3D Geomechanical reservoir model for Appraisal and Development of Emi-003 field In Niger Delta, Nigeria

Abstract

In this paper, geomechanical parameters were effectively integrated in 3-D geostatic model of Emi-003 reservoir in the Niger Delta basin, Nigeria for deformability and rock strength appraisal using well logs and 3D seismic volume. Unconsolidated sandstone and compacted shale were delineated and evaluated by determined elastic moduli (Poisson ratio, Young modulus, Bulk modulus, Shear modulus and Compressibility) and the Unconfined compressive strength (UCS) using sonic logs and petrophysical analysis, correlations and cross plots for comparison of the evaluated reservoir strength, physical properties (such as modulus, porosity, velocity) of the five mapped zones from five vertical wells in the studied reservoir for validation were done. Finally, incorporation of elastic properties, unconfined compressive strength in 3D static model of the studied reservoir was carried out to capture strong lateral variance of rock elastic moduli and strength into areas where well control may not exist. especially off the well points. The results show average parameters of the weakly cemented sand to have lower Poisson ratio, Young, Bulk, Shear modulus and Unconfined compressive strength (0.27, 2.3GPa, 10.8GPa, 6.91GPa, 14.21MPa respectively,) high compressibility and porosity (0.13 GPa-1, 0.26) conversely the compacted shale have higher Poisson ratio, Young, Bulk, Shear modulus and rock strength as (0.36, 8.91GPa, 18.05GPa, 21.09GPa, 56.44MPa respectively) lower compressibility and porosity (0.05 GPa-1, 0.05 respectively). There is a marked increase of rock strength and elastic moduli with relative decrease in porosity. The mechanical failure in the NNW direction of the reservoir will be relatively lower than other areas as analyse using the 3D earth model. The information gathered will help manage reservoir stress and strain induced during development and maximize reservoir performance, while mitigating risk.