The usual strategy adopted by Petrobras in the complex turbidite reservoir in the Marlim Sul field is to drill a pilot well to investigate the base and top of the reservoir followed by a sidetrack to gyrosteer inside the sandstone bodies. Because of the magnetic interference generated by the 9 5/8-in casing, a regular magnetometer-based RSS required spacing of approximately 15 m from the shoe to correctly orient the bit in the desired direction and start a sidetrack. This necessary spacing had the potential to lead to a complete exit of the sandstone body, jeopardizing the well placement.