http://196.220.128.81:8080/xmlui/handle/123456789/185 Mon, 06 Apr 2026 10:28:52 GMT 2026-04-06T10:28:52Z http://196.220.128.81:8080/xmlui/handle/123456789/5632 AQUIFER VULNERABILITY STUDY IN THE VICINITY OF SOME SELECTED DUMPSITES IN ITAOGBOLU, SOUTHWESTERN NIGERIA JAYEOBA, OLUSANYA The aquifer vulnerability to contamination risk may increase daily due to continuous dumping of waste in an area within a typical Basement Complex terrain of Itaogbolu in Ondo State, southwestern Nigeria. The aim of the research is to develop a composite aquifer vulnerability map around some selected dumpsites within the area using a modified ‘DRASTIC’ (DRASTIC-L) model. DRASTIC model accounts for seven aquifer parameters namely, depth to water table, net recharge, aquifer media, soil media, impact of vadose zone and hydraulic conductivity. However, the modified DRASTIC (DRASTIC-L) incorporates land use as additional input parameter and the analysis was performed using ArcGIS software to prepare a vulnerability map of the study area. Data from Vertical Electrical Soundings (VES), remote sensing and hydrogeology were used for the eight parameters. The VES involved fifty six (56) depth soundings using Schlumberger array, with half maximum current electrode separation (AB/2) of 65 m. The remotely sensed parameters were extracted using LANDSAT 7 Enhanced Thematic Mapper Plus (EMT+) and Digital Elevation Model (DEM). The DRASTIC-L Vulnerability Index (DVI) was calculated as the sum of product of ratings and weights assigned to each of the parameter on the scale of 1 to 10 and 1 to 5 respectively. Using the produced vulnerability index, the area was classified into five classes; very high, high, medium, low and very low vulnerability zones. The research revealed that, part of the dumpsites falls within the high vulnerable zone; hence the groundwater within the area may be under the threat of contamination from the leachate products of the dumpsites. Using the chemical analysis of water samples within the classified zones to validate the model, the modified DRASTIC-L shows a reliable accuracy of 76%. M.Tech. Sat, 01 Apr 2023 00:00:00 GMT http://196.220.128.81:8080/xmlui/handle/123456789/5632 2023-04-01T00:00:00Z http://196.220.128.81:8080/xmlui/handle/123456789/5631 INTEGRATION OF ROCK PHYSICS AND SEISMIC INVERSION FOR LITHOFACIES DFERENTIATION AND RESERVOIR FLUID PREDICTION OF “AA” FIELD, NIGER-DELTA ADEKUNLE, ABIOLA Integrated approach of rock physics and seismic inversion analysis were ultilised in enhancing lithology and fluid differentiation in “AA” field, offshore Niger Delta. The data set used for the study includes prestack seismic and a suite of well logs from two wells. Rock physics concepts were utilised to understand the sand and fluid trend from background trends. Seismic inversion was ultilised to unravel the elastic responses of the sand saturated with the fluid and that of non-hydrocarbon bearing. Computation of reservoir properties from well log data using well-established equations was also executed. Two horizons were identified and mapped from seismic sections using seismic attributes such as amplitude and reflection geometry. The petrophysical parameters of the two reservoirs (RES-1 and RES-2) were also estimated to evaluate the quality of reservoirs. RES-1 has average volume of shale of 15%, effective porosity 29% and permeability of 755 mD while RES-2 has average volume of shale of 23%, effective porosity of 24% and permeability 589 mD. Rock physics diagnostics was carried out for quantitative analysis of lithologies and fluids. The crossplots analyzed classify the study area into hydrocarbon sands, brine and shale based on large separation between the gas sand and background trend. Simultaneous inversion revealed that the elastic parameters at the zone of interest are low compare to the surrounding rocks indicating low compressional wave velocity, low shear wave velocity, low density and low impedances in the two reservoirs. These responses showed that the reservoirs are gas saturated. Integration of rock physics and seismic inversion has added another dimension in the differentiation of lithologies and different fluids within the hydrocarbon bearing sands and also helped in characterizing the study field. M.Tech. Sat, 01 Apr 2023 00:00:00 GMT http://196.220.128.81:8080/xmlui/handle/123456789/5631 2023-04-01T00:00:00Z http://196.220.128.81:8080/xmlui/handle/123456789/5626 INTEGRATING ATTRIBUTE ANALYSIS AND