Borehole instabilities are frequently encountered when drilling through finely laminated, organic rich shales, clays, or other weak rocks and should be avoided to assure a successful exploitation and safe production of the reservoir. Borehole instabilities, such as borehole breakouts or drilling induced tensile fractures, may lead to poor cementing of the borehole annulus, difficulties with recording and interpretation of geophysical logs, low directional control and in the worst case the loss of the well. If these problems are not recognized and expertly remedied, pollution of the groundwater or the emission of gases into the atmosphere can occur since the migration paths of the hydrocarbons in the subsurface are not yet fully understood.
- determination of mud window
- recommendation of mud weights
- determination of casing setting depth