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This study investigates the weathered layer parameters of the Gbaran (OML 28) field in the Niger Delta using uphole refraction. 57 boreholes were bored and logged to study stratum components and characteristics. Weathered layer thickness ranges from 15.1m to 4.3m, with an average unconsolidated layer thickness of 6.9105m. Most of the unconsolidated stratum is silt or clay. This stratum has seismic wave velocities from 299 to 997m/s, averaging 697.14m/s. Consolidated stratum velocities average 1742.58m/s, ranging from 1551 to 1925. Subsurface refraction surveys were conducted at numerous locations, drilling and logging 57 boreholes. The acquisition plan included flushing drilling, cut lithology sampling, and logging from 0 to 60 metres. The velocities and thicknesses measured for each uphole site distinguish worn and cemented layers. Weathered layer thickness shows geological formation-influenced variations. Weathered layer velocity is 299-997m/s lower than consolidated layer velocity. Consolidated layer velocity is 1551-1925 m/s. Weathered layer thickness, velocity, and consolidated layer velocity are examined, focusing on thickness-velocity relationships. The recommendations include foundation design, construction methods, water management, geotechnical research, seismic design, monitoring, and geotechnical specialist coordination. Seismic refraction surveys can characterize underlying material variations and aid engineering design and risk assessment in the Niger Delta's dynamic geology. [ABSTRACT FROM AUTHOR]

In order to interpret the airborne magnetic data and to evaluate the approximate location, depth, and geometry of the magnetic sources within Obudu area using standard Euler deconvolution method, high resolution aeromagnetic data over the area was processed digitally and analyzed using Oasis Montaj 8.5 software. Data analysis and enhancement techniques including reduction to equator, horizontal derivative, first and second vertical derivatives, upward continuation and regional-residual separation were carried out. Standard Euler deconvolution for structural indices of 0, 1, 2, and 3 were obtained. Results show that the total magnetic intensity ranges from -122.9nT to 147.0nT, regional intensity varies between -106.9nT to 137.0nT, while residual intensity ranges between -51.5nT to 44.9nT indicating the masking effect of deep-seated structures over surface and shallow subsurface materials. Results also show that the positive residual anomalies have a NE-SW orientation which coincides with the trend of major geologic structures in the area. Euler deconvolution for all the structural indices has depth to magnetic sources ranging from <0m to >2000m. Interpretation of the various structural indices revealed the locations and depths of the source bodies and the existence of geologic models including sills, dykes, pipes, and spherical structures. This area is characterized by shallow basement materials and represents a good prospect for solid mineral exploration. [ABSTRACT FROM AUTHOR]

The geomechanical characterization of the reservoirs of "Beta Field" was carried out to predict the stability of hydrocarbon reservoir rocks and hence, mitigate drilling and exploitation challenges within offshore Niger Delta. Gamma ray, sonic, and density logs from four wells within the field, including core data and 3D reflection seismic volume from the area, were integrated to determine rock mechanical and petrophysical properties from empirical equations, and generate 3D geomechanical models using Petrel and Ms-Excel software. Principal stresses operating within the reservoirs and pore pressure were also estimated from empirical models. Cross plots of these rock parameters were obtained to ascertain the relationship between them and obtain model equations. Results show that the rock mechanical properties have lower values in sand units than shale units with petrophysical parameters having lower values in shale. Average values of 13.70GPa, 0.33, 13.30GPa, 32.32GPa, 5.12GPa, 0.07, and 0.022mD were obtained in shale; while 0.30, 10.94GPa, 0.30, 12.76GPa, 25.19GPa, 4.11GPa, 0.19, and 192.00mD were recorded in sand for Young's modulus, Poisson ratio, bulk modulus, uniaxial compressive strength, shear modulus, effective porosity, and permeability respectively. Mean pore pressures observed in sand and shale units are 13,683psi and 15,662psi while mean total vertical stress, maximum and minimum horizontal stresses recorded in the reservoirs are 28,392psi, 25,537psi and 20,781psi respectively. Comparative analysis of obtained rock mechanical and strength parameters with the principal stresses operating within the reservoirs show that the studied reservoirs and by extension reservoirs of this petroleum play are stable. [ABSTRACT FROM AUTHOR]