With the depletion of current oil reserves, drilling engineering is emerging to even more challenging environments. The pre-salt carbonate reservoirs is an example of that, now at the pinnacle of the Brazilian development projects, these reservoirs are located around 200km away from coast, in over 2100m water depth and up to 7000m below sealevel. Since the discovery of these huge fields in 2007 it was believed that the biggest challenge is to overcome the thick salt layer but nowadays drilling into the reservoir has become even more challenging. Carbonate formations are very heterogeneous and total losses are often experienced when fractures or vugs are encountered. The lost circulation in high rates can result in a well control issue if gas starts to flow into wellbore, manly it occurs due to loss of hydrostatic pressure. Pressurized Mud Cap Drilling (PMCD) is one of Managed Pressure Drilling (MPD) variations applied in situations where total or severe losses are experienced. This paper addresses a discussion regarding the application, fluid selection, safety consideration and well control issues using this technique.

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