Feasibility of periodic stabilizers for extending coiled tubing reach

Abstract

Coiled tubing (CT) operations are widely used to maintain and service wellbores for optimal production. Compressive forces, arising from friction, can cause buckling induced lock-up of the CT, bringing the operation to a halt. This paper investigates the feasibility of using strategically placed periodic supports in the wellbore to increase the buckling stability of the CT. Tubing force analysis (TFA) and finite element analysis (FEA) models from literature are modified and used in conjunction to determine exact locations of the individual supports. For the investigated CT operation this resulted in a total of 2153 periodic supports spanning 7 regions of stabilization covering 1890 m. With a strength and strain wise feasible individual support length of 2 mm, the accumulated collapsed length of supports is 4.3 m. This length scale makes it realistic to bring the periodic supports into the wellbore with the bottom hole assembly during CT operations. Conducted experiments demonstrate how inadequate support causes potential detrimental effects for the operation, however, sufficient periodic support maintains its stabilizing integrity beyond the point of helical buckling.