Synchronous rig specifications
Technical Specifications
SJ's complete line of workover rigs covers maximum static load ranging from 585kN to 2,250kN, maximum workover depth up to 9,000m (2-7/8” DP), and maximum installed power of 1,260HP. The following tables provide complete specifications for all synchronous rig models.
XJ Series Self-Propelled Workover Rigs — Complete Specifications
The following table provides complete technical parameters for all XJ series self-propelled workover rigs, including both single-engine and dual-engine synchronous configurations. Dual-engine parallel operation is standard on larger models and optional on mid-range models.
| Model | Workover Depth 2-7/8″ DP (m) | Workover Depth 3½″ DP (m) | Nominal Hook Load (kN) | Max Static Load (kN) | Drawworks HP | Wireline Dia. (mm) | Traveling System | Mast Clearance (m) | Floor Height (m) |
|---|---|---|---|---|---|---|---|---|---|
| XJ250 | 2,000 | — | 400 | 675 | 250 | φ22 | 3×4 | 21.0 | 2.2 |
| XJ350 | 3,200 | 2,500 | 600 | 900 | 350 | φ26 | 3×4 | 31.7 | 3.7 |
| XJ450 | 4,500 | 3,500 | 800 | 1,125 | 450 | φ26 | 4×5 | 34.0 | 3.7 |
| XJ550 | 5,800 | 4,500 | 1,000 | 1,350 | 550 | φ26 | 4×5 | 34.0 | 4.5 |
| XJ650 | 7,000 | 5,500 | 1,200 | 1,470 | 650 | φ29 | 4×5 | 35.0 | 4.5 |
| XJ1000 | 8,000 | 6,500 | 1,500 | 1,800 | 750 | φ29 | 5×6 | 38.0 | 6.0 |
| XJ1200 | 9,000 | 7,500 | 1,800 | 2,250 | 1,000 | φ32 | 5×6 | 39.3 | 6.7 |
Additional specification notes for XJ series:
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Max static load ranges from 675kN (XJ250) to 2,250kN (XJ1200)
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Installed power ranges from 235HP to 1,300HP across the product line
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Racking board height is uniformly 17.2m (to rig floor) for XJ350 through XJ1200 models
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Carrier drive type progresses from 6×6 (XJ250) to 14×10 (XJ1200), reflecting increased weight and capacity
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All XJ series rigs can be configured for single‑engine or dual‑engine paralleling operation
XJ1000 Dual-Engine Workover Rig — Detailed Specifications
The XJ1000 is a large self‑propelled workover equipment with dual engines, primarily used for medium and deep well workover, oil testing, fishing, and pumping operations. The double engine compounding power system provides operational flexibility and redundancy.
| Parameter | Specification |
|---|---|
| Workover Depth (2-7/8″ DP) | 8,000 m |
| Workover Depth (3½″ DP) | 6,500 m |
| Workover Depth (4½″ DP) | 5,000 m |
| Max Static Hook Load | 1,800 kN |
| Drawworks Horsepower | 750 hp |
| Traveling System | 5×6 |
| Wireline Diameter | φ29 mm |
| Mast Clearance Height | 38 m |
| Substructure Floor Height | 6 m |
| Carrier Drive Type | 14×8 |
| Power Configuration | Dual‑engine standard with paralleling gearbox |
Technical data source: SJ Petroleum Machinery Series of Self-propelled Workover Rigs catalog.
XJ1200 Dual-Engine Workover Rig — Detailed Specifications
The XJ1200 is SJ's highest‑capacity workover rig, designed for ultra‑deep workover operations up to 9,000m.
| Parameter | Specification |
|---|---|
| Workover Depth (2-7/8” DP) | 9,000 m |
| Workover Depth (3½” DP) | 7,500 m |
| Workover Depth (4½” DP) | 6,000 m |
| Max Static Hook Load | 2,250 kN |
| Drawworks Horsepower | 1,000 hp |
| Traveling System | 5×6 |
| Wireline Diameter | φ32 mm |
| Mast Clearance Height | 39.3 m |
| Substructure Floor Height | 6.7 m |
| Carrier Drive Type | 14×10 |
| Power Configuration | Dual‑engine standard with paralleling gearbox |
Technical data source: SJ Petroleum Machinery Series of Self-propelled Workover Rigs catalog.
