A PROTON RELAXATION STUDY OF IMMISCIBLE LIQUID ARRANGEMENT IN MICROPOROUS STRUCTURES

The relaxation behaviour of immiscible hydrogenated liquids in well characterized microporous porcelain structures after a well defined stepwise preparation was studied to obtain information on the contact with surfaces and on the reciprocal arrangement in the pore space. Water-wet samples were fully saturated by brine, then brought to irreducible water saturation by oil and finally to residual oil saturation by brine. This step-wise preparation was repeated using deuterium oxide instead of brine. The observed changes of the H-1 spin-lattice relaxation curves reflected each step of preparation. The quantitative analysis of the curves gave evidence that no contact occurred between surfaces and oil because of a layer of water on the surface, except when only oil was present. On the contrary, when the wettability properties of the surfaces were changed, our data indicated that a contact between oil and walls occurred. So, the traditional picture of water-oil arrangement at the pore-length scale was verified for water-wet samples, whereas a more complex picture arose for oil-wet samples. While on one hand this study on model systems can help in explaining the information content of relaxation curves in more general conditions and systems, on the other hand it yields useful indications on some solid-liquid and liquid-liquid interaction effects in the displacement processes by water or by oil in microporous geometries.