Abstract
Casing-while-drilling is a relatively new well construction process or technology for simultaneously drilling and casing a wellbore, and has been utilized globally over the last 15 years or so. This technology has shown advantages of reducing overall drilling time and cost. It has demonstrated signs of reducing hole problems, such as mud losses, through plastering effect because of the rotation of the casing string against the formation. It provides assurance to case off unstable formations while drilling, resulting in significantly reduced well construction costs.
Saudi Aramco has made several field test runs of this technology beginning in early October 2008, including deployments of both simple casing drilling with drill-through casing bit (non-retrievable) system and advanced bottom hole assembly (BHA) retrievable system designed for directional casing drilling. This paper will document the lessons learned from implementation of the technology, including planning and design, rig operations, problems encountered, modifications made to reduce risk after extensive review and investigation, and finally, successful deployment of a directional casing drilling to the planned casing point with a 17" x 13-⅜" system. In addition, the paper briefly outlines the further required improvements of casing drilling tools to ensure continued success in the future.
