Underbalanced drilling increases deliverability from gas storage wells

Kinder Morgan, Inc. implemented a drilling program in 2003 to compare the deliverability from gas storage wells, between tubing-conveyed drilling (TC) and underbalanced drilling (UD). Nine conventional TC perforated well with 8 3/4-in. hole was drilled from the surface casing shoe through the reservoir, using a Bentonite mud with low fluid loss and low solid content. Eight underbalanced wells were drilled just above the top of the reservoir, and 7-in. casing was set and cemented. The UB wells delivered O.54 MMcfd/ft, about 50% better than the conventional TC wells.