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GIS-Based Geological Hazard Mapping Using Statistical Analysis and Cell Assignment Method for Western Sichuan Region, China
Chaoyang Li,
Bo Xiang,
Duo Qian,
Jianjing Zhang,
Yin Cheng
Issue:
Volume 11, Issue 3, June 2022
Pages:
50-62
Received:
26 April 2022
Accepted:
9 May 2022
Published:
19 May 2022
Abstract: Geological hazards pose severe threats to the natural ecological environment, which endanger human life, cause damage to the environment, and undermine social stability. Studying geological hazards is intended to minimize or reduce any potential losses or threats. Although geotechnical hazards present a complex problem, hazard mapping and zoning studies can improve predictions and reduce losses. Based on the principle of geological hazard zoning, this paper describes a GIS-based approach to regional mapping for geological hazards, including collapse, landslide, debris flow, and overall geological hazards. First, four main factors affecting the occurrence of geological hazards, namely, digital elevation model (DEM), soil property, vegetation type, and average annual rainfall, are determined for analysis. Afterward, the investigated region of western Sichuan province, China, is divided into cells using GIS. The factors are then valued and assigned to the cells for statistical analysis. According to the relationship between the development/occurrence of geological hazards and various influencing factors, the region is first zoned with different degrees of susceptibility. Moreover, the response degree values for different levels of susceptibility to different influencing factors are determined for each cell, and then the superposition values of response degree for each cell are calculated for different geological hazards. Finally, the mapping of each geological hazard is done based on the calculated superposition value ranges. The mapping result demonstrates that the proposed approach is efficient and practical for determining the hazard susceptibility of regional geological hazards in western Sichuan province. The conclusions of this study can provide valuable information regarding the prevention and management of similar disasters in a region.
Abstract: Geological hazards pose severe threats to the natural ecological environment, which endanger human life, cause damage to the environment, and undermine social stability. Studying geological hazards is intended to minimize or reduce any potential losses or threats. Although geotechnical hazards present a complex problem, hazard mapping and zoning st...
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Expression of Shear-Fault Type Fractures (Ruptures) in the Geomagnetic Field (AR): The Example of the Lisagor Mineral Field
Gagik Varazdat Markosyan,
Lyuba Baratov Mirzoyan
Issue:
Volume 11, Issue 3, June 2022
Pages:
63-68
Received:
16 April 2022
Accepted:
10 May 2022
Published:
26 May 2022
Abstract: The article has discussed the possibilities of magnetometry (magnetic prospecting) for mapping shear-fault fractures and the regularities of their separation in a magnetic field. Geological-tectonic preconditions of occurrence of fractures and their significance are represented as mine control structures. Especially shear-fault fractures, in addition to mechanical changes in the domain structure of the environment, lead to disorientation of the magnetic moments of the domain and reduction of the magnetic moment. As a result, the intensity of the geomagnetic anomalous field decreases to a certain extent in the fracture zone, which is sometimes impossible to record during the magnetic survey, especially when the disturbance occurred in the area of complex sedimentary rocks with weak magnetism. The solution to this problem, especially in the folded region, is possible by the presence of a magnetically active horizon with a steep slope (basic dykes, magnetite sandstones, etc.), which has undergone a shear-fault rupture. The article presents the shear-fault type fractures detected by geomagnetic studies in the Lisagore mineral field of AR. These fractures are expressed in several sliding episodes of the magnetically active horizon of the argillites with sandstone interlayers, which is also described in the geological map. The argillites themselves do not have magnetic properties, so their magnetic activity is explained by the presence of magnetite sandstones thin interlayers, which are described by a series of high-intensity linear anomalies of T field that are interrupted and deviated from each other by the magnitude of the amplitude of the slide at the fracture sites.
Abstract: The article has discussed the possibilities of magnetometry (magnetic prospecting) for mapping shear-fault fractures and the regularities of their separation in a magnetic field. Geological-tectonic preconditions of occurrence of fractures and their significance are represented as mine control structures. Especially shear-fault fractures, in additi...
