SAGD (Steam Assisted Gravity Drainage) Water Treatment
De-oiling and boiler feed water treatment for thermal heavy-oil recovery — recycling produced water to OTSG and drum-boiler steam.
Sector overview
SAGD injects high-quality steam into the reservoir to mobilize bitumen, which returns as a hot emulsion of water, bitumen and dissolved silica, hardness and organics. Project economics demand recycling roughly 90%+ of produced water back to steam.
Two linked duties define the plant: (1) de-oiling to strip residual bitumen and organics, and (2) boiler feed water (BFW) conditioning — warm/hot lime softening or ion exchange, with evaporation where required — to meet once-through steam generator (OTSG) or drum-boiler specifications, which are silica- and hardness-limited.
Process overview and application parameters
Process steps
- 1Skim tank / FWKOHot tankage recovers bulk bitumen from the returning emulsion.
- 2Induced gas flotationRemoves dispersed bitumen ahead of the oil-removal filters.
- 3Oil removal filters (nutshell)Walnut-shell ORFs polish oil to protect downstream softening.
- 4Warm / hot lime softenerPrecipitates silica and hardness for OTSG-grade water.
- 5After-filter + weak-acid IXPolishes residual hardness — to <1 mg/L for drum boilers.
- 6Evaporator (option)Mechanical vapor compression for drum-boiler / near-ZLD quality.
Application parameters (feed water)
| Oil / bitumen in produced water | 100 – 2,000 mg/L |
| Temperature | 80 – 95 °C (hot process) |
| Dissolved silica | 150 – 400 mg/L |
| Total hardness | 10 – 500 mg/L |
| TDS | 2,000 – 10,000 mg/L |
| Organics / TOC | Elevated |
| pH | 7 – 9 |
Modular treatment train
Modular Process-Train Schematic · Block flow
What makes this water hard — and how we solve it
Silica scaling in OTSG tubes.
Warm/hot lime softening (or evaporation) controls silica to the boiler limit.
Residual hardness for drum boilers.
Weak-acid cation ion exchange polishes hardness to <1 mg/L.
Oil fouling of softeners, IX and membranes.
Robust upstream de-oiling (IGF + nutshell oil-removal filters) protects the BFW train.
High-temperature operation and lime-sludge handling.
Hot-process design and materials; thickener plus filter press for sludge dewatering.
Filtration approach & system required
Approach
De-oiling first (IGF + nutshell oil-removal filters), then media after-filtration of the softened water.
Evaporator path selected where drum-boiler or near-zero-liquid-discharge quality is required.
Filtration system / unit operations
- Skim tanks / FWKO and induced gas flotation
- Oil removal filters (walnut-shell)
- Warm / hot lime softener with clarifier
- After-filters and weak-acid cation ion exchange
- Mechanical vapor compression (MVC) evaporator (option)
- Sludge thickening and filter-press dewatering
System specification, performance & layout
Indicative system specification
| Capacity | Matched to steam-oil ratio (SOR) and plant rate |
| Process | Hot-process trains; evaporator option for ZLD |
| Materials | CS / SS for high-temperature service |
| Climate | Cold-climate winterized buildings |
| Automation | PLC / SCADA with hardness & silica analyzers |
Performance parameters (guaranteed, tested)
| Oil in BFW | < 1 – 5 mg/L |
| Silica (OTSG) | Within OTSG limit; near-zero for drum boilers |
| Hardness (drum boiler) | < 1 mg/L |
| Water recycle | > 90 % |
| TOC | Controlled to protect boilers |
Plant layout & general arrangement
- •Large central plant: produced-water tank farm, flotation, softener/clarifier, IX and evaporator building.
- •Dedicated sludge-handling area with thickener and filter press.
- •Winterized, enclosed buildings for cold-climate operation.
Project deliverables
- 1Water characterization & treatability study (design basis)
- 2Process selection, mass balance, P&ID and treatment-train design
- 3Pilot / trial skid where required to de-risk performance
- 4Detailed mechanical, civil, structural and E&I engineering
- 5Equipment design, fabrication and Factory Acceptance Test (FAT)
- 6Delivery, site construction and mechanical installation
- 7Electrical installation, instrumentation, controls & SCADA integration
- 8Commissioning, performance test to guaranteed spec & operator training
- 9Continuous Operations & Maintenance (O&M) and remote monitoring
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