XJ750 Dual-Engine Workover Rig — Detailed Specifications (Mid-Range Synchronous Model)
The XJ750 adopts double Caterpillar C15 engines with Allison transmissions. It is the best‑selling mobile drilling rig for both oil drilling and workover purposes, reaching 3,000m drilling depth and 8,000m workover depth with 1,700kN max hook load.
| Parameter | Specification |
|---|---|
| Drilling Depth (4½" DP) | 3,000 m |
| Workover Depth (2-7/8” DP) | 8,000 m |
| Workover Depth (3½” DP) | 6,500 m |
| Max Hook Load | 1,700 kN |
| Effective Lines | 10 |
| Wireline Diameter | φ29 mm |
| Traveling System | 6×5 |
| Mast Net Height | 38 m |
| Drawworks Rated Power | 373 kW (500 hp) × 2 |
| Engines | 2 × Caterpillar C15 ACERT AIII, 325 kW (440 hp) each |
| Transmissions | 2 × Allison M5610HR |
| Racking Board Height | 24 m |
| Racking Board Capacity | 3,000 m (4½” DP) |
| Max Wind Velocity | 30 m/s |
| Carrier Drive Type | 14×8 |
| Max Travel Speed | 45 km/h |
Technical data source: SJ PETRO XJ750 product specification.
XJ450 / XJ550 / XJ650 — Dual-Engine Optional Configurations
These mid‑range workover rigs are available with single‑engine or dual‑engine paralleling operation. Specifications below for reference:
| Parameter | XJ450 | XJ550 | XJ650 |
|---|---|---|---|
| Max Hook Load (kN) | 1,125 | 1,350 | 1,470 |
| Minor Repair Depth (2-7/8" Tubing, m) | 5,500 | 7,000 | 8,500 |
| Heavy Repair Depth (2-7/8” DP, m) | 4,500 | 5,800 | 7,000 |
| Drawworks HP | 450 | 550 | 650 |
| Mast Height (m) | 31.3 | 32 | 34 |
| Drive Model | 10×8 | 10×8 | 12×8 |
| Power Configuration | Single or dual‑engine | Single or dual‑engine | Single or dual‑engine |
Technical data source: XJ series workover rig product listing.
XJ1800 Dual-Engine Workover Rig — Specifications
The XJ1800 uses a mature and reliable double engine compound power system with imported CAT engines and Allison transmissions. Power devices can work together or individually, with paralleling boxes distributing input from multiple power sources to the rig's rotating systems.
| Parameter | Specification |
|---|---|
| Max Static Hook Load | 1,800 kN |
| Workover Depth (73mm DP) | 8,000 m |
| Workover Depth (88.9mm DP) | 6,500 m |
| Traveling System | 5×6 |
| Wireline Diameter | φ32 mm |
| Mast Clearance Height | 38 m |
| Floor Height | 6 m |
| Engines | 2 × CAT C15, 540 bhp each |
| Transmissions | 2 × Allison M5620AR |
| Drawworks Fastline Pull (max) | 280 kN |
| Rotary Table Max Speed | 450 rpm |
| Drive Type | 14×8 self‑propelled |
| Chassis | Heavy‑duty workover special 14×8 chassis with strong cross‑country power |
Technical data source: XJ1800 double engine workover rig product specification.
AC-VFD and DC Synchronous Drilling Rigs — Land Drilling Specifications
For land drilling applications, SJ offers ZJ series drilling rigs with AC-VFD and AC‑SCR‑DC drive systems, featuring dual‑motor and quad‑motor synchronous control.
ZJ70/4500DS AC-SCR-DC Drilling Rig — Dual-Motor Drawworks
The ZJ70/4500DS is a desert drilling rig with AC‑SCR‑DC drive system providing infinitely variable speed control for the drawworks, rotary table, and mud pumps. The dual‑motor drawworks configuration ensures balanced load sharing through master‑slave control architecture.
