Mero Giant Field: A Successful Case of Recovery Optimization During Development

Abstract Five years after Mero Field commercial declaration, around 200.000 bbl/d are being produced, with an expected production peak over 600.000 bbl/d to be reached in the next years. Successful results are being achieved with a reservoir-oriented strategy to minimize risks and maximize value. The main aspects of this strategy, which aims at attaining a recoverable oil volume of more than 3 billion barrels, is described in this work. Mero's development strategy combines two main phases: the first focused on data acquisition for definition of the global development plan and flexibilities necessary for further optimizations and the second focused on the plan implementation using the flexibilities to optimize results during deployment. On the first step, a development plan with four 180.000 bbl/d production systems and a FPSO of 50.000 bbl/d was conceived, with produced high CO2 content gas full reinjection (WAG) as the recovery method. However, relevant reservoir uncertainties remained, which required actions for guaranteeing that risks could be mitigated and opportunities could be seized during the projects’ execution. Some of the applied strategies were: an itinerant EWT unit allocated on main dynamic uncertainty areas, the anticipation of a few development wells in strategical reservoir positions, the use of flexible EPCI contracts allowing a range of possible flowlines extension acquisition, and an integrated multidisciplinary rigs schedule using preceding wells data to define next locations final position. Anticipated wells along with EWTs were important to appraise critical reservoir regions and to verify communication between different reservoir zones. Seismic data improvements enabled a better reservoir characterization. However, only during the second phase of the above-mentioned development strategy, using all the gathered information together was it possible to identify in a more precise manner relevant aspects, such as the presence and location of igneous bodies in the reservoir zone, a new area of the reservoir to be drained, and the aquifer characteristics. With knowledge evolution, reducing uncertainties and confirming opportunities, changes in drainage plan were then accomplished after FID, using the EPCI flexibilities milestones, defining the final wellhead locations and well trajectories closer to each project's first oil. The first three Mero projects have already gone through this optimization process with expected gains up to two hundred million barrels of additional oil recovery. A balance between audacious strategies for project and profit acceleration and flexibility strategies for path correction and optimization has been fundamental for the development of complex fields, such as the pre-salt ones. The strategy herein presented is leading to a successful development of Mero Field and may be used for the development of other offshore projects to maximize recovery and economics.