This U.S. industry comprises establishments primarily engaged in performing support activities, on a contract or fee basis, for oil and gas operations (except geophysical surveying and mapping, site preparation, construction, and transportation activities). Services included are exploration; excavating slush pits and cellars, well surveying; running, cutting, and pulling casings, tubes, and rods; cementing wells, shooting wells; perforating well casings; acidizing and chemically treating wells; and cleaning out, bailing, and swabbing wells. Cross-References. Establishments primarily engaged in--