THE LITHO-DENSITY* LOG

1981 ◽  
Vol 21 (1) ◽  
pp. 200
Author(s):  
J. Bowler
Keyword(s):  
Bulk Density ◽  
Cross Section ◽  
Gamma Ray ◽  
Effective Atomic Number ◽  
Well Logs ◽  
Heavy Minerals ◽  
Shallow Marine ◽  
Natural Gamma ◽  
Chemical Content ◽  
Gas Bearing

The Litho-Density Log (LDT) measures a new formation parameter, Pe, the effective photoelectron cross-section. This measurement is made at the same time as the measurement of bulk density, ρb. The equipment is com bined with Gamma Ray and Compensated Neutron Loqqinq (CNL*) devices.Pe is a function of Z. the effective atomic number. The Z of a formation determines its chemical content and therefore its lithology.The effect of gas on the Pe measurement is almost neglible so it becomes a good lithology Indicator in non-shaly gas-bearing reservoirs. As a result, it provides a means for confirming porosity determinations made with corrected bulk density and CNL porosity data.The radioactive logging parameters for a number of sedimentary minerals have recently been computed. With this knowledge and the addition of the Pe measurement it is possible to discriminate between tight streaks and heavy minerals such as siderite.A number of clays, such as glauconite, may be identifiable with cross-plot methods. Knowledge of the presence of glauconite, which is thought to be formed in shallow marine waters, can be useful in establishing depositional environments.If a Natural Gamma Ray Spectroscopy (NGS*) Log is available, additional cross-plots are proposed which will enhance the identification of clay mineralsSeveral of the proposed interpretation techniques are illustrated with data from Australian and other well logs.*Mark of Schlumberger

scholarly journals The use of spectral natural gamma-ray analysis in reservoir evaluation of siliciclastic sediments: a case study from the Middle Jurassic of the Harald Field, Danish Central Graben

2003 ◽  
Vol 1 ◽  
pp. 349-366 ◽  
Author(s):  
Ida L. Fabricius ◽  
Louise Dahlerup Fazladic ◽  
Armgard Steinholm ◽  
Uffe Korsbech
Keyword(s):  
Middle Jurassic ◽  
Gamma Ray ◽  
Clay Content ◽  
Heavy Minerals ◽  
Reservoir Evaluation ◽  
Fine Grained ◽  
Natural Gamma ◽  
The Difference ◽  
Siliciclastic Sediments ◽  
Quartz Grains

Danish Central GrabenA cored sandstone interval from the Middle Jurassic Harald Field of the Danish North Sea was chosen for an investigation of the mineralogical sources for the gamma-ray activity, and with the purpose of determining how the Spectral Natural Gamma (SNG) log could be used as an indicator of reservoir quality. Core intervals of quartz arenites and quartz wackes were selected. Although no linear relationship was found between clay content and potassium (K), thorium (Th), or uranium (U), the K content characterises three discrete lithofacies. Lithofacies I has a grain-supported texture, with a predominance of quartz grains; only minor fine-grained matrix is present. Sandstones of lithofacies I have a low K content and most of the K is hosted in feldspar. Porosity varies between 23% and 28% and permeability is in the range 200–2000 mD. Lithofacies II sandstones have a grain-supported texture, with a predominance of quartz grains; fine-grained matrix fills the intergranular volume. Sandstones of lithofacies II have an intermediate K content, with K-feldspar, mica, and illite as the main sources. Porosity varies between 11% and 17% and permeability is in the range 0.4–25 mD. Lithofacies III has a matrix-supported texture with quartz grains floating in a clay-rich matrix. Samples from lithofacies III have the highest K signal. Illite and illitised kaolinite are roughly equal in importance as sources of K. Porosity is up to 11% and permeability up to 0.5 mD. The Th and U content of all lithofacies is governed primarily by the presence of heavy minerals; no apparent general relationship between U and Total Organic Carbon (TOC) was found. Comparisons between the core measurements of K, Th, and U, and the SNG log disclosed a discrepancy between the calibrations of laboratory and borehole measurements. For U the discrepancy contains an erratic element, whereas the difference for K and Th can be eliminated by correction factors. Thus, the conclusions based on laboratory measurements appear to be applicable to the log data, and, using corrected K values, the facies subdivision can be extended throughout the reservoir section based on the SNG log.

