Introduction
Earth science downhole logging is a drilling engineering procedure that uses several methods to measure physical properties of rock formations present within a borehole. Downhole logging is used to assess the rock and fluid content around the borehole and to determine the characteristics of the underlying rock formations. It is most commonly used during the exploration and development of hydrocarbon reservoirs, including oil and gas. Downhole logging plays an important role in hydrocarbon exploration and subsequent development as it is an effective way to determine the composition of the subsurface before drilling.
Various Types of Downhole Logging
Downhole logging commonly uses three main types of measurements: natural gamma radiation, caliper and resistivity. Natural gamma logs measure the natural radiation that is emitted from the formations, providing a measure of organic content and lithology. Caliper logs measure the size and shape of the borehole, which can provide information about drilling fluid loss during drilling. Resistivity logs measure the resistivity of the formation and its fluids, which helps to determine the presence and extent of hydrocarbons.
The most common logging methods are litho logs, dipmeter logs and seismic logs. Litho logs measure the size and type of rock formations in the borehole in order to identify the lithologies present. Dipmeter logs measure the direction and angle of dip of formations in the wellbore and are used to identify fractures and other structure in the formations. Seismic logging measures the velocity of seismic waves travelling through the rock. This can be used to measure porosity and identify formations that may contain hydrocarbons.
Purpose of Downhole Logging
The purpose of downhole logging is to collect information about the rock formation around the wellbore in order to make informed decisions about where to drill and develop hydrocarbon reservoirs. This information can also be used to identify potential flow paths for hydrocarbons and provide an estimate of reserves. Another purpose of downhole logging is to ensure that drilling operations are carried out safely, because several of the measurements can be used to monitor the pressure and temperature of the subsurface.
Conclusion
Downhole logging is an important technique used in drilling engineering. It provides important information about subsurface formations that can be used to determine the content and characteristics of subsurface formations, which can then be used to make informed decisions about exploration and development of hydrocarbon reserves. Downhole logging is also used to ensure the safety of drilling operations by monitoring the pressure and temperature of the subsurface.
