Luciano, the use of the word "underbalance" is not appropriate...

Luciano, the use of the word "underbalance" is not appropriate in this context. None of the Mukuyu wells have been drilled underbalance because being underbalance means that the mud weight has been deliberately made less than formation pressure whilst drilling. Drilling underbalance means controlling a well whilst drilling so that hydrocarbons can be produced at surface. This method offers a way of ensuring no mud enters the formation. IVZ would not have chosen to drill underbalance because as a wildcat well the actual formation pressure was unknown.