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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]

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]

3D geomechanical characterization of "Fuja" field reservoirs, Niger Delta, was carried out to evaluate the mechanical properties of the reservoir rock which will assist in reducing drilling and exploitation challenges faced by operators. Bulk density, sonic, and gamma-ray logs from four wells were integrated with 3D seismic data and core data from the area to estimate the elastic and inelastic rock properties, pore pressure, total vertical stress, as well as maximum and minimum horizontal stresses within the reservoirs from empirical equations, using Petrel and Microsoft Excel software. 3D geomechanical models of these rock properties and cross-plots showing the relationship between the elastic and inelastic properties were also generated. From the results, Young's modulus, bulk modulus, bulk compressibility, shear modulus, Poisson's ratio, and unconfined compressive strength recorded average values of 5.11 GPa, 5.10 GPa, 0.023 GPa−1 , 2.39 GPa, 0.39, and 39.0 GPa, respectively, in the sand, and 6.08 GPa, 6.09 Gpa, 0.016 GPa−1 2.84 GPa, 0.42, and 42.3 GPa, respectively, in shale, implying that the sand is less elastic and ductile and will deform before the shale under similar stress conditions. Results also revealed mean pore pressures of 13,248 psi and 15,220 psi in sand and shale units, respectively, mean total vertical stress of 28,193 psi, mean maximum horizontal stress of 26,237 psi, and mean minimum horizontal stress of 21,532 psi. From the geomechanical models, the rock elastic and inelastic parameters revealed higher values around the northeastern and parts of the eastern and western portions of the reservoir implying that mechanical rock deformation will be minimal in these sections of the field compared to other sections during drilling and post-drilling activities. The generated cross-plots indicate that a relationship exists between the elastic rock properties and unconfined compressive strength. Stress estimations within the reservoirs in relation to the obtained elastic and rock strength parameters show that the reservoirs are stable. These results will be invaluable in mitigating exploration and exploitation challenges. [ABSTRACT FROM AUTHOR]

Geophysical analysis was carried out to evaluate the challenges encountered in land seismic exploration within the study area. This analysis cuts across various stages in land seismic acquisition. These stages include the following: the availability of the prospect map as originally planned by the prospect owners—the client, the desk study and planning of this map by the seismology section (planning seismologist) for acquisition convenience and the field implementation of the acquisition which the survey, drill and recording (preloading, shooting, swath move, line check, LAUX crew and recording platform) sections carried out. The challenges observed included environmental challenges, noise interference, weather conditions (statics or electrostatics interference), line break, faulty equipment, wrong detailing, cake or expired explosives, poor or compromised supervision, security and permit challenges. These challenges are peculiar to Nigeria due to inadequate implementation of policies that guide human settlements and activities. Nigeria is within the climate region where most at times it is very impossible to control natural events like cloudy weather, rainfall, thundering and lightening. As such, the problem of static charges interfering with acquired seismic data becomes inevitable, mostly during the rainy season. Almost total dependency on imported technology and lack of readily available experienced manpower also contribute to these challenges, most especially when it has to do with proper inspection of equipment and materials required for the acquisition and supervision processes. Approaches to follow to minimize the observed challenges were equally highlighted. [ABSTRACT FROM AUTHOR]