Potential Implementation of Casing while Drilling Technique in the Western Desert Fields of Egypt

Abstract

Casing While Drilling (CWD) technique allows the operator to simultaneously drill and case a wellbore section in only one run without the necessity to pull the drill string out of the hole. This innovative technique comes into play in time when oil and gas well drilling faces a lot of challenges such as excessive lost circulation, formation fluid influx, formation instability, etc. CWD is implemented into today drilling activities in order to safely and economically deal with these obstructive challenges. In addition to eliminating/minimizing the effects of these challenges, it remarkably improves the entire economics of the drilling project. Researches and developments are continuously on their ways to further improve the performance of the technique in order to minimize its limitations. A lot of case studies all over the world have been analyzed and their related practical lessons have been stated. Based on a study carried out on five shallow wells and seven deep wells drilled between 2007 and 2008 in the region of Western Desert, lost circulation and stuck pipe represented more than 80% of the drilling problems. The study revealed that CWD could be an alternative approach in the region to eliminate/minimize the aforesaid problems as was the case in numerous fields in the world. Therefore, the potential applicability of CWD technique in the region has been widely discussed. A proposed drilling program that suits CWD has been given. Special reference has been also given to casing string design, mud program, hydraulics optimization, bit selection criteria, working conditions and operational parameters such as WOB and RPM.