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Okoli Austin E. Agbasi Okechukwu E. Lashin Aref A. Sen Souvik 《Natural Resources Research》2021,30(2):1411-1425
Natural Resources Research - This work integrates seismic and well log data to establish a 3D reservoir model of the Q-Field, which is a prolific onshore hydrocarbon field situated in the Central... 相似文献
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In July, heating of the continents in the Northern Hemisphere results in strengthened monsoon systems which bring rains to West Africa. In Nigeria, the annual rainfall total decreases from over 3,800 mm at Forcados on the coast to under 650 mm at Maiduguri in the north-east of the country. June, July, August and September are the rainiest months throughout the country. In many parts of the south, however, there is “supposed to be” a slight break in the rains for some 2 to 3 weeks in late July and early August or the so called “August break”. In this study, we are underscoring the obvious that climate is changing. The daily series of rainfall data for 1983–2003 analyzed between the months of July–August for some sites in the Eastern humid zone of Southern Nigeria shows that the “August break” may indeed “be breaking”. We have discussed some practical approaches to climate change research in this monsoon region. 相似文献
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Okechukwu E. Agbasi Magnus U. Igboekwe Godwill U. Chukwu Etuk E. Sunday 《Arabian Journal of Geosciences》2018,11(11):274
Quantitative rock physics analyses were used to determine the lithology and pore fluid of a reservoir in the Niger Delta. Inaccurate prediction of lithology and pore fluid results in the inaccurate determination of other petrophysical properties and parameters such as porosity, permeability, and net pay. This research is to predict lithology and pore fluid using rock physics analysis. However, reservoir zones were also predicted. Density, compressional wave velocity, and shear wave velocity logs were used as input to calculate elastic parameters such as velocity ratio, Poisson’s ratio, and bulk modulus. The calculated velocity ratio log was used to differentiate between sand and shale. Poisson’s ratio and velocity ratio using Goodway interpretation template were carried out and used to delineate pore fluid content, gas sand, oil sand, and sandstone formation from crossplot analysis. 相似文献
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Ogbonnaya Igwe Wilfred Mode Okechukwu Nnebedum Ikenna Okonkwo Ifeanyi Oha 《Environmental Earth Sciences》2014,71(5):2465-2480
This paper analyses the dominant mechanisms of slope failures and identifies potential obstacles to landslide-hazard reduction at the Iva Valley area, Enugu, Nigeria. The landscape is replete with landslide scars and gullies of varied sizes and the slope deposits comprise unconsolidated, friable sands inter-bedded with thin units of montmorillonitic claystone. Forty-three landslide events were identified in the study area with most being shallow, short run-out movements with slip-surface depth <2 m. The study found the landslides mainly occur in the beginning of rainy season characterized by short duration, high intensity rainfall. An integrated approach comprising field mapping, laboratory tests and numerical analyses reveals that the barren nature of the slopes prior to the outset of rainy season, high rainfall intensity, erosion, overgrazing, soil characteristics and the site’s unique lithologic sequence are the main causes of instability. Shearing tests under several conditions showed that the soils strongly strain-soften until low steady-state strength is achieved. A computer code, based on this strength reduction technique, used input parameters obtained from the field and laboratory studies to simulate a landslide with similar structure, travel distance and distribution area. It is noted that urbanization has gradually increased the vulnerability of the society’s poor to landslide hazards as they now erect unplanned residence (tents and blocks) on the slopes. This work is part of a regional study aimed at finding ways of protecting the vulnerable by generating data that could be used to build future landslide susceptibility map. 相似文献
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Under the WCoE/IPL project, Landsat Enhanced Thematic Mapper plus (ETM+) and ASTER GDEM data were used to analyze factors associated with frequent debris flow and rock-debris avalanche on the Nigeria-Cameroon mountain range. Detailed processing of the ETM+ imageries of the vulnerable portions on the western part of Adamawa plateau was carried out to identify structural trends relatable to the slope failures. The processing identified the structural characteristics of the study area and clearly distinguished the lineaments associated with the debris flow and rock-debris avalanches. The strongly weathered and fragmented gneissic rocks, shallow groundwater table, as well as the distribution of faults and joint sets were significant factors predisposing the slopes to rapid movements. Recent landslides occurred at the locations with high lineament density and in areas close to major faults and long lineaments. The interaction among the moving mass, slope geometry, local geology, topography, and drainage then resulted in a long runout and a high degree of spreading. Analysis of the ASTER–GDEM delineated landforms, slope morphology, and drainage patterns, which was not possible with conventional mapping techniques. Integration of these results yielded reasonable interpretation of the predisposing factors for the long runout failures and provided logical basis for future landslide susceptibility analysis in the area. Accurate investigation of the predisposing factors and characteristics of landslides in environments that have experienced past failures is therefore important in understanding areas that may be susceptible to landsliding in future. 相似文献
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The work discusses the effect in the variations of secondary radioclimatic parameters in Nsukka, Nigeria. The data collected from the measured atmospheric profile using two automatic wireless weather stations for 3 years were used to estimate the propagation condition, geoclimatic factor, and effective earth radius. The result shows that, the calculated median value of k-factor is 1.595, with an absolute span of 0.26 of the standard value of k-factor 1.333 owing to the increase in relative humidity during the rainy seasons and intensive temperature inversion in the morning and early afternoon periods of December due to the dry harmattan for the season. Also, from the result super-refraction propagation condition was observed for about 7 months of a year, while ducting condition dominates the remaining 5 months in the region. The regression analysis of k-factor as a function of ground refractivity showed that the pair is strongly correlated (0.9996). These results have not been obtained in the region and it will help in planning of radio wave line-of-sight for better signal reception. 相似文献
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