CASE STUDY

Shadow Plug Milling

Shadow Plug Milling; TVD: 3,200m; MD: 6,500m

  • DURATION

    14 days of engineering and pre-job planning; 17 wells completed in 8 months.

  • THE SITUATION

    A major oil company operating in the Duvernay Shale had plug and perf completed a field with Baker Shadow plugs; a plug that was intended to eliminate well interventions to produce. Plugs were made of 4140 steel with an ID of 1.9” once the ball had dissolved. The plugs failed to dissolve and were sanding off. After months of attempting to mill the plugs with coil tubing, limited results were achieved due to lack of weight on the bit.

  • THE SOLUTION

    Piston was contacted. Due to limited weight on the bit on long laterals, rotation of pipe was required. Piston supplied a 285K hydraulic workover unit with a HALO drilling system. BHA’s were a basic design, and a slow rotation while applying more weight would provide better results than coil tubing units. A 3.701 mill, 3 string magnets, 2 12K BPV’s with nipples on bottom and 3,100m up-hole as well as a 2-3/8 s135 double shouldered connection was used. Drilling parameters of 2 to 4 DaN W.O.B. with RPM between 120 and 160 was used. Pason data acquisition was used for monitoring pump rates, W.O.B., RPM, Torque, Pressure and Hookload. Piston customized an Iron Roughneck to increase efficiency with handling drill pipe which increased trip times to 600 joints per 12-hour shift. Plug milling time varied between 45 minutes and 2 hours with an average of 5 plugs per mill with 3,500 to 6,000psi at surface. After milling out the first well in 14 days, all coil tubing units were released.

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