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Well Containment Analysis – WCA - is a set of integrity analysis criteria in a shut in scenario performed during the well design phase. The installation of a capping and shut in of the well shall not induce hydrocarbon leakages to the seabed. One of the integrity analysis criteria within WCA is a situation in which the well, in a blowout scenario, is closed with the capping, and a fracture is then initiated at a specific casing shoe of the well, propagating through shallow formations. The analysis ensures that the time for fracture propagation to reach the mudline is longer than the time to drill a relief well and have the well controlled. When considering a situation of a fracture propagation in a blowout scenario after capping and controlling the well there are two main possibilities: (I) a shallow reservoir can absorb the hydrocarbon flow from a deeper reservoir, (II) the time required for the fracture propagation to reach the seabed is greater than the time needed to control the well in blowout situation, guaranteeing that there is no fluid broaching to the seabed. When considering the time for fracture propagation, a safety margin is needed due to uncertainties in the geological data. This work aims to present a few case studies where well projects didn’t attend WCA analysis considering P90 pore pressure scenario and needed further analysis to ensure attendance of well integrity. In this situation, studies were done considering fracture propagation beginning after the well closure due to a hypothetic blowout, trying to analyze if hydrocarbons would broach to the mudline, and if so, how much time such an event could occur. Study results show the impact of geology and geomechanics on fracture propagation. There are situations in which the fracture remains confined due to the presence of a shallower reservoir and others where the fracture broaches to the mudline in a short amount of time. This analysis has the potential to turn the concept of well integrity more flexible, allowing the well designer to combine, in a tentative optimal way, a safe and feasible design in more challenging scenarios.

An appraisal well was drilled in Brazilian pre-salt area using overbalance drilling fluid, with conventional techniques. While drilling reservoir (in a 12 1/4" phase), total losses were found. Unsuccessful attempts with LCM and cement pills revealed that only MPD/PMCD techniques could deliver the well to TD. It was decided to anticipate the installation of the 9 5/8" casing, covering only the upper portion of the reservoir, and well was suspended. The remaining reservoir could be drilled later with a rig equipped with MPD system. This well was designed as a 2-zones intelligent completion in cased hole configuration. Due to the fluid losses a new design had to be considered. Due to reservoir uncertainties, definition on the separation between zones would only be taken after drilling the remaining reservoir section. To overcome this challenge without adding time and complexity to the overall design, the best solution was to perforate the cased hole section after drilling the remaining section, meaning doing it with reservoir communicated to the wellbore and in PMCD mode. Several options were evaluated to design the TCP operation in PMCD. Well control strategies, contingencies, thermal effects, and dynamic shocks were considered. The solution consisted in running the TCP with a closed string, without NRVs and having robust contingencies in case of washout or drillpipe failure after perforating. The well was drilled, and total fluid losses occurred again. It was then successfully perforated still in PMCD, then lower and upper completion were installed. Despite these challenges, this was the fastest intelligent completion in all Petrobras pre-salt fields so far.