Match the equipment to the field condition, not the catalogue.

How to use these references

Read the condition, confirm the envelope, then scope the rig.

Each reference below starts from a common field condition and works through the equipment decisions that condition forces: the rig class, the climate and protection package, the chassis or carrier choice, and the support trucks that belong in the same mobilisation. The figures shown are the published rated values for the base units; the final configuration is confirmed against the well data, the site survey and the destination climate. Send those three inputs with the inquiry so the quotation is built to the actual envelope rather than to a generic catalogue spec.

1. Desert and high-temperature fields (continuous 45–55°C).

Desert duty is defined by heat, dust and solar load rather than by the rig's rated horsepower. The cooling system is the first gate: the radiator, fan drive and charge-air cooler are sized for the maximum ambient, and the hydraulic and transmission oil coolers are upsized so continuous pumping and hoisting duty does not derate. The air intake gets a multi-stage dry filter with a pre-cleaner so silica dust does not shorten engine and compressor life, and the electrical enclosures and connector seals are rated for sustained high interior temperatures under direct sun.

For the equipment choice, the truck-mounted workover rigs (150HP to 850HP) are the usual core for desert well service because they relocate between remote pads without road support. The paint system and undercoating use a UV-stable and corrosion-resistant specification, and the tyre and rim package is selected for soft-sand traction and heat cycling. Confirm the maximum sustained ambient, the sand and dust exposure, and the planned road condition on the site survey: those three inputs move the cooling and air-intake spec more than the rig class does.

Desert duty items to confirm

Condition	Configuration focus
Maximum sustained ambient	Upsized cooling, derate margin, oil cooler
Sand and dust load	Multi-stage air intake, sealed enclosures
Pad access and surface	Tyre package, chassis ground clearance, outrigger pads
Day-night temperature swing	Hydraulic oil grade, seal material, fuel and water heat management

2. Plateau and cold-region fields (-30°C to +10°C).

Cold-region duty reverses the cooling problem into a heating problem. The engine needs cold-start aids, a block heater and a rated battery pack so the unit starts at the published minimum ambient without external power; the hydraulic system uses a low-temperature oil and a pre-heat circuit so the steering, the hoisting and the outrigger functions respond within minutes of start-up instead of being limited by viscous oil. The mast, substructure and pipe racking are designed for the combined wind and ice load, and the operator cabin gets a heated and insulated enclosure so the crew can run continuous shifts.

The ZYT workover and drilling fleet is configurable for plateau and cold-region service: the 350HP and larger truck-mounted classes and the skid-mounted ZJ series both accept the cold-start, heat-dissipation and anti-icing packages. Confirm the minimum design ambient, the altitude (which derates naturally aspirated engines and drives turbocharger selection), and whether the site has grid power for pre-heat: those three items decide whether the cold-start package is sufficient or whether a heated enclosure and auxiliary heater are added.

3. Mountain and mud-season access roads.

Mountain and seasonal-mud sites are limited by the chassis, not by the hoisting rating. A rig that cannot reach the pad on a narrow, sloping or muddy road delivers zero productivity regardless of its hook load. The 350HP XJ350 uses a 10×8 self-propelled chassis; the 450HP and larger truck-mounted classes use 12×8 all-terrain carriers with selected axle configuration, tire and suspension package for grade ability and soft-ground floatation. The overall length, the loaded height and the turning radius are confirmed against the road survey and any bridge weight limits on the route.

For very tight sites, the 150HP and 250HP units on 6×4 chassis have a smaller footprint and lighter road load, and they rig up in a smaller pad. The derrick-carrying truck and the truck-with-crane (rated 8,000 kg at 2.0 m or 5,000 kg at 2.25 m, boom reach to 15,000 mm) handle the mast and auxiliary lifts on site. Confirm the road gradient, the turning radius at switchbacks, the bridge and culvert limits, and the mud-season window: the chassis class is chosen on those numbers, not on the catalogue photos.

4. Coastal and salt-atmosphere sites.

Coastal and offshore-adjacent sites impose a corrosion environment that inland rigs are not built for. The salt atmosphere attacks uncoated fasteners, electrical contacts, radiator fins and hydraulic cylinder rods within the first season, so the equipment spec moves from "standard paint" to a coastal package: hot-dip galvanised or stainless fasteners, zinc-rich primer and polyurethane topcoat, sealed electrical junction boxes, and corrosion-resistant exhaust and tank hardware. The radiator core and oil cooler are specified with copper or alloy fins rated for salt fog, and the hydraulic cylinders use chrome rods with wiper and seal kits selected for salt exposure.

