Drives for oil & gas: drawworks, pumps, gas pumping units and wellhead hydraulics
Oil & gas places demands on drive equipment that rarely appear together elsewhere: peak ratings up to 10 MW on main oil pipeline pumps and compressor-station gas pumping units (GPUs), dual braking systems on drawworks with a mandatory emergency circuit, heavy V-belt and gear drives for 800–2,200 kW mud pumps, and dense hydraulics for BOPs and spiders. The wellhead of an open-cycle well sees normal atmosphere, but gas releases are possible, so part of the drive train is supplied in Ex-rated execution. Equipment is selected for peak torque with a 1.5–2.5 safety margin and for conditions where the failure of a single unit paralyzes an entire field.
Industry-typical tasks
- Drawworks drum drive of 100–500 metric tons hook load — motor + gearbox + dual braking system (service band/disc + emergency)
- Rotary table drive — motor through a gearbox and gear coupling, table torque up to 60 kN·m, reversing duty during drilling and reaming
- Mud pumps of 800–2,200 kW via V-belt or gear drive — continuous S1 duty, discharge pressure up to 35 MPa
- Main oil pipeline pumps — high-voltage motors of 2,000–8,000 kW at 6/10 kV, capacity control via an HV variable-frequency drive
- Electric-driven gas pumping units (GPUs) at compressor stations rated 6,300–32,000 kW — synchronous/asynchronous HV motors as an alternative to gas turbines
- Service and workover (well-servicing) winches with regenerative braking through an HV inverter
- Hydraulic systems for BOP stacks, spiders and elevators — 16–35 MPa power units with duplicated pumps and accumulator banks
- Slurry pumps and centrifuges for drilling-mud cleaning — 75–315 kW drives with VFD control
Gearboxes
In oil & gas, a gearbox is used where high torque must be delivered at low speed (drawworks drum, rotary table) or where the motor and the driven machine run at fundamentally different speeds (main oil pipeline pump trains, GPUs at turbo speeds). Key criteria are a service factor of at least 1.8 for drilling duty, output-shaft bearing life under combined radial-axial loading, and the ability to handle frequent reversals with peaks of 2.5× rated torque.
Drawworks gearbox
A two- or three-stage parallel-shaft gearbox with a herringbone output stage transmits torque from the drive motor to the winch drum. Rigs with 100–500 metric tons hook load are built around CGC ZSY/ZLY gearboxes rated for at least 25,000 hours of service life. Reversing duty during tripping requires careful rotor balancing and tolerance for angular misalignment of the output shaft toward the gear coupling to the drum.
- — Gear ratio 8–25
- — Output torque 80–600 kN·m at hook load
- — Service factor ≥ 1.8 for drilling, ≥ 2.0 for workover/well-servicing
- — Reversing duty up to 30 cycles per hour
- — Forced circulating lubrication with oil cooler
Rotary table gearbox
A bevel or bevel-helical gearbox with a built-in gear coupling to the cardan shaft from the drawworks. It delivers up to 60 kN·m on the rotary table at 0–250 rpm, with reversing duty during fishing and reaming. On modern top-drive rigs the rotary table is a back-up, but the gearbox must still cope with the full drilling cycle.
- — Output torque 30–60 kN·m
- — Loaded reversals up to 50 cycles per shift
- — Gear coupling on the input-shaft side
- — Seals protected against drilling-mud ingress
Mud-pump gear drive
An alternative to the V-belt drive — an integrated gearbox between the motor and the triplex pump. It is used on modern FA/FB-series pumps rated 1,600–2,200 kW. A single housing makes for a more compact layout and less maintenance (no periodic belt replacement), but it requires careful shaft alignment and foundation vibration damping.
- — Gear ratio 4.5–6.5 (motor 750–1,000 rpm → pump 100–150 rpm)
- — Output torque 150–250 kN·m
- — Service factor ≥ 1.5
- — Vibration-isolating mounts under the foundation
Gear motors for rig auxiliaries
BONENG K- and F-series gear motors drive cuttings conveyors, shale shakers, centrifuges and slurry pumps in mud-cleaning circuits. Continuous S1 duty in dust and oil mist. Seal resistance to oil-based drilling mud is critical.
