Composite frac plug milling on coiled tubing
MAX. DOG LEG SEVERITY12° @ 100 ft
PLUGBACK TOTAL DEPTH12,970 ft
BOTTOM HOLE TEMPERATURE120°F
HYDROSTATIC PRESSURE1,776 psi
CASING SIZE5.5” (4.89” ID)
Predicted lock up depth for the 2.375“ coil was at 11,700 ft. The plugs were located at 12,030 ft and 12,500 ft, respectively. It was decided to mill out the 5.5” plugs using a 4.79” bit mounted on a mud motor deployed by a CT Well Tractor® on coiled tubing.
By using a tractor to pull the coiled tubing, the risk of helical buckling was also eliminated, enabling the longer reach required for this successful intervention. The entire operation was carried out without any events and demonstrated the efficiency of the chosen approach.
CT Well Tractors are designed to give a constant and known traction force at a predetermined pumped down fluid flow rate to establish a controlled situation and ensure that the target depth of milling is reached. In this particular case, the average speed of the tractor was about 35 ft/min while the average pull force was 2,500 lbs
The original Well Tractor was in fact a version designed to run on Coiled Tubing. Harnessing the fluids pumped from surface it is an essential tool for overcoming helical buckling or washouts.