In offshore Malaysia, the use of coiled tubing (CT) e-line has become a viable alternative to perforate new wells as it eliminates the use of an expensive offshore drilling rig for the completion process. The CT can convey long gun strings in horizontal completions in a single run, while creating the necessary underbalanced conditions.
As the field development evolved, it required drilling complex extended reach wells (ERW) to access reservoirs farther from existing platforms, imposing more difficulties for the operation. The CT is predicted to lock up before reaching the target depth in some of the new wells. In addition, operational inefficiencies in past campaigns were common, primarily due to the design of CT e-line equipment used. Occasionally, the disconnect tool was actuated accidently due to sensitivity to pumping flow rates.
A solution based on the combination of a hydraulically actuated CT wired tractor and a new CT e-line head design with unique features was proposed and implemented during a recent perforating campaign. In this solution, the tractor provided the force necessary to overcome the CT lockup and conveyed the guns to total depth (TD). Unlike most CT e-line head designs, the one used had the ability to circulate fluids through the assembly down to the CT tractor, enabling its actuation. The technical solution, field experience and results are presented.
The perforating campaign included six highly deviated wells and two highly ERW [TD to true vertical depth (TVD) ratio of 3:1] for which the CT wired tractor was needed. All wells were successfully perforated under balance, with no observed sand production. The longest gun string conveyed to TD was 597 ft in length. Zero incidents were recorded in a total of 16 runs, in spite of the limited field test status of the CT e-line head design.
This is the first recorded use of a CT e-line application with CT wired tractor for perforating purposes in ERW. Thus, the operational envelope of CT e-line applications is expanded, addressing the intervention needs of the future field development plans based on the ERW design in the area.