Interpretation of total gamma logs in thin and dipping beds

Geophysics ◽  
1980 ◽  
Vol 45 (12) ◽  
pp. 1847-1856
Author(s):  
Donald C. Moore
Keyword(s):  
Gamma Ray ◽  
Mass Attenuation Coefficient ◽  
Integral Function ◽  
Calibration Model ◽  
Linear Absorption Coefficient ◽  
Linear Absorption ◽  
K Factor ◽  
Proportional Relationship ◽  
Dip Angle ◽  
Gamma Ray Log

The proportional relationship between the grade‐thickness product and the area under a gross gamma‐ray log is well known and generally accepted as correct. A set of conditions for its correctness is derived. It is shown that the proportionality factor (K factor) is independent of the dip angle of the bed, because both the thickness of the bed (measured along the borehole) and the area under the gross gamma‐ray log increase in the ratio of the secant of the dip angle. Experimental data supporting this conclusion are presented. It is also shown that the dip angle of a relatively thick bed can be estimated by deconvolving the log near the edge of the bed. Finally, the comparison parameters between a formation and a calibration model are shown to be grade, gamma‐ray mass attenuation coefficient, moisture content, and an integral function of the build‐up factor and the gamma‐ray linear absorption coefficient.

ATMOSPHERIC ABSORPTION OF 2.62 MEV GAMMA‐RAY PHOTONS EMITTED FROM THE GROUND

Geophysics ◽  
1975 ◽  
Vol 40 (6) ◽  
pp. 1058-1065 ◽  
Author(s):  
R. L. Grasty
Keyword(s):  
Absorption Coefficient ◽  
Gamma Ray ◽  
Dead Time ◽  
Detector Efficiency ◽  
Aircraft Structure ◽  
Linear Absorption Coefficient ◽  
Linear Absorption ◽  
Electronic Circuitry ◽  
Gamma Ray Spectrometer ◽  
Radioactive Concentration

The actual measured decrease in gamma radiation with altitude, as measured by a gamma‐ray spectrometer, was found to be less than predicted on simple theoretical grounds. The various factors which reduced this apparent absorption were Compton scattering in the ground and in the air, the variation of detector efficiency with angle, the mass of material of the aircraft structure and detector housing below the detectors, the dead‐time of the electronic circuitry, and an increase in ground radioactive concentration with depth. When these effects were incorporated, experimental and theoretical values of the linear absorption coefficient in air for 2.62 Mev photons were found to agree.

Deconvolution of gamma‐ray logs in the case of dipping radioactive zones

Geophysics ◽  
1981 ◽  
Vol 46 (2) ◽  
pp. 198-202 ◽  
Author(s):  
John G. Conaway
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Gamma Ray ◽  
Experimental Studies ◽  
Borehole Diameter ◽  
Dip Angle ◽  
Gamma Ray Log ◽  
Simple Numerical Model

It has been shown both theoretically and experimentally that the grade‐thickness product of a zone of uranium or other radioelement, computed on the basis of a gamma‐ray log, will vary inversely with the cosine of the angle between the radioactive zone and the normal to the borehole. I present experimental studies in model boreholes containing dipping radioactive zones, extending the theory of deconvolution of gamma‐ray logs to the case of dipping zones. The experimental data were found to agree well with a simple numerical model which takes into account borehole diameter, detector length, and thickness of the radioactive zone as well as dip angle.

scholarly journals Enhancement of the Shielding Capability of Soda–Lime Glasses with Sb2O3 Dopant: A Potential Material for Radiation Safety in Nuclear Installations

2020 ◽  
Vol 11 (1) ◽  
pp. 326
Author(s):  
M.I. Sayyed ◽  
K.A. Mahmoud ◽  
O.L. Tashlykov ◽  
Mayeen Uddin Khandaker ◽  
M.R.I. Faruque
Keyword(s):  
Attenuation Coefficient ◽  
Elastic Moduli ◽  
Gamma Ray ◽  
Radiation Safety ◽  
Soda Lime ◽  
Mass Attenuation Coefficient ◽  
Transmission Factor ◽  
Linear Attenuation Coefficient ◽  
Neutron Shielding ◽  
Removal Cross Section

