Well Logging-The Exploration of Subsurface Geology

Various types of measuring devices are lowered on cable into holes drilled for oil or gas for the purpose of logging formation and borehole properties. Among major objectives of oil well logging are the location of porous zones, bed definition, and interpretation for lithology and hydrocarbon saturation. These objectives are realized indirectly by measurement of related physical parameters. Several devices are described for the borehole measurement of electrical, nuclear, sonic, and radioactive quantities, and environmental problems encountered in the design of such devices are discussed. Many of the measuring techniques developed for this purpose are applicable in other fields such as oceanography.