New Breakthrough in Polymer-Flooding Produced Water: KFM Active Filter Media Boosts Green Recovery

In the field of oil production, the wide application of tertiary oil recovery technology, also known as enhanced oil recovery, has played an important role in safeguarding national energy security. However, the by-product of this technology, polymer-containing produced water, has become an environmental problem that troubles oilfield enterprises.

Polymer-containing produced water refers to the produced water generated after polymer flooding technology is used in tertiary oil recovery. Because of the presence of oil-displacing agents, usually high-molecular-weight polymers such as polyacrylamide, this type of wastewater has the characteristics of high viscosity, poor flowability and complex composition. Compared with ordinary oilfield produced water, polymer-containing produced water is significantly harder to treat.

According to statistics, major domestic oilfields generate as much as several hundred million cubic meters of polymer-containing produced water every year. If discharged directly without effective treatment, it would not only cause serious environmental pollution but also waste a large amount of recyclable water resource. How to treat polymer-containing produced water efficiently has become an issue that oilfields must face for sustainable development.

Treatment difficulties

The difficulty in treating polymer-containing produced water lies mainly in the following aspects:

First, high viscosity and poor flowability. Residual polymers such as polyacrylamide in the wastewater greatly increase the viscosity of the water, making it flow poorly and easily clogging treatment equipment.

Second, high suspended solids content. Polymers mix with soil and sand from the formation to form large amounts of suspended solids that are difficult to settle. These solids are small in particle size and highly stable, making them hard for conventional filtration equipment to remove effectively.

Third, severe oil-water emulsification. During tertiary oil recovery, crude oil is in full contact with polymer, forming a highly emulsified oil-water emulsion with extremely small oil droplets, usually below 10 microns, which is very difficult to separate.

Fourth, filter media tend to harden. Conventional filter media such as quartz sand and walnut shell have smooth surfaces and lack active groups, so they cannot effectively adsorb polymers. After long-term operation the media easily harden and fail, requiring frequent backwashing or replacement and driving up maintenance costs.

Shortcomings of conventional technologies

In the past, polymer-containing produced water was mainly treated with the following processes:

Gravity settling: suspended solids settle naturally under gravity, but the solids in polymer-containing produced water are small in size and low in density, so settling efficiency is very low.

Conventional flotation: bubbles are generated to carry suspended solids upward for separation, but the effect on highly emulsified polymer-containing produced water is limited.

Ordinary filter media filtration: quartz sand, walnut shell and anthracite are used as media, but these have smooth surfaces and limited porosity, give weak adsorption of polymers and fine suspended solids, and easily harden and fail.

Chemical demulsification: chemicals are added for demulsification, but this increases operating costs and may cause secondary pollution.

Each of these conventional methods has its limitations and can hardly meet the combined requirements of efficient oil removal, thorough filtration, stable operation and lower cost at the same time.

SINOKLE's new solution

In response to the industry pain points of polymer-containing produced water treatment, SINOKLE Technology (Shenzhen) has developed a combined treatment process built aroundCDOFan ozone advanced oxidation unit +CDFUcyclonic dissolved-air flotation + the KFM active filter media filter as its core equipment, using technological innovation to crack the industry's challenge.

The core principle of KFM

The KFM active filter media filter uses a new type of silicate active medium as its filter material. This active medium is produced through 60 precision manufacturing steps and super-hydrophilic modification, giving it the following unique properties:

Melting point as high as 1,200 degrees C: excellent high-temperature resistance.

Specific gravity of about 1.25: moderate density and good backwashing performance.

Odorless and insoluble in water: chemically stable.

Permanently negatively charged surface: the core advantage of KFM.

The remarkable role of the negative charge

The permanent negative charge on the surface of the KFM media is the core of the technology. This negative charge produces two key effects:

First, efficient adsorption: the negative charge exerts electrostatic attraction on positively charged particles and colloidal substances in the water, effectively capturing fine particles below 20 microns. This is a key capability that ordinary filter media cannot achieve.

Second, a self-sterilizing function: the negatively charged environment inhibits bacterial growth, prevents the formation of biological slime on the media surface and extends media service life.

Technical features

The KFM active filter media filter offers the following notable advantages:

1. High filtration accuracy

The filtration accuracy of ordinary media is usually 20-50 microns, whereas with the adsorption effect of the negative charge, the KFM media achieves an actual filtration accuracy of better than 2 microns, markedly improving effluent quality.

2. No hardening and easy washing

After a period of operation, conventional media become clogged with pollutants and harden, requiring frequent backwashing. Because of the electrostatic repulsion of the negatively charged surface, pollutants do not readily adhere to the KFM media, backwashing works well and the media do not harden over long-term operation.

3. Long service life

Ordinary media usually need replacing every 1-2 years, whereas the KFM media can last more than 5 years, giving a lower whole-life cost.

4. Stable effluent

The KFM media is insensitive to water quality fluctuations; even when influent quality varies considerably, the effluent remains consistently up to standard.

5. Strong adaptability

The KFM media suits all types of oilfield wastewater, including ordinary produced water, polymer-containing produced water and fracturing flowback fluid, giving it a wide range of applications.

Application case

The KFM active filter media filter has been successfully applied in a number of oilfield projects with remarkable results.

In a large oilfield's polymer-containing produced water treatment project, the KFM active filter media filter was used as the advanced treatment unit. Actual operating data show:

Suspended solids removal: from 80 mg/L in the influent down to below 5 mg/L.

Particle size distribution: particles above 2 microns are essentially removed.

Backwash cycle: more than 3 times longer than with conventional media.

Effluent quality: consistently meeting the reinjection standard.

The successful implementation of this project solved the polymer-containing produced water treatment problem for the oilfield enterprise, creating good economic and environmental benefits.

Final thoughts

As the country's environmental requirements continue to rise, oilfield wastewater treatment has become a key factor constraining enterprise development. With its unique technical advantages, the KFM active filter media filter provides an efficient, reliable and economical solution for polymer-containing produced water treatment.