Amalgamating Biosteering and Productivity Index Trend Analysis on the First Underbalanced Coiled Tubing Drilling (UBCTD) Injector Well in the Middle East to Improve Well Performance in Real-Time

Abstract Sharjah National Oil Corporation (SNOC) undertook an Underbalanced Coiled Tubing Drilling (UBCTD) drilling project to improve three wells’ performance in its gas-storage reservoir. The project's success was crucial towards ensuring energy security in Sharjah and increasing the operational capacity of the gas-storage reservoir. A unique combination of biostratigraphy, production data and bottomhole drilling parameters was applied to maximize lateral length in the high productivity reservoir zones to support this vision. The three-well UBCTD pilot campaign involved setting a whipstock in a 7″ liner, milling a casing exit for sidetracking, and drilling 3-5/8″ lateral wells. The laterals utilized UBCTD technology and methods to eliminate formation damage, enhance production, and improve drilling performance. An integrated real-time biosteering, productivity index (PI), trend analysis and sub-surface geological monitoring methodology was adopted to achieve the project objectives. Biosteering was performed by preparing thin sections from cuttings samples and petrographic analysis conducted to identify indicative microfacies and microfossils. The analysis was integrated with gamma ray (GR), logs to identify the reservoir layer and stratigraphic position of the drill-bit relative to the target reservoirs. The integration of biosteering, PI trend analysis, and sub-surface geological monitoring aimed to optimize drilling and production efficiency. The well's measured productivity was transient during drilling, leading to a "pseudo-PI" calculation. While this was not a reliable predictor under steady-state conditions, it effectively indicated productivity when the drill bit intersected the reservoir. Flow rate changes signaled the impact of drilling zones, with increased rates indicating enhanced productivity. Concurrently, the formation's biostratigraphy was assessed, recording trends across multiple laterals to identify productive biozones. Geosteering then optimized lateral trajectories within these zones to maximize productivity. This holistic approach allowed for real-time adjustment, ensuring drilling and production activities were aligned with reservoir characteristics, ultimately enhancing overall efficiency and output. This paper underscores the benefits of integrating data from diverse sources to enhance reservoir and well performance analysis. It also highlights the pitfalls of information silos hindering data sharing among teams striving for a common goal. As a comprehensive guide, this paper provides an in-depth discussion of a workflow that integrates drilling, formation, and reservoir data to optimize productivity enhancement strategies.