Geomechanics and Wellbore Stability Services

Borehole images show evidence of stress related instability in the form of tension fractures and borehole breakout. These features may be quantified and used to evaluate the geological stresses and porepressure, or the mechanical properties of the rocks penetrated.

Conversely, knowledge of stress and mechanical rock properties enable the planning or design of wells which are mechanically stable.

Productivity is also related to geomechanics. The stability of boreholes or perforation cavities is related to pressure drawdown and production rate. A geomechanical analysis helps optimise production rates and completion design.

Cobra (Borehole Instability Log)

Cobra is our proprietary methodology for creating logs of mechanical properties and stresses, and to combine them with the well trajectory to make a log of borehole instability.

On a log plot track from 0 to 180 degrees of relative bearing, color-coded bands are displayed, corresponding to the sector of the borehole which is in either compressive or tensile instability, at each particular depth dependent combination of pore pressure, stress and rock properties.

Cobra is based on elastic theory (Lade and Mohr-Coulomb failure criteria). The prediction of rock strength is calibrated to test data through a multivariate procedure.