scholarly journals Measurement of Photon Matter Interaction Parameters for some Iodine Compounds

2020 ◽  
Vol 1 (9) ◽  
pp. 421-426
Author(s):  
Adnan Küçükönder ◽  
Saniye Tekerek
Keyword(s):  
Attenuation Coefficient ◽  
Cross Section ◽  
Gamma Ray ◽  
Effective Atomic Number ◽  
Mass Attenuation Coefficient ◽  
Effective Electron ◽  
Iodine Compounds ◽  
Beam Experiment ◽  
Experimental Values ◽  
Mass Attenuation

In this study, total atomic cross-section (σta), total moleculer cross-section (σtm) total electronic cross-section (σte), effective atomic number (Zeff), effective electron density (Neff) and Kerma (K) were determined both experimentally and theoretically values for some iodine compounds. Experimental mass attenuation coefficient (µ/ρ) values for some iodine compounds were calculated with the data obtained from the test results. The theoretical mass attenuation coefficient values of these compounds were calculated with the WinXCOM data program. Also, we have performed the measurements for the calculations of experimental values mass attenuation coefficient using direct transmission experimental geometry. The transmission photon intensity of halogene iodine compounds were measured in a narrow beam experiment geometry was used 59.543 keV γ-ray from an 241Am radioactive source. The tranmissions spectra from iodine compounds were recorded with a Si (Li) detector having a resolution of 155 eV FWHM at 5.9 keV (55Fe) and coupled to a 1024 channel analyzer through a spectroscopic amplifier. This study was provided that new insights into the literature since mass attenuation coefficient experimental values of some I compounds have not been determined previously. More research should be done to observe the changes in the chemical structure of iodine compounds with gamma-ray interaction. This study will shed light on further research.

The Early Ordovician Middle Shale Member (Am3) of the Amdeh Formation and further evidence of conodont faunas from the Sultanate of Oman

2018 ◽  
Vol 156 (08) ◽  
pp. 1357-1374 ◽  
Author(s):  
AP Heward ◽  
CG Miller ◽  
GA Booth
Keyword(s):  
Gamma Ray ◽  
Trace Fossils ◽  
Heavy Minerals ◽  
Sultanate Of Oman ◽  
Shallow Marine ◽  
Middle Ordovician ◽  
Early Ordovician ◽  
Coastal Deposits ◽  
Conodont Fauna ◽  
Gamma Ray Log

AbstractThe Middle Shale Member of the Amdeh Formation is interpreted to be of Early Ordovician age based on its trace fossils, stratigraphic context and a newly discovered fauna of conodonts. The member abruptly overlies the Lower Quartzite Member, which may be Early Cambrian, and passes gradationally-upward into the Upper Quartzite Member, which is probably Early–Middle Ordovician. The 542.5 m thick Middle Shale Member can be divided into two parts: a shaly lower part, and a sandy upper part that contains an influx of heavy minerals. Bioturbation by marine trace fossils is one of the most obvious characteristics of the member. The shales and sandstones are interpreted to be of Cruziana and Skolithos ichnofacies and represent shallow-marine shelf, shoreface, beach and coastal deposits. Sparse shelly fossils occur in the sandy upper part, principally bivalves, inarticulate brachiopods, ostracods and conodonts. The small assemblage of conodonts includes elements interpreted to be Tremadocian (Tetraprioniodus, Drepanoistodus, Drepanodus, Scolopodus, ?Tropodus, Semiacontiodus and Teridontus), and others which may be Floian or ancestral forms of Floian taxa (Balognathidae gen. et sp. indet. A & B and aff. Erraticodon). No acritarchs have been recovered, probably due to high temperatures experienced during burial to >6 km. It is likely that the Middle Shale Member is the seaward equivalent of the Mabrouk and Barakat formations, and an outcrop gamma-ray log supports such a correlation. The trace fossils, sedimentology, conodont fauna and the general lack of macrofossils are in keeping with the regional Tremadocian–Floian of the Arabian margin of Gondwana.

