TRANSITION ZONES ANALYSIS USING EMPIRICAL CAPILLARY PRESSURE MODEL FROM WELL AND 3D SEISMIC DATA, ‘STEPHS FIELD’, NIGER DELTA

Abstract

The analysis of transition zones using empirical capillary pressure from well and 3D seismic data, ‘Stephs field’ Niger Delta has been carried out. The aim of this study is to analyze the reservoir transition zones to remove the effect of mobile water above the oil-water contact using Goda empirical capillary pressure model in the absence of core data/information. Potential reservoirs were delineated and petrophysical parameters computed from well logs. Geological structure (fault) were mapped on the seismic section. Horizons were mapped and time structure maps were generated. Checkshot data was used to tie the well to the seismic section and to convert the time structure map to its depth equivalent. Reservoir properties were modelled using Sequential Gaussain Indicator (SIS) and Sequential Gaussian Simulation (SGS). Capillary pressure curves were generated. Three reservoirs (RES B, C and E) were utilized for this study with Net thicknesses ranging from 194.14 m to 304.89. The effective porosity within the reservoirs ranges from 10 to 30% and the permeability ranges from 100 to >1000 mD which is an important characteristics of good hydrocarbon bearing zone A total of 6 faults were mapped, 3 major growth faults (F1, F4 and F5) and 3 minor faults cut across the entire area. The capillary pressure log, curves and models generated was useful in identifying the impact of mobile water in the reservoir. The volume of oil estimated without taking transition zone into consideration was found to be higher at 273*106, 406*106 and 732*106 mmbbls than the volume of oil estimated while taking transition zone into account 242*106, 256*106 and 641*106 mmbbls for reservoir B, C and E. These results indicate the presence of mobile water. These has further establish that conventionally, recoverable hydrocarbon is usually overestimated, hence, the need to perform transition zones analysis for enhance hydrocarbon recoverable for cost-effective extraction and profit maximization.