Seismic attribute map for gas detection

A system, comprising:

• a well site;
• a drilling system;
• and
• a seismic processor comprising a computer processing unit capable of executing instructions stored in a non-transitory computer storage medium which causes the seismic processor to perform functions comprising:
• obtaining, a relative amplitude preserved seismic volume acquired in a time-domain for a subterranean region of interest;
• transforming, the relative amplitude preserved seismic volume acquired in the time-domain into a low-frequency monospectral amplitude volume;
• determining, a seismic attenuation volume from the relative amplitude preserved seismic volume acquired in the time-domain;
• generating, a low-frequency monospectral amplitude map for a surface of interest by averaging the low-frequency monospectral amplitude volume over a depth-window around the surface of interest;
• generating, a seismic attenuation map for a surface of interest by averaging the seismic attenuation volume over a depth-window around the surface of interest;
• determining, an attribute map based, at least in part, on the seismic attenuation map for the surface of interest, and on the low-frequency monospectral amplitude map for the surface of interest;
• determining, a presence of gas in the subterranean region of interest based, at least in part, on the attribute map;
• determining, a well path through the subterranean region of interest using the attribute volume;
• and
• drilling the well path using a drilling system.