Produced Water Reinjection Treatment Technology for Oilfields
1. Overview of reinjection water
As national environmental standards keep tightening, oilfields are moving towards total pollutant control and compliant reinjection. Faced with increasingly strict rules, water treatment systems must run continuously and stably, ensure compliant discharge and eliminate any risk of leakage. At the same time, as fields enter mid-to-late life the water cut of produced fluid keeps rising, placing higher demands on the efficiency, compactness and stability of treatment equipment. However, current produced water systems generally suffer from weak shock resistance, fluctuating performance and complex operation and maintenance, which constrains further oilfield development. Reinjection water treatment has therefore become an urgent need in oilfield produced water management.
2. Conventional reinjection water technologies and their limits
Previous reinjection water processes have clear shortcomings. Inclined plates with walnut shell or fibre-ball filtration, for instance, are permeable, but chemical dosing and aged oil reduce system reliability and shock resistance, making effluent quality hard to keep stable. Combinations of settling tanks with centripetal flotation, fibre-ball or multimedia filters and ceramic membranes involve complex flows, high energy demand and high operating cost, and also suffer poor shock resistance and marked effluent fluctuation. Processes using settling tanks with centripetal flotation, fibre-ball or multimedia filters and ultrafiltration membranes struggle in high-temperature environments; membrane materials adapt poorly to crude oil, long-term stability is insufficient, and high salinity adds to the difficulty and cost of operation and maintenance.
3. Advantages of SINOKLE reinjection water treatment
SINOKLE’s new-generation reinjection water process centres on cyclonic dissolved-air flotation and integrates an HAC cyclone separator, high-precision active filters and SiC microfiltration membranes into an integrated solution for oilfield produced water. The process achieves short-flow treatment of produced fluid without chemical agents, runs stably, meets reinjection standards, produces skimmed oil with low water content and allows the solids to be filter-pressed and safely transported off site.
Reinjection water treatment equipment
4. Two SINOKLE reinjection water schemes
SINOKLE has designed two process schemes to suit different project conditions, processes and treatment difficulties, meeting produced water standards A1 and A2 respectively.
Scheme 1: two-stage HAC + two-stage CDFU + two-stage KFM filters, achieving the A2 standard
Scheme 2: two-stage HAC + two-stage CDFU + SiC membrane filter + CDFU, achieving the A1 standard
Treatment performance
5. Features of the SINOKLE reinjection water process
The schemes offer the following advantages:
(1) Mature process with strong shock resistance and stable, reliable performance;
(2) Purely physical demulsification — no chemicals, no aged oil, no secondary pollution, with good environmental benefits;
(3) Short process flow, small footprint, few operating units, simple operation and relatively low operating cost;
(4) Two-stage cyclonic oil-water separators and two-stage cyclonic dissolved-air flotation make downstream treatment more stable and reliable;
(5) Advanced filtration technology ensures stably compliant water quality.
These schemes not only bring discharge quality up to national standards but also help raise oilfield production efficiency and overall economic performance.
