Abstract
Coiled tubing (CT) is routinely deployed in wells producing from multiple pay intervals. Multizone completions induce pressure gradients that present significant operating risks to CT operations. Kicks and lost circulation can cause reservoir damage, blowouts, and lost pipe. Countless CT strings have been lost in wells because of uncontrolled well responses during treatments.
Wellsite observations have improved the diagnosis and prevention of circulation problems caused by differential pressures. Some of the specific factors influencing these problems are formation fluid levels, well geometry, interval height, and temperature. Reservoir management techniques can reduce the hazards imposed by differential pressures. However, because kicks and lost circulation cannot always be avoided, contingency plans are necessary. Prejob calculations and planning procedures can help operators establish practices that minimize the adverse effects of kicks and lost circulation.
A comprehensive strategy for CT operations includes contingency planning. While some risk must be assumed in all well-intervention processes, proactive planning can minimize problems and increase the potential for success.
