MudCap Drilling When? Techniques for Determining When to Switch From Conventional to Underbalanced Drilling

摘要

Throughout the planning and hazard analysis phases ofrnunconventional drilling techniques, one question continues tornarise: When is it appropriate to switch from conventionalrndrilling to underbalanced operations?rnThe one condition that must exist before choosing anrnunderbalanced operation is first encountering a need for thernapplication of the technique. That the problem cannot bernsolved using conventional, less expensive means must also berndetermined. In many fields with no historic use ofrnunderbalanced techniques, one or more attempts to solve thernproblem utilizing conventional techniques are carried out untilrnthose methods are shown to be ineffective.rnWhen the appropriate conditions have been satisfied,rnseveral other criteria exist that affect the decision to make thernswitch from conventional circulation to underbalancedrnmethods, including Safety, Economics and Logistics.rnUsing data and examples from MudCap Drilling (MCD)rnscenarios from around the world, this paper demonstrates thernprocess and techniques that have been utilized to successfullyrndetermine when the critical point has arrived to make thernswitch.rnThe development of a simple flow chart that can bernutilized at the field location in making the determination tornswitch based on satisfaction of pre-determined criteria is alsorndemonstrated.rnWork and presentations to date have concentrated onrnanswering the questions of ‘Why’ and ‘How’ to performrnvarious underbalanced operations, with very little emphasis onrn‘When’ to perform the underbalanced operation. While thisrnanswer is often self-evident, in many cases there is substantialrnleeway in determining what conditions should be present.rnThis is particularly true when the “Why” has no bearing onrnpreventing formation damage.