Method for estimating depth of hydrocarbon reservoir

A method of estimating a depth of a hydrocarbon-water contact of a hydrocarbon reservoir in a structure, the method comprising:

• a. analysing one or more samples obtained from the structure to generate a relationship relating resistivity to hydrocarbon-water contact depth;
• b. obtaining a resistivity measurement of the hydrocarbon reservoir;
• and
• c. estimating the hydrocarbon-water contact depth from the relationship relating resistivity to hydrocarbon-water contact depth and the resistivity measurement of the hydrocarbon reservoir;
• wherein analysing one or more samples comprises:
• obtaining images of a pore structure of the one or more samples;
• and
• obtaining one or more capillary pressure measurements of the one or more samples, the method further comprising:
• d. using the images and the one or more capillary pressure measurements to calibrate a relationship between at least one of a saturation and capillary pressure or in a resistivity model of at least a part of the structure;
• e. using the estimated hydrocarbon-water contact depth to estimate a volume of the hydrocarbon reservoir;
• f. using the estimated volume of the hydrocarbon reservoir to determine whether to extract hydrocarbons from the hydrocarbon reservoir;
• and
• g. drilling, based on the hydrocarbon-water contact depth, at least one of an appraisal well associated with exploring for hydrocarbons or a production well associated with extracting hydrocarbons from a hydrocarbon reservoir with the production well.