Petroleum Geomechanics: From the Plate-Scale to the Reservoir-Scale

The last 10-15 years have seen an explosion in the application of present-day stress data to petroleum exploration and development-related issues. Borehole breakouts, zones of wellbore where the cross-sectional shape is enlarged and elliptical, were first-named and recognised as being due to present-day stresses in the late 1970s (Figure 1). However, even by the early 1990s, few in the oil industry were familiar with borehole breakouts. Now they are used routinely, along with other present-day stress data, to<br>○ evaluate fault reactivation and reservoir seals; ○ evaluate naturally fractured reservoirs; ○ assess wellbore stability, and; ○ plan fracture stimulation and water flooding operations. This talk will illustrate how the reservoir geomechanical model (present-day stress and strength data) is determined using logging and drilling data. It will discuss the plate-scale, regional and local tectonic controls on present-day stress with examples from Brunei and the North Sea. Finally it will illustrate the application of the geomechanical model to exploration and development, with examples from Brunei and the North Sea.