This paper presents a new intelligent completion solution recently introduced in Brazilian pre-salt fields, such as Búzios and Mero. Since the introduction of open hole wells with intelligent completion in 2019, this kind of design has become the prevalent architecture in pre-salt. However, the current completion design, with the ICVs in the upper completion, limits the number of remotely controlled intervals to a maximum of two. The new solution aims to deliver additional zonal control. As an initial step, Petrobras has organized some close interactions with all major service providers, looking for possible solutions for new well designs that could meet the requirements. The development of these new concepts was followed by a selection process when the most suitable solution was identified. After this step, the engineering team went into the detailing phase, where some technology and experience gaps were identified. A plan was put in place to develop the missing technologies and to gradually introduce the new design in the field to "derisk" the projects and achieve the required readiness. A well configuration with ICVs installed directly in open hole was selected. This allows deploying more than 2 valves in each well, as the concentric flow design is not required. In the other hand, running them in open hole results in some risks and uncertainties that were not applicable in cased hole. Wellbore stability, control lines integrity and zonal isolation are just some of the aspects that were part of the well engineering studies. A new expandable packer assembly with feed through capability was developed for proper and reliable zonal isolation. Other important guidelines for the project were workover readiness and compatibility with severe fluid losses scenarios. For both challenges, downhole disconnection systems are being developed. They will allow the disconnection and reconnection of the control lines in downhole environment. Additional equipment is also under development to allow installing the lower completion in a dual trip approach along with the use of MPD techniques. As part of the introduction of the new solution, three full open hole 3-zones intelligent completion systems were installed in Mero and Búzios field in 2021. Though none of them used the downhole disconnection system, a successful and valuable experience was obtained regarding the intelligent completion deployment in open hole. The comprehensive solutions envisioned for well construction in pre-salt fields include the fast development and intense application of new technologies, resulting in groundbreaking concepts. A significant cost reduction is expected with the new design and was already observed in the 3 pilot wells. At the same time, it also delivers all the required functionalities and incorporates improvements for the well life cycle. The introduction of this innovative concept is a game changer for pre-salt projects.
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.
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