Definition - What does Abnormal Pressure mean?
Abnormal Pressure is the fluid pressure of the reservoir pore which is different from the normal gradient pressure of saltwater. This pressure is linked with pressure which is higher than the normal pressure, the raised difficulty for well designer and raised risks of the well control problems. High pressure gradient of about ten pounds per gallon comparable to fluid density is considered to be abnormal. The pressure gradient below normal is known as subnormal. Abnormal Pressure can be found in various reservoirs which produce hydrocarbons.
Petropedia explains Abnormal Pressure
Abnormal Pressure lies either below or above the normal pressure gradient and thus can be over pressured or subnormal. The mechanism that generates the Abnormal Pressure can be complicated and can vary from one region to another. The pressure is the hydrodynamic phenomena where time has a great role. All the Abnormal Pressure occurrences have limited lifespan and are directed by a continued presence of a cause for over pressure on one hand and by efficacy of seal on the other hand. These pressures are generated under the compacted regions as the shale matrix cannot support overburdened stress.