DRILLING MUD EVALUATION OF SOUTHWEST QUEENSLAND WELLS

Abstract

One of the primary functions of a drilling fluid is to provide suitable conditions for the safe and effective evaluation of the wellbore. Current drilling fluid evaluation techniques rarely include the costs of poor or inconclusive well evaluation or other mud related costs such as rig time lost due to hole problems and additional cement required for washed out hole.

In a study of 17 exploration and appraisal wells drilled in southwest Queensland, inclusion of all measurable mud related costs radically changed previously held beliefs on mud system cost effectiveness. The study showed a cost advantage of approximately 30 per cent when using KCI-polymer over wells drilled with gellignosulphonate. Mud product consumption cost was shown to be only part of what must be considered when evaluating the overall cost effectiveness of a drilling fluid. Evaluation of a mud system was shown to require a detailed analysis of all drilling and evaluation problems encountered during the course of drilling a well.