Geophysical well logging for engineering geophysical exploration

Application of geophysical methods in drilling. Commonly used in engineering geophysical prospecting include apparent resistivity logging, natural potential logging, natural radioactivity logging, sonic logging, etc. Comprehensive analysis of several well logging curves can divide the borehole formation lithology profile. The porosity of the formation can be measured using neutron-gamma logging or sonic logging methods. The natural potential logging method can also measure the salinity of groundwater in layers in mud boreholes. The movement of groundwater in a well can be studied using well fluid resistivity logs or well velocity meters. In-hole photography and in-hole optical TV can obtain actual images of the drilling profile, while ultrasonic TV logging can obtain clear hole wall images in the mud, which can distinguish lithology, identify fissures, caves, casing cracks, etc., and even The occurrence of rock formations can be determined. Downhole detectors with different logging methods each have their own characteristics. However, the measured parameters are converted into electrical signals, transmitted via cables to surface logging tools and recorded on paper, tape or magnetic tape.