January, 2025 || Volume 29 No.01
Volume 29(1) (2025)1-6
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1
Development of Spectral gamma-ray logging probe using LaBr3(Ce) detector and testing of its application in geophysical prospecting for uranium
Habeeb Ali Khan, Srinivasulu, A. Markandeyulu, G. Udaya Laxmi, M.N. Chary (Retd.)1 and Prakhar Kumar
1Atomic Minerals Directorate for Exploration and Research, Begumpet, Hyderabad-500016, India
2 Centre of Exploration Geophysics, Osmania University, Hyderabad-500007, India
https://doi.org/10.71122/JIGU.29(1)2025.001
ABSTRACT
Spectral gamma ray logging is a useful technique for uranium exploration during the large-scale borehole drilling stage. It can detect sub-surface uranium-bearing formations, quantify uranium concentration, and map geological structures. Traditionally, NaI(Tl) crystal is used as a detector in spectral logging probes. The coring boreholes drilled for uranium exploration have a limited diameter, necessitating smaller detectors in Spectral gamma ray logging probes. This limitation resulted in reduced sensitivity, increased high-energy thorium contributions in uranium and potassium channels, and thus pose challenges in accurately quantifying uranium content with the NaI(Tl) detector. Advances in detector technology, such as LaBr3(Ce), CeBr3 and CsI(Tl) scintillation detectors, offer improved energy resolution and sensitivity in smaller form factors. The LaBr3(Ce) detector has various advantages over standard NaI(Tl) detectors of the same size, such as high density, superior light output, good linearity, faster response time, and improved energy resolution. In this regard, an attempt was made to use a LaBr3(Ce) detector in the spectral gamma-ray logging probe. A spectral gamma-ray logging probe using a small 1-inch diameter x 1-inch height LaBr3(Ce) detector was developed to perform gamma-ray spectroscopy in slim borehole environments. The probe was attached to a vehicle-mounted multi-para borehole logging system. The probe was calibrated using gamma-ray sources of known energies and standard boreholes with known uranium, thorium, and potassium concentrations. The spectral gamma-ray logging was performed in a borehole with a radioactive zone around the Sarangapalli area, Guntur district of Andhra Pradesh (India). The logging results were compared with laboratory core sample analysis results to confirm the credibility of the probe’s ability to measure K, U, and Th concentrations in a drilled borehole.
2
Petrographic study of Umlatdoh limestone in parts of Meghalaya, north-east India with an emphasis on diagenetic and depositional attributes
Anni Rani Das, Meghali Baruah*, Mrinal Kanti Pathak, Devesh Walia and Shikhar Kumar
Department of Geology, North-Eastern Hill University, Shillong – 793022 (India)
https://doi.org/10.71122/JIGU.29(1)2025.002
ABSTRACT
Early Eocene Umlatdoh Limestone of Sylhet Limestone Group have been studied to understand their framework constituents and diagenetic processes. Additionally, an approach was made to infer the depositional environment of this limestone based on the abundance of biogenic assemblages. Two vertical profile sections were measured and representative rock samples were collected for petrographic study. The limestones of the study area are classified as wackestone, packstone and grainstone, dominated by calcareous green algae (Dasycladalean algae) and large benthic foraminifers. An open lagoonal to proximal middle shelf environment has been envisaged during the deposition of the studied limestone. The diagenetic overprints of these limestones are characterized by several key diagenetic features, including micritization, cementation, compaction, dissolution and neomorphism. These diagenetic processes occurred in marine phreatic, meteoric phreatic, mixed meteoric phreatic, and burial diagenetic environments. Micritization of allochems, cementation by isopachous and granular calcite, neomorphism, and bioclast recrystallization occurred during meteoric-phreatic diagenesis. Meteoric-vadose diagenesis led to extensive dissolution and the infilling of fractures with sparry calcite. During burial diagenesis, blocky calcite cementation appears to have become prominent.
3
Reservoir characterization using a hybrid of particle swarm optimization: A case study from the Blackfoot field, Canada
1Department of Geophysics, Institute of Science, Banaras Hindu University, Varanasi-221005, India
2Department of Earth Sciences, Indian Institute of Technology, Bombay, Mumbai-400076, India
https://doi.org/10.71122/JIGU.29(1)2025.003
ABSTRACT
The development, management, and optimization of a reservoir depend on precise reservoir characterization. There are several methods for doing this, however in the current work, seismic inversion based on the hybrid particle swarm optimization (HPSO) methodology is used. In this method, a local optimization method called quasi-newton method (QNM), combined with a global optimization method called PSO to maximize their benefits and minimize their downsides are used. The global optimization method takes a lot of time to converge whereas, Quasi-Newton method is rapid, but heavily dependent on the initial model. The present study takes these two limitations into account. To characterize the reservoir, the hybrid PSO uses post-stack seismic data to predict acoustic impedance and porosity in the inter-well zone. The effectiveness of this newly devised method is first evaluated using synthetic data, and then it is applied to the real data from the Blackfoot area in Canada. The findings show that for both the synthetic and real data, the inverted outcomes closely match the observed data. The analysis anticipated that the inter-well acoustic impedance and porosity volume would vary from 6000 to 12000 m/s*g/cc and 5-22%, respectively. These volumes display extremely detailed subsurface data. The analysis of inverted findings reveals an abnormal zone inside the two-way transit time frame of 1045 to 1065 ms, ranging from low-impedance 6500-9000m/s*g/cc, and high porosity >15%. This unconventional area is classified as a reservoir. The method is particularly useful in nearby regions where detailed subsurface information needs to be estimated, even with limited prior data.
