What are problems caused by abnormal fluid pressure in an oil field?

please list me the problems that are made by pore and fracture pressures during exploration and drilling of an oil reservoir?What are problems caused by abnormal fluid pressure in an oil field?
Its not a huge problem if you know beforehand that you will be drilling into an over pressured zone, you simply increase your drilling fluid (mud) density such that the pressure the mud exerts is greater than the reservoir pressure. If you do not know this and drill into an over pressured zone you will take a kick, (The well will begin to flow) depending on how much of the hole is already cased will determine how much pressure you can control on the surface with the blow out preventors, in 99% of the cases you will be able to control the well, mix drilling mud to the right density and slowly gain control. If you are unable to gain control you will have a blow out, when this happens whether its oil or gas the drilling rig will usually catch on fire and will be destroyed, there is potential for loss of life. If the gas is sour the drilling supervisor has a flare gun and once the men are safely off the rig he has to set the rig on fire to prevent the sour gas from escaping. (its highly poisonous)What are problems caused by abnormal fluid pressure in an oil field?
Abnormal Pressure is a very typical term being used in Oil field.


This essentially mean ';High Formation Pressure';. If not controlled (there are ways to control it during drilling), there is a ';kick';, or a disastrous ';blow out';.
The main problem that I see is the potential for a blowout if your drilling mud weight is too low. The pore pressure in the fromation will seek the easiest route to relieve pressure, this could cause a blow out as mud and gas escape up the borehole and could injure your drillers and crew, as well as machinery, and crete a possible spill (if you are drilling off shore for instance, you could have a release to the ocean).