Integration of Well Log Analysis and 3-D Seismic in Reserve Estimation of Hydrocarbon Bearing Sands in Q-Field, Niger-Delta Nigeria

Abstract

Well log analysis and 3D seismic interpretation were effectively integrated to estimate hydrocarbon reserve in Q-field, Niger-Delta, Nigeria. The study objectives were to evaluate petrophysical parameters (net-pay thickness, porosity, water saturation and volume of shale) and estimate area extent of all hydrocarbon bearing sands from subsurface mapping and seismic interpretation.The workflow procedures for analysis involved the delineation of six hydrocarbon bearing sands (A, B, C, D, E and F) and the determination of petrophysical parameters from three well logs, while the 3-D seismic interpretation involved picking of three growth faults (A, B and C) as well as three antithetic faults(D, E and F). The faults were assigned, and four different horizons were picked along the fault planes cutting through sands A, B, D and E respectively. The horizons were interpolated through series of procedures to create isomap layers and were subsequently gridded and converted to generate both time and depth structure maps.The results from well log analysis showed that Q-field had average values of 114.5 feet, 21.0%, 25.2%, and 18.0% for the net-pay thickness, porosity, water saturation and volume of shale respectively while 3-D seismic interpretation showed area estimate of 8,557.44 acres, 1,830.78 acres, 1,680.31 acres, and 2,035.17 acres for sands A, B, D and E respectively.The study concluded that Q-field bears considerable amount of about 284.852 million barrel of oil reserve which could be exploited for commercial uses at profitable rate and about 1.72 billion cubic feet of original gas in-place.