Abstract
AbstractDrilling S-shape wells across highly heterogenetic formations and at high inclination is particularly challenging due to increased risks, such as differential sticking, total losses and well control. This often leads to poor performance, stuck incidents, fishing operations and sidetrack. This paper aims to share the technological evolution and engineering approach to well planning and operations execution to deliver S-shape wells with long step out and high deviation.A thorough review of operational risks and associated non-productive time was performed in each hole size, namely 16" and 12". This combined with a crescent step-out, due to surface location limitations and production requirements, significantly impacted performance. Comprehensive geological and offset well analysis were put in place to select the best well design and trajectory with focus on risk reduction and outperformance. The main contributing factors to achieve that were divided into different categories: bottom hole assembly (BHA) design and latest directional drilling technology; drilling fluid selection and bridging strategy; casing running considerations; and cementing design.Following the new engineering approach and technology deployment, over 30 S-shape wells have been delivered with various step-out lengths (maximum of 3,500 ft) and tangent inclinations (maximum of 32°). Flowless operations, record wells and longest step-out S-shape were delivered throughout project life. Trajectory planning, optimized light BHA, combined with autonomous directional drilling technology and dynamic survey-while-drilling service were crucial to minimize plan complexity, stuck pipe risk whilst meeting the desired targets. Fit-for-purpose drilling fluid design and bridging strategy further helped on differential sticking and downhole mud losses prevention. For the casing to reach the bottom, it was also essential to have low friction factors through centralization stand-off optimization, lubricity enhancement and customized running schedule. Light cement slurry design and cementing job remote monitoring minimized equivalent circulating density (ECD) while ensuring solid cement bond and well integrity with real-time top of cement identification.The gradual evolution of engineering and technology deployment based on well-customized risk assessment led to drilling the most challenging S-shape wells and record-breaking performance in the gas field in the Middle East. This strategy will serve as a reference for service companies and operators to accelerate learning curve and achieve similar step change operations.