Elastic moduli were theoretically computed using the Makishima–Mackenzie model for SiO2–Na2O–CaO glasses doped with Sb2O3 contents. The calculated elastic moduli (Young’s, bulk, shear, and longitudinal modulus) were observed to increase with an increase in the Sb2O3 contents. The microhardness showed an increase, while Poisson’s ratio decreased with the rise of the Sb2O3 contents. In addition, gamma-ray and neutron shielding parameters were evaluated for the investigated glasses. The linear attenuation coefficient (LAC) was simulated using the Monte Carlo N-particle transport code (MCNP-5). Other parameters, such as the mass attenuation coefficient (MAC), transmission factor (TF), and half-value layer, were calculated based on the simulated LAC. The addition of Sb2O3 content was observed to enhance the investigated glasses’ shielding parameters, where the highest LAC was achieved for the SCNSb10 glass with 10 mol% Sb2O3 and decreased from 0.441 to 0.154 cm−1 at gamma energies between 0.248 and 1.406 MeV. Furthermore, the fast neutron effective removal cross-section (∑R) was computed theoretically. The calculated results showed that the highest ∑R was equal to 0.0341 cm2g−1 and was obtained for the SCNSb0 glass, which had no Sb2O3 content, while the lowest ∑R was equal to 0.0286 cm2 g−1 for the SCNSb10 glass sample. The present work was carried out to examine the advantages of the soda–lime glasses with different Sb2O3 contents in several photon shielding applications, especially for radiation safety in nuclear installations.

Bayesian deconvolution of gamma‐ray logs

Geophysics ◽  
1987 ◽  
Vol 52 (11) ◽  
pp. 1535-1546 ◽  
Author(s):  
Ping Sheng ◽  
Benjamin White ◽  
Balan Nair ◽  
Sandra Kerford
Keyword(s):  
High Frequency ◽  
Gamma Ray ◽  
Simulated Data ◽  
Field Measurements ◽  
Bayesian Optimization ◽  
Frequency Noise ◽  
High Frequency Noise ◽  
Data Application ◽  
Gamma Ray Detector ◽  
Gamma Ray Log

The spatial resolution of gamma‐ray logs is defined by the length 𝓁 of the gamma‐ray detector. To resolve thin beds whose thickness is less than 𝓁, it is generally desirable to deconvolve the data to reduce the averaging effect of the detector. However, inherent in the deconvolution operation is an amplification of high‐frequency noise, which can be a detriment to the intended goal of increased resolution. We propose a Bayesian statistical approach to gamma‐ray log deconvolution which is based on optimization of a probability function which takes into account the statistics of gamma‐ray log measurements as well as the empirical information derived from the data. Application of this method to simulated data and to field measurements shows that it is effective in suppressing high‐frequency noise encountered in the deconvolution of gamma‐ray logs. In particular, a comparison with the least‐squares deconvolution approach indicates that the incorporation of physical and statistical information in the Bayesian optimization process results in optimal filtering of the deconvolved results.

Theoretical Study of the Photon Interaction for Zirconium Alloy at 1 keV to 100 MeV

2016 ◽  
Vol 675-676 ◽  
pp. 730-733
Author(s):  
Chumphon Khobkham ◽  
W. Chaiphaksa ◽  
P. Limkitjaroenporn ◽  
P. Prongsamrong ◽  
P. Wiwatkanjana ◽  
...  
Keyword(s):  
Attenuation Coefficient ◽  
Total Mass ◽  
Zirconium Alloy ◽  
Gamma Ray ◽  
Mass Attenuation Coefficient ◽  
Chemical Compositions ◽  
Electron Densities ◽  
Attenuation Coefficients ◽  
Effective Atomic Numbers ◽  
Mass Attenuation

In this work, the total mass attenuation coefficient and partial interactions of the zirconium alloy have been calculated by WinXCom program at 1 keV-100 MeV gamma ray energies. Zr2(Fe,Ni) alloys was studied for the mass attenuation coefficients, photoelectric absorption, incoherent, coherent and pair production processes. The effective atomic numbers and electron densities were also calculated. The calculated results show that the total mass attenuation coefficient decreased with increasing of gamma rays energy. The value of total mass attenuation coefficient of each material was different, which depend on chemical compositions of alloy. The partials interactions, effective atomic numbers and electron densities were also calculated and discussed.

scholarly journals Representative Elementary Length to Measure Soil Mass Attenuation Coefficient

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
J. A. R. Borges ◽  
L. F. Pires ◽  
J. C. Costa
Keyword(s):  
Attenuation Coefficient ◽  
Gamma Ray ◽  
Clayey Soil ◽  
Physical Property ◽  
Soil Mass ◽  
Mass Attenuation Coefficient ◽  
Soil Bulk Density ◽  
Elementary Length ◽  
Increasing Demand ◽  
Mass Attenuation

