- Aug 13, 2019-
Well logging refersgenerally to the use of instruments to learn about the characteristics of awell during or after drilling operations. The oil and gas industry hasdeveloped many different types of instruments, or "logs" For example,pressurewhile drilling logs measure thepressure inside and outside the drill bit in real time.Electriclogs measure theelectric potential and resistivity of the formation, and can identify theboundaries between formations and the fluids within them. Gammaray logs measure thenatural radioactivity of rock. Sonicand ultrasonic logs can be used tomeasure the porosity and lithology of a formation.Caliperlogs measure thesize of the hole that has been drilled. Temperaturelogsmeasuretemperature gradients in a well.Cementevaluation logs can helpidentify the amount and quality of cement in the annular spacer.