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.

Field examples of the joint petrophysical inversion of resistivity and nuclear measurements acquired in high-angle and horizontal wells

Geophysics ◽  
2014 ◽  
Vol 79 (3) ◽  
pp. D145-D159 ◽  
Author(s):  
Olabode Ijasan ◽  
Carlos Torres-Verdín ◽  
William E. Preeg ◽  
John Rasmus ◽  
Edward Stockhausen
Keyword(s):  
Gamma Ray ◽  
Water Saturation ◽  
Joint Inversion ◽  
Resistivity Measurement ◽  
Well Logs ◽  
Electrical Anisotropy ◽  
High Angle ◽  
Natural Gamma ◽  
Well Trajectory ◽  
Well Log Analysis

A recently introduced interpretation workflow has confirmed that inversion-based interpretation is more reliable than conventional well-log analysis in high-angle (HA) and horizontal (HZ) wells because the former accounts for well trajectory and shoulder-bed effects on well logs. Synthetic examples show that the inversion workflow could improve the estimation of hydrocarbon volumes by 15% and 10% in HA and HZ intervals, respectively. Using field examples of thinly interbedded calcite-cemented siltstone formations, we document results of the joint petrophysical inversion of logging-while-drilling multisector nuclear (neutron porosity, density, natural gamma ray, photoelectric factor) and multiarray propagation resistivity measurement for improved formation evaluation in HA/HZ wells. Under the assumption of multilayer formation petrophysical models, the inversion approach estimates formation properties by numerically reproducing the available measurements. Subsequently, inversion-derived hydrocarbon pore volume is calculated for assessment of reservoir pay. Application of the joint inversion-based interpretation in challenging field examples highlights petrophysical characteristics such as capillary trends or water saturation variations in a hydrocarbon column influenced by reservoir quality and formation electrical anisotropy which otherwise remain inconspicuous with conventional and quick-look interpretation of well-logs.

scholarly journals VÝSLEDKY VRTNÉHO PRŮZKUMU NA LOKALITĚ HOLUBICE (SPODNOBADENSKÉ SEDIMENTY KARPATSKÉ PŘEDHLUBNĚ)

2014 ◽  
Vol 21 (1-2) ◽  
Author(s):  
Slavomír Nehyba ◽  
Václav Zborník ◽  
Vladimíra Jašková
Keyword(s):  
Grain Size ◽  
Gamma Ray ◽  
Facies Analysis ◽  
Primary Source ◽  
Heavy Minerals ◽  
Shallow Marine ◽  
Facies Associations ◽  
Mineral Compositions ◽  
Drill Holes ◽  
Depositional Setting

Early Badenian deposits of the Carpathian Foredeep were newly studied in the sedimentary successions from drill holes Holubice 1 and Holubice 2. Facies analysis together with study of grain size, the shape and roundness of the coarsest grains, the mineral compositions of selected heavy minerals (garnet, rutile) and the gamma-ray spectra, were all used for better understanding the depositional setting and provenance. Studied sediments were deposited in coastal and shallow marine environments. Six lithofacies was recognised in the sedimentary succession in the drill holes. They have been combined into two facies associations – lower clastic one and upper carbonate one, refl ecting deposition in shallow marine settings, upward shallowing trend and reduction of siliciclastic input. The primary source of the material is located mainly in the metamorphic rocks (gneisses, amphibolites and granulites). The spectral gamma-ray logs show vertical organization, which is consistent with the facies analysis and partly also grain-size. A significant reduction of terrigenous input is connected with deposition of carbonates (sandy limestones) in the upper part of the succession.

