Petrophysical Evaluation and Reserve Estimate of the Reservoir Sands in ‘George’ Field, Offshore Niger Delta, Nigeria

Abstract

Petrophysical Evaluation of ‘George’ Field Offshore Niger Delta, Nigeria was carried out with a view to determining the hydrocarbon potential of the area. The data set used for the study includes a suite of geophysical well logs from four wells A, B, C and D.  Lithologies were identified from the gamma ray log, resistivity and the gamma ray logs were used for delineation and correlation of reservoirs across the wells. Petrophysical parameters were determined for five mapped reservoirs across the wells.  Five reservoirs AB_1, AB_2, AB_3, AB_4 and AB_5 were delineated from the well logs. The petrophysical analysis from reservoir AB_1, are: the thickness values ranging from 27-75 m, volume of shale (Vsh) 0.0041-0.15, porosity (φ) 26- 39%, permeability (k) 50- 250md, water saturation (Sw) 5.1- 64% and hydrocarbon saturation (Sh) 36- 95% . Reservoir AB_2 has a range of thickness from 28-61 m, volume of shale (Vsh) 0.038-0.14, porosity (φ) 21- 36%, permeability (k) 79- 184 md, water saturation (Sw) 7.58- 39% and hydrocarbon saturation (Sh) 61- 92%. Reservoir AB_3, has a range of volume of shale (Vsh) from 0.069-0.3, porosity (φ) 22- 35%, permeability (k) 59- 175 md, water saturation (Sw) 41- 60% and hydrocarbon saturation (Sh) 40- 59% and the thickness varied from 19-52 m. Reservoir AB_4, mapped in the four wells has range of volume of shale (Vsh) 0.065-0.11, porosity (φ) 27- 32%, permeability (k) 59- 131md, water saturation (Sw) 13- 85% and hydrocarbon saturation (Sh) 15- 87% and the thickness varied from 17-28 m. Reservoir AB_5, has a range of volume of shale (Vsh) from 0.017-0.97, porosity (φ) 25- 36%, permeability (k) 103- 178 md, water saturation (Sw) 11-54% and hydrocarbon saturation (Sh) 46- 89% and the thickness varied from 29-69 m. The results of the hydrocarbon pore volume estimation in barrels shows that the five reservoirs mapped within the George field has revealed the presence of hydrocarbon in amount that is favourable for commercial exploitation.