Dynamic Effective Stress Coefficient: Results and Issues

Pore pressure prediction from seismic data is of paramount importance in oil exploration and production. During the exploration phase, seismic data may be used to access potential abnormal pore pressure regions, often known as geopressure zones. On the development phase, along the lifetime of a field, it is desirable to know the location of pressure barriers, in order to plan new injector wells. The estimation of pore pressure from seismic is usually based on the behavior of compressional-wave velocity or impedance with stress. This paper discusses the concept of effective stress, often misused on velocity to pressure transforms, and presents some experimental estimative of the effective stress coefficients. Some practical caveats on the measurement technique are also illustrated through the use of an idealized synthetic experiment.