Precise Well Landing in High-Resistivity Layered Limestone Using Novel Multi-Depth Triaxial Collocated Resistivity Array

Abstract This paper demonstrate the successful first landing in a high-resistivity layered limestone reservoir using a triaxial-collocated Multi-Depth (Shallow- Medium- Deep- Ultra-Deep) resistivity RSS integrated platform delivering both Reservoir Mapping Inversion (RMI) and an At Bit Inversion (ABI), combined with high dogleg capability (8°/100 ft) Rotary Steerable System (RSS). A challenging high resistivity limestone formation with thin layer was targeted for precise 1-ft landing. Traditional deep and ultra-deep azimuthal resistivity tools struggle in low contrast environments. To address this, a novel and first in the LWD world, a triaxial collocated multi-depth resistivity platform was deployed combining a Reservoir Mapping Inversion (RMI) and an At Bit Inversion (ABI). The run featured the first deployment of this innovative integration with the Rotary Steerable System tool to achieve 8°/100 ft DLS. The case study shows a comparison of triaxial collocated technology and previous generation pseudo-triaxial, non-collocated technology architecture. The inputs from the new triaxial multi-depth resistivity platform improved the boundary mapping position accuracy and internal layer delineation due to innovative antenna design and wider frequency bandwidth. This run marked the first well landed in a high resistivity, low contrast limestone reservoir using a novel multi-depth azimuthal resistivity RSS integrated platform. The Reservoir Mapping Inversion (RMI) enabled improved detection of internal boundaries, while the At Bit Inversion (ABI) provided real-time confirmation of standoff and proximity during the landing phase. Together, they facilitated accurate steering in a zone with minimal resistivity contrast and multiple internal layers. The integrated RSS platform delivered the required high dogleg (8°/100 ft) to execute the aggressive landing plan without compromising wellbore stability or tool reliability. Both inversions enabled real-time adjustments, leading to successful placement within 1 ft below the reservoir top, without the need for sidetracks or corrections. Following this landing, a conventional ultra-deep azimuthal resistivity tool was run, allowing for a comparison within the same resistivity environment between the triaxial collocated architecture (used during landing) and the previous pseudo-triaxial, non-collocated ultra-deep system (used during the horizontal section). The novel platform delivered better boundary clarity and finer vertical resolution, significantly improving reservoir characterization and reducing interpretation uncertainty by up to 50%.