Detection techniques are used whilst drilling the well. They are basically used to detect an increase in pressure in the transition zone. They are based on three forms of data:
1. Drilling parameters – observing drilling parameters (e.g.ROP) and applying empirical equations to produce a term which is dependent on pore pressure.
2. Drilling mud – monitoring the effect of an overpressured zone on the mud (e.g. in temperature, influx of oil or gas).
3. Drilled cuttings – examining cuttings, trying to identify cuttings from the sealing zone.