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Geological and Seismic Delineation of D2000 and D4000 Petroleum Reservoirs Within Afenmai Field, Niger Delta Basin, Nigeria
Christopher Imoukhai Unuevho,
Kalu Mosto Onuoha
Issue:
Volume 11, Issue 3, June 2022
Pages:
69-78
Received:
23 April 2022
Accepted:
17 May 2022
Published:
31 May 2022
Abstract: Afenmai Field is an old petroleum discovery within Central Swamp Depobelt on the eastern part of the Nigerian Niger Delta basin. Eight wells were drilled within the field, and Wells 006 and 008 respectively encountered petroleum in the D2000 Sand and D4000 Sands. This study was conducted to firm up the reservoirs’ spatial extent as well as their pore fluid distribution, which has hitherto been unattended to. To achieve this, the reservoirs were correlated within a framework of parasequence sets that was created from sequence stratigraphic interpretation of combined lithologic, geophysical and foraminiferal data. The reservoir tops were then tied at Well 008 to seismic reflections within a 3D seismic volume, and mapped through the volume. Root mean square (RMS) amplitude was extracted from the seismic volume along mapped reservoir surface. The depth maps produced reveal a southward concave, major synthetic structure building fault across the entire field. A series of en echelon synthetic faults are revealed on the NW and SE of the upthrown block of the major synthetic structure building fault. The D2000 Sand constitutes a rollover anticline with entrapped saturated petroleum in a four-way anticlinal closure that lacks fault support. The western, eastern and northern parts of the reservoir are yet to be penetrated by a well. Petroleum is entrapped in a three-way closure within the D4000 Sand in the western part of the upthrown block of the major synthetic structure building fault. Average RMS amplitude characterise the petroleum reservoir at Well 008 location and immediate vicinity. The values become low westward within the delineated reservoir. Opportunity for productive drilling exists within the undrilled part of the delineated reservoir, westward of Well 008. Opportunities for productive drilling also exist within the undrilled western, eastern and northern parts of the delineated D2000 reservoir sand.
Abstract: Afenmai Field is an old petroleum discovery within Central Swamp Depobelt on the eastern part of the Nigerian Niger Delta basin. Eight wells were drilled within the field, and Wells 006 and 008 respectively encountered petroleum in the D2000 Sand and D4000 Sands. This study was conducted to firm up the reservoirs’ spatial extent as well as their po...
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Geological and Geo-electrical Outlining of Graphite Deposits Within Kagara, North-Central Nigeria
Christopher Imoukhai Unuevho,
Akobundu Nwanosike Amadi,
Stephen Jude Ejepu,
Emmanuel Emeka Udensi
Issue:
Volume 11, Issue 3, June 2022
Pages:
79-88
Received:
23 April 2022
Accepted:
17 May 2022
Published:
31 May 2022
Abstract: The specific locations of graphite exposures in Kagara, their host rocks, as well as their spatial extent and gross volume have hitherto remained unaddressed. This study focused on spatially outlining the deposits and conservatively ascertaining their gross volume, using combined surface geological mapping and geoelectrical surveying techniques. The geoelectrical surveying aspect comprised 1D geoelectrical (electrical resistivity, spontaneous potential, induced polarization) sounding, and 2D geoelectrical (electrical resistivity and induced polarization) tomographic surveying conducted using ABEM Terrameter (SAS 4000). The 1D electrical resistivity data were processed and interpreted using WinResist version1.0 resistivity inversion software. The 2D geoelectrical tomographic data were processed and interpreted using RES2DINV computer program. The rock outcrops found are quartzose - micaceous as well as graphitic schists, amphibolite, quartzite, coarse grained biotite granite, and exposures of graphite bodies. The graphite bodies are hosted within the schist and quartzite. The schist, amphibolite and quartzite rock bodies appear to be lateral metasediment equivalents, and therefore are synchronous. The geoelectrical attributes of the graphite bodies are 2-90 Ωm resistivity value, combined with 1-20 ms induced polarisation and negative spontaneous potential values. The deposits exist within 0.7 – 12 m depth interval, occupy 1470509.0 m2 surface area, and constitute 14705090.0 m3 conservative gross volume. The graphite deposits appear to be sheet like bodies interlaid with the quartzite and schist bodies.
Abstract: The specific locations of graphite exposures in Kagara, their host rocks, as well as their spatial extent and gross volume have hitherto remained unaddressed. This study focused on spatially outlining the deposits and conservatively ascertaining their gross volume, using combined surface geological mapping and geoelectrical surveying techniques. Th...
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Development of a Reservoir Simulator to Model Single-Phase Flow in Porous Media
Babilas Hountondji,
François de Paule Codo,
Paul Maurille Lanmandjèkpogni
Issue:
Volume 11, Issue 3, June 2022
Pages:
89-95
Received:
7 April 2022
Accepted:
28 April 2022
Published:
8 June 2022
Abstract: Any groundwater reservoir requires tools to predict future performance as well as to optimize its operation. It is then necessary to simulate groundwater flow in porous media because of the uncertainty and heterogeneity associated with reservoirs. This study developed a reservoir simulator for modeling a single-phase flow in a porous medium. The development of the simulator consists of the physical and mathematical modeling of the reservoir. A MATLAB code was developed to describe groundwater flow in order to appreciate reservoir hydrodynamic pressure distributions from hydraulic head as a function of radial distance while varying the production flow. The formulation equation obtained was solved by the direct method. Examples of graphical plots generated from the simulator illustrate that before the coordinate point P (r=33.74m; h=286.65m) for any value of production flow, hydraulic head or hydrodynamic pressure of the reservoir increases equally with radial distance. This reflects the same drop in the static pressure of the reservoir. Beyond point P, there is a further increase in the hydraulic head, i.e., the hydrodynamic pressure of the reservoir as the production flow increases with the increase in population. This results in a drop in the static pressure of the reservoir in proportion to the increase in the production flow. The variations of the production flow carried out show that the static pressure of the reservoir decreases when the production flow increases. Finally, the simulator to predict the hydraulic head distributions i.e., the hydrodynamic pressure of the reservoir in single-phase flow during production periods is a springboard towards the implementation of multi-phase fluid flow formulations.
