Ultra-High-Definition Resistivity Mapping Technology: Advancing Efficient Early Development in Offshore Reserve

Abstract The early development of a new oil field is crucial, as it significantly impacts the overall recovery rate and economic efficiency. However, this stage poses challenges due to limited data on geological structures, reservoir characteristics, and formation evaluation. In early 2024, a development project for X Field commenced offshore China, aiming to complete initial development and start production by year-end. Characterized by a shallow-water delta environment, this field's complex depositional setting complicates understanding of sand body distribution and fluid systems. To enhance reservoir exposure in individual wells, deepen geological insights, and optimize development plans, Ultra-High-Definition Resistivity (UHDR) mapping while drilling technology was employed as a targeted measure in this project. The UHDR mapping service offers real-time, integrated resistivity inversion with an impressive depth-of-detection (DOD) around the borehole, re-constructing up to eight bed-boundary layers coupled with a high resolution of 0.2 meters. This capability allows for remote mapping of reservoir boundaries, thin interlayers, fluid contacts, and resistivity distribution, enabling proactive wellbore position optimization and enhancing understanding of reservoir distribution. UHDR technologies significantly facilitated the early development phase of the new oilfield, offering key benefits: Multi-layer boundary mapping: During the lateral section, both the target roof, floor and interbeds were accurately delineated. The geometry of the isolated sand bodies could be depicted as well.Maximization of Reservoir Exposure: UHDR enabled proactive geosteering strategy with optimizing the trajectory, maximizing the reservoir exposure and avoid unnecessary shale penetration, which effectively reduced costs and shortened the well construction timeline.Assessment of sand-body connectivity and fluid systems: In regions characterized by multi-phase channel stacking and sandbar-type deposits, the sand-body and connectivity and fluid systems are complex. Integration with multidisciplinary data facilitated the assessment of fluid types and boundaries, allowing for adjustments to the further well placement strategy. (Note: "Well Placement" in this paper refers to strategic planning and positioning of wells before drilling, distinct from "Geosteering."). UHDR mapping while drilling technology played a pivotal role in the early development of the X Field, achieving an impressive average net-to-gross (NTG) ratio of over 94.2%. Its interdisciplinary application optimized development strategies, and the synergistic effects led to production results that exceeded expectations. The authors believe this technology can extend to the early development of other similar oil fields, and multiple application examples will be presented in this paper.