Combined Natural Gamma Ray Spectral/Litho-Density Measurements Applied to Complex Lithologies

1982 ◽  
Author(s):  
John A. Quirein ◽  
John S. Gardner ◽  
John T. Watson
Keyword(s):  
Gamma Ray ◽  
Density Measurements ◽  
Natural Gamma

Elemental analysis using natural gamma-ray spectroscopy

1994 ◽  
Vol 353 (1-3) ◽  
pp. 558-561 ◽  
Author(s):  
A. Aksoy ◽  
A.A. Naqvi ◽  
F.Z. Khiari ◽  
F. Abujarad ◽  
M. Al-Ohali ◽  
...  
Keyword(s):  
Elemental Analysis ◽  
Gamma Ray ◽  
Natural Gamma ◽  
Gamma Ray Spectroscopy

Quaternary chronostratigraphic framework and sedimentary processes for the Gulf of Cadiz and Portuguese Contourite Depositional Systems derived from Natural Gamma Ray records

2016 ◽  
Vol 377 ◽  
pp. 40-57 ◽  
Author(s):  
Johanna Lofi ◽  
Antje Helga Luise Voelker ◽  
Emmanuelle Ducassou ◽  
F. Javier Hernández-Molina ◽  
Francisco J. Sierro ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Gulf Of Cadiz ◽  
Sedimentary Processes ◽  
Natural Gamma ◽  
Gulf Of Cádiz ◽  
Depositional Systems

scholarly journals A python code for automatic construction of Fischer plots using proxy data

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Daming Yang ◽  
Yongjian Huang ◽  
Zongyang Chen ◽  
Qinghua Huang ◽  
Yanguang Ren ◽  
...  
Keyword(s):  
Data Processing ◽  
Open Source ◽  
Lake Level ◽  
Gamma Ray ◽  
Data Series ◽  
Proxy Data ◽  
Cycle Number ◽  
Automatic Construction ◽  
Natural Gamma ◽  
Graphic Representations

AbstractFischer plots are widely used in paleoenvironmental research as graphic representations of sea- and lake-level changes through mapping linearly corrected variation of accumulative cycle thickness over cycle number or stratum depth. Some kinds of paleoenvironmental proxy data (especially subsurface data, such as natural gamma-ray logging data), which preserve continuous cyclic signals and have been largely collected, are potential materials for constructing Fischer Plots. However, it is laborious to count the cycles preserved in these proxy data manually and map Fischer plots with these cycles. In this paper, we introduce an original open-source Python code “PyFISCHERPLOT” for constructing Fischer Plots in batches utilizing paleoenvironmental proxy data series. The principle of constructing Fischer plots based on proxy data, the data processing and usage of the PyFISCHERPLOT code and the application cases of the code are presented. The code is compared with existing methods for constructing Fischer plots.

Physics, applications, and limitations of borehole neutron-gamma density measurements

Geophysics ◽  
2019 ◽  
Vol 84 (1) ◽  
pp. D39-D56 ◽  
Author(s):  
Mathilde Luycx ◽  
Carlos Torres-Verdín
Keyword(s):  
Environmental Effects ◽  
Gamma Ray ◽  
Vertical Resolution ◽  
Neutron Detectors ◽  
Density Measurements ◽  
Gamma Density ◽  
Limited Applicability ◽  
Empirical Density ◽  
Cesium 137 ◽  
Pulsed Neutron

Radioactive chemical sources can pose security, health, and environmental risks when used to estimate rock porosity in situ. The oil industry has been developing solutions to eliminate radioactive chemical sources in borehole nuclear logging. Pulsed neutron generators have successfully replaced chemical sources in neutron tools, but cesium-137 is still mainly used for borehole density measurements. Neutron-activated gamma-ray measurements (neutron-gamma) are a possible alternative to radioactive chemical sources in density tools. Despite recent advances, the measurement faces challenges regarding density accuracy across diverse solid and fluid rock compositions and nonnegligible sensitivity to borehole environmental effects. We have examined a theoretical, albeit realistic, logging-while-drilling neutron-gamma density (NGD) tool operating with two inelastic gamma-ray detectors and two fast neutron detectors. With a strong emphasis on measurement physics and source-sensor design, the tool delivers density accuracies comparable to those of gamma-gamma density (GGD) tools with [Formula: see text] error in shale-free formations and [Formula: see text] in shale and shaly formations. Our work also compares NGD with GGD in terms of depth of investigation (DOI), vertical resolution, and sensitivity to borehole environmental effects to determine optimal logging conditions. NGD accuracy is limited in the presence of standoff. With inputs of caliper and mud type, empirical density corrections can be applied up to 0.64 cm (0.25 in) standoff. NGD also has limited applicability in thinly bedded formations with maximum vertical resolution of 76 cm (2.5 ft). However, the measurement outperforms GGD in the presence of invasion because its DOI is twice as large.

Natural Gamma Ray Tool Response Discrepancies: Not Always Due to the Calibration!

2018 ◽  
Author(s):  
Françoise Allioli ◽  
Luisa Nicoletti ◽  
Christian Stoller ◽  
Libai Xu
Keyword(s):  
Gamma Ray ◽  
Natural Gamma

Use of Natural Gamma Ray Spectral Logging in Evaluation of Clay Minerals

1982 ◽  
Vol 6 (4) ◽  
pp. 335-360 ◽  
Author(s):  
Walter H. Fertl ◽  
George V. Chilingarian ◽  
T. F. Yen
Keyword(s):  
Clay Minerals ◽  
Gamma Ray ◽  
Natural Gamma
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