| Parameter | Specification |
|---|---|
| Nominal Drilling Depth (114mm DP) | 7,000 m |
| Max Hook Load | 4,500 kN |
| Drawworks Rated Power | 1,470 kW (2,000 hp) |
| Drive System | AC‑SCR‑DC infinitely variable speed control |
| Drawworks Configuration | Dual‑motor with master‑slave control |
| Mast Type | Front-opening, single-pole, integral lift |
| Mast Height | 45 m |
| Effective Lines | 6×7 |
| Wireline Diameter | φ35 mm |
| Rotary Table Opening | 952 mm |
| Mud Pumps | 2 × FB-1300 (1,300 hp each) |
| Mud Pump Max Pressure | 35 MPa |
| Solid Control System | 4‑stage purification system |
| Mud Tank Capacity | 280 m³ |
| Generator Sets | 5 × 700 kW (total 3,500 kW) with wind and sand protection |
ZJ90DB AC-VFD Drilling Rig — Quad-Motor Synchronous Drive
The ZJ90DB is SJ's most advanced ultra‑deep well synchronous rig, proven in 9,000m drilling operations including 23 wells in Northwest China reaching 9,270m depth. Six of these rigs have been exported to Kuwait — the first large‑scale batch export of Chinese super deep well drilling rigs to the Middle Eastern high-end market. The rig uses advanced AC-VFD technology with quad‑motor synchronous control.
| Parameter | Specification |
|---|---|
| Drilling Depth (4½” DP) | 9,000 m |
| Max Hook Load | 5,850 kN (1,315,000 lb) |
| Drawworks Power | 2,200 kW (3,000 hp) |
| Drive System | AC-VFD with quad‑motor synchronous control |
| Motor Control | Master-slave with load sharing |
| Control Architecture | PLC-based with SIMOLINK communication |
| System Power Supply | AC 600‑690V |
| Mast Design | Dual-beam double-triangular column |
| Mast Weight Reduction | 30% vs conventional designs |
| Rig-Up/Down Time | Two days |
| High-Temperature Rating | 50°C with heavy sandstorms |
| Core Components | 100% domestically manufactured; 90%+ overall domestic content |
Technical data source: SJ Petroleum Machinery ZJ90DB desert rig deployment data and news reports. Power supply specifications from industry standard AC‑VFD drilling rig technology references.
ZJ Series AC-VFD Drilling Rigs — Complete Model Range
The following table provides specifications for SJ's complete ZJ series AC-VFD drilling rigs with synchronous drive capability:
| Model | Drilling Depth (4½" DP, m) | Max Hook Load (kN) | Drawworks Power (kW/hp) | Motor Configuration | Drive Type |
|---|---|---|---|---|---|
| ZJ30/1700DB | 3,000 | 1,700 | 600 / 800 | Single or dual‑motor | AC-VFD |
| ZJ40/2250DB | 4,000 | 2,250 | 800 / 1,100 | Single or dual‑motor | AC-VFD |
| ZJ50/3150DB | 5,000 | 3,150 | 1,100 / 1,470 | Dual‑motor standard | AC-VFD |
| ZJ70/4500DB | 7,000 | 4,500 | 1,470 / 2,000 | Dual or quad‑motor | AC-VFD |
| ZJ90/6750DB | 9,000 | 6,750 | 2,200 / 3,000 | Quad‑motor | AC-VFD |
Note: ZJ series models use AC‑VFD electric drive with master‑slave motor control and regenerative braking capability. ZJ90 models use quad‑motor synchronous drawworks configurations.
BigEasy Series — Trailer-Mounted AC-VFD Synchronous Rigs
The BigEasy series (BE770 and BE550) are new conceptual AC VFD drilling rigs jointly developed by SJ and LOADMASTER, featuring special module, trailer‑mounted structure and fast transportation without a crane. The entire rig installs using only six trailers.
| Parameter | BE550 (ZJ40D) | BE770 (ZJ50D) |
|---|---|---|
| Drilling Depth (4½" DP) | 4,000 m | 5,000 m |
| Max Hook Load | 2,450 kN / 550,000 lb | 3,430 kN / 770,000 lb |
| Drive System | AC-VFD electric | AC-VFD electric |
| Motor Configuration | AC synchronous (dual-motor capable) | AC synchronous (dual-motor capable) |
| Structure | Full trailer-mounted modules | Full trailer-mounted modules |
| Installation | Six trailers, no crane required | Six trailers, no crane required |
| Mast Type | Three-section telescoping, hydraulic raise | Three-section telescoping, hydraulic raise |
| Substructure | Parallelogram design, folding transport | Parallelogram design, folding transport |
| Drawworks Position | High-mounted for AC drive | High-mounted for AC drive |
| Control | Integrated instrumentation in driller’s cabin | Integrated instrumentation in driller's cabin |
| Control Architecture | PLC-based with VFD integration | PLC-based with VFD integration |
Technical data source: SJ and LOADMASTER BigEasy series joint development specification. AC‑VFD drilling rig specifications from industry standard technical references.
