Abstract
Coiled Tubing Drilling, grown significantly in recent years, is normally associated with high angle to horizontal and extended reach wells. It is, however, in these applications that hole problems become more troublesome because of inefficient cuttings removal. Among the many parameters affecting efficient cuttings transport in Coiled Tubing Drilling are pump rates, well dimensions, fluid properties, solids sizes, solids loading and hole inclination. Several attempts have been made to determine the optimum operating range of these parameters but complete and satisfactory models have yet to be developed.
The purpose of this paper is to provide a critical review of the state of the art on efficient cuttings transport during Coiled Tubing Drilling, present the critical parameters involved, establish their range according to what is observed in practice and propose a different approach for predicting the minimum suspension velocity. Finally the laboratory system that has already been set up is presented. Its primary purpose is to allow the gathering of good quality data, missing from the literature, which could enhance our understanding of the flow of solid – liquid mixtures in annuli.