- — Power 1.5–75 kW
- — K-series (bevel-helical) or F-series (parallel-shaft)
- — NBR/FKM seals resistant to hydrocarbons
- — IP55 protection, tropical-climate execution
Gearboxes for main oil pipeline pump trains
A single-stage parallel-shaft or coaxial speed-up gearbox is installed between the 6/10 kV HV motor and the main oil pipeline pump when the motor is low-speed and the pump is rated for 3,000–4,500 rpm. Continuous S1 duty, G2.5 rotor balancing, and a forced-lubrication oil-cooling unit are required.
- — Gear ratio 1.5–3.5 (speed-up)
- — G2.5 rotor balancing
- — Forced lubrication with filtration and cooling
- — Vibration monitoring per ISO 10816-3
Electric motors
Oil & gas is one of the prime applications for high-voltage machines at 6, 10 and 11 kV rated from 800 kW to 32 MW. Main oil pipeline pumps, compressor-station GPUs and the main drives of top-drive rigs are all HV-motor territory. Alongside them, a large fleet of 0.4 kV low-voltage motors handles auxiliary drives, with a portion supplied in explosion-proof execution (Ex d, Ex e) for the wellhead area and frac pads.
Motors for main oil pipeline pumps
High-voltage asynchronous or synchronous motors of 2,000–8,000 kW at 6 or 10 kV. Continuous S1 duty; capacity control through an HV variable-frequency drive saves up to 25% of electricity compared with valve throttling. WOLONG WD3000 and YHTM series with forced water cooling are rated for 24/7 operation over 8,000 hours between maintenance intervals.
- — Rated power 2,000–8,000 kW, voltage 6/10 kV
- — Rated efficiency no lower than 96%
- — VFD-compatible (Class H insulation)
- — Insulated bearing on the non-coupling end
- — Vibration, winding and bearing temperature monitoring (Pt100)
Motors for electric-drive GPUs at compressor stations
Electric-driven GPUs are an alternative to gas turbines, economically attractive when grid capacity reserves are available and discharge pressure is 6.3–7.5 MPa. Synchronous motors of 6,300–32,000 kW at 10 kV with brushless excitation are typical. Capacity control via an HV variable-frequency drive is critical for variable-flow operation.
- — Rated power 6,300–32,000 kW, voltage 10/11 kV
- — Synchronous with brushless exciter (predominantly)
- — Speed 1,500–5,500 rpm matched to the centrifugal compressor
- — Forced cooling IC81W (water-to-air) or IC616 (air-to-air)
- — HV-inverter compatibility per NEMA MG1 Part 31
Main drives for drilling rigs
Modern drilling rigs are powered by 600–2,200 kW drives distributed between drawworks, mud pumps and rotary table. Both DC machines with thyristor control (legacy rigs) and AC motors with HV inverters (new rigs) are used. WOLONG supplies motors of both categories, including explosion-proof YBX3 series for the wellhead area where gas releases are possible.
- — Rated power 600–2,200 kW, voltage 0.69 kV or 6 kV
- — Starting torque ≥ 1.8× rated under string load
- — S4 thermal reserve — 60 starts per hour during tripping
- — Ex-rated YBX3 execution (Ex d IIB T4) for the wellhead area
- — Forced ventilation with cooling-air reserve
Motors for mud pumps
One of the most loaded drives on a rig — an 800–2,200 kW mud-pump motor running in S1 duty while delivering 30–60 L/s of drilling fluid at pressures up to 35 MPa. Both asynchronous WOLONG YE/YBX3 machines at 6 kV and DC motors for legacy rigs are used. Starting is performed via a soft starter or direct on-line when the section has sufficient capacity.
