Shayan. Mashhadi - Department of Petroleum Engineering, Faculty of Chemical Engineering, Tarbiat Modares University,Tehran, Iran

The Casing Drilling System (CDS) provides an alternative to the conventional drilling system by using ordinary casing forth drill-string.In this project, at first we will have a general explanation about casing drilling methods. Differences between other methods are discussed and equipment and facilities needed to assess the utility of these methods will be presented. Then, the casing drilling procedure will be discussed. Moreover, the benefits and advantages over other drilling methods are described. Then, the problems which can be faced during the drilling, will be explained and what the limitations will be given.After that the bit status used in this method and features and characteristics of these bits will be discussed. Furthermore, optimization conditions will be explained and whether it is cost effective for us or not.At the end, we will focus on statistics and the number of the countries which have reached this technology

wellbore, casing drilling, formation.