[Product images: SJ’s BigEasy series trailer-mounted synchronous rig — six-trailer, crane-free installation for remote operations]
Technical Data — Synchronous Drive Control Specifications
Understanding the drive system specifications is essential for proper configuration and maintenance.
Diesel-Mechanical Synchronous — Dual-Engine Paralleling
| Parameter | Specification |
|---|---|
| Power source | Two diesel engines of identical or matched rating |
| Paralleling mechanism | Transfer case or paralleling gearbox with overrunning clutches |
| Operation modes | Single engine, dual engine parallel (full power) |
| Load sharing | Mechanical or hydraulic load balancing |
| Switching logic | Manual or automatic (emergency power transfer) |
| Engine models (typical) | CAT C9, C15, C18, CAT3512; Allison transmission integration |
| Applicable rigs | XJ series workover rigs (XJ750, XJ1000, XJ1200, XJ1800) |
| Transmission (typical) | Allison 4700/4700 OFS, 4700/5600/5620, M5610HR |
AC-VFD Synchronous — Master-Slave Dual-Motor Control
| Parameter | Specification |
|---|---|
| Master mode | Speed control (closed-loop vector) |
| Slave mode | Torque control (torque following) |
| Communication method | High-speed fieldbus (Profibus, SIMOLINK) or dedicated fiber optic link |
| Load sharing accuracy | Perfect load equalization between motors |
| Dynamic response | Instantaneous torque tracking |
| Control integration | PLC-based with touchscreen HMI |
| Brake system | Regenerative braking (energy recovery) or dynamic braking resistor bank |
| Applicable rigs | ZJ series AC-VFD drilling rigs (ZJ30DB through ZJ90DB) |
| Motor type | AC induction or synchronous AC motors |
| Overload capacity | 200% torque for 60 seconds (typical) |
AC-VFD Synchronous — Quad-Motor Drawworks Control
| Parameter | Specification |
|---|---|
| Number of drive motors | Four (typical for ZJ90 class) |
| Motor control | Master-slave with distributed torque reference |
| Communication | High-speed synchronization bus between all four drives |
| System power | AC 600‑690V main bus |
| Drive type | Dedicated inverter per motor (quad-inverter configuration) |
| Load distribution | Electronic torque averaging |
| Failure mode | Continued operation at 50‑75% capacity with one motor offline |
| Synchronization accuracy | Within electrical angle tolerance |
| Gearbox protection | Torque limit monitoring to prevent mechanical damage |
| Application | 9,000m ultra‑deep well drilling rigs (ZJ90DB) |
Key Components — Mast and Substructure Specifications
For mast and substructure specifications on workover rigs, refer to the XJ series mast height and traveling system data provided above. All SJ masts and substructures comply with API Spec 4F.
API 4F Mast Compliance
All SJ vertical rig structures (masts, derricks, and substructures) are designed and manufactured in strict compliance with API Spec 4F (latest edition, PSL 1 or PSL 2 as required). The mast (derrick) with different loading is designed and fabricated according to API 4F.
Mast specifications across XJ series:
| XJ Model | Mast Clearance Height (m) | Racking Board Height (m) | Floor Height (m) | Traveling System |
|---|---|---|---|---|
| XJ250 | 21.0 | 7.7 | 2.2 | 3×4 |
| XJ350 | 31.7 | 17.2 | 3.7 | 3×4 |
| XJ450 | 34.0 | 17.2 | 3.7 | 4×5 |
| XJ550 | 34.0 | 17.2 | 4.5 | 4×5 |
| XJ650 | 35.0 | 17.2 | 4.5 | 4×5 |
| XJ1000 | 38.0 | 17.2 | 6.0 | 5×6 |
| XJ1200 | 39.3 | 17.2 | 6.7 | 5×6 |
Technical data source: SJ Petroleum Machinery Series of Self-propelled Workover Rigs catalog.
