This U.S. industry comprises establishments primarily engaged in drilling oil and gas wells for others on a contract or fee basis. This industry includes contractors that specialize in spudding in, drilling in, redrilling, and directional drilling. Performing exploration (except geophysical surveying and mapping) services for oil and gas on a contract or fee basis--are classified in U.S. Industry 213112, Support Activities for Oil and Gas Operations; and Performing geophysical surveying and mapping services for oil and gas on a contract or fee basis--are classified in Industry 541360, Geophysical Surveying and Mapping Services.