Milling scale on electric wireline

Downhole hardware
CLE.OFF.ABZ.10.04.V1 Milling scale on electric wireline - Well Intervention  - Welltec
  • Increased production: Additional four million cubic ft of gas/day
  • Time savings: 23 days
  • Costs: Reduced by 60%
  • Required crew: Reduced from 23 to 11 people


Offshore UK, it was found that 2/3 of a perforated interval was obstructed by sand/scale fill. Conventional wireline bailing had been attempted but without success. The operator then approached Welltec® and worked closely together to implement a new system for removing debris from the well bore utilizing an auger powered by the Well Tractor® motor. The operation took place in December 2004 and was the first time such technology was used in the UK North Sea. It was also the world’s first application of milling scale on electric wireline in a gas well.


Due to superior efficiency, the Well Tractor and Well Miller® were selected to remove barium sulfate build-up inside the wellbores. Extensive testing before mobilization led to two mill sizes being chosen: 3.8” to open up through the scale and 4.2” run to give the required final ID.

A total of 42 ft of barium sulfate scale was successfully removed from two wells in 12 days – the same time it would have taken just to rig up/down the coiled tubing equipment offshore.


Full access to the reservoir was re-established for future operations and the operation eliminated heavy lift requirements.