Flow show

• If a high pressure zone is drilled and overcomes the hydrostatic pressure of the column of drilling fluid, the fluid or gas in the high-pressure zone will begin to enter the borehole and increase the amount of fluid coming out of the hole. By monitoring the flow, rig personnel will know in advance before the flow becomes critical.
• If a low pressure zone is drilled and is overcome by the hydrostatic pressure of the column of drilling fluid, the low pressure zone may begin to take fluid and decrease the amount of fluid coming out of the hole. By monitoring the flow, rig personnel will know in advance before losing too much drilling fluid down the hole and/or losing so much fluid that the hydrostatic pressure of the column of mud becomes so low that a blowout situation becomes imminent.