Geostatistical depth map based hydrocarbon exploration

A non-transitory computer-readable medium storing one or more instructions executable by a computer system to perform operations comprising:

• obtaining one or more seismic attributes at a plurality of wellbores of a hydrocarbon reservoir;
• determining, based on the obtained one or more seismic attributes, a plurality of prior velocity maps of the hydrocarbon reservoir;
• determining, based on the plurality of prior velocity maps, a plurality of velocities accounting for a velocity trend defining an external drift;
• determining, based on the plurality of velocities, a plurality of depth map realizations;
• determining, based on the plurality of depth map realizations, a plurality of gross volumetric uncertainties of the hydrocarbon reservoir combining a fixed fluid contact with the plurality of depth map realizations to quantify uncertainty in gross rock volume estimates;
• and
• controlling, based on the plurality of gross volumetric uncertainties drilling equipment for well placement in the hydrocarbon reservoir.

A computer-implemented system, comprising:

• one or more computers;
• and
• one or more computer memory devices interoperably coupled with the one or more computers and having tangible, non-transitory, machine-readable media storing one or more instructions that, when executed by the one or more computers, perform one or more operations comprising:
• obtaining one or more seismic attributes at a plurality of wellbores of a hydrocarbon reservoir;
• determining, based on the obtained one or more seismic attributes, a plurality of prior velocity maps of the hydrocarbon reservoir;
• determining, based on the plurality of prior velocity maps, a plurality of velocities accounting for a velocity trend defining an external drift;
• determining, based on the plurality of velocities, a plurality of depth map realizations;
• determining, based on the plurality of depth map realizations, a plurality of gross volumetric uncertainties of the hydrocarbon reservoir combining a fixed fluid contact with the plurality of depth map realizations to quantify uncertainty in gross rock volume estimates;
• and
• controlling, based on the plurality of gross volumetric uncertainties drilling equipment for well placement in the hydrocarbon reservoir.