Definition - What does Pressure Equalization mean?
Pressure equalization, also known as cross flow, can be defined as a condition of fluid pressure equilibrium between two production zones. Pressure equalization occurs when fluid in a reservoir flows from a zone at high pressure to the zone at low pressure.
This communication happens between two production zones with different pressure characteristics. Fluids flow from the wellbore to the reservoir or from the formation to the wellbore and is commonly observed in reservoirs that have high stratification. Communication between the layers mainly occurs through wellbores.
Trenchlesspedia explains Pressure Equalization
The pressure gradient in a stratified layer initiates fluid flow from the near wellbore toward the production field. The wellbore pressure decreases due to flux into the more permeable layers. The pressure in more permeable layers may also become less than the pressure in the other layers.
The layer that is producing fluid with pressure higher than that in the wellbore will flow through the well and enter into layers having lower pressure. This phenomenon is known as pressure equalization or cross flow. Pressure equalization can be either natural or forced cross flow which may cause sand production in the wellbore due to pressure drawdown which may also be carried into the low pressure layers along with the fluid.