Product Types — SJ Synchronous Rig Configurations
| Type | Configuration | Drive Type | Depth Range | Primary Application |
|---|---|---|---|---|
| Type 1 | XJ Series Dual-Engine Workover Rig | Diesel-mechanical with paralleling gearbox | 2,000–9,000m workover | Workover, fishing, oil testing, pumping |
| Type 2 | XJ Series Heavy-Duty Workover Rig (XJ750/XJ1000/XJ1200/XJ1800) | Dual-engine standard, paralleling gearbox | 8,000–9,000m workover; 3,000m drilling | Heavy workover, mobile drilling |
| Type 3 | ZJ Series AC-VFD Synchronous Land Rig | AC-VFD electric with master-slave motor control | 3,000–9,000m drilling | Conventional land drilling, multi-well pad |
| Type 4 | ZJ90DB Quad-Motor Ultra-Deep Rig | AC-VFD with quad-motor master-slave control | 9,000m (field-proven to 9,270m) | Ultra-deep HPHT, desert drilling |
| Type 5 | BigEasy Trailer-Mounted Synchronous Rig (BE550/BE770) | AC-VFD electric, trailer-mounted, crane-free | 4,000–5,000m drilling | Remote operations, no crane support |
Type 1: XJ Series Dual-Engine Workover Rig
Self-propelled, truck-mounted workover rigs with dual-engine paralleling capability. Available from XJ450 (optional) through XJ1200 (standard). XJ1000 and XJ1200 models feature dual-engine as standard configuration.
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Best for: Workover operations requiring continuous uptime, medium to deep well intervention
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Depth range: 2,000–9,000m workover depth
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Key advantage: Emergency power switching keeps rig running when one engine fails
Type 2: XJ Series Heavy-Duty Workover Rig (XJ750/XJ1000/XJ1200/XJ1800)
Larger-capacity XJ models with dual-engine standard. XJ750 adopts double CAT C15 engines with Allison transmissions, reaching 8,000m workover depth and 3,000m drilling depth. XJ1000 and XJ1200 are primarily used for medium and deep well workover, oil testing, fishing, and pumping operations.
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Best for: Heavy workover, mobile drilling, deep well interventions
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Depth range: 8,000–9,000m workover; 3,000m drilling
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Key advantage: Dual-engine as standard configuration with maximum power availability
Type 3: ZJ Series AC-VFD Synchronous Land Rig
Full-scale land drilling rigs with AC-VFD electric drive and master-slave motor control. Available from ZJ30 through ZJ90 with dual or quad-motor drawworks configurations. Features PLC-based control with VFD integration and regenerative braking.
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Best for: Conventional land drilling requiring maximum power efficiency and uptime
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Depth range: 3,000–9,000m drilling depth
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Key advantage: Perfect load sharing eliminates mechanical "nodding” and "shaking”
Type 4: ZJ90DB Quad-Motor Ultra-Deep Synchronous Rig
SJ's most advanced synchronous rig. Quad-motor drawworks with master-slave load balancing. Six rigs exported to Kuwait — first large-scale batch export of Chinese super deep well drilling rigs to the Middle Eastern high-end market. Core components 90%+ domestically manufactured.
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Best for: Ultra-deep HPHT drilling, Middle Eastern desert operations
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Depth range: 9,000m (field-proven to 9,270m)
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Key advantage: Continuous power across all depth ranges; 50°C desert rating
Type 5: BigEasy Trailer-Mounted AC-VFD Synchronous Rig
New conceptual AC VFD drilling rigs jointly developed by SJ and LOADMASTER. Features special module, trailer-mounted structure, and fast transportation without a crane. Entire rig installs using only six trailers.
