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Successful Optimization Roadmap Enhanced the Drilling Performance in the 8.5 Inch Lateral Sections of Extended Reach Multilateral Wells


 Great efforts are invested in improving oil and gas reservoir recovery to meet the rise in local energy consumption and global demand. To improve the production and ultimate recovery of a major oil field in the Middle East, extended-reach drilling (ERD) is executed in wells with long horizontal multilaterals to achieve maximum reservoir contact (MRC), the increase in ERD wells demand led to many drilling challenges and difficulties.
 The challenges in designing ERD wells are multiple, such as trajectory control, well collision avoidance, hole cleaning efficiency, high torque & drag, differential sticking, wellbore stability, Logging-while-drilling (LWD) log quality and long circulating hours. In recognition of this, the dedicated operator and service team developed a drilling optimization roadmap that addresses the drilling challenges at the greatest performance impact. The optimization roadmap comprises enhanced trajectory design, drillstring design, drilling fluids and system hydraulics design, and subsurface geomechanical modelling in the planning phase, in addition to realtime formation evaluation, hole cleaning and torque and drag monitoring, and drillstring vibrations management in the execution phase.
 The exploitation of 4 inch and 5 inch tapered drillstring as opposed to complete 5 inch drillstring for drilling torque reduction and its related tripping behavior was explored on the first Optimization stage of the optimization plan, using this approach successfully reduced drilling torque, but the tripability out of hole became problematic and more difficult. The first stage outcome called for utilizing complete 5 inch drillpipe string in addition to oil-based mud (OBM) lubricant (OMNI-LUBETM) that resulted in 20-25% reduction of the drilling torque. Tripability improved compared to 4 inch drill pipe in the second optimization stage, but still facing some issues in few laterals. On the final optimization stage, the engineering & operations team introduced the Dog Leg Reamer tool on top of the drilling bottomhole assembly (BHA) which resulted in a significant improvement in the tripping behavior in addition to a smoother hookload along in the drilled interval. The implementation of the holistic drilling system design and optimization methodologies helped achieving new performance records, lateral after lateral. The optimization roadmap delivered a proven performance in the most challenging drilling environments.
 The key technical challenges, performance optimization roadmap, job execution, and post well evaluation of the drilling performance are presented in this paper.