This paper was prepared for presentation at the SPE/IADC Drilling Conference held in Amsterdam, The Netherlands, 27 February-1 March 2001.

This paper will provide a case study of the evolution of the drilling systems and techniques used to redevelop a dolomite formation located in the Indian Basin Field, Eddy County, New Mexico, USA. This study will compare data on wells drilled by Kerr-McGee over the past five years in this field where gas productivity ranges from 1000 MCFPD to 10,0000 MCFPD per well from the Upper Pennsylvanian (U. Penn) Cisco and Canyon formation.

The following drilling fluid systems utilized to drill 16 subject wells will be discussed:

Conventional. Four wells were drilled using conventional water based drilling fluids. When mud loss was encountered in the U. Penn, lost circulation materials (LCM) were used to regain and/or maintain circulation

Drilling "blind" or "dry". Two wells were drilled with this modification of the conventional system. Once returns were lost, fresh water was pumped down the drill string to keep the bit face cleaned and drilling would proceed to total depth.

Air/Mist. Three wells were drilled using this medium. A string of casing was set prior to drilling into the U. Penn. An air/mist system was then utilized to drill to total depth. The well was completed open hole.

"Aphron" drilling fluid. This method was similar to the conventional drilling operation, but the drilling fluid system was converted to an "energized air bubble" mud system prior to drilling into the main pay. A total of seven wells were drilled with this system, with more planned. With the aphron system, problems seen with cementing, logging, running casing, and completing were significantly reduced.