This article will demonstrate how to perform volume metric well control. There are a total of 5 steps as listed below;
Step 1 – Calculation
Three calculations must be determined before conducting volumetric well control.
1. Safety Factor (SF) – The Safety Factor (SF) in an increase in bottom hole pressure which we allow to happen naturally when gas influx migrates up with the shut in well. SF is important because it will allow the bottom hole pressure to be over formation pressure so the well is not in underbalance condition while conducting later steps. Typically, SF is around 50 – 200 psi. If the initial shut in casing pressure is very close to maximum allowable surface pressure. Personnel must select small safety factor to prevent fracturing formation.
2. Pressure Increment (PI) – It is pressure used as a working pressure while conducting Volume Metric well control. This pressure will be equal amount of hydrostatic pressure of mud bled during each step.
3. Mud Increment (MI) – It is volume of mud bled off from the annulus to reduce hydrostatic pressure by amount of Pressure Increment. It is very important that the rig must have an accurate measurement to measure small amount of mud bled from annulus. Mud Increment is determined by the following equation:
Mud Increment is in bbl.
PI is pressure increment in psi.
ACF is annular capacity factor in bbl/ft
MW is mud weight in ppg.