Browsing by Author "Ibrahim, K. O."
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Item Estimation of Hydraulic Properties of Aquifer Systems Using Geophysical Methods(Published by Department of Civil Engineering, University of Ilorin, Ilorin, Nigeria, 2018) Ibrahim, K. O.; Yusuf, M. A.; Iheme, O. K.; Ali, O. K.Determining aquifer characteristics is important in the sustainability and management of groundwater resources. Estimating aquifer properties by means of pumping test is financially cost and requires much time, therefore, applying geoelectric method in characterizing aquifer properties is an alternative method and cost effective. Geoelectric method was employed to determine hydraulic characteristics of groundwater aquifer systems in the rural localities of Ilorin, Northcentral Nigeria. Twenty (20) VES data were collected using Schlumberger array with a maximum half current electrode (AB/2) spacing of 100m. Sounding curves were initially interpreted by partial curve matching which gave resistivities of the layers with thicknesses and later inverted by IPI2 WIN software. The characteristics nature of the curves obtained from the VES data shows that the study area consists of three to five geoelectric layers. The results of the interpretation indicates that top soil possess resistivity and thickness ranges between 44.1- 862Ωm and 0 – 2.5m, second layer which is lateritic layer possess resistivity and thickness between 106 - 2001 Ωm and 0.6 – 10.3m, third layer is weathered basement having resistivity and thickness ranges from 22.3 – 166 Ωm and 3.1 – 52.0m while the fourth layer is fractured basement with resistivity and thickness between 78.4 - 138 Ωm and 14.8 – 71.1m and final layer is fresh basement which possess resistivity ranges between 40.1 – 136 Ωm. The hydraulic characteristics of the aquifers in the area determined from geoelectric parameters shows that hydraulic conductivity ranges between 0.16 – 24.8 m/day, transmissivity between 0.5 – 408 m2 / day and porosity was determined in the laboratory from collected field core samples with values ranges between 26 – 41% and these implies that aquifer systems in the area have tendency of transmitting water that good for sustaining water need of the area. This study has proved the usefulness and effectiveness of geoelectric method in characterizing groundwater aquifer systems.Item Geophysical Investigation of Basement Rock Structures around a proposed Dam Site,(Adamawa Stete University, 2017) Raji, Wasiu O; Adeoye, Taiye, O; Ibrahim, K. O.A combination of carefully selected geophysical surveys comprising very low frequency electromagnetic (VLF-EM) and electrical resistivity (VES) methods was employed to study the basement rock structures in a proposed dam site within University of Ilorin campus. Data acquired in the survey were processed to inverted subsurface geological model, 2D conductivity structures and geo-electric cross-sections for the area. The results were interpreted to delineate the subsurface rock and structure, the number of geo-electric layers, and to select a suitable area for the construction of dam extension. The four geo-electric layers delineated correspond to lateritic top-soil layer, weathered rock layer, fractured rock layer, and the fresh basement rock. The VLF-EM and resistivity cross-section revealed a series of competent and weak zones. The weak zones are characterized by weathered/fractured rocks, and they correspond to areas of low resistivity anomalies in VES survey and high conductivity anomalies in VLF-EM survey. Competent rock zone corresponds to area of high electrical resistivity anomalies and low conductivities in VLF-EM tomogram. Depth to fresh basement rock in the weak zone ranges from 7.8 – 14.8 m. The competent rock zones correspond to high resistivity anomalies in electrical resistivity cross-section and low conductivity anomalies in VLF-EM tomograms. Depth to fresh basement rock in the competent zone ranges from 3.3 – 6.8 m. the competent zone recommended for the construction of the dam extension.Item Hydrocarbon Reserve Estimates and Risks Assessment in ‘X’ Ray Field, Niger Delta, Nigeria.(Adamawa State University, 2018) Raji, Wasiu O; Adeoye, Raiye, O; Ibrahim, K. O.Hydrocarbon exploration and production is a high-risk venture. The uncertainties surrounding return on investment is taking a new dimension under the current industry condition. The dwindling nature of crude oil price requires robust assessment of the likelihood of occurrence, the range of possible outcomes, and the threat of loss throughout the life of a hydrocarbon field. Hydrocarbon prospecting in ‘X’ ray field, Niger Delta, Nigeria, revealed two gas prospects inter-bedded in thick shale sequences. Petroleum system elements were evaluated for the two prospects using a set of 3D seismic cube and well logs. Risks associating with each petroleum element were assessed. Result of study shows that the reservoir, trap, and seal are in-place and effective for hydrocarbon accumulation and production. However, organic rich rock that generated the gas accumulation was not found within the field. The absence of source rock within the field indicates high risk for the source and migration path. Average hydrocarbon saturations obtained from the prospects are 0.69, and 0.57 respectively. The estimated gas volumes of 38,620,000,000 BTU(37,892,707 scf)and 1,437,000,000 BTU (1,397,652 scf)for reservoirs 1 and 2 respectively were found to be substantial, to yield positive returns, but continuous charging of the reservoir through the life of the field is a cause for concern. It is presumed that the gas accumulation is generated by a regional source or a source located outside the field under study. To allow well-informed business decision, acquisition and analysis of more data from the neighboring field are recommended.Item Wavefield Separation For Shear Wave Reflections Enhancement.(Federal University of Technology, Minna, Nigeria, 2019) Raji, Wasiu O; Adeoye, Taiye, O; Ibrahim, K. O.; Harris, J. M.S-waves in borehole seismic data can provide velocity, attenuation, anisotropy and reflectivity information that are crucial for delineating reservoir geometry and fluid flow structures. Despite the success and other potential benefits of including shear waves in the interpretation of seismic data to discriminate gas related amplitude anomalies from non-hydrocarbon related amplitude anomalies, little efforts have been applied to the development of shear wave technology. S-waves processing is yet to become a routine in borehole geophysics. This paper describes a procedure and some techniques for processing shear waves in a multi-component borehole seismic data– as a precursor for S-wave reflection imaging. The procedure is divided into three key stages, namely: suppression of P-wavefield in the multi-component data; attenuation of non-reflection arrivals in the S-wavefield; and separation of S-S reflection into up-going and down-going components. A set of high resolution crosswell data acquired in a west Texas Oil field, U.S.A is used to test the method. The processed data confirmed the appropriateness of the method presented in this paper. The results yielded separated up-going and down-going S-S reflections that are traceable to the various reflectors depths. Shear wave reflection processing is a key stage in the development of shear wave technology for in oil and gas application.