Casing while Drilling (CwD) have been through advancement cycles from where this technology started since the early 1970's. At that time, CwD requirements were understood, but the equipment was not available. As application for CwD grows with a variety of challenges, more suitable equipment is now available – not only on the surface but also the downhole to meet the operation objective.
In one of the applications here in Middle East, top hole sections drilling through different formations consists of carbonate, sand and shale. However, carbonate formation in this application is the main challenge with drilling through the losses, followed by formation instability, which resulted in stuck incidents.
CwD strategy divided into two elements – remedial and optimization. For remedial element, offset analysis required to determine the level of formation instability surrounding the subject well where a decision will be made either to use CwD from the begging or to be considered as a contingency in case unforeseen borehole instability issue encountered. Whilst for optimization element, CwD application will be utilized to drill the top sections regardless the borehole instability risk, in this element it is must to show some time savings to cover the additional involved cost.
In one of the wells as an example, offset wells showed a history of formation instability related issues with one of the wells was abandoned, and another one was side-tracked. CwD was selected instead of drilling conventionally, and as a result, this well successfully drilled to casing depth without any of the lost time due to hole problems that was experienced by most of the offset wells.
With a much better understanding of drilling challenges, equipment availability, and capability, CwD will be able to open more opportunities to drill the well safer and faster as becoming a standard operation in drilling top sections. This paper discusses in general the challenges and solutions provided along with field results.