Gas present in the mud circulating system when the bit is off-bottom and there is no vertical movement of the drill string. ... For this condition to occur, the contributing formation must be underbalanced by the mud system at some point within theanbsp;...
|Title||:||Development Geology Reference Manual|
|Author||:||Diana Morton-Thompson, Arnold M. Woods|
|Publisher||:||AAPG - 1993-01-01|