As a former field in classical physics, geophysics established itself as an independent science several decades ago. In the broad sense of the term, it is a geoscience that helps in describing the Earth and its surroundings by physical methods. Geophysics is commonly used in the oil and gas industry. Paul Favret and many other professionals who have worked in the industry have an educational background in geophysics. Today, geophysics largely puts emphasis on the physics of the solid Earth as well as the upper atmosphere.
Paul Favret talks about geophysical surveys and methods
Geophysical surveys basically include the implementation of geophysical methods to determine the geological, structural, as well as physical and mechanical characteristics of the foundation soil indirectly. Such methods are commonly used for determining the properties, thickness, and layout of individual layers below the terrain surface on which the construction of a particular structure has been planned. Geophysical surveys are generally performed from the soil surface, such as through boreholes, excavations, or even in a combination of placing detectors and sources. The survey scope, types of methods, and work techniques depend on many factors. These factors include the geological and topographic conditions, availability of funds, and the key survey purpose.
Geophysical surveys may provide valuable data on a much larger volume of soil or rock mass in comparison to conventional soil and rock mass surveys, and result in improved time and economic savings. Paul Favret mentions that a number of geophysical methods are used today, including electromagnetic, magnetic, seismic, and electrical.
Seismic surveys largely include placing geophones into strategic patterns with the aim of providing information about the properties of rocks multiple kilometers below the surface of the Earth. The survey team generally creates vibrations with the help of small explosives or truck-mounted vibrating weights. These vibrations are measured as they pass through layers of the Earth.
Magnetic Surveys are known to specify variations of the magnetic field of the Earth owing to the presence of magnetic minerals. Tiny variations in the magnetic content of particular metals help technicians interpret rock types, and allow them to competently identify resources. Magnetometers often provide good resolution of small, near-surface features. They additionally respond strongly to burned soil, brick, steel, iron, and several types of rocks. It also is possible to detect subtle anomalies caused by decayed organic material or disturbing soil through magnetic surveys.
Radiometric surveys essentially measure gamma rays that are emitted from the Earth through the natural decomposition of common radiogenic materials. As a result, people are able to assess gamma radiation from the top 30 centimeters of the ground. This task might be performed from the air or directly on top of the ground for identifying metallic and industrial minerals.
Gravity surveys involve the use of gravimeters that aid in measuring the gravity field to determine variations in rock density. Technicians are required to take gravity measurements during particular intervals of distance and record the accurate height at every location. Such surveys help in to identify areas that have energy resource deposits.