After 4 years of production, an oil well at 80-m depth offshore Canada experienced a drastic water cut increase up to 76%. To increase oil production and reduce the water cut, the operator decided to perforate a new interval. During the wireline drift run, a hard obstruction was encountered at ~5,000-ft MD, 120 m above the proposed perforation interval, preventing further progress.
The type of debris and length of the obstacle was unknown, but scale was expected based on the field history. The operator decided to try a milling run to clear the way for the perforating guns—a daunting task in the highly deviated well (>80°) and sour gas environment (210 ppm H2S, 1.2% CO2) with temperatures up to 215 degF and pressures up to 6,700 psi. Due to rig-up height and limited deck space on the offshore rig, use of coiled tubing (CT) was not an option.
The solution had four main components:
The TuffTRAC tractor conveyed the milling tool to the proper depth in the highly deviated lateral well while generating the weight on bit and controlling torque. Once the obstacle was encountered, the milling operation began. Debris management was accomplished by maintaining flow through the tool and picking up regularly.
This strategy enabled milling more than 50 m, moving completely through the restriction in a single run. An additional milling pass confirmed that the toolstring could freely access the perforation zone. Pulling out of hole confirmed that there was no trace of debris on the bit.
Three perforating runs were conducted without encountering any obstruction to pulling the guns after shooting was finished. Overall, 3 days and considerable deck space were saved by using wireline instead of CT. This highly successful intervention demonstrated the ability of the ReSOLVE service to access and clear well obstructions through wireline intervention and save time and costs that would have been involved when using heavier tools.