STRUCTURAL MODELLING FOR EVALUATION OF THE HYDROCARBON POTENTIAL OF ‘BA’ FIELD, NIGER DELTA OBATA, TEMILOLUWA LOUIS 3D seismic and well log data have been used to map the stratigraphy and hydrocarbon potential of an offshore field in Niger Delta. This environment is a high risk environment characterized by complex geologic structures and low sand to shale ratio. The data base comprised 3D seismic lines, borehole logs from five wells and checkshot survey. Lithology interpretation was done using gamma ray log and hydrocarbon bearing reservoirs were mapped using a combination of gamma ray and deep resistivity logs. Well log correlation was carried out using similarity in log signatures. Computation of petrophysical parameters such as net to gross, volume of shale, porosity, permeability and hydrocarbon saturation was done using standard equations. Identification and mapping of network of faults was carried out on the basis of amplitude, reflection geometry and frequency. Seismic attributes such as variance edge, root mean square, minimum and maximum amplitudes were also utilized to compliment structural interpretation. Two horizons located at a time window ranging from 3 to 4 milliseconds were picked on the basis of prospectivity, event strength and continuity. Reservoir properties modelling were also carried out to evaluate the spatial distribution of facies and their effects on reserves estimation and hydrocarbon production. Uncertainty evaluation using deterministic and probability were analysed to reduce risk in oil and gas production. The stratigraphy is composed of alternating sands and shale units. The reservoirs located at a depth interval of 2.4 to 3.0m have average effective porosity of 32%, volume of shale 10%, net to gross 80%, hydrocarbon saturation 87% and permeability 1100 mD. Well correlation panel depicted the general stratigraphy, lateral and vertical extent of the reservoir units. The probable structure harboring oil and gas is a faulted anticline. The reserves of gas for reservoirs 1 and 2 are 1.4*10^6 and 1.8*10^6 MSCF. Integration of seismic structural analysis and reservoir facies modelling has contributed immensely in revealing structural complexities and economic potentials of the field with a view to reducing risk and enhancing future field development. M.Tech. Mon, 01 Aug 2022 00:00:00 GMT http://196.220.128.81:8080/xmlui/handle/123456789/5626 2022-08-01T00:00:00Z http://196.220.128.81:8080/xmlui/handle/123456789/5625 SEQUENCE STRATIGRAPHY AND SEISMIC ATTRIBUTES ANALYSIS FOR HYDROCARBON POTENTIAL EVALUATION OF “JONES” FIELD, NIGER DELTA JONES, ABIODUN Seismic attributes and sequence stratigraphy have been used to characterized hydrocarbon bearing reservoir in a field, offshore Niger Delta. Hydrocarbon and non-hydrocarbon bearing sands were identified from gamma ray and resistivity log responses. Well log chronostratigraphic correlation was done using the principle of similarities in log responses and time stratigraphic surfaces. Log sequence evaluation was done by the analysis of log amplitude and stacking patterns of facies succession. Computation of petrophysical properties of reservoir rocks was executed using well established equations. Identification and mapping of network of faulting using seismic attributes such as amplitude and reflection geometry was carried out. Seismic sequence analysis using reflection terminations was used for the mapping of three depositional sequences on the basis of reflection character analysis. The general stratigraphy is alternation of sands and shales typical of Agbada Formation. Average petrophysical properties of the three reservoirs mapped include: net-to-gross sand thickness of 0.78, volume of shale 15%, porosity 21%, water saturation 43%, hydrocarbon saturation 57% and permeability 405 mD Typical seismic facies associated with the mapped sequences include; parallel, parallel/sub-parallel, divergent/convergent and chaotic. This arrangement of facies connote sand-shale interbedding within a low to high energy depositional environment. The probable structure harboring oil and gas is faulted and unfaulted anticlines. Amplitude maps analysis showed that structural highs coincided with zones of thick sediment accumulation. The depositional environment deduced from seismic and well logs ranges from delta plain, shelf and slope respectively. M.Tech. Wed, 01 Mar 2023 00:00:00 GMT http://196.220.128.81:8080/xmlui/handle/123456789/5625 2023-03-01T00:00:00Z