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Impact of solar activity on ~200-year cyclic variations in groundwater recharge rates in the Badain Jaran Desert, Inner Mongolia, Northwest China
Rajesh Rekapalli1,2, R.K.Tiwari1 and Animesh Mandal3
1CSIR-National Geophysical Research Institute, Hyderabad-500007, India
2AcSIR- National Geophysical Research Institute, Hyderabad-500007, India
https://doi.org/10.71122/JIGU.29(1)2025.004
ABSTRACT
Understanding groundwater recharge variations is crucial for assessing the impact of climatic and solar influences on water resources. We attempt here to quantify the cyclic solar forcing on groundwater recharge rate (GRR) through the analysis of ~ 700 years of GRR data from the dry lands of the Badain Jaran Desert in Northwest China and Total Solar Irradiance (TSI) data using principal component analysis and statistical methods. Our results confirm a significant role of solar activity in groundwater recharge variations. Singular spectrum analysis of GRR and TSI time series reconstructed from the first three principal modes, revealed common spectral peaks, indicating a significant influence of solar activity on GRR. We observed that a small portion of solar variation (~ 0.021%) of TSI appeared in the second and third eigenmodes of TSI, is found to be responsible for the ~200-year cyclic variability. Approximately 33.66% of the GRR variability is attributed to long-term solar activity trends, while 11.81% is associated with the ~200-year Suess solar cycle. Additionally, residual spectral analysis suggests potential influences of shorter solar cycles (63±10 years, 33±3 years, 24±2 years, and 18±2 years) and non-linear solar phenomena. Thus, this study provides critical insights into the coupling between solar activity and groundwater recharge, emphasizing the importance of long-term and cyclic solar influences, in modeling future groundwater scenarios under changing climatic conditions.
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Finite Element solutions of Maxwell fluid flow towards a stretching surface with addition of thermal radiation, porous medium and magnetic field
Nagaraju Bathula* and Kishan Naikoti
Department of Mathematics, Osmania University, Hyderabad-500007, Telangana, India.
https://doi.org/10.71122/JIGU.29(1)2025.005
ABSTRACT
Numerical simulations were used to study the flow of a Maxwell fluid across a non-linear stretching sheet. The effects of thermal radiation, magnetic field, and porous media, were all taken into account within the parameters of the experiment. The non-linear governing equations and the associated boundary conditions were solved using an approach called the finite element technique. Several technical features were used to examine the effects of various factors on the temperature, concentration, and velocity profiles. This study considered parameters like, the magnetic field , permeability , nonlinear stretching sheet, Prandtl number, and the thermal radiation. The study also examines the graphical depictions of how the physical elements affect the skin-friction coefficients along the x and y - directions and heat transfer rate. This was done in tandem with the findings, which are shown graphically.
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Kinematics of the Capricorn microplate and its surrounding regions as inferred from the analyses of GPS data
1CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad- 500 007, India
2National Centre for Earth Science Studies, Triuvanthapuram-695011, India
3Department of Earth Sciences, Indian Institute of Technology, Roorkee-247667, India
https://doi.org/10.71122/JIGU.29(1)2025.006
ABSTRACT
The Capricorn microplate, located between the Indian and Australian Plates, is a prominent tectonic block introduced between the two plates, primarily to explain the inconsistency observed in the Indian oceanic plate motions and the prevailing intraplate seismicity. We evaluated the kinematics of this microplate, relative to adjacently located other tectonic plates using GPS data to understand the underlying plate tectonic processes and associated deformation/strain patterns. The lengths of baseline are computed from the DGAR GPS site, placed at the northern fringe of the Capricorn Plate, and adjacently positioned other GPS sites in different geotectonic blocks. The estimated baseline lengths indicate a relative convergent tectonics between Capricorn microplate and southern tip of India with a rate of 1 mm/yr. In comparison, a much higher rate of convergence (about 18 mm/yr) is seen between the Capricorn microplate and the Sunda Plates. Such a high rate of convergence, if persists, would considerably shrink the wide diffusive boundary that currently exists between the Capricorn microplate and the Sunda blocks. Similarly, the baseline length changes between Capricorn microplate and Australia, indicate a shortening at a rate of about 10 mm/yr, which is in good agreement with earlier findings with a diffusive convergent boundary inferred between Capricorn microplate and Australia. A complex rate of change in baseline length is also noticed between this plate and the two different sites inside the African Plate. The DGAR-ZAMB station pair shows divergence between the two plates at a rate of 9 mm/yr, while the DGAR-SUTH (southern margin of Africa) pair shows convergence at a rate of ~4 mm/yr. The observed divergence between the Capricorn and Rovuma microplates, can be explained by the presence of Comores hotspot in the Somalian Plate, which is centered between north Madagascar and Rovuma microplate. This feature causes deformation due to magmatic extrusion led internal rifting (or spreading) below the Comores Islands and its surrounding regions. Consequently, a broad deformation zone is being formed east to the Rovuma microplate due to internal rifting of the Somalian Plate that includes the northern part of Madagascar and northernmost part of the Lwandle Plate.