- — Rated power 800–2,200 kW
- — Continuous S1 duty over the well's drilling cycle (30–90 days)
- — Optional Ex-rated execution for rigs close to the wellhead
- — Class F insulation with Class B temperature rise reserve
- — IP55 minimum, protected against dust and oil mist
Braking systems
Drawworks set the toughest braking requirements in heavy industry: when a string of up to 500 tons is being hoisted, a brake failure drops the string into the wellbore and loses the entire well. API Spec 7K and GOST R 53364 therefore require two independent braking systems — a service brake (driller-controlled) and an emergency brake (triggered by loss of power or by exceeding the lowering-speed setpoint). Similar requirements apply to workover/well-servicing winches, spiders and elevators.
Drawworks main (service) brake
A band or disc brake on the winch drum, controlled by the driller through a lever and a pad with a pneumatic/hydraulic booster. Modern rigs are equipped with HUAWU DBS multi-caliper water-cooled disc brakes that allow string-lowering speed to be controlled without overheating. Legacy rigs use band brakes with friction blocks.
- — Braking torque margin of 1.75–2.0× peak hook load
- — Water cooling of brake discs (for disc brakes)
- — Hydraulic or pneumatic actuator booster
- — Friction-pad service life of at least 200 trips
- — Stepped lowering-speed control
Drawworks emergency brake
A spring-applied, hydraulically released disc brake — a separate set independent of the service brake. On loss of power, on an emergency-stop press or on exceeding the lowering-speed setpoint (typically 1.5× rated), the brake closes automatically within 0.15–0.3 s. HUAWU YPZ2/SBD and ZHONGHAI SB series are sized to hold the full string load and are certified to API 7K.
- — Spring-applied, hydraulically released
- — Closing time on loss of power ≤ 0.3 s
- — Braking torque ≥ 1.75× full string load
- — Pad-wear and position monitoring (limit switches)
- — API 7K or GOST R 53364 certification
Brakes for wellhead workover winches (A-50, A-60 units)
The wellhead area of an open-cycle well is a place where gas releases are possible during reservoir work, so brakes on workover and well-servicing units are supplied in Ex-rated execution: ZHONGHAI SBD-Ex, HUAWU YWZ-Ex with a dual closing system. The workover winch itself is less powerful than a drawworks (30–80 metric tons hook load), but the requirement for two independent brakes still holds.
- — Ex d IIB T4 for the wellhead area
- — Two-brake arrangement (service + emergency)
- — Braking-torque margin of 1.75× rated
- — Resistance to weather and salt mist on offshore platforms
- — Manual release option for string evacuation
Brakes for mud-pump and rotary-table drives
TKT/TKK shoe brakes with electro-hydraulic thrusters are installed on the high-speed shaft between motor and gearbox/sheave. Their job is to stop the pump rotor on loss of power and prevent reverse fluid flow through the pump. They are also used on the rotary-table drive to lock the string for make-up/break-out.
- — Electro-hydraulic thruster Ed-50 to Ed-301
- — Closing time ≤ 0.5 s
- — Manual release option for maintenance
- — Pad-wear monitoring (limit switch)
Couplings
Four coupling types sit between the main units of drilling and pumping equipment: drum-type gear couplings on drawworks and rotary tables (high torque, misalignment compensation), cardan spindles on top-drive rotary tables, flexible pin-and-bushing couplings on mud and main oil pipeline pumps (pulsation damping), and hydrodynamic (fluid) couplings on mud pumps (soft start, overload protection). Selection follows a 1.5–2.5× torque margin and the permissible shaft misalignment after thermal growth.
Gear couplings for drawworks and rotary tables
YONGJING GIICL and LONGXUAN WGZ are double-engagement drum-type gear couplings transmitting up to 600 kN·m with compensation of radial and angular misalignment. They are installed between the drawworks gearbox and the drum, and between the cardan shaft and the rotary-table gearbox. The crowned tooth form allows operation at angular misalignment up to 1.5°, which is critical for thermal growth of housings after several hours of tripping.