With increasing demand for better yield in agricultural areas, soil physical property representative measurements are more and more essential. Nuclear techniques such as computerized tomography (CT) and gamma-ray attenuation (GAT) have been widely employed with this purpose. The soil mass attenuation coefficient (μs) is an important parameter for CT and GAT analysis. When experimentally determined (μes), the use of suitable sized samples enable to evaluate it precisely, as well as to reduce measurement time and costs. This study investigated the representative elementary length (REL) of sandy and clayey soils forμesmeasurements. Two radioactive sources were employed (241Am and137Cs), three collimators (2–4 mm diameters), and 14 thickness (x) samples (2–15 cm). Results indicated ideal thickness intervals of 12–15 and 2–4 cm for the sources137Cs and241Am, respectively. The application of such results in representative elementary area (REA) evaluations in clayey soil clods via CT indicated thatμesaverage values obtained forx > 4 cm and source241Am might induce to the use of samples which are not large enough for soil bulk density evaluations (ρs). As a consequence,ρsmight be under- or overestimated, generating inaccurate conclusions about the physical quality of the soil under study.

scholarly journals Methotrexate Detection Based On The Optical Properties Of Carbon Nanotubes And Silver Nano Particles Nanocomposites

2021 ◽  
Vol 7 (3) ◽  
pp. 1323
Author(s):  
Fida Mohammad Mohammadi
Keyword(s):  
Carbon Nanotubes ◽  
Refractive Index ◽  
Nonlinear Refractive Index ◽  
Nano Particles ◽  
Optical Measurements ◽  
Carbon Electrode ◽  
Linear Absorption Coefficient ◽  
Linear Absorption ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

<p>In this experiment, glassy carbon electrode with multi walled carbon nanotubes<br />nanocomposites have been prepared in different concentration in order to see if<br />methotrexate is anticancer drug. For the purpose of characterizing the structures,<br />nanocomposites were analyzed by scanning electron microscope. Optical measurements of different concentrations were conducted by z-scan method and the results show that by rising the concentration, nonlinear refractive index and linear absorption coefficient increases. The values of nonlinear refractive index are in orders of 𝟏𝟎−𝟖 𝒄𝒎𝟐 𝒘.</p>

scholarly journals Sequence Stratigraphy of Well DX, Gongola Sub-Basin, Upper Benue Trough, Nigeria

2019 ◽  
Vol 23 (10) ◽  
pp. 1855-1860
Author(s):  
F.O. Amiewalan ◽  
E.O. Bamigboye
Keyword(s):  
Gamma Ray ◽  
Third Order ◽  
Depositional Sequence ◽  
Benue Trough ◽  
Sequence Stratigraphic ◽  
Surface System ◽  
Sequence Boundaries ◽  
System Tracts ◽  
Maximum Flooding Surface ◽  
Gamma Ray Log

: Biostratigraphic study of Well DX has yielded Cretaceous miospores and dinoflagellates cysts which heightened the recognition of sequence boundaries (SB), Maximum Flooding Surfaces (MFS) and associated Systems Tracts. Five maximum flooding surfaces between 95.6 Ma and 89.0 Ma, four sequence boundaries between 96.4 Ma and 93.0 Ma and threedepositional sequences were identified with varying average thicknesses of sediments interpreted from the gamma ray log and biostratigraphic data. The threedepositional sequences interpreted are -depositional sequence I (96.4 Ma - 95.4 Ma) (8240 ft. - 8120 ft.), depositional sequence II (95.4 Ma - 94.0 Ma) (8120 ft. - 7850 ft.) and depositionalsequence III (94.0 Ma - 93.0 Ma) (7850 ft. - 7550 ft.). All the depositional sequences fall within the third order cycle. The age of the well was attempted based on the presence of some selected marker fossils - Ephedripites spp., Classopollis spp., Spiniferites spp., Cyclonephelium distinctum, Cyclonephelium vannophorum, Subtilisphaera spp., Eucomiidites spp., Triorites africaensis, Odontochitina costata and Droseridites senonicus recovered from the studied intervals and was dated Albian - Santonian. The Sequence stratigraphic interpretations are useful in further deepening the knowledge of thesubsurface geology of the studiedwell in Gongola Sub Basin, Upper Benue Trough of Nigeria.Keywords: Sequence Boundary, Maximum Flooding Surface, System tracts, Depositional sequence

scholarly journals A Comparison of Machine Learning Approaches for Prediction of Permeability using Well Log Data in the Hydrocarbon Reservoirs