All ZYT truck-mounted workover rigs, support trucks and skid units can be ordered with the coastal / anti-corrosion treatment. Confirm the distance to the shore, the presence of H2S or CO2 in the produced fluids (which changes the material and seal selection beyond atmospheric corrosion), and the planned maintenance interval: the coastal package is sized to the worst expected exposure, not to the average.

5. Heavy oil and paraffin-prone wells.

Heavy oil and waxy wells need thermal and mechanical intervention that a plain workover rig does not provide. The boiler truck supplies hot-oil and hot-water circulation for wax removal and flow-line recovery; the swabbing unit and swabbing tool (YCZ series) handle unloading, production testing and liquid level recovery; and the well flushing and paraffin removal truck runs the flow-line and tubing wash. The workover rig itself is sized to the tubing and rod load, which is usually in the 250HP to 450HP truck-mounted class for heavy-oil well service.

The support fleet is what turns a hoisting job into a completed well: the boiler truck, the swabbing unit and the flushing truck mobilise together so the wax cut, the swab run and the tubing pull happen in one site visit. Confirm the produced fluid temperature, the pour point and wax appearance temperature, the typical flow rate, and the planned intervention frequency: those numbers decide whether a single boiler truck is enough or whether a second unit and the fluid supply truck (750 m3/h at 45 m head) are added.

6. High-pressure water injection and secondary recovery.

Water injection and secondary recovery fields run dedicated pumping equipment rather than workover rigs as the core asset. The ZJ series water injection pumps (ZJ3GY125, ZJ3ZY125 and larger) cover suction pressures to 1.5 MPa and discharge pressures across the injection manifold envelope, and the series of plunger pumps (3ZB-145 class, 145 kW input, 280 SPM, 135 mm stroke) cover the lower-flow higher-pressure end. The pump selection is driven by the injection pressure and the required rate at each wellhead, not by a catalogue maximum.

For the site, confirm the injection pressure at the wellhead, the required rate per well and the number of wells, the water quality and whether filtration is needed, and the power supply on site (grid, diesel generator set or the oilfield power equipment package). The pump skid, the high-pressure manifold, the pulsation dampener and the instrumentation are sized as one package so the interface between the pump and the injection network is not left to site assembly.

7. Mature fields with high move counts.

Mature fields make money by keeping wells online, and the equipment decision is driven by the move count rather than by the deepest well. A self-propelled truck-mounted rig rigs up and down without crane and low-bed trailers, and each move avoids the hire cost, the road permits and usually a full day of rig-up labour. The 150HP, 250HP and 350HP classes cover the shallow and mature well band; the 450HP, 550HP, 650HP, 750HP and 850HP classes extend the envelope to heavier strings and occasional deeper interventions.

The commercial check is straightforward: estimate the annual move count, write down the per-move saving from self-propelled relocation, and multiply the two. If the result reaches the price difference between truck-mounted and skid-mounted within two to three years, the chassis pays for itself. In mature fields with dozens of wells and service cycles measured in weeks, that calculation usually falls clearly on the truck-mounted side. Confirm the well count, the typical service cycle, the road condition between wells and the rig-up time expectation: the rig class is chosen on those operating numbers.

8. Deep drilling campaigns with skid-mounted rigs.

Deep drilling moves the rig from a mobile carrier to a skid-mounted installation. The ZJ series skid rigs cover the drilling envelope: the 1000HP ZJ40D drills to 2,000–3,200 m on 127 mm drill pipe with a 2,250 kN hook load; the 1500HP ZJ50D reaches 2,800–4,500 m with a 3,150 kN hook; the 2000HP ZJ70DB reaches 4,000–6,000 m with a 4,500 kN hook; and the 2500HP ZJ80 reaches 5,000–8,000 m with a 6,750 kN hook on a 7×8 traveling system. The mast is a K-type structure from 43 m to 48 m, and the substructure height is selected to match the cellar and the BOP stack.

The skid package is delivered as a coordinated installation: drawworks, rotary table (ZP series), mud pump complement, solids control, electrical or mechanical drive, and the auxiliary power unit. Confirm the planned drill pipe size and casing programme, the derrick load case (jointed pipe vs. single), the mud pump flow and pressure requirement, the power supply at the location, and the move plan between well sites: the skid rig is sized to the drilling programme, not to a single well depth.

What to send with a deployment inquiry.

For any of these references, the fastest path to a firm quotation is the field profile: the operating condition (one of the references above or a description of the site), the well data (depth, tubular size, casing programme, pressure and fluid), the site survey (road, pad, climate, power, water), the quantity and the destination. With that profile, the rig class, the climate and protection package, the chassis choice and the support truck complement are scoped as one package rather than as individual catalogue picks.