The situation

The operator was unable to complete the well due to a narrow operating window. High pressure gas from just below the casing shoe entered the well while experiencing losses from the producing formation at the same time.

The solution

M-I SWACO pressure control equipment, including a HOLD RCD and an AUTOCHOKE, was installed. The mud weight was reduced from 13.2 ppg to 12.5 ppg (below pore pressure) to reduce the Equivalent Circulating Density (ECD) while drilling to avoid losses. VIRTUAL HYDRAULICS was used to model the well, and the applied annular pressure was calculated in order to hold a constant bottomhole pressure for all stages of the operations.

To prevent gas influx, up to 900 psi of annular pressure was applied during connections, while 1,000 psi was held when stripping out to compensate swabbing.

The results

The well was successfully drilled and completed without non-productive time (NPT) from losses or influxes. Thorough modeling and execution ensured the drilling, rollovers, tripping and cementing were successfully completed using MPD techniques by @balance Services.

The details

Prior to using MPD, the operator had fought losses and influxes for a long period without being able to drill to the desired well TD. The difference between static and circulating conditions was too great for the operating window for this particular well. By using MPD, the pressure in the well stayed within the operating window by holding a near-constant bottomhole pressure. With conventional drilling, the difference is approximately 1 ppg Equivalent Mud Weight (EMW) whereas MPD kept the pressure difference within 0.1 ppg EMW.