scholarly journals Soil Gas Measurements of Radon, CO2 and Hydrocarbon Concentrations as Indicators of Subsurface Hydrocarbon Accumulation and Hydrocarbon Seepage

2021 ◽  
Vol 13 (7) ◽  
pp. 3840
Author(s):  
Marko Cvetković ◽  
Josipa Kapuralić ◽  
Marija Pejić ◽  
Iva Kolenković Močilac ◽  
David Rukavina ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Soil Gas ◽  
Gamma Ray Spectrometry ◽  
Hydrocarbon Accumulation ◽  
Near Surface ◽  
Migration Pathway ◽  
Sampling Points ◽  
Oil Seepage ◽  
Gas Measurements ◽  
Migration Pathways

Soil gas measurements of radon (222Rn), CO2, and hydrocarbon concentrations, as well as gamma-ray spectrometry, were conducted at two separate locations to estimate the measurement results for known locations of hydrocarbon accumulations in the subsurface and oil seepage on the surface. The aim of the study was to confirm the applicability of the method for identifying migration pathways (e.g., faults) and to detect possible seepages of hydrocarbons to the surface as well as to investigate possible health issue potential about the soil gas analysis results. Site A investigations were performed with a large number of sampling points to provide sufficient spatial coverage to capture the influence of subsurface lithologic variability as well as the influence of the migration pathway on the measured parameters. For the investigation of site B, sampling points were positioned to reflect the situation between the area above producing hydrocarbon fields and areas with no confirmed accumulation. The results presented show that it is possible to distinguish the near-surface lithology (gamma-ray spectrometry), characterize the migration pathway, and indicate the area of oil seepage at the surface. Areas above the known hydrocarbon accumulations generally have elevated radon concentrations and detectable heavier hydrocarbons with sporadic methane in soil gas, which contrasts with the lower radon levels and lack of detectable heavier hydrocarbons in soil gas in the area with no confirmed hydrocarbon accumulation in the subsurface.

Types of Hydrocarbon Migration Pathways and Hydrocarbon Accumulation in the Yakela Fault-Convex, Tarim Basin

2013 ◽  
Vol 295-298 ◽  
pp. 2749-2752
Author(s):  
Xiao Long Luo ◽  
Liang Jie Tang
Keyword(s):  
Tarim Basin ◽  
Hydrocarbon Accumulation ◽  
Lateral Migration ◽  
Long Distance ◽  
Hydrocarbon Migration ◽  
Migration Pathway ◽  
Fault Type ◽  
Migration Pathways ◽  
3D Seismic Data ◽  
Field Geology

The existence of abundant hydrocarbon has been discovered in the Yakela Fault-convex, Tarim Basin, after reconstructing and superimposing for several periods. Through interpretation of 3D seismic data up to date, combined with the circumferential field geology, after comprehensively analyzing the characteristics of development on hydrocarbon migration passages and its relationship with hydrocarbon accumulation, this paper holds that it is divided into fault type, unconformity type and carrier bed type in the Yakela fault-convex. The unconformities and the carrier beds are the main lateral migration passage of gas and oil for long distance. The faults are the main vertical migration pathway of hydrocarbon, and the hydrocarbon can arrive at any strata with fault. It is significant to know the hydrocarbon migration pathways in the study area for exploration in future.

scholarly journals Radiometric Surveys for Detection of Uranium in Dhofar Region, Sultanate of Oman

2019 ◽  
Vol 24 (1) ◽  
pp. 36
Author(s):  
Narasimman Sundararajan ◽  
Bernhard Pracejus ◽  
Salah Al- Khirbash ◽  
Talal Al-Hosni ◽  
Ala Ebrahimi Ebrahimi ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Radioactive Decay ◽  
Sampling Interval ◽  
Uranium Mineralization ◽  
Gamma Ray Spectrometry ◽  
Sultanate Of Oman ◽  
Near Surface ◽  
The World ◽  
Uranium Exploration ◽  
Proterozoic Basement

The Proterozoic basement of the Dhofar region of the Sultanate of Oman might be considered as a potential source of Uranium mineralization like other Proterozoic basins of the world, which collectively contribute 30%-40% to the global production.  Uranium exploration assumes great importance in this part of the world and therefore geochemical and geophysical exploration for Uranium was initiated.  Initial, random sampling of the study area with Gamma ray spectrometry as well as in situ XRF (Xray Florescence) analysis indicated the presence of   around 30-40 ppm of Uranium. Since Gamma ray spectrometry results in the calculation of the heat produced during radioactive decay of Potassium (K), Uranium (U) and Thorium (Th) within the rocks in the study area, measurements were acquired along eleven traverses of varying length from 100-250 m at a traverse interval of 20 m and sampling interval of 10 m. Individual plots of the concentrations  of radioelements such as U, K and Th have shown favorable anomalous radioactive sources. Besides this, Uranium to Thorium (eU/eTh) and Uranium to Potassium (eU/K) ratio plots have been presented and the alteration zones associated with Uranium mineralization through all traverses have been identified. Further, the generated composite ternary image based on the combination of K, Th and U from Gamma ray spectrometry determines different relative amounts of radioelements and paves the way for deciphering the level of radioactivity in the study area. However, there seems to be no presence of strong Uranium anomalies in the near surface of the limited study area. As the study area is heavily faulted, the depth to concealed  subsurface fault structures  is  estimated to be around  64 m based on Hartley spectral analysis of total magnetic anomaly (line-6). 

