Abstract
Concentric tube well servicing technology is employed in numerous applications where pressure and fluid containment must be controlled at the surface. By design, the primary mechanism for maintaining pressure and fluid containment in these types of concentric-tube services is the purpose-built well control stack working in combination with fluid flow control devices in the surface treatment piping. As such, concentric tube well servicing systems have a unique advantage in that they are not bound by use of balance-weight fluids to maintain pressure and flow control as employed in conventional jointed-pipe rig systems.
However, when service conditions dictate that well pressure be at balance at the surface, well control practices which focus on fluid hydrostatics must be employed. Although based on the processes used in conventional jointed-pipe rig systems, coiled tubing well control practices performed concentric to existing well tubulars are more complex and require greater attention in design and implementation.
This paper provides an overview of the recommended coiled tubing well control stack and flow control device configurations for defined pressure control conditions and offers practical approaches which address the various concerns unique to coiled tubing well control applications.
