GEOPHYSICAL AND GEOTECHNICAL INVESTIGATION, AND LIME STABILIZING EFFECT ON SUBGRADE FAILURE AROUND A SECTION OF LAGOS-ABEOKUTA HIGHWAY

Olurotimi Victor OJEKUNLE — 2025-12-18

An electrical resistivity survey and geotechnical investigations were employed to examine the factors responsible for incessant roadway failure along sections of the Lagos-Abeokuta highway in Southwestern Nigeria. A study on the efficacy of lime as a stabilizing agent on failed subgrade soil was also conducted. Electrical resistivity imaging and laboratory geotechnical tests with the aid of grain size analysis, Atterberg’s limits, the standard proctor compaction test, the CBR (unsoaked and soaked), and the compression test (UCS) were carried out for this study. The 2D resistivity images reveal incompetent subgrade layers with resistivity values ranging between 12– 88.3 Ω.m, and values ranging between 21.5 and 127.3 Ω.m at a depth of approximately 2 m for the VES investigation. The laboratory geotechnical tests’ results along the failed segments also reveal poor subgrade soils which are composed of clay, clayey sand, and sandy clay; with plasticity indices ranging between 29.4 and 31.5, and average values of 74.5 KN/m2 and 1.69 g/cm3 for the UCS and maximum density, respectively. However, with lime admixture to the soil samples in 2%, 4%, 6%, 8%, and 10% proportions, there was a progressive improvement in the shear strength of the clayey soil samples, owing to the reduction in the plasticity and increase in the MDD and UCS.

ENHANCED RESERVOIR CHARACTERIZATION OF PHEM FIELD, OFFSHORE NIGER DELTA: INTEGRATION OF SEISMIC ATTRIBUTES AND RESERVOIR PROPERTY MODELING

Rotimi SALAMI — 2025-12-18

This study provides a comprehensive characterization of hydrocarbon-bearing reservoirs in the Phem Field, offshore Niger Delta, integrating well logs, seismic attributes, and petrophysical modeling for enhanced exploration and production. Three key reservoirs (R-1, R-2, and R-3) were identified within the Agbada Formation, exhibiting intercalated sand and shale layers with variable thickness and significant hydrocarbon potential. Well log analyses based on gamma ray (GR), resistivity, and neutron-density (N-D) logs revealed increasing shale content with depth, aligning with the stratigraphy of the Agbada Formation. Time and depth structure maps highlighted key structural features and hydrocarbon trapping mechanisms, supported by fault-controlled anticlinal structures. Seismic attribute analysis, particularly RMS amplitude and average envelope, delineated high-amplitude zones correlating with high-porosity sands and favorable reservoir facies, providing strategic targets for exploration. Petrophysical modeling, including net-to-gross (NTG), porosity, and permeability models, confirmed superior reservoir quality in specific zones, with NTG values reaching 95% and porosity ranging from 0.12 to 0.42. Additionally, water and hydrocarbon saturation models underscored zones with strong hydrocarbon presence and minimal water content, marking promising areas for efficient hydrocarbon recovery. These integrated findings highlight the Phem Field's robust hydrocarbon potential, offering valuable insights for optimized reservoir management and future development.

GeoScience Engineering

GEOPHYSICAL AND GEOTECHNICAL INVESTIGATION, AND LIME STABILIZING EFFECT ON SUBGRADE FAILURE AROUND A SECTION OF LAGOS-ABEOKUTA HIGHWAY

ENHANCED RESERVOIR CHARACTERIZATION OF PHEM FIELD, OFFSHORE NIGER DELTA: INTEGRATION OF SEISMIC ATTRIBUTES AND RESERVOIR PROPERTY MODELING