Pressure measurements and fluid sampling

A common objective of a data gathering programme is the acquisition of fluid samples. The detailed composition of oil, gas and water is to some degree reguired by almost every discipline involved in field development and production. 

The pressure measurment and fluid sampling procedures can be repealed at multiple depths in the reservoir. 

In some cases when drilling fluids invade a very low permeability zone, pressure equalisation in the formation can take a considerable time. The pressure recorded by the tool will then be close to the pressure of the mud and much higher than the true formation pressure. This is known as supercharging. Supercharging pressures indicate tight formation, but are not useful in establishing the true fluid pressure gradient. 

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