Brazilian Pre-Salt: An Impressive Journey from Plans and Challenges to Concrete Results

摘要

In the early 2000s the context of the pre-salt formations was conceptual geological models of possible oilrnbearing reservoirs underneath a thick salt layer, many technical challenges, uncertainties and risks. Pastrnonly eight years from first discovery (2006), there are nine production systems, FPSOs, in operation,rnreaching an average oil rate of more than 700 thousand barrels per day and a cumulative productionrngreater than 400 million barrels of oil, through 34 production wells. To optimize recovery, the firstrndesulfated sea water and gas injectors were started. But these impressive numbers cannot be taken fromrngranted: although nature has revealed prolific reservoirs, much experience, talent, planning and perseverancernwere necessary.rnThe first articles addressing the pre-salt fields had a focus on the technical challenges faced on firstrnyears: the heterogeneous nature of the microbial carbonate reservoir, the 2,000 m salt layer and drillingrnconcerns associated, the variable CO_2 content and compositional grading in the reservoir fluids, flowrnassurance issues and special demands concerning subsea engineering, well construction and processingrnplant. The main drivers and development strategies were also established: staged development, based onrnextended well tests (EWTs), multi well production pilots and definitive systems prioritizing the standardizationrnof well projects and production systems. Now, challenges and plans are rewarding the efforts, asrndepicted by the concrete production numbers achieved to date.rnIn this text, a historical perspective of the pre-salt exploration and development is presented, emphasizingrnthe previous unknowns and uncertainties and how they were treated in order to attain the results.rnAs we still have a lot to learn, since we are just on the beginning of the development of this extraordinaryrnpetroleum province, a look to the future and the present efforts on optimization are also commented.