Drilling Risk Reduction

Earth stresses dictating a uniform stress state across an exploration wellbore are generally only possible in shallow, essentially hydrostatic conditions. Stress differences increase with depth in most basins (left). Maintaining directions of uniform stress across a wellbore can be achieved in most inclined and horizontal wellbores by knowing SHmax Direction (SHD) and Magnitude (SHM), in other words the stress state, in the planning stage. These accurate, quantified, ideal stress conditions can be obtained from ubiquitously available 3D or close-spaced 2D reflection seismic, pre-drill.


Wellbore stability issues such as breakout and pack-off prediction are controlled by both parts of geomechanics (i) Earth stresses acting on (ii) rocks of varying physical properties. PSI provides (i) and (ii) is widely available in the industry. On wildcats, (i) can be provided without any offset wellbore information, and (ii) in that case provides the only need for otherwise unavoidable uncertainty.


In highly stressed environments, strong Earth shear can be a source of failures at multilateral junctions and along the wellbore. Similar stability problems around sidetracks can be reduced if there is flexibility with the location of the kick-off point acquired from knowing the stress conditions at the time of the sidetrack.


PSI recently published a technical article on PESA Technical News, dealing with stress from seismic. For a pdf of this article please use the link below:

Stress from Seismic