A Model of Pore Pressure and Effective Stress Changes During Hydrocarbon Depletion by Slowness Integrated Data Analysis

This paper focus on the use of slowness data analysis to identify and characterize the pore pressure and effective stress changes during oil field production, since the pore pressure estimation plays an important role in oil and gas industry. Pore pressure estimation is included in substantial prerequisite before taking a major step to start drilling, production or recovering a well. Moreover, the precise pore pressure estimation will determine the safety, profits and success in both production and recovery. To accomplish the objective of this study, the methodology consists of several broad stages. It dealt with field mapping to create stratigraphy model, coring/sampling, velocity measurement with saturations and pressures (i.e. pore and confining) variations, velocity analysis for constructing the empirical equation of pressure, saturation and pore pressure relationship in each facies, pore pressure and effective stress changes estimation model from interval velocity and transit time analysis. The pore pressure and effective stress changes model was established for characterizing the changes in pore pressure and effective stress due to hydrocarbon production. Variation in fluid saturation was considered to hydrocarbon production scenarios. During the reservoir production, the fluid flows out leading to a reduction in pore pressure. This reduction produced slowing seismic velocities and inversely to effective stress. The characterization of pore pressure and effective stress changes due to changes in fluids saturation linked to velocity anomalies can be useful in monitoring hydrocarbon production.