Refined reservoir mapping while drilling for a strategic exploitation of deep-development reservoirs

Deep-development reservoirs commonly exhibit high water-cut production and complex, dispersed remaining oil distributions with localized enrichment. Aggressively exploiting these reserves often compromises ultimate recovery and long-term reservoir sustainability. Conventional exploration methods face limitations in accurately characterizing such complex subsurface environments, necessitating more advanced and precise techniques for effective reservoir management. This study aims to develop and validate a refined reservoir mapping-while-drilling approach based on ultra-deep reservoir mapping services (UDRMS). The primary goal is to enable quantitative and strategic geosteering in complex reservoirs to enhance remaining oil recovery, support sustainable development, and mitigate drilling risks. This UDRMS uniquely combines a deep depth of detection (DOD, up to 30 m) with high vertical resolution (1 m). Which can bridge the scale gap between seismic interpretation and conventional well logs, enabling real-time construction and refinement of a detailed two-dimensional (2D) reservoir-scale profile while drilling. Key reservoir architectural elements-such as microstructure features, sand body geometry, connectivity, superposition patterns, and fluid contacts-were accurately delineated. The derived model was used to strategically guide both the landing and lateral sections of horizontal wells. Field applications in the Bohai Bay Basin demonstrated the effectiveness of this approach, yielding the following quantitative outcomes: (1) The well landing point was strategically adjusted upward by 9 m based on an accurately mapped Oil-Water Contact. (2) A heterogeneous lithological reservoir was successfully identified and salvaged under high-risk geological conditions. (3) Actual well performance exceeded expectations, increasing remaining oil recovery by 5-7.5%. (4) The refined 2D reservoir profile facilitated progressive extension of development into deeper and more challenging targets. The UDRMS-based refined reservoir mapping-while-drilling technique represents a significant advancement over conventional methods. It provides a reliable and strategic solution for enhancing recovery in mature and deep reservoirs, supporting sustainable development, and reducing uncertainty in complex formations.