Running casing from a floating offshore vessel bears increased risk because of the requirement for a subsea stack and the influence of vessel heave. The complete paper presents a solution involving using drilling fluids with varying properties to overcome drag to allow the casing to reach the planned depth. This approach to overcoming drag forces by using drilling-fluid weight and rheological properties enables large casings to be run to deeper depths in extended-reach wells where fully evacuated flotation or rotation are not feasible.
Introduction
The North Sea has historically been, and continues to be, a tremendously challenging environment for drilling and casing offshore wells. The well discussed in this paper is in a field in the East Shetland Basin of the North Sea with a water depth of 451 ft from the sea floor to the surface.
