Why is shale more radioactive than sandstone?
History of gamma ray tools Because clay minerals have large cation exchange capacities, they permanently retain a portion of the radioactive minerals present in trace amounts in their parent igneous micas and feldspars. Thus, shales are usually more radioactive than sedimentary rocks.
What is a gamma ray simple definition?
A gamma ray is electromagnetic radiation of the shortest wavelength and highest energy. Gamma-ray radiation has wavelengths generally smaller than a few tenths of an angstrom (10−10 meter), and gamma-ray photons have energies greater than tens of thousands of electron volts.
What is gamma ray in oil and gas?
Gamma ray logging is a method of measuring naturally occurring gamma radiation to characterize the rock or sediment in a borehole or drill hole. It is a wireline logging method used in mining, mineral exploration, water-well drilling, for formation evaluation in oil and gas well drilling and for other related purposes.
What is emitted in gamma ray?
A gamma ray (g) is a packet of electromagnetic energy (photon) emitted by the nucleus of some radionuclides following radioactive decay. Gamma photons are the most energetic photons in the electromagnetic spectrum.
Why is gamma rays high in shale?
The higher levels of radiation in shale are caused by absorption of thorium by clay minerals, the potassium content of clay minerals (principally illite), and uranium fixed by associated organic material.
What best describes a gamma ray?
Gamma-rays have the smallest wavelengths and the most energy of any other wave in the electromagnetic spectrum. These waves are generated by radioactive atoms and in nuclear explosions. Gamma-rays are the most energetic form of light and are produced by the hottest regions of the universe.
What is gamma Imaging?
Imaging with gamma rays is creating medical diagnostic images using gamma rays emitted by tiny amounts of radionuclides administered to patients, photons of penetrating electromagnetic radiation emitted from an atomic nucleus.
Why is gamma ray log used as a shale indicator?
Gamma-ray scans of core are also taken to reconcile core depths with log depths. In most stratigraphic and petroleum geological applications, the gamma ray log is used as a “shale log,” both to discriminate shales from “clean” formations, and to estimate the relative shale proportions in shaly reservoir units.
What does a gamma ray log tell you?
Gamma ray (GR) logs measure the natural radioactivity in formations and can be used for identifying lithologies and for correlating zones. As shale content increases, the gamma ray log response increases because of the concentration of radioactive material in shale.
What is a curie of radiation?
A curie is also a quantity of any radionuclide that decays at a rate of 37 billion disintegrations per second (1 gram of radium, for example). The curie is named for Marie and Pierre Curie, who discovered radium in 1898.