Summary Coiled tubing (CT) pipe design is increasingly constrained by longer laterals and higher dogleg severity, yet published workflows remain dominated by manual, designer-dependent iteration across forces, hydraulics, and fatigue models. This approach is slow, inconsistent between designers, and rarely explores enough of the wall-thickness (WT) design space to ensure a near-optimal geometry. A digital CT pipe design optimizer is introduced that ingests a well survey and an initial pipe specification, then iteratively reshapes the WT profile using a forward evaluation loop wrapped around an existing coiled tubing force (CTF) model and a derivative-free Powell search. Candidate designs are ranked using an objective function that prioritizes reaching target depth and maximizing weight on bit (WOB) and pull on bit (POB) at depth while penalizing peak stress utilization and net pipe weight. Benchmarking against a vertical well with an analytical optimum reproduces the optimal WT profile within 0.08 mm (0.003 in.). Across six additional vertical, J-, S-, and extended-reach wells measured depth (MD)/true vertical depth (TVD) 1.0–5.9, the optimizer increased POB by up to 8.5 klbf, extended reach by up to 471 m (1,545 ft) where baseline designs fell short, and reduced dry pipe weight by as much as 43% in weight-constrained scenarios. For field use, engineers provide the mission profile, select target total depth (TD)/WOB/POB and yield stress (YS) limit, and tune optional weighting to prioritize reach, force margins, or net pipe weight; the optimizer returns a manufacturable WT profile, key performance indicators (KPIs) with comparison against the baseline design, and a one-click export into the design simulation.
Fonseca et al. (Wed,) studied this question.