Specifying a coiled tubing unit comes down to six decisions: injector capacity, tubing and reel, well control, power pack and cabin, mounting and transport, and the documentation and commissioning scope. This guide walks through them in the order a project actually settles them, for units from 40K to 160K built by Sino Petroleum Equipment Group, Qingdao, China.
Step 1 — Fix the injector capacity
Capacity is chosen from the maximum pick-up and snub force the intervention needs, not from a nominal tonnage. Work from the deepest TVD, the largest CT outside diameter, the weight of the string in the well fluid, the BHA weight, and the friction expected in the completion — then add margin for the operations in the program.
| Injector class | Typical use | Notes |
|---|---|---|
| 40K | Shallow vertical wells, fill clean-out, nitrogen lifting, logging runs | Lightest package, skid or trailer, single reel |
| 60K | Routine onshore workover and clean-out, 1.5″ CT string | Most common onshore specification |
| 80K | Deeper vertical and deviated wells, milling, extended reach | Skid and trailer versions in catalog |
| 100K | Heavy-duty workover, larger CT OD, higher over-pull | Larger reel and power pack |
| 160K | Deep, high-force interventions | Engineered order, not a catalog item |
Step 2 — Size the coiled tubing and the reel
Reel capacity falls quickly as tubing OD and wall thickness increase. The reel must hold the working string, the BHA and a margin. Catalog examples: a 1.5″ × 6600 m high-pressure reel skid, and a 2″ × 6500 m reel skid rated for 15,000 PSI service. Quick-detachable drum skids and yard spoolers are available when strings are changed frequently.
Step 3 — Choose the well control stack
The stack has to match wellhead pressure and tubing OD. A quad ram configuration (blind or shear, pipe, slip, kill) is the common choice for CT work. Catalog pressure control equipment covers 3-1/16″ at 10,000 PSI, 4.06″ at 10,000 PSI and 5.12″ at 10,000 and 15,000 PSI, with NACE anti-H2S lubricators for sour service and wellhead adapter flanges to suit the tree.
Step 4 — Power pack, cabin and controls
Power pack sizing follows the maximum simultaneous hydraulic demand of injector and reel at working pressure. The 60K to 100K units use a Caterpillar C13 class diesel engine; 180K liquid nitrogen pump skids use a C15 class engine. The control cabin houses injector, reel, BOP and pumping controls, with the layout (skid-mounted, trailer-mounted or remote) agreed at drawing approval.
Step 5 — Mounting and transport
Skid-mounted units suit platforms, rig floors and fixed yards: compact footprint, cheaper sea freight, crane already on site. Trailer-mounted units suit multi-well onshore campaigns: one road-legal package carrying reel, injector, power pack and cabin, so rig-up time per well drops sharply. Export packing, container loading plans and lifting drawings are part of the delivery documents either way.
Step 6 — Documentation, acceptance and commissioning
Specify the documentation you need at the order stage: general arrangement and hydraulic drawings, factory acceptance test report, material and pressure test certificates, operation and maintenance manuals, packing list. Third-party inspection, client witness testing and on-site commissioning support can be included in the scope.
Sizing and procurement questions
How many metres of coiled tubing do I need for a 4,000 m well?
Plan for the deepest TVD plus the BHA length plus a working margin, and remember that reel capacity falls as tubing OD and wall thickness increase. A 1.5 inch string on a 6600 m reel leaves usable margin for a 4,000 m well; a 2 inch string is normally paired with a larger reel because each metre of larger tubing occupies more drum volume.
Does a coiled tubing unit always come with a nitrogen unit?
No, but they are frequently paired. Nitrogen is used for displacement, pressure testing and foam or energized fluid work, and liquid nitrogen pump skids from 15K to 180K with 10,000 to 15,000 PSI discharge are offered as a separate package so that the CTU and the nitrogen skid can be specified independently.
What determines the number of operators for a CT intervention?
A basic onshore package runs with a supervisor, an injector operator, a reel or pump operator and a well control hand. The crew size grows with offshore manning rules, night operations, simultaneous nitrogen and fluid pumping, and the amount of equipment that has to be rigged up per well.
How is the unit shipped and rigged up?
Skid units ship as a small number of liftable modules with lifting points and sea-fastening details; trailer units ship road-ready or as trailers plus separate reel. Export packing, container loading plans, lifting drawings and a rig-up sequence are part of the delivery documentation so that the receiving yard can plan crane capacity in advance.
Can you support commissioning and training on site?
Yes. Commissioning support, operator training and factory acceptance testing with the client present can be included in the order scope. The scope, duration and number of engineers are agreed in the commercial offer.
What information should I put in an enquiry?
Give the operating envelope: maximum TVD, CT outside diameter and expected length, wellhead pressure, well fluid and H2S presence, ambient temperature, mounting preference, required injector capacity, and the intervention services to be performed. That is enough to return a configuration, a technical proposal and a price.
Next step
Send the operating envelope — maximum TVD, CT OD and length, wellhead pressure, well fluid and H2S presence, ambient temperature, mounting preference and the intervention services to be run — to sales@coiledtubingunit.com. You get back a configuration, the drawing package scope and a price for that specific unit. See also the coiled tubing unit FAQ and the unit range.