- — Torque 50–600 kN·m
- — Angular misalignment up to 1.5°
- — Grease lubrication via grease nipple, 6-month interval
- — API 7K certification for drilling duty
Cardan spindles for rotary-table and top-drive trains
YONGJING SWP/SWC are universal-type cardan drives connecting the gearbox to the rotary table or top drive. They accommodate significant axial travel (up to 200 mm) and angular misalignment (up to 10° per joint), needed to compensate travelling-block stroke and thermal deformations.
- — Torque 30–200 kN·m
- — Permissible joint angle up to 10°
- — Forged-steel spiders with rolling-element bearings
- — Balancing per GOST 22061-76 above 500 rpm
Hydrodynamic couplings for mud pumps
JIAOHUA YOX/COX are oil-filled fluid couplings that provide soft starting of triplex pumps under load and protect the motor from overload during water hammer or discharge-line blockage. Rated slip is 2–3%; a fusible plug set at 145–160 °C dumps oil overboard on overheat. They are especially justified with direct on-line motor starting (without a soft starter or VFD).
- — Rated slip 2–4%
- — Fusible plug set at 145–160 °C
- — Oil fill 70–85% of internal volume
- — Thermal capacity for 4–6 loaded starts per hour
Flexible pin-and-bushing couplings for main oil pipeline and mud pumps
LONGXUAN LX (LMC) and YONGJING LMS are pin-and-bushing couplings with elastomer sleeves connecting motors to pumps. They damp starting shocks and torque pulsations from piston pumps. On main oil pipeline pumps they are often combined with a shear-pin safety coupling, which protects the gearbox and the motor if the impeller jams.
- — Torque 5–125 kN·m
- — Radial misalignment compensation 0.2–1.0 mm
- — Elastomer service life of at least 30,000 hours
- — Optional shear-pin safety element
Applications gallery
Our solutions for this industry
SDS portfolio brands that cover typical applications in this industry.
- WOLONGHV motors for oil pipeline pumping and GPUs (WD3000, YHTM) up to 12 MW; DC and AC drilling motors; explosion-proof YBX3 for the wellhead area
- CGCZSY/ZLY-series gearboxes for drawworks and rotary tables with a service factor ≥ 1.8 and at least 25,000 hours of life under peak tripping loads
- HUAWUDrawworks braking systems — water-cooled disc service brake (DBS) plus spring-applied emergency brake (YPZ2/SBD), API 7K certified
- JINGUDisc brakes for drilling rigs and wellhead winches, in oil & gas-certified configurations
- ZHONGHAIEx-rated brakes for workover/well-servicing winches (SBD-Ex), Ex d IIB T4 execution for areas where gas releases are possible
- YONGJINGGIICL drum-type gear couplings for drawworks and rotary tables; SWP/SWC cardan spindles for rotary-table and top-drive trains
- LONGXUANWGZ drum-type gear couplings and LX flexible pin-and-bushing couplings for main oil pipeline and mud pumps with pulsation damping
- JIAOHUAYOX/COX hydrodynamic couplings for mud pumps — soft start and motor protection against water hammer and line blockage
- BONENGGear motors for rig auxiliaries — cuttings conveyors, shale shakers, centrifuges in mud-cleaning circuits
- HUALIGeneral-purpose low-voltage motors for auxiliary drives across oilfield infrastructure
- DONLYKey brand for drilling-equipment hydraulics — cylinders, power units and valves for BOP stacks, spiders and elevators; working pressure up to 35 MPa
- HUADEHydraulic valves and directional control valves for wellhead equipment and BOP control systems
- INIHydraulic components for control systems of drilling and pumping equipment
- INVTOil & gas HV variable-frequency drives for main oil pipeline pumps and GPUs with regenerative braking on service winches
Image credits: Maksim Safiullin (CC BY 3.0) · Wilfra (Public domain) · Robert Nunnally (CC BY 2.0) · Pi3.124 (CC BY-SA 4.0) · LaurelBloch (CC BY-SA 4.0)