Optimizing Horizontal Well Placement in Turbidite Sands with the Use of New Reservoir Mapping-While-Drilling Systems: A Case Study from Offshore Brazil

Abstract

The Frade field, located in Campos Basin, offshore Brazil, is currently being developed using the latest advancements in reservoir mapping-while-drilling (RMWD) systems to aid horizontal well placement and enhance reservoir characterization. The technologies implemented include the high-definition (HD-RMWD), and the three-dimensional (3D-RMWD) systems, which convert ultra-deep electromagnetic measurements into a map of the resistivity profile around the borehole. The HD-RMWD provides multilayer detection using a 1D deterministic parametric inversion engine that provides a detailed 2D resistivity map along the well trajectory, resulting in enhanced capabilities for geosteering and reservoir characterization. This system was implemented in the horizontal wells drilled in Frade since 2022. For landing, an actual vertical detection of around 20 m TVD has helped to set casing in the desired target, identifying the presence of shallower layers—that could result in a poor landing—when present. Within the reservoir, the radial depth of detection achieved with a two-receiver configuration was on the order of 30 m TVD, enough to map top and base of sandstone geobodies while identifying the occurrence and dipping of multiple thin beds. The 3D-RMWD extends the application of this type of technology to the most complex reservoir settings and enables azimuthal geosteering. A set of new measurements—the full 360° electromagnetic tensor—is acquired and transmitted in real time using a new data compression algorithm, and then converted into 3D resistivity volumes derived from a cloud-based 2D transverse inversion technique. Results from the use of the 3D-RMWD technology in Frade—first case in Brazil's offshore operation—showed the 3D mapping capability of different geobodies in a complex geological environment. It also showed how reservoir properties were changing transversally along the well trajectory. A previous-generation RMWD system was used in offshore Brazil for 13 years, and this paper presents the experience gained from using the latest developments. The HD-RMWD system represents a significant advance by providing a finer resistivity map around the borehole, while the 3D-RMWD technology opens a whole new area of application, especially for complex reservoir characterization and provides means for azimuthal geosteering, which is currently an avoided practice.