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Best for: Remote desert operations, areas without heavy crane support
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Depth range: 4,000–5,000m drilling depth
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Key advantage: Fast mobilization with synchronous drive reliability
*[Product images: SJ's ZJ90DB quad-motor synchronous rig in Kuwait — field-proven in 50°C desert operations with quad-motor master-slave control]*
Applications — Where SJ Synchronous Rig Specifications Matter Most
| Application | Recommended Model | Drive Type | Why Synchronous Specifications Matter |
|---|---|---|---|
| Shallow to medium well workover | XJ450 (dual‑engine optional) | Diesel-mechanical paralleling | Single-engine sufficient for light loads; dual-engine available for peak demand |
| Medium to deep well workover | XJ650–XJ1000 (dual‑engine standard) | Diesel-mechanical paralleling | Emergency power switching prevents downtime; both engines for heavy lifts |
| Heavy workover with mobile drilling | XJ750 or XJ1800 (dual‑engine standard) | Diesel-mechanical paralleling | 3,000m drilling depth + 8,000m workover depth from single synchronous platform |
| Ultra-deep workover (9,000m) | XJ1200 (dual‑engine standard) | Diesel-mechanical paralleling | Largest capacity workover rig with dual-engine redundancy |
| Land drilling – conventional | ZJ series (dual‑motor standard on large models) | AC-VFD master‑slave | Perfect load sharing; regenerative braking; 200% overload capacity |
| Land drilling – ultra-deep (9,000m) | ZJ90DB (quad‑motor) | AC-VFD master‑slave | Four motors sharing load; continued operation at 50‑75% if one fails |
| Remote drilling – no crane support | BigEasy BE550/BE770 (trailer-mounted) | AC-VFD electric, crane‑free | Synchronous drive in mobile package; six trailers, no crane required |
| Desert ultra-deep drilling | ZJ90DB with desert package (quad‑motor) | AC-VFD master‑slave | 50°C rating; sandstorm protection; quad-motor reliability |
| Pad drilling / cluster wells | ZJ series with walking system | AC-VFD master‑slave | Distributed motor loads for frequent moves and restart cycles |
Market Context — Global Demand for Synchronous Rigs
The global workover rigs market continues to expand, driven by increasing demand for well intervention in mature fields and the ongoing replacement of older single-engine rigs with more reliable synchronous configurations. The MENA region is forecast to see an average rig demand of 680 land drilling rigs between 2025 and 2029 — a 31% increase over the previous five years. Within this market, synchronous rigs (dual-engine and multi-motor configurations) are the fastest-growing segment as operators prioritize uptime and reduced NPT.
[Product images: SJ’s dual-engine control panel — load balancing and engine status monitoring for synchronous operation]
Why Choose SJ for Your Synchronous Rig Specifications?
1. Complete synchronous product line — workover and drilling, diesel and electric
SJ is one of the few manufacturers offering both diesel‑mechanical dual-engine workover rigs (XJ series) and AC‑VFD/AC‑SCR‑DC dual/quad-motor drilling rigs (ZJ series) — plus trailer-mounted synchronous rigs for remote operations (BigEasy series). One manufacturer, all synchronous drive technologies.
2. Field-proven across thousands of wells
SJ's dual-engine workover rigs have been field-proven across China’s major oilfields and international markets. The XJ1000 and XJ1200 dual-engine workover rigs are standard offerings with documented performance in medium and deep well workover, oil testing, fishing, and pumping operations. The ZJ90DB quad-motor rig has drilled to 9,270m in Northwest China, and six units are now operating in Kuwait's northern oilfields.
3. API-certified — every component meets global standards
All SJ synchronous rigs are designed and manufactured in compliance with API Spec Q1, 4F, 7K, 8C, 6A, and 16C. Manufacturing processes can be supervised by customers and inspected by any third-party certification agency.
4. Vertically integrated manufacturing — complete quality control
SJ designs, manufactures, and tests all synchronous rig components in-house across seven production lines and three assembly lines. Full vertical integration means you’re not assembling components from multiple vendors and hoping they integrate.
5. 50,000 m² assembly yard with full FAT before shipment
Every synchronous rig undergoes full factory acceptance testing (FAT) at SJ's 50,000 m² rig assembly yard with 24 rigging-up positions, where 750‑ton load tests can be performed. Customer-witnessed testing is available.
6. Global after-sales support
SJ maintains regional support infrastructure across the Middle East and other key markets. For the six-rig ZJ90DB batch export to Kuwait, SJ provided comprehensive field support.
7. 70+ years of manufacturing heritage
From our founding in Lanzhou in 1941 to the present day, SJ has delivered more drilling and workover rigs to more oilfields than any other Chinese manufacturer. Our Technical Center employs 314 engineers and researchers across three research institutes, and we are authorized to operate a post-doctoral research station.
