Horizontal Open Hole Gravel Pack Challenges and Lessons Learned from More than 60 Offshore Wells Performed in Peregrino Field

Abstract The Campos basin is a sedimentary basin located in offshore Brazil, between the north coast of Rio de Janeiro State and the south coast of Espírito Santo State and is composed of several fields. Among, Peregrino is made mainly of a high-permeability sandstone reservoir in a water depth of 120 m, producing a 14° API grade oil at a moderate reservoir temperature (60° C). To maintain the reservoir pressure, the production drive mechanism is composed by reinjection of produced water and pressure support from the aquifer. Artificial lifting method is required to improve production. The well construction design used, to keep production economically feasible, was to drill and complete long horizontal wells passing through the reservoir. In unconsolidated sandstone reservoirs, sand control methods are mandatory due to the risk of sand production. In the case of Peregrino field, oil producing wells required the use of screens and gravel pack while injector wells required stand-alone screens. Thorough engineering was required, and many lessons learned were acquired during the gravel packing of 66 wells since the first well was completed in 2011. Although the wells are part of the same field, different completion scenarios were observed in each well, requiring specific design in conjunction with the lessons learned and the best practices to overcome those challenges. Considering that most of the wells have long open-hole lengths from 1,300m to almost 2,300m, a big challenge was the high friction during the alpha and beta wave propagation. The balance between increasing the pumping rate to prevent proppant settling and the increase of friction pressures without fracturing the formation was a key to the success. Beyond this challenge, many others were faced such as high losses prior to the pumping, shale areas in the interval, use of autonomous inflow control devices (AICD) screens, changes in proppant type and concentration strategy, vessel mobilization strategy change, introduction of a new rig in the field, etc. The success of this project is clearly based on gravel pack packing statistics as ∼95% of the completed wells were fully packed and on the improvement in the operational safety over the years of operations. This paper outlines and describes the design, completion and lessons learned that were used in the past 13 years of gravel pack operations in the Peregrino field, which can be used as reference and benchmark for other offshore horizontal open hole gravel pack projects around the globe. To a large extent focus on simple and robust solutions and operations. Peregrino has contributed with many good learning points for gravel pack operations.