Intervention programmes are bought against a depth rating and a deck footprint, but they are won or lost on speed control. A unit that can only trip fast cannot hold a production logging pass steady, and one that is precise at low speed wastes hours on the way to bottom. The skid-mounted wireline unit answers both by pairing a very wide speed range with a choice of drive, which is what makes one skid usable for logging, perforating, fishing and testing without changing carriers between jobs.
Depth Class and Drum Capacity Define the Unit
Five depth classes are offered, rated by maximum operating depth and matched to drum capacity for standard 12.7 mm cable, which is 0.5 inches in diameter:
5,000 meters class: 5,500 meters of cable, 50 kN maximum lifting load
10,000 meters class: 10,700 meters of cable, 85 kN
15,000 meters class: 15,000 meters of cable, 156 kN
Selecting on depth alone is a mistake, because cable capacity always exceeds the rated operating depth by a margin. That margin is deliberate: it allows a full-depth run plus the wraps that must stay on the drum, and it leaves room for the re-spooling that follows a cable cut or a damaged section. A 5,000 meters unit is about 16,400 feet of reach, and the 15,000 meters unit close to 49,200 feet, which is the span that separates a land workover programme from a deepwater one.
Skid-Mounted Wireline Unit Speed Range and Drive Options
The winch transmission uses electro-proportional control with variable fine-tuning, giving a stated range of 20 to 10,000 meters per hour. At the bottom of that range the unit can creep at roughly 66 feet per hour for precise positioning over a perforating interval; at the top it runs near 33,000 feet per hour for tripping. Two drive options are available, hydraulic drive and variable frequency motor drive, and the choice is usually made on what the location already has: a platform with hydraulic power available tends to take the hydraulic package, while a land location with reliable electric supply takes the variable frequency motor. Both give stable low-speed control, which is the harder of the two requirements and the one that decides whether a slow logging pass is usable.
Anti-Magnetization Drums Protect Measurement Data
The drum assembly is built with high-strength anti-magnetization material at a relative permeability of 1.1 or less. That specification is easy to overlook and expensive to ignore: a magnetised drum can bias magnetic and electromagnetic sensors in the tool string, particularly the production logging sensors that depend on clean magnetic readings for fluid identification. Keeping the drum close to non-magnetic removes a systematic error source at the surface rather than trying to correct for it in processing, and the benefit applies to every run made from that unit rather than to a single job.
Braking Architecture and Hazardous-Area Certification
Safety is built around triple protection: neutral parking, manual braking and emergency braking, with the brake designed to engage automatically if hydraulic pressure is lost so that a power failure does not become a dropped string. For hazardous locations the unit uses an intrinsic explosion-proof design that carries DNV certification and is suitable for Zone 2 operation, which is the classification most production platforms and many land wellsites apply to the area around the wellhead. Certification is what allows the skid to be craned onto a live platform without a separate hazard review for the winch package itself.
Matching a Skid-Mounted Wireline Unit to the Wellsite
Configuration is where the unit is fitted to the job. Single-drum, double-drum and chainless winch structures are all offered, and one skid supports both wireline and slickline work by changing the cable and the pressure control equipment. Power can come from a diesel engine, an electric motor or a power take-off, sized to the horsepower the programme needs. Cabins are insulated and heated for arctic work and air conditioned for desert and tropical locations, and the operator console integrates pneumatic, hydraulic and electrical controls in one panel so that line tension, depth and speed are read together rather than from three separate displays.
Speed range and certification are what separate a general-purpose winch from an intervention unit. A skid-mounted wireline unit rated from 5,000 meters to 15,000 meters, controllable from 20 meters per hour upward and certified for Zone 2, covers logging, perforating and fishing on one carrier.
For more information, please contact China Vigor at info@vigorpetroleum.com or call +0086 29 81161513.
