A New High-Efficiency Process for Oilfield Produced Water Treatment
1. Characteristics of Oilfield Produced Water
Oilfield produced water is a by-product of the oilfield extraction process and the largest volume of wastewater generated during oil production. Depending on the oilfield location, the quality of the reinjection water, geological conditions and the oil recovery method, the characteristics of produced water are not entirely the same; its general characteristics are as follows: high oil content, particulate impurities, high inorganic salt content, and other properties.
2. SINOKLE Proposes a NewHigh-EfficiencyTreatmentCombinedProcess for Oilfield Produced Water
Targeting Produced Water ProblemsSINOKLEThe new process developed by SINOKLE has the following features: strong shock resistance, stable and reliable performance; purely physical demulsification with no chemicals, no aged oil and no secondary pollution, giving good environmental benefits; a short flow scheme, small footprint, few moving parts, simple operation and low cost; two-stage cyclonic dissolved air flotation with strong shock resistance ensuring stable and reliable subsequent treatment and high economic returns; and advanced filtration technology delivering stable performance and high precision, ensuring consistently compliant water quality.
Item | Oil in water mg/L | Suspended solids mg/L | Median particle size |
Scheme 1 effluent | ≤10 | ≤5 | ≤3 |
Scheme 2 effluent | ≤6 | ≤2 | ≤1.5 |
Scheme 3 effluent | ≤5 | ≤1 | ≤1 |
3. Technical Advantages
Cyclonic dissolved air flotation (CDFU) has clear technical advantages
No. | Technical indicator | Conventional CFU (conventional cyclonic flotation) | Conventional dissolved air flotation | CDFU(cyclonic dissolved air flotation) |
1 | Treated water quality | Oily (and suspended solids containing) wastewater | Oily (and suspended solids containing) wastewater | Oily (and suspended solids containing) wastewater |
2 | Retention time | <3 min | 15~40 min | <5 min |
3 | Oil removal efficiency (single stage) | 60%-80% | 60%~85% | >90% |
4 | Suspended solids removal rate (single stage) | 50%-70% | 50%~70% | >80% |
5 | Removed particle size (>80%) | >10 um | >5 um | >3 um |
6 | Bubble generation method | Jet device or mechanical cutting, etc. | Dissolved air pump / other dissolved air methods | Dissolved air |
8 | Bubble diameter | 300μm ~ 1000μm | 5 um - 100 um (uniformity moderate) | 5μm ~ 30μm |
9 | Air introduction method | No recirculation or partial water recirculation | Partial water recirculation | Partial water recirculation |
10 | Pressure consumption | 0.15 MPa-0.3 MPa (no recirculation); 0.05 MPa-0.1 MPa (partial water recirculation) | 0.05 MPa-0.1 MPa (partial water recirculation) | 0.05 MPa-0.1 MPa (partial water recirculation) |
11 | Control mode | Enclosed operation, automatic control | Manual, open type | Enclosed operation, automatic control |
12 | Waste oil discharge | Pressure oil and slag discharge, no mechanical power | Relies on a scraper, mechanical slag discharge | Pressure oil and slag discharge, no mechanical power |
13 | Technical features | Compact structure, but unstable performance, large chemical dosage, large scum volume, and relatively poor removal of emulsified oil and fine suspended solids. | Long retention time, large footprint, low flotation efficiency, requires chemical addition, and unstable oil and suspended solids removal. | Compact structure, high removal of emulsified oil and fine suspended solids, no chemical agents required, little scum. |
14 | Application scope | Produced water treatment at oilfields or offshore production platforms, etc. | Onshore sites with low requirements on footprint and weight, etc. | Difficult wastewater such as emulsified oil and fine suspended particles at oilfields or offshore platforms |
15 | Structural form | Vertical tank | Reinforced concrete | Pressure vessel, skid-mounted equipment |
4. Application Case
Produced Water Treatment Equipment at an Oilfield
Before treatment: inlet wastewater oil content <= 1000 ppm, SS <= 500 ppm, treatment capacity 2400 m3/d, equipment: two-stage..
After treatment: outlet water oil content <= 10 ppm, SS <= 10 ppm.
