Volumetric Analysis of Selected Reservoirs in Ogbenu Field, Niger Delta, Nigeria Using 3D Seismic and Well Log Data

Abstract

Volumetric analysis of selected reservoirs in the Ogbenu field, Niger Delta, Nigeria was carried out using 3D seismic and well log data. The objectives include the identification and selection of suitable reservoirs, correlating the reservoirs across the field, generating synthetic seismograms and seismic-to-well ties, performing structural interpretation of faults and horizons to generate time and depth structure map, identifying potential prospects and volumetric analysis to estimate the volume of hydrocarbon in place. The adopted methodology comprises structural, petrophysical and volumetric analysis facilitated by Petrel and Techlog software suites. Well log were utilized to identify distinctive features and cross-well stratigraphic correlation which revealed complex variations, indicating a potential thickening trend in the Agbada sequence towards the southwest. Faults and horizons were mapped to establish the structural framework, unveiling a faulted rollover anticline influenced by lateral fault block movements, contributing to a complex structural style. Detailed analysis of seismic responses, synthetic seismograms, and petrophysical parameters from the well log led to the identifying and correlating of eight prospective reservoir intervals (Reservoir A to H). Average petrophysical parameters, including thickness, porosity, Not-to-Gross ratio, volume of shale, and water saturation were derived from the petrophysical analysis, confirming the eight reservoirs exhibit good petrophysical properties, indicating their potential as promising prospects. The reservoirs exhibit varying qualities, with a southward decline in reservoir quality and indications of gas-water contacts in reservoir A with a similar trend across the other reservoir units. The estimated Original Oil in Place volume were. Reservoir A (29,025.57 MMBOE), B (23.95 MMSTB), C (2,776.37 MMBOE), D (48.19 MMSTB), E (16.69 MMSTB), F (131.98 MMSTB), G (42.19 MMSTB) and H (102.60 MMSTB). This integrative approach revealed complex reservoir variations and structural intricacies, enhancing the understanding of future exploration and production strategies in the Ogbenu field.