The Revolution Continues: Milling Scale on Electric Wireline  

December 2004

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 on a bailer system 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 efficiency, the Well Tractor and Well Miller were selected to remove barium sulphate build-up inside the wellbores. A total of 42 ft of barium sulphate scale was successfully removed from the two wells. The result was that the field was able to export an additional 4 million cubic ft of gas a day. Furthermore, full access to the reservoir was re-established for future operations.
 

Savings

The advantages compared to coiled tubing were palpable. All 42 ft of scale were cleared in 12 days – the same time it would have taken just to rig up/down the coiled tubing equipment offshore. Production was increased to an additional 3 million scf/day in the first well and to 1 million scf/day in the second well. Total cost of the operation was reduced by 60% to £300,000.

In addition, only half the personnel were required to do the job, which reduced human exposure to risk offshore.