Abstract: Any groundwater reservoir requires tools to predict future performance as well as to optimize its operation. It is then necessary to simulate groundwater flow in porous media because of the uncertainty and heterogeneity associated with reservoirs. This study developed a reservoir simulator for modeling a single-phase flow in a porous medium. The de...
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Litho-Bio Facies Analysis and Systematic Paleontology of Sediments in Amansiodo-1 Well, Anambra Basin, Southeastern Nigeria
Lukman Musa Adamu,
Nuhu George Obaje,
Rufai Ayuba,
Musa Tevorushung Kovona,
Dare Anacetus Adesina,
Nsikan Jackson Etukudo,
Umaru Ohiani Aliyu
Issue:
Volume 11, Issue 3, June 2022
Pages:
96-108
Received:
10 April 2022
Accepted:
23 April 2022
Published:
8 June 2022
Abstract: Sixty-two (62) ditch cutting samples were obtained from Amansiodo-1 well within the Anambra Basin, Nigeria, at depth intervals between 16 - 2191 m and analyzed for lithofacies, Foraminiferal, and systematically described. A total of thirty (30) benthonic foraminiferal species were retrieved: twenty-six (26) arenaceous and four (4) calcareous. The age of the well is determined to be Maastrichtian base on the appearance of benthonic arenaceous Haplophragmoides saheliense (Petters) species. Facies analysis of the samples indicated ten (10) lithofacies and two (2) facies associations. The facies comprise a base to top, the shale facies, shale/sandstone facies, shale/mudstone facies, mudstone/coal facies, sandstone/clay facies, mudstone/clay facies, very coarse sandstone facies, coarse sandstone facies, sandstone/clay facies and siltstone/clay facies, association FA-1 (subtidal) and FA-2 (Intertidal) corresponding to the Mamu Formation in the Anambra Basin. The studied sediments are assigned a shallow marine depositional environment based on the triangular plot of foraminiferal suborder test type (arenaceous, porcelaneous, and hyaline) and lithofacies distribution. The paleosalinity studies suggest a transition from brackish to an open marine depositional environment. Also, paleo-oxygenation of the sediments is anoxic based on foraminiferal distribution and the ratio of epifaunal to infaunal benthonic foraminifera respectively.
Abstract: Sixty-two (62) ditch cutting samples were obtained from Amansiodo-1 well within the Anambra Basin, Nigeria, at depth intervals between 16 - 2191 m and analyzed for lithofacies, Foraminiferal, and systematically described. A total of thirty (30) benthonic foraminiferal species were retrieved: twenty-six (26) arenaceous and four (4) calcareous. The a...
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3D Seismic Data Interpretation in Gumry Field, Melut Basin
Mohammed Kabashi Mohamed Mustafa,
Abdalla Gumaa Farwa,
Ahmed Mohamed Ahmed Salim
Issue:
Volume 11, Issue 3, June 2022
Pages:
109-120
Received:
14 April 2022
Accepted:
5 May 2022
Published:
20 June 2022
Abstract: This work describes interpretation of 3D seismic data of Gumry area which is located in Blocks 3 & 7 in Melut Basin the South of Sudan. The data used in this study was acquired by Blue Nile Geophysical Company (BGC) in 2004. The 3D data was interpreted by the author at the SUDAPET CO. LTD in Khartoum – Sudan, Vertical Seismic Profiling data (VSP) and Check-Shot data of the Gumry-1 well were used. The data quality is good and adequate for the objectives. Geoframe software has been used which enables to display inline, cross line and time slice and also enables checking of the consistency of the interpretation from line to line. Synthetic seismogram has been generated for Gumry _1 well for seismic data tie. Time and depth maps have been generated for the top of Yabus Formation. The 3D data interpretation clarifies that there are many oil structures found in study area such as normal faults, faulted trap, graben, half graben, and faulted anticline. Faults system in Gumry area consists of normal faults, trending NW-SE, with some of them dipping SW and others dipping NE. Gumry oil field prospects are mainly fault block structure, located at the block up thrown side of the normal Fault block.
