil-wet, which is called the oil-wet critical water fraction; and combining the critical water fraction and the oil-wet critical water fraction in order to determine the wettability of the underground formation.
The invention also discloses the related apparatus for performing downhole measurement of the wettability of an underground formation traversed by a borehole, the apparatus having a longitudinal axis and being lowered in the borehole along the longitudinal axis, the apparatus comprising: a first sensor for measuring the water saturation of the underground formation; a second sensor for measuring the resistivity of the underground formation; and first and second sensors being located substantially at the same position along the longitudinal axis of the apparatus, and first and second sensors measuring a same locution of the underground formation; and the apparatus: determines the critical water fraction of the underground formation from the water saturation and the resistivity; determines the oil-wet critical water fraction of the underground formation; and deduces the wettability of the underground formation from the critical water fraction and the oil-wet critical water fraction..
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