GPR, TDR, and geochemistry measurements above an active gas vent to study near-surface gas-migration pathways

Geophysics ◽  
2008 ◽  
Vol 73 (1) ◽  
pp. A11-A15 ◽  
Author(s):  
Elena Pettinelli ◽  
Stan E. Beaubien ◽  
Salvatore Lombardi ◽  
A. Peter Annan
Keyword(s):  
Water Content ◽  
High Water ◽  
Time Domain Reflectometry ◽  
High Water Content ◽  
Gas Migration ◽  
Secondary Effects ◽  
Near Surface ◽  
Geologic Storage ◽  
Migration Pathway ◽  
Migration Pathways

The migration of deep gas to the atmosphere along faults and associated structures is important in many fields, from studying the natural contribution of atmospheric greenhouse gases leaking from geothermal areas to ensuring the safety of man-made natural gas and carbon dioxide [Formula: see text] geologic-storage sites. Near-surface geophysical and geochemical techniques were applied to a naturally occurring gas vent located along a deep terrestrial fault to better understand the structure and geophysical response of this gas-migration pathway. A number of ground-penetrating radar (GPR) profiles were first conducted across the vent. Spot samples were then measured along one of these profiles for in situ apparent permittivity (using time-domain reflectometry — TDR), complex permittivity on dried samples (using a capacitivecell), soil-gas composition, and clay and bulk mineralogy. Results show how the migrating gas induces secondary effects that modify the signature of the vent as seen in the GPR profiles. In particular, high flux rates across the vent core (i.e., the central portion of the vent) result in a total lack of vegetation, which in turn leads to high water content that is likely responsible, together with increased bulk conductivity, for GPR signal blanking. In the transition zone surrounding the core, a water-content minimum and other changes contribute to a deeper GPR signal penetration that highlights dipping events. Data show that the structure itself is slightly asymmetrical, which may indicate more fracturing to one side of the feature. This study shows that GPR surveys are capable of imaging secondary effects induced by gas migration in soils above a structural discontinuity, even if the structure itself cannot be imaged.

The role of airborne geophysics for detecting hydrocarbon microseepages and related structural features: The case of Remanso do Fogo, Brazil

Geophysics ◽  
2012 ◽  
Vol 77 (2) ◽  
pp. B35-B41 ◽  
Author(s):  
Julia B. Curto ◽  
Augusto C.B. Pires ◽  
Adalene M. Silva ◽  
Álvaro P. Crósta
Keyword(s):  
Gamma Ray ◽  
Sedimentary Cover ◽  
Structural Features ◽  
Magnetic Data ◽  
Gamma Ray Spectrometry ◽  
Horizontal Gradient ◽  
Near Surface ◽  
Residual Values ◽  
Basement Structures ◽  
New Occurrences

The first direct indication of hydrocarbon occurrence in Remanso do Fogo area (Minas Gerais State, Brazil) was the existence of microseepages. However, Quaternary sedimentary cover in the area made the identification of new occurrences and associated controlling structures quite difficult. This study investigated the spatial distribution of hydrocarbon related gases in shallower to intrasedimentary depths in Remanso do Fogo area, using airborne gamma-ray spectrometry and magnetic data. The geophysical data were processed using techniques designed to suppress the influence of regional geological signatures. Known and possible new occurrences of microseepages were detected by mapping low residual potassium values and high uranium residual values in relation to potassium, termed as DRAD values, which resulted from the subtraction of potassium from uranium residual values, using a Thorium (Th)-normalizing approach. The validation of these occurrences was done based on existing gas geochemistry data in the soil. For the magnetic data, the amplitude of the analytic signal, combined with the total horizontal gradient of the subtraction between the 1200- and 400-meter upward continuations, enhanced the northwest–southeast and east–west magnetic lineaments, which are partially related to the microseepages and the drainage of the area. The distinction of near-surface and deep signatures also allowed the general identification of intrasedimentary and basement structures, which are potentially controlling the occurrences of seepages in the area.

Gamma-Ray Spectrometric Analysis of Some Trace Elements in the Human Articular Disc of the Mandible

1963 ◽  
Vol 03 (02) ◽  
pp. 175-182 ◽  
Author(s):  
Bo Bergman ◽  
Rune Söremark
Keyword(s):  
Trace Elements ◽  
Neutron Activation ◽  
Quantitative Data ◽  
Thermal Neutron Flux ◽  
Gamma Ray ◽  
Dry Weight ◽  
Gamma Ray Spectrometry ◽  
Spectrometric Analysis ◽  
Articular Disc ◽  
Group Separation

SummaryBy means of neutron activation and gamma-ray spectrometry the concentrations in the human mandibular articular disc of the following elements have been determined: Na, Mn, Cu, Zn, Rb, Sr, Cd, W, and Au. The discs were obtained at necropsy from seven men and nine women, ranging in age from 56 to 71 years.The activation was carried out in a thermal neutron flux of about 1.7 XlO12 neutrons × cm−2 × sec.−1 for about 20 hours. A chemical group separationwas performed before the gamma-ray spectrometry. Quantitative data based on the dry weight of the cartilage samples were obtained by comparing the photo-peak area of the identified elements with those of appropriate standards.

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