Phosphate Prospecting Using Natural Gamma Ray Well Logging in the Khneifiss Mine, Syria

2002 ◽  
Vol 11 (1-4) ◽  
pp. 61-68 ◽  
Author(s):  
J. ASFAHANI
Keyword(s):  
Gamma Ray ◽  
Well Logging ◽  
Natural Gamma

Computer Simulation of Two Nuclear Well Logging Methods

1981 ◽  
Vol 21 (03) ◽  
pp. 315-322 ◽  
Author(s):  
Harry D. Smith ◽  
Ward E. Schultz
Keyword(s):  
Monte Carlo ◽  
Nuclear Reactor ◽  
Gamma Ray ◽  
Radiation Transport ◽  
Theoretical Method ◽  
Well Logging ◽  
Theoretical Simulation ◽  
Monte Carlo Techniques ◽  
Epithermal Neutrons ◽  
Natural Gamma

Abstract Monte Carlo techniques have been used to simulate the response of a multi window natural gamma ray spectral log to varying borehole conditions and to investigate the potential of a porosity logging concept using a ratio of fast to epithermal neutrons. Introduction There are many situations in nuclear well logging research when it would be highly desirable to have a theoretical method of realistically simulating the measurements made by a downhole logging instrument. In the early stages of research into the feasibility of a logging concept, it would be possible to make an accurate theoretical determination of whether the idea should be pursued. Should the concept turn out to be unsound, the expense and time required to design, build, and test a logging system would be avoided. In later stages of log development, the theoretical model could be used to assist in optimizing sonde design and specifications. In situations where a logging device already has been developed fully, such a model also could be used to ascertain much information about the way the physical device works. As an illustration, a theoretical simulation of a neutron (n, ?) logging sonde could provide information regarding the relative importance of the gamma rays scattered into the detector from the various downhole materials (Le., toolcase, borehole fluid, formation, cement, and well casing). The depth of investigation into the formation and the significance of neutrons in the gamma ray detector could be estimated also. Few of these parameters could easily be determined experimentally. Monte Carlo radiation transport techniques,1,2 which long have been used by scientists involved in nuclear reactor shielding design and radiation dosimetry, perhaps provide the best methods for fulfilling the theoretical nuclear logging objectives mentioned. Several papers in this area have been published.3–6 Our paper briefly describes both the Monte Carlo method and the specific Monte Carlo computer programs - SAM-C7 and an updated version SAM-CE8 - which we have been using in nuclear logging applications. Two specific illustrations are discussed. The first example involves the simulation of a natural gamma ray spectral logging device. Monte Carlo results are presented which indicate that significant errors can be introduced into the elemental concentrations obtained from these instruments unless compensations are made for differing borehole conditions. The second example describes how we have used Monte Carlo program SAM-CE to simulate an untested porosity logging technique that uses a ratio of fast to epithermal neutrons. The sensitivity and linearity of this ratio to changes in porosity were determined from the program, as were the effects of changing matrix type. These results then are compared with calculations simulating a conventional dual-spaced epithermal porosity measurement under identical lithologic conditions. The two examples presented in this paper involve relatively simple geometries to facilitate concept comprehension by the reader. Much more complex geometries also are well within the capabilities of SAM-CE or other current Monte Carlo programs.

scholarly journals Thermal Conductivity Estimation Based on Well Logging

Mathematics ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1176
Author(s):  
Jie Hu ◽  
Guangzheng Jiang ◽  
Yibo Wang ◽  
Shengbiao Hu
Keyword(s):  
Thermal Conductivity ◽  
Gamma Ray ◽  
Fluid Model ◽  
Thermal Structure ◽  
Geometric Mean ◽  
Well Logging ◽  
Square Root ◽  
Offshore Area ◽  
Natural Gamma ◽  
Neutron Porosity

The thermal conductivity of a stratum is a key factor to study the deep temperature distribution and the thermal structure of the basin. A huge expense of core sampling from boreholes, especially in offshore areas, makes it expensive to directly test stratum samples. Therefore, the use of well logging (the gamma-ray, the neutron porosity, and the temperature) to estimate the thermal conductivity of the samples obtained from boreholes could be a good alternative. In this study, we measured the thermal conductivity of 72 samples obtained from an offshore area as references. When the stratum is considered to be a shale–sand–fluid model, the thermal conductivity can be calculated based on the mixing models (the geometric mean and the square root mean). The contents of the shale and the sand were derived from the natural gamma-ray logs, and the content of the fluid (porosity) was derived from the neutron porosity logs. The temperature corrections of the thermal conductivity were performed for the solid component and the fluid component separately. By comparing with the measured data, the thermal conductivity predicted based on the square root model showed good consistency. This technique is low-cost and has great potential to be used as an application method to obtain the thermal conductivity for geothermal research.

Well logging—A 25‐year perspective

Geophysics ◽  
1985 ◽  
Vol 50 (12) ◽  
pp. 2504-2529 ◽  
Author(s):  
Donald D. Snyder ◽  
David B. Fleming
Keyword(s):  
Shear Wave ◽  
Gamma Ray ◽  
Well Logging ◽  
Well Logs ◽  
Well Log ◽  
Acoustic Logging ◽  
Full Waveform ◽  
Natural Gamma ◽  
Neutron Porosity ◽  
Gamma Ray Emission

Developments in the field of well logging over the last 25 years are reviewed. Surface and borehole instrumentation have evolved significantly, taking advantage of modern digital and analog integrated circuits. Most open‐hole petroleum well logs are now recorded digitally. Digital logs are also frequently acquired in cased‐hole petroleum, mineral, and geotechnical applications. Nuclear well‐log measurements have become accepted and reliable. New measurements include borehole compensated density and neutron‐porosity, sidewall epithermal neutron‐porosity, and most recently litho‐density. The neutron decay log, developed early in the 25‐year period, has undergone a number of major improvements since its introduction. Probes which make spectral measurements of natural gamma‐ray emission, and gamma‐ray emission from neutron interactions with matter have also been developed. Resistivity measurements are now made with probes which combine three or more sensors each with different depths of investigation so that information about the borehole invasion profile can be acquired. Acoustic logging methods have expressed major developments and improvements. The compensated sonic measurement was introduced early in the period along with the cement bond logging method. Interest in measurement of shear‐wave velocity has produced new direct shear‐wave measurements as well as improved acoustic probes for full‐waveform acoustic logging. Other interesting or promising methods which have been developed or improved during the period include the borehole televiewer, the borehole gravimeter, and the nuclear magnetic resonance log. The digital computer provides powerful capabilities for well‐log analysis both at the well site and in the office. Analysis of complex sand‐shale and carbonate formations using two or more logs in a simultaneous solution of a litho‐porosity model is now routine. Powerful signal processing techniques are being applied to “deconvolve” well logs, to enhance or synthesize images of the wellbore, and to estimate or extract information from full‐waveform acoustic logs. While new or improved measurements have been introduced and log analysts now have access to powerful computers and graphic work stations, understanding of the petrophysical significance of the measurements lags behind the basic hardware measurement and interpretation technology.

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.

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