Chapter 16
Wellbore Imaging Technologies Applied to Reservoir Geomechanics and Environmental Engineering

Colleen A. Barton
GeoMechanics International, Inc.
Palo Alto, California, U.S.A.

Mark D. Zoback
Stanford University
Department of Geophysics
Stanford, California, U.S.A.

ABSTRACT

Drilling-induced wellbore failures provide critical constraints on the in-situ state of stress. Knowledge of the relationship between natural fracture systems and tectonic stresses has direct application to problems of reservoir performance, fluid migration, and wellbore stability. Acoustic, electrical, and optical wellbore images provide the means to detect and characterize natural fracture systems and to discriminate these from induced wellbore failures. New techniques of wellbore-image analysis are presented to distinguish attributes of natural fractures from induced failures in borehole-image data. The performance of low-permeability fractured reservoirs is controlled by the in-situ state of stress and by the distribution and orientation of natural fractures and faults. We discuss case studies of the relationships among natural fracture systems, in-situ stress, and permeability. These case studies involve geothermal reservoirs and a petroleum reservoir; one case study involves geotechnical site characterization.