Geological Hazards

Studying a stress section with a planned well trajectory and a pressure-depth graph (PDG of that well), the geophysicist can mark potentially active faults which are best traversed perpendicularly by the wellbore (above left, B, rather than vertically, A). The geologist can relate areas of high stress and fault planes likely to be fractured or prone to sloughing to zones of mud loss in adjacent wells, plus overpressure, etc. This allows the well planning engineer to possibly redesign the well trajectory and inclination in the early stages of planning, keeping in mind that not all exploration wells have to be vertical, ie, B rather than A.


These trouble spots can be noted and plotted on the PDG using the TVDSS linear scale (centre), and the sub-horizontal sections can better displayed using MDSS plotted linearly.


Every well, no matter how simple it is expected to drill, should have a PDG run to check for unexpected or potential geological variables which only 3D or close spaced 2D seismic and resulting stresses can detect, so that in case of the unexpected, like a forced sidetrack, the stresses are on-hand to best solve these time wasting issues quickly.