The First Upward Swarf-less Section Mill Deployment in Asia Pacific – Save 50% Milling Duration

Abstract

Several wells in South Sumatera area have experienced with well integrity problem of high sustained casing pressure in B annulus (9 5/8” – 13 3/8” casing annulus); and required restoring well integrity of the annulus during P&A work. Barriers need to be in place to restore the well integrity. To install barrier in such condition, the annulus must be accessed by means of section milling. The section mill operation will be performed on the 9-5/8” casing and regain access to 13-3/8” casing in a particular depth interval.

There were 2 wells (Well X and Y) that were the subject to the section mill operation on 9-5/8” casing. Conventional Section Milling System was performed on well X; however, the Conventional System came with its own challenges such as, mechanical stuck pipe incident on well X which significantly increased the operation time, tons of metal swarf was returned at surface which increased the HSE risk greatly during clean up at surface and disposal and rate of milling penetration was limited by swarf handling.

In the second well Y, 9-5/8” upward swarf-less section mill system was deployed to overcome the challenges from the first well. With its Innovative upward direction section mill using left hand motor and auger assembly, the technology eliminates all swarf to surface and gives multiple added value. Firstly, it enabled 50% less time to perform section milling. Thus, the carbon emission from the operation was significantly reduced as well. Secondly, no swarf (milled casing debris) was returned to surface. Thus, it eliminated stuck BHA tendency, risk to damage surface equipment, and reduced environmental impact.

After the 9-5/8” upward swarf-less section mill had been done, operator was able to set an inflatable plug across the section-milled depth without encountering any issue, put cement column, and eliminate sustained casing pressure. 9-5/8” upward swarf-less section mill system saved 3.5 days of rig time compared to the previous section milling operation. By having this operation’s duration optimization, 4.6 tons of carbon emission was reduced.

Globally, the technology had been run 4 times since 2018 and this project allowed to bring the technology the first time in Asia Pacific in 2022.