Current Trends and Future Development in Casing Drilling

Operators in the Oil and Gas (O&G) Industry are constantly seeking cost-effective methods of drilling and producing oil and gas wells to optimize production and maximize profits. Conventional drilling methods have been plagued with huge operational and financial challenges, such as cost of purchasing, inspecting, handling, transporting the drill string and most importantly, tripping in-and-out of the drill string whenever the Bottom Hole Assembly (BHA) needs a replacement or when total depth is reached. The tripping in-and-out of the drill string not only contributes to Non-Productive Time (NPT) but also leads to well control difficulties, including wellbore instability and lost circulation. Casing Drilling, otherwise known as Casing while Drilling (CwD) or Drilling with Casing (DwC) has been under development for over a decade and has only been executed successfully in recent times as a result of advances in technology. Casing Drilling encompasses the process of simultaneously drilling and casing a well, using the active casing. This paper presents current applications of casing drilling, along with practical applications and limitations. A study is also undertaken in discussing the possibility of applying retrievable liner drilling to further improve on the casing drilling technique. The main advantages that are evident by this future development are the casing string cost savings, its application in wellheads requiring limited number of casings and in some subsea well control situations.