Mahakam field was experiencing gas production decline in some offshore wells. Previous interventions done in the past indicated the high probability of scale and sand which had reduced the production flow path, it had also prevented perforation gun from reaching the target depth in order to perform additional perforation to increase well potential.
Considering existing perforated reservoirs in the wells were still productive, Pertamina Hulu Mahakam (PHM) preferred to use well clean out method without invading/damaging open reservoirs. The additional cost of lost or deferred production was always unwanted. The deployment of traditional rig or coiled tubing unit to help restoring production came with considerable cost due to the equipment and personnel requirements. Consequently, PHM continually looked for new techniques to reduce this challenge. Milling on wireline, where applicable, was one solution since it could be performed in rig-less environment.
The delivery of wireline deployed milling services had been provided by conveying a specially designed milling tool which had its own built in control, power and drive section. The bit design could be customized to make the tool fit for specific application.
For a milling tool to operate properly on wireline, there were 2 physical principles that were needed to be dealt with; weight on bit (WOB) and anti-torque. To address this, wireline tractor was used.
This system fit perfectly with the context of mature field; simple, cost-effective, safe and easy to handle.