Successful Application of Managed Pressure Drilling and Cementing in Naturally Fractured Carbonates Environment of Prohorovskoe Exploration Well

This technical paper provides the result of utilizing MPD technology for drilling and cementing a 127 mm production liner withing the Zadonian horizon D3zd in an exploratory well of the Prohorovskoe field. The previous wells drilled with a conventional approach in the field had complicated issues such as circulation losses and well control. It was complexified with high hydrogen disulfide concentration in reservoir oil which was a health hazard to a site personnel. As a result, to eliminate all complications, resources and operational time were needed. To prevent and eliminate complications in a long wall, core drilling and well completion, managed pressure drilling (MPD) and cementing technology with semi-automatic control system was applied. The project is unique as such complicated jobs with the core drilling and cementing with MPD were executed for the first time in The Komi Republic. MPD approach allowed to figure out bottomhole safe conditions and maintain ECD within a required pressure window. It is necessary to notice that a part of the section was core drilled. Knowing the window between pore and fracture pressures safety limits, a run-in-the-hole design with further cementing job was optimized. The execution was done flawlessly without circulation losses and well control issues. In comparison to a previous well in the Prohorovskoe field, MPD allowed to shorten loss circulated mud volume from 2 2215 m3 to 0 m3 and avoid non-productive time. Through accomplished goals and lessons learned, new grounds to well owners and well services in a field development stage are broken.