Method for determining a relation between an initial saturation and a residual saturation in a first fluid in a porous sample and related assembly

A method for determining a relation curve between an initial saturation and a residual saturation in a first fluid in a porous sample, the method comprising:

• providing a porous sample;
• substantially saturating the porous sample with a second fluid;
• measuring a local volume of the second fluid in a plurality of regions of the porous sample;
• introducing a first fluid in the porous sample and applying a mechanical load to establish a steady state profile of a saturation in the first fluid in the porous sample and to create in each region of the plurality of regions, a different saturation in the first fluid;
• measuring an initial local volume of the second fluid in each region of the porous sample, and determining a measured initial saturation in the first fluid in each region from the initial local volume of the second fluid in each region;
• generating a rise of a capillary ascension flow of the second fluid through the porous sample;
• during the rise of the capillary ascension flow, simultaneously measuring, in each region of the plurality of regions, a local volume of the second fluid, at successive instants, advantageously until the local volume is substantially steady, and determining, for each region, a plot of saturation in the first fluid in each region as a function of time, from the local volume of the second fluid measured at successive instants;
• determining a measured residual saturation in the first fluid in each region from the plot of saturation in the first fluid in each region as a function of time;
• determining the relation curve between the initial saturation in the first fluid and the residual saturation in the first fluid based on the measured initial saturations and the measured residual saturations in each region.