Abstract: This work describes interpretation of 3D seismic data of Gumry area which is located in Blocks 3 & 7 in Melut Basin the South of Sudan. The data used in this study was acquired by Blue Nile Geophysical Company (BGC) in 2004. The 3D data was interpreted by the author at the SUDAPET CO. LTD in Khartoum – Sudan, Vertical Seismic Profiling data (VSP) a...
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Detection of Uranium Anomalies and Alteration Zones Using Airborne Gamma-Ray Spectrometry at Gabal Attala and Its Surrounding Area, Eastern Desert, Egypt
Issue:
Volume 11, Issue 3, June 2022
Pages:
121-129
Received:
26 May 2022
Accepted:
16 June 2022
Published:
27 June 2022
Abstract: Gamma-ray spectrometry method is widely used in various fields. The study area is located in the Central Eastern Desert of Egypt and covers about 1200 square kilometers. The rock units in the study area can be organized in ages from the Precambrian (mainly granite) to Quaternary. Airborne gamma-ray spectrometry data were collected by Aero-Service, 1984. The main objectives of this study are to detect hydrothermal alteration zones and the uranium anomalies in the study area. The processing of the data was conducted to generate radioactive element concentration maps (K, eU and eTh). Hydrothermal alteration zones such as potassic and phyllic altered areas were detected using the Potassium Ternary Composite Image map and the eTh/K map. The F-parameter technique and K ideal method were used to determine the locations of the potassium-enrichment. These locations are characteristically associated with the orogenic gold mineralization in the study area. Fourteen radioactivity zones were classified based on the Interpreted Radio-Spectrometric Zonation (IRSZ) Map. These zones were divided into high, medium and low radioactive response where zones of high radioactive response were revealed as zones 1, 6, 9 and 13. Uranium anomalies have been identified as these anomalies are abundant in eU values and also associated with higher values of eU/eTh and eU/K, where the maximum value of eU is associated with the Younger Granite with a value of 18.831 ppm. These uranium anomalies are associated with Taref Formation, Post-Hammamat felsite, Quaternary deposits and Younger Granite. The locations of uranium anomalies are considered important exploration targets, as these locations are promising and have priority for ground geophysical and geological follow-up.
Abstract: Gamma-ray spectrometry method is widely used in various fields. The study area is located in the Central Eastern Desert of Egypt and covers about 1200 square kilometers. The rock units in the study area can be organized in ages from the Precambrian (mainly granite) to Quaternary. Airborne gamma-ray spectrometry data were collected by Aero-Service, ...
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Repercussions of Agro-Pastoralism on Soil Condition in Western Serengeti, Tanzania
Pius Yoram Kavana,
Ephraim Japhet Mtengeti,
Anthony Zizimus Sangeda,
Christopher Mahonge,
John Bukombe,
Stephen Nindi,
Robert Fyumagwa
Issue:
Volume 11, Issue 3, June 2022
Pages:
130-141
Received:
9 May 2022
Accepted:
30 May 2022
Published:
30 June 2022
Abstract: Overgrazing of rangeland and continuous cultivation of cropland are among human activities contributing to the deterioration of soil properties. To elucidate the effect of agro-pastoral activities on soil properties in western Serengeti, we examined soil properties in four land use types, namely fallow land, communal grazing land, mixed grazing land and wildlife dominated grazing land. The soil sampling sites were along the landscape from village lands towards protected areas while crossing all four land use types. Soil pH was not significantly different (p≥0.05) although it was relatively low in fallow and communal grazing lands. Clay content in soils was not affected by land use types whereas sand and silt contents were significantly different (p≤0.05) among land use types. In terms of soil nutrients, OC, CEC and soil P showed a significant difference (p≤0.05) among land use types but land use did not affect TN and Ca2+. Bare land within quadrats was highest in communal grazing lands (1233 cm2/quadrat) and lowest in wildlife dominated grazing lands (906 cm2/quadrat). Protected areas represented by wildlife grazing sites had the highest soil stability expressed in terms of soil structure stability index. Soil quality declined with increase in bare land. Further, high density of grazing animals caused a decline in soil properties. The study demonstrated that the four land use types had negative influence on soil properties. It was further noted that the current practices of livestock grazing and cultivation had higher negative effects on soil properties than the other land use types. Long term monitoring study on impacts of agro-pastoralism in western Serengeti is needed so as to establish proper stocking rates to avoid reaching an irreversible soil properties deterioration situation.
Abstract: Overgrazing of rangeland and continuous cultivation of cropland are among human activities contributing to the deterioration of soil properties. To elucidate the effect of agro-pastoral activities on soil properties in western Serengeti, we examined soil properties in four land use types, namely fallow land, communal grazing land, mixed grazing lan...
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