Method for estimating hydrocarbon saturation of a rock

A method for estimating hydrocarbon saturation of a hydrocarbon-bearing rock from a resistivity log and a rock image, comprising:

• obtaining a resistivity log and a density log for a field having a hydrocarbon-bearing formation;
• obtaining a 3D image of a rock from the hydrocarbon-bearing formation in the field, wherein the 3D image is comprised of a plurality of voxels and the 3D image has a resolution;
• processing the 3D image to segment the 3D image by selecting each voxel of the 3D image to represent either a pore space in the rock or solid material in the rock;
• estimating an image porosity of the rock from the segmented 3D image, the image porosity lacking a sub-resolution porosity of the rock;
• determining a corrected porosity adapted to account for the sub-resolution porosity of the rock;
• estimating a corrected cementation exponent of the rock from the image porosity and the corrected porosity of the rock;
• estimating the hydrocarbon saturation of the hydrocarbon-bearing rock using the corrected cementation exponent;
• and
• converting the resistivity log to a continuous saturation profile using the estimated hydrocarbon saturation and the density log.