Calculate Effective Atomic Number, Mass and Cross-Section Attenuation Coefficients for Nonanoic Acid by Using Gamma-Ray Sources

2021 ◽  
Vol 19 (11) ◽  
pp. 15-21
Author(s):  
Ali Adil Turki Aldalawi ◽  
Mohammed Yahya Hadi ◽  
Rawaa A. Hameed
Keyword(s):  
Attenuation Coefficient ◽  
Cross Section ◽  
Atomic Number ◽  
Gamma Ray ◽  
Effective Atomic Number ◽  
Mass Attenuation Coefficient ◽  
Nonanoic Acid ◽  
Attenuation Coefficients ◽  
Effective Electron ◽  
Mass Attenuation

The effective atomic number (Z effective), total atomic cross-section (б Total) electron density (N effective) have been Measured depending on the mass attenuation coefficient (μ/ρ). By using Gamma-ray radiation (γ), emitted from sources (57𝐶𝑜, 133𝐵𝑎, 22𝑁𝑎, 137𝐶𝑠, 54𝑀𝑛, 𝑎𝑛𝑑 60𝐶𝑜) with energies from (0.122, 0.356, 0.511, 0.662, 0.84, 1.17, 1.275 𝑎𝑛𝑑 1.33𝑀𝑒𝑉) respectively. using the Sodium Iodide Scintillation Detectors NaI (Tl) at 662 keV and resolution about 8.2% have been measured the mass attenuation coefficients for the sample “Nonanoic acid its common name Pelargonic acid” it’s chemical formula C9H18O2. The data from the mass attenuation coefficient were then employed to study Zeffective, Neffective, and бtotal of the sample. In the presence of gamma-ray energy, it was discovered that the effective atomic number and effective electron densities first drop and they tend to remain nearly constant. The experimental values obtained by Zeffective and Neffective were in excellent agreement with the theoretical values. The theoretical data that is accessible is obtained from XCom, which is available online. The study's findings aid in understanding how (μ/ρ) values change when Zeff and Neff values vary in the case of H, C, and O based biological molecules such as fatty acids.

scholarly journals Measurement of Total Electronic Cross-Section, Total Atomic Cross-Section, Effective Atomic Numbers, Effective Electron Densities and Kerma for Some Br Compounds

2021 ◽  
Vol 2 (1) ◽  
pp. 024-029
Author(s):  
Tekerek Saniye ◽  
Küçükönder Adnan
Keyword(s):  
Electron Density ◽  
Attenuation Coefficient ◽  
Cross Section ◽  
Atomic Number ◽  
Gamma Ray ◽  
Effective Atomic Number ◽  
Mass Attenuation Coefficient ◽  
Transmission Method ◽  
Effective Electron ◽  
Mass Attenuation

The aim of this study is to calculate the experimental and theoretical the mass attenuation coefficient some Br compounds by using transmission method. Also using these values were determined the total electronic section, total atomic section, effective atomic number, effective electron density and Kerma. We performed the calculations of these values in attenuation by using direct excitation experimental geometry. The total attenuation cross sections of some halogene Br compounds were measured in a narrow beam good geometry using a high resolution Si(Li) detector in the energy with γ photons at 59.543 keV from Am-241 annular source. Theoretical mass attenuation coefficient values were computed from the XCOM data programme, based on mixture rule method. This study provide new insight into the literature since the values of effective atomic number, electron density and Kerma for some Br compounds have not been determined before. According to the results shown in mass attenuation coefficient, Zeff and Neff of Br compounds are closely associated with chemical structure. This research were undertaken to explore how Bromine compounds is gamma ray shielding material.

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