Abstract This study highlights significant production gains achieved through the application of an advanced ultra-deep electromagnetic (UDAR) logging tool in mature offshore carbonate reservoirs. By addressing challenges related to fluid distribution and horizontal well placement, the tool enhanced Geosteering precision and enabled more informed decisions about well trajectory, avoiding unwanted fluid contacts. This precision was crucial in optimizing the design of the lower completion, including decisions regarding blank pipe lengths and calling an early Total Depth (TD) after mapping the conductive zones and geological anomalies which resulted in well life extension. The utilization of UDAR tool in these case studies led to substantial value creation in production, amounting to 294 million in 2024. This study focuses on three cases and discusses how the tool's ability to reduce geological uncertainty and mapping reservoir zones was instrumental in achieving these production gains, which are critical for future field development in such mature carbonate settings. The primary challenge was to maintain the well trajectory of the three wells within the optimum zone while accurately identifying conductive zones. This precision was essential to blank out unnecessary intervals in the oil producer wells (A, B, and C) and optimize the fit to purpose completion design to preserve the well life. Additionally, post-rig operations conducted by barge were planned to verify the effectiveness of the completion deployment, ensuring it met our operational requirements and aligned with our objectives. During these post-rig operations, assessing the production performance was crucial to demonstrate the effectiveness of the UDAR tool utilization. In each case, the major challenges highlighted by Reservoir Engineers prior drilling were successfully addressed. In Well A, an early TD was called after the UDAR mapped the increase of a low resistivity zone from the bottom of the target, delaying water influx and increasing well life. In Well B, the UDAR mapped the low resistivity zone below the target, leading to a move to the secondary target zone and blanking that interval in the completions stage. In Well C, the well's trajectory was placed in the optimum zone, minimizing risks related to formation dipping and conductive layers above the trajectory. Post-barge operations indicated dry oil in all three wells, delivering expected rates and extending well life in the absence of artificial lift. In contrast, nearby wells are either suffering or unable to flow due to high water cut. For effective reservoir management during complex oil wells drilling in water risky areas, a proactive geosteering approach using UDAR inversions has shown significant benefits over traditional strategies that rely on shallow directional measurements. This method improves reservoir access, accelerates drilling operations, and streamlines the well completion process, reducing overall costs and operational complexity.
Mohammed et al. (Mon,) studied this question.