Effectiveness of AICD Completion for Long Term Water Shutoff: Workflow for Selection & Success of Autonomous Completion Type to Meet EOR Challenges in Multilayer Well in Chad

Abstract This paper presents intelligent water control technology advancement and effectiveness that can control water influx, enhance oil recovery, and manage pressure in multi-layer reservoirs. To boost oil extraction beyond primary/secondary methods, Autonomous Inflow Control Devices (AICDs) downhole tools that restrict unwanted fluids while enabling oil flow are integrated into Enhanced Oil Recovery (EOR) strategies to reduce water cut, enhance well productivity, and increase recoverable oil volumes. The water control completion mechanism is explored, automatically identifying fluids according to physical properties such as viscosity and density. The innovative design of the inflow channel structure restricts water. Selection for production by the water control device is based on the principles of operation, performance, and structural integrity for long-term water control. This study aids in selecting optimal options for managing water in scale-, corrosion-, and hydrate-prone environments. The paper presents advanced intelligent water control technology applied in Chad for regulating water influx, enhancing oil recovery, and managing multi-layer reservoir pressure. Its innovative inflow channel design restricts water based on viscosity and density differences, enabling automatic pressure adjustment. AICDs regulate oil and water flow rates by exploiting differences in fluid viscosity and inertial force: high-viscosity oil flows efficiently through short, low-resistance channels, while low-viscosity water encounters long, high-resistance paths with central baffles that induce rotation to slow its flow and minimize interference. This physical-property-based design enables optimized, real-time control of oil and water inflow. The unique AICD with no moving parts and an integrated structure, it functions throughout the well’s life cycle, offering a reliable solution for sustainable water management. This oil field in Chad has a layered edge-water reservoir with primary formations PI1-PI4. Well X-4, in the central-western region, began production in April 2014 from PI1-PI3 through self-injection. The well spans 1092.56-1196.50m across 11 layers. In July 2015, production switched to an electric pump, maintaining stable output for nearly two years. By mid-2017, the water cut rose to 50%, prompting water injection adjustments, which stabilized it at 20%. After autonomous inflow control device (AICD) completion in 2021 and testing after 20 days, oil output increased to 318.3 bbl/d from 223.3bbl/d, while the water cut reduced to 13%. The well successfully entered the low-water-cut liquid extraction phase, demonstrating effective flow regulation, water control, and oil enhancement. Unique AICD water control screen has shown improved efficiency in liquid extraction and oil enhancement. After AICD operation and increasing daily production, daily oil increased by 0.48 times on average, water cut gradually decreased to 13%. Up to Mar.4th 2024, cum. increased oil is above 118,000bbl, and cum water decrease is over 3,000bbl, stable production has lasted for more than 1294 days. Also, this paper presents the optimal operating conditions for AICDs, which rely on viscosity and density differences, in Oil/Water and Oil/Gas systems. It emphasizes the importance of selecting devices based on fluid characteristics for long-term performance.