Reservoir evaluation of “T-X” field (Onshore, Niger delta) from well log petrophysical analysis

Abstract

Three wells A1, A2 and A3 were identified on the ‘T-X’ field in onshore Niger Delta. A comprehensive petrophysical analysis on one of the wells (well A1) was carried out in order to come up with physical properties such as shale volume, porosity (Φ),   permeability (K), fluid saturation, and net pay thickness, among others for future development planned of the oil field. A well log  data from this field have been  examined and analyzed. The logs include gamma ray (used for the identification of lithology),  resistivity and porosity logs (used for delineating hydrocarbon bearing reservoirs). Wireline log analysis was employed in the characterization of the  reservoirs in the well studied; the hydrocarbon sands were delineated by the use of gamma ray, resistivity and density/neutron from which the reservoir quality were determined. Fluid types defined in the reservoirs on the basis of  neutron/density log signatures were basically water, oil and gas.Eighteen (18) reservoirs (AR1 to AR18) were identified, among which twelve (12) are hydrocarbon-bearing reservoirs. Permeability and porosity values range between 1-6206md and 6-28%  respectively. Water saturation recorded between 15-100% in the identified  reservoirs which indicated that the proportion of void spaces occupied by water varied from low to high values, thus, indicating both low and high hydrocarbon saturation. Plot of  hydrocarbon saturation and porosity showed a linear trend and strong linear relationships between permeability and porosity was also observed in all the reservoirs identified indicating that they are permeable and have pores that are strongly interconnected. This study has really demonstrated that petrophysics has a vital role to play in reservoirs characterization.

Keywords: Reservoir sands, petrophysical properties, reservoir quality, Lithology and Wireline logs.