2021 ◽  
Vol 2 (2) ◽  
pp. 82-99
Author(s):  
Mohsen Talebkeikhah ◽  
Zahra Sadeghtabaghi ◽  
Mehdi Shabani
Keyword(s):  
Neural Network ◽  
Random Forest ◽  
Gamma Ray ◽  
Accurate Determination ◽  
Coefficient Of Determination ◽  
Support Vector ◽  
Learning Approaches ◽  
Statistical Parameters ◽  
Southwest Of Iran ◽  
Gamma Ray Log

Permeability is a vital parameter in reservoir engineering that affects production directly. Since this parameter's significance is obvious, finding a way for accurate determination of permeability is essential as well. In this paper, the permeability of two notable carbonate reservoirs (Ilam and Sarvak) in the southwest of Iran was predicted by several different methods, and the level of accuracy in all models was compared. For this purpose, Multi-Layer Perceptron Neural Network (MLP), Radial Basis Function Neural Network (RBF), Support Vector Regression (SVR), decision tree (DT), and random forest (RF) methods were chosen. The full set of real well-logging data was investigated by random forest, and five of them were selected as the potent variables. Depth, Computed gamma-ray log (CGR), Spectral gamma-ray log (SGR), Neutron porosity log (NPHI), and density log (RHOB) were considered efficacious variables and used as input data, while permeability was considered output. It should be noted that permeability values are derived from core analysis. Statistical parameters like the coefficient of determination ( ), root mean square error (RMSE) and standard deviation (SD) were determined for the train, test, and total sets. Based on statistical and graphical results, the SVM and DT models perform more accurately than others. RMSE, SD and R2values of SVM and DT models are 0.38, 1.63, 0.97 and 0.44, 2.89, and 0.96 respectively. The results of the best-proposed models of this paper were then compared with the outcome of the empirical equation for permeability prediction. The comparison indicates that artificial intelligence methods perform more accurately than traditional methods for permeability estimation, such as proposed equations. Doi: 10.28991/HEF-2021-02-02-01 Full Text: PDF

scholarly journals Microfaunal Signals and Paleoenvironmental Reconstruction Sediments in Well Z-1, Offshore Dahomey Basin, South-Western Nigeria

2020 ◽  
pp. 50-61
Author(s):  
Anthonia Nwanese Asadu ◽  
Charles Ojonuba Ameh
Keyword(s):  
Gamma Ray ◽  
Accessory Mineral ◽  
Paleoenvironmental Reconstruction ◽  
Planktic Foraminifera ◽  
Rock Samples ◽  
Foraminiferal Species ◽  
Depositional Settings ◽  
Dahomey Basin ◽  
Abundance And Diversity ◽  
Gamma Ray Log

Fifty ditch cutting rock samples from well Z-1, OPL 310 offshore Dahomey basin, south western Nigeria were analyzed for their microfaunal and lithofacies content for the purpose of reconstructing the environment of deposition. Standard techniques of foraminifera slide processing and analysis was followed for the recovery of foraminifera while the gamma ray log complemented the rock samples for the lithofacies analysis. The lithological analysis revealed two lithofacies units in a generally fining upward sequence. The basal sandstone unit is characteristically milky white to brownish, coarse-pebbly grained, sub-angular to round and poorly to well sort with intercalation of shale. This unit is overlain by light to dark grey, moderately hard and non-fissile shale/mudstone sequence with intercalation of sand. Accessory mineral assemblage present in the formations includes mica flakes, glauconite pellets, carbonaceous detritus and ferruginous materials. The basal sandstone unit belong to the Oshosun Formation while the upper shaly unit is typical of Afowo Formation. Microfaunal study showed good recovery of abundant and well diversified planktic and benthic foraminiferal species. Forty-two (42) planktic, sixty-five (65) benthic calcareous and one benthonic arenaceous foraminiferal species were recovered. Micropaleontologically, Paleoenvironmental deductions were based primarily on the assemblage, abundance and diversity of benthic foraminiferal species and presence or absence of planktic foraminifera. Accessory mineral presence also aided the interpretations. Integration of lithological and micropaleontological synthesis enhanced the delineation of two environmental subzones over the analyzed interval, the outer neritic and the upper bathyal depositional settings corresponding to Afowo and Oshosun Formation respectively. A lowstand prograding wedge which is a good exploration target offshore was recognized between intervals 3400 ft to 3500 ft. In conclusion, the rock succession studied, penetrated Afowo and Oshosun Formations, and were deposited in an environment ranging from outer neritic to upper bathyal settings.

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