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The application of sensor-based logging technology in logging
Published in Ahmad Safuan Bin A Rashid, Junwen Zhang, Advances in Mineral Resources, Geotechnology and Geological Exploration, 2023
Natural gamma-ray logging is based on the natural radioactivity of the formation. With the development of the oil field, radioactive materials are continuously transported and accumulated, resulting in radioactive anomalies in the water flooded layer of the oil well, the water injection horizon of the water injection well, and the channeling outside the casing. In the exploration and development of oil and gas fields, the natural gamma logging curve is mainly used to divide lithology, determine the shale content of reservoir, stratigraphic correlation, track and locate perforation, evaluate reservoir water flooding, judge the channeling outside the casing of oil and water wells, and determine the water absorption of water injection wells. Laser optical fiber nuclear sensor is produced based on optical fiber transmission and optical fiber sensor. It uses the physical effects such as optical fiber photo loss and photoluminescence. It can develop a sensitive probe for the energy level range of nuclear detection and prolong the service life of the photomultiplier tube.
Geophysical Applications
Published in Stephen M. Testa, Geological Aspects of Hazardous Waste Management, 2020
The natural gamma (or gamma ray) logging technique is the most commonly used log for the purpose of lithology, and subsequent stratigraphic correlation and relative permeability. This technique measures naturally occurring total gamma radiation from the rocks penetrated by the borehole. The sonde used does not discriminate between gamma radiation from naturally occurring isotopes of potassium (K40), thorium (Th232), and uranium (U238), although the record of gamma radiation depends upon the naturally occurring radioisotopes present. The average content of K40, U238, and Th232 based on 200 shale samples analyzed is on the order of 2% of the total K content in total volume, 6 ppm, and 12 ppm, respectively.
A review of major rare earth element and yttrium deposits in China
Published in Australian Journal of Earth Sciences, 2022
A new type of Nb(Ta)–Zr(Hf)–REE–Ga polymetallic deposit of volcanic origin in the upper Permian coal-bearing strata of eastern Yunnan, southwestern China, which was briefly described by Dai et al. (2010), is characterised by an abnormal significant anomaly in the natural gamma logging curve and high concentrations of rare metal elements (Dai et al., 2018). This polymetallic mineralisation is derived from the interaction between alkaline volcanic ash deposits and subsequent percolation of low-temperature fluids. The intense and extensive alkaline volcanism of the early late Permian possibly originated from the coeval Emeishan large igneous province (Zhao et al., 2017). This unique Nb(Ta)–Zr(Hf)–REY–Ga polymetallic mineralisation of pyroclastic origin is both economically and geologically significant. Since REY or Zr(Hf)–Nb(Ta)–Ga ore beds of alkali-volcanic-ash origin in coal and coal-bearing sequences show strong positive natural gamma-rays in well logging, natural gamma-ray logging could be considered as a useful tool in geophysical prospecting for such deposits (Dai et al., 2010, 2016). Such rare metal mineralisation in Chongqing, Sichuan and Guizhou provinces is likely to be the lateral extension of the studied polymetallic mineralised beds in eastern Yunnan, SW China. Therefore, for the next exploration stage, the lowest units of the Wuchiapingian (mainly Xuanwei and Longtan formations) in southwestern China with highly anomalous natural gamma-ray log responses (Dai et al., 2012) are the next primary target areas.