Enhanced Prediction of Wellbore Stability Using Seismic-Based Geomechanical Modeling

Abstract

TX 75083-3836 U.S.A., fax 01-972-952-9435. AbstractThe set of geologic medium parameters controlling wellbore stability includes minimum and maximum horizontal stresses, pore and fracture pressure, and intensity of natural fracturing. In this paper, we demonstrate the use of 3D seismic data for mapping these parameters related to certain depth interval. In our approach, the transfer from seismic data to the set of parameters above is carried out using geomechanical modeling. In contrast to routine techniques stemming from elastic Earth model, the mechanical model we use is based on the poroelastic Biot's theory for saturated porous rocks with elements of plasticity included to predict pore pressure and fracture pressure. Respectively, in addition to seismic velocity, the input data for the modeling includes a series of petrophysical and mechanical properties such as the rock density, porosity, permeability, the Poisson ratio, rock cohesiveness, angle of internal friction, and sometimes, the dilatancy angle. The combined use of seismic and petrophysical data provides for a more accurate prediction of stresses, pressures and fracturing as compared to traditional approaches. Hence, a more accurate conclusion on the expected stability of a wellbore with a particular trajectory at each particular site and each particular depth interval can be derived from the modeling results.