Geosciences and Remote Sensing

Geomechanics

Geomechanics is the study of how soils and rocks deform, sometimes to fail-ure, in response to changes of stress, pressure, temperature and other envi-ronmental parameters. In the petroleum industry, geomechanics tends to focus on rocks, but the distinction becomes blurred because unconsolidated rocks can behave like soils.

Geomechanics is relatively young as a science and even younger in its application to the petroleum industry. However, it applies to nearly all aspects of petroleum extraction from exploration to production to abandonment and across all scales, from as small as the action of individual cutters on a poly-crystalline diamond compact (PDC) bit through drilling wells and perforating to as large as modeling fields and basins. Over the last 30 years, geomechanics has come to play an increasingly important role in drilling, completion and production operations. This trend continues as operators pursue oil and gas production from shales, in which mechanical anisotropy—the variation of mechanical properties with orientation—plays a vital role.

At the wellbore scale, geomechanics is central to understanding how drill bits remove rock, characterizing borehole stability, predicting the sta-bility of perforation tunnels and designing and monitoring hydraulic frac-turing stimulation programs. At the reservoir scale, geomechanics helps model fluid movement and predict how fluid removal or injection leads to changes in permeability, fluid pressure and in situ rock stresses that can have significant effects on reservoir performance. Engineers use geome-chanical modeling to predict and quantify these effects for life-of-reservoir decisions such as placing and completing new wells, enhancing and sustain-ing production, minimizing risk and making new investments.