Atlanta Field: Developing Heavy and Viscous Oil in a Challenging Environment

摘要

Atlanta is a post-salt oil field located in the original Block BS-4 ring fence, 185 km off the city of Riornde Janeiro, in the Santos Basin, Brazil, under water depth of approximately 1550 m. However, AtlantarnField is not just another ultra-deepwater project; for its development, several other challenges shall bernovercome, such as the low burial depth, its highly unconsolidated sandstone reservoir, the heavy andrnviscous crude flow assurance, the need for high power artificial lift pumping system, and the complexrncrude treatment at topsides, among others.rnThe field was discovered in 2001, followed by an appraisal program with a vertical well drilled yet inrnthe same year to test the high porosity Eocenic unconsolidated sandstones and sample its heavy andrnviscous oil (14°API and 228 cP in reservoir conditions). In 2006, a horizontal well proposed to test thernfield development concept cast a shadow in the reliability of the project after facing several drilling,rncompletion and production problems imposed by the high challenging environment. These included poorrndirectional control leading to phase abandonment and well sidetracking, massive fluid loss, gravel packingrnfailure, ESP operational issues, partially conclusive drill stem test (DST), and a severe damaged wellborern(skin u0002 40).rnAfter considering technology improvements and revisiting development concepts, an extensive preparationrnand a complete assessment of past operations were performed. During 2013 and 2014 thernconsortium led the drilling, completion and testing of the first two horizontal producers planned for thernfield development. Wells were drilled with good directional control and barely any fluid loss, reproducingrnwith great fidelity the proposed trajectory. They were both completed with sand control screens and gravelrnpacked throughout the 800 m near horizontal (88°) section in the reservoir. A slant section of 80 m wasrnconstructed just before reaching the reservoir for electrical submersible pump (ESP) installation. ThernDSTs were conducted with ESP both near the reservoir and near the seabed to test the performance ofrndifferent artificial lift concepts. Results confirmed the high reservoir permeability and the great performancernof the drilling and completion phases, delivering the first two producers of the field with nornformation damage. Productivity indexes for both wells were in the high end of the expected performance.rnThis paper presents a full review of the Atlanta Field, emphasizing its main challenges and how theyrnwere overcome by the successful construction and testing of the first two production wells, recovering thernreliability of the project and encouraging the consortium to move on to the next phase. Also, the updatedrnfield development plan is described, highlighting the challenges to be faced during the next phase of thernproject.