Patent ID: 7397240

Claim:
A method for analyzing a porous rock sample by measuring a wettability of the porous rock sample in a presence of water and oil, comprising determining a water wet pore surface of the sample and an oil wet pore surface of the sample when the sample is saturated with water and oil, and calculating a wettability index from a combination of the water wet pore surface and the oil wet pore surface wherein the water wet pore surface and of the oil wet pore surface is determined when the sample is saturated with water and oil from measurements of relaxation times obtained from the surfaces of the sample placed in a nuclear magnetic resonance device and calculating the wettability under index by: a) measuring the relaxation times of the water-saturated sample; b) measuring the relaxation times of the sample in the presence of oil and water, in a zone approaching saturation of the sample; c) measuring the relaxation times of the oil in the sample in the presence of water, in a zone approaching saturation of the sample; d) measuring relaxation times of the sample in a state of 100% oil saturation; e) combining measurements of the relaxation times obtained from a)-d) so as to obtain the wettability index; and f) using the wettability index to analyze the porous rock sample.