STRUCTURAL FRAMEWORK AND HYDROCARBON POTENTIAL OF THE AGBOMA FIELD, ONSHORE NIGER DELTA BASIN, NIGERIA.

Abstract

This study presents an integration of seismic attributes and petrophysical analysis for the re-evaluation of the hydrocarbon potential of the Agboma Field, Onshore Niger Delta Basin, using 3-D seismic reflection data and a suite of geophysical well-logs. The Agboma Field has experienced a steady decline in hydrocarbon production at an average of 42% over the last five years. Understanding the trapping mechanisms, reservoirs’ vertical and lateral extent, quality and connectivity within the Agboma Field forms the basis for this research. The methods employed include lithofacies and petrophysical analysis of the well-logs, seismic-to-well tie, volume and surface attribute analysis, fault and horizon mapping, layer cake velocity model, time-depth conversion and prospect evaluation. The lithofacies analysis and correlation of the delineated facies show that the reservoirs vary in thickness and are laterally continuous across the field. Four hydrocarbon-bearing reservoirs named AMR-1, AMR-2, AMR-3, and AMR-4; and one prospect reservoir named AM-Prospect reservoir which is the major contribution of this study were identified and correlated. Petrophysical analysis indicates that the sandstones generally have excellent reservoir quality with an average effective porosity of 26% permeability of 715 mD and hydrocarbon saturation of 74%. The AM-Prospect reservoir has a net-to-gross of 100% and is commercially viable for increased oil production within the Agboma Field with Stuck Tank Oil Initial In Place (STOIIP) of 341 MMSTB and 362 MMSTB for AM Prospect 1a and 1b respectively. The structural interpretation shows that the Agboma Field is characterized by four down-to-basin normal faults that compartmentalized the field into four blocks labelled blocks A to D. The reservoir structural map document fault-dependent and rollover anticlinal structural closures that show high RMS amplitudes conforming to structures in the undrilled blocks B and C and interpreted as AM Prospect 1a and 1b. The results of this studydemonstrate the importance of integrating petrophysics, seismic attributes and structural framework analysis in evaluating oldhydrocarbon-producingg fields for increased hydrocarbon production.