Drilling with Casing Technique Successfully Overcome Massive Thief Zone

The Lima field, located offshore in North West Java Indonesia, encountered major challenges to both drilling and cased off problematic zone during running casing operation due to severe lost circulation conditions. Specifically, severe mud losses in the major loss zone were recorded in Pre-Parigi formation. The operator has experienced massive loss problems while drilling the 8-1/2 inch section. Unsuccessful sidetracking operations with conventional drilling technique has urged operator to look for alternative drilling methods to case off the massive thief zone. The drilling with casing system has been identified as one drilling technique that may repairthe troublesome thief zone. This non-retrievable system, which utilizes casing as drill string, allows the string to immediately be cemented in place once targeted depth is achieved, hence eliminating the risk of casing tripping failure through massive lose zone with conventional drilling method. The special designed aluminum crown casing bit is drillable by subsequent section conventional bit without additional clean out trip. This paper will discuss the planning, implementation and finally the results of 7 inch drilling with casing technique through the problematic Pre-Parigi lost circulation zone.