TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractAlthough Coiled Tubing Underbalanced Drilling has proven advantageous in reducing formation damage, increasing penetration rates, and potentially eliminating well stimulation treatments it is still regarded as one of the higher risk service operations being performed in the world today. Some operators who have utilized Coiled Tubing Underbalanced Drilling previously site that unreliable downhole tools, long rig-up times, and hole cleaning issues contribute to higher costs and unacceptable risks involved with this application. In order to maximize the advantages of Coiled Tubing Underbalanced Drilling and minimize the perceived risks, careful assessment and close scrutiny of each aspect of the operation must be carried out.This paper outlines the planning and execution responsibilities of two companies working synergistically to provide an operator with their expertise in each area of service. Contracting integrated work-over services for a Coiled Tubing Underbalanced Drilling project on a well where previous drilling operations had failed was felt necessary by the well operator to maximize the wells potential, increase the probability of success, and minimize the risk involved. Well history of the previous drilling attempts, pre-job planning and engineering, equipment and tool specifications, operational execution, and benefits achieved through an integrated approach are discussed. The results of the drilling operation and suggested improvements of the integrated service approach are also reviewed.