Successful Deployment of High Risk Monobore Completion in Fracture HPHT Unconventional Reservoir Using Floatation Technology Enhances Well Accessibility

Abstract Major Challenges while planning HPHT well in unconventional reservoir. The required mud weight to drill is 22ppg. were high torque, friction-factors. Well torque and drag simulations showed that planned completions were not deployable without rotation of the string and the deployment of the frac string required a very low friction factor that could only be reached by Oil based mud(OBM) or rotationwas huge impact. This paper describes the detailed key factors design criteria to deploy these risky completions. To drill cost-effective wells in a multi-disciplinary team was formed to review the design of unconventional wells and propose a cost-effective solution. Because of the complicated nature of the frac wells, they often use compression on the string to force it down which results in an excessive force which induces helical and sinusoidal buckling. The requirement of very low friction factors to deploy frac string with high mud weight; the new technology of floating the string,rotation of the string with low friction centralizers was introduced. The engineering design for the same was worked with risks of well control were mitigated. The well was a pilot to put concept to floatation inorder to deploy frac strings to Target depth(TD). The actual friction factor for Fluid systems with mud weight 20ppg and above is 0.45-0.5. The well architecture is complex and challenging due to its very short vertical section to landing point. This requires negative displacement to achieve the well objective with high dog leg severity per 100ft of 5 and above. The deployment of frac string can be achieved only by floatation or rotation. Rotation requires a high torque connection that directly impacts the well AFE. The floatation collar comprises of high-pressure glass disk that allows trapping air below the disk. The concept of flotation is to reduce drag and Friction factor of the frac string with the open hole which allows smooth deployment to TD. It is deemed necessary to use this technology along with low friction composite centralizers. The drilling fluid was customized to provide smooth ECD and circulating pressures targets to avoid increasing the risk of dynamic induced loss of circulation. The premium lubricant reduced the friction factor by 0.01. The cost of this technology is negligible compared to the risk associated with failure to deploy frac string. This was a new concept put to test which was the most cost effective with several new ideas and technologies being used. This service company idea bagged savings 30% cost by avoiding use of expensive high torque connections and systems. This concept will be applied to all future wells.