Frequently Asked Questions (FAQ)
Q1: What is the difference between "dual-engine paralleling” and "master-slave motor control” in synchronous rigs?
Dual-engine paralleling (diesel-mechanical) uses two diesel engines operating in parallel through a mechanical transfer case or paralleling gearbox. Engines can run individually or together, with automatic load sharing. This configuration is common on XJ series workover rigs. Master-slave motor control (AC-VFD electric) uses two or more AC electric motors driving the same gearbox, controlled by VFDs where one motor operates in speed mode (master) and the others in torque mode (slave) for perfect load sharing. This configuration is common on ZJ series AC-VFD drilling rigs.
Q2: What drilling depths can SJ synchronous rigs handle?
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XJ series dual-engine workover rigs: 2,000–9,000m workover depth (depending on model)
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XJ750: 8,000m workover depth, 3,000m drilling depth
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ZJ series land drilling rigs: 3,000–9,000m drilling depth (depending on model)
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ZJ90DB: 9,000m (field-proven to 9,270m)
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BigEasy series: 4,000–5,000m drilling depth
Q3: What is the operating temperature range for SJ synchronous rigs?
SJ synchronous rigs are available in multiple environmental ratings:
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Standard: -20°C to +50°C
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Desert package: +55°C continuous operation with enhanced cooling and sand protection (ZJ90DB Kuwait configuration)
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Arctic package: -45°C with low-temperature steel and hydraulic fluids
Q4: What API certifications do SJ synchronous rigs hold?
All SJ synchronous rigs are API Q1, ISO 9001, and HSE management system certified, with API monograms for Spec 4F (structures), 7K (drilling and well-servicing equipment), 8C (hoisting equipment), 6A (wellhead equipment), and 16C (choke and kill manifolds). Masts are designed and fabricated according to API 4F.
Q5: What is the difference between AC-VFD and AC-SCR-DC drive on ZJ series synchronous rigs?
AC-VFD (Variable Frequency Drive): AC motors with VFD control, typically using master-slave architecture for synchronous operation. Offers regenerative braking, higher efficiency, reduced maintenance. AC-SCR-DC (Silicon Controlled Rectifier — Direct Current): DC motors with SCR power conversion using AC generators and rectifiers. Simpler technology with proven reliability for medium-depth drilling. SJ offers both depending on customer preference and operational requirements.
Q6: What is the benefit of quad-motor drawworks on the ZJ90DB?
Four AC motors driving the same gear train through master-slave control provides distributed load sharing, reduced stress on each motor, continued operation at 50‑75% capacity if one motor fails, and smoother power delivery for ultra-deep well drilling.
Q7: What is the maximum hook load across SJ synchronous rigs?
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Light workover (XJ250): 400kN nominal / 675kN max static
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Medium workover (XJ450-XJ550): 800‑1,000kN nominal / 1,125‑1,350kN max static
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Heavy workover (XJ1000-XJ1200): 1,500‑1,800kN nominal / 1,800‑2,250kN max static
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Land drilling (ZJ70): 4,500kN max hook load
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Land drilling (ZJ90): 5,850kN max hook load
Q8: Can SJ synchronize more than two engines or motors?
Yes. For ultra-deep well drilling rigs, SJ offers quad-motor configurations (four AC motors) using distributed master-slave control architecture. For diesel workover rigs, dual-engine is standard; larger configurations are available on custom order.
Q9: What is the lead time for an SJ synchronous rig?
Lead times vary based on model, depth rating, and configuration:
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XJ series dual-engine workover rigs (standard): 6‑9 months from order confirmation to FAT
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ZJ series AC-VFD synchronous drilling rigs: 8‑12 months
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ZJ90DB quad-motor synchronous rig: 10‑14 months
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BigEasy series (BE550/BE770): 8‑10 months
Q10: How does SJ verify synchronous control performance before shipment?
All SJ synchronous rigs undergo full factory acceptance testing (FAT) at our 50,000 m² assembly yard. For AC-VFD master-slave systems, load sharing validation is performed with both motors operating under full load to verify perfect torque balancing. Customer-witnessed testing is available.
