Design Optimization for Hydraulically Driven Agitation Tool in Extended Coiled Tubing Reach Application

Abstract As the boundaries are pushed with increased length of horizontal wells, coiled tubing (CT) well intervention capabilities are challenged requiring new technologies to expand existing capabilities. When utilizing coiled tubing, standard best practice is to first utilize CT modeling software to optimize CT size and weight for maximum reach. After choosing the right CT size, the next and most critical factor to address in extending the reach is, drag and frictional forces between the CT and the wellbore. Reducing friction and delaying helical buckling will significantly increase the reach. Several versions have been created utilizing various pressure pulse tools in the CT bottom hole assemble (BHA) to accomplish this task. These tools work by creating vibration or pressure pulses that allow for a delay in the onset of the helical buckling of CT and are widely utilized and accepted as solutions. However, existing agitation tool limitations have been reached. A newly designed and developed, hydraulically driven agitation tool (HDAT) to extend CT reach delivers continuous frequency pressure waves along the entire length of the CT. The HDAT provides a reduction in static friction and converts that to a dynamic friction form along the CT string. The continuous hydraulic agitation reduces the onset of helical buckling and thus reduces CT helical contact points, resulting in lower resistance force. The development, design, and lab testing for the HDAT has been through extensive development stages resulting in three generations of the tool, with each version providing an incrementally improved performance. The latest generation HDAT has been designed to function at optimum operational frequencies and produce excitation that works on a longer section of the CT. The performance advancement of the newly designed HDAT generation was achieved after extensive lab testing with a field run reaching a total depth of 24,500 ft over a 4,600 ft open hole lateral section. The new HDAT was redesigned to improve performance and reliability to achieve an effective matrix acid stimulation treatment. The lessons learned from previous generations were imbedded to extend the reach of the CT in the most challenging extended reach wells.