Step-by-Step Breakdown of Flowback Fracturing Fluid Treatment: What CDOF, CDFU, Screw Press and Filter Each Do

Step-by-Step Breakdown of Flowback Fracturing Fluid Treatment

Flowback fracturing fluid is characterized by high viscosity, oil content and suspended solids. SINOKLE's process assigns these different challenges to separate treatment stages, forming the core technical route of "CDOF ozone catalytic oxidation for deep gel-breaking and viscosity reduction + CDFU cyclonic dissolved air flotation for efficient oil and solids removal + precision filtration". This article breaks down each stage in process order.

1. Collection Tank + Gravity Settling

After the flowback fluid returns to the surface, it enters a collection tank, where gravity settling removes the large-particle solids such as sand and silt it carries. This stage consumes no chemicals and serves to protect downstream equipment and reduce the load on subsequent units. At the same time, the collection tank is the reflux node of the entire process — the wastewater discharged from the screw press dewatering returns here.

2. Catalyst Dosing + CDOF: Deep Oxidation, Gel-Breaking and Viscosity Reduction

The flowback fluid is pumped to the CDOF unit for deep oxidation and viscosity reduction; a catalyst is dosed before it enters the CDOF unit to enhance the oxidation effect.

CDOF (an integrated ozone advanced catalytic oxidation and flotation unit) is a patented technology of SINOKLE. It integrates ozone multi-catalytic oxidation, hydraulic cavitation and cyclonic dissolved air flotation, and is a domestically original high-efficiency integrated oxidation and flotation unit capable of rapidly and efficiently removing petroleum, suspended solids, colloids, COD, bacteria and various other pollutants from wastewater.

The unit consists of an oxygen generation system, an ozone generation system, an efficient ozone dosing system, a multi-catalytic reaction system and a cyclonic dissolved air flotation system. It enables the synergistic enhancement of core technologies such as homogeneous and heterogeneous catalysis, cyclonic technology, dissolved air flotation, cavitation, supercritical catalytic oxidation and fully enclosed pressurized oxidation, and has been granted a PCT international patent.

In this process, CDOF's task is to "bring the viscosity down" — unless the colloid and polymer structures are broken open, the subsequent flotation cannot effectively capture the oil and solids.

3. Flocculant + CDFU: Oil and Solids Removal

After gel-breaking, the flowback fluid is dosed with a dedicated flocculant and enters the CDFU unit for flotation. CDFU (Cyclonic Dissolved Gas Flotation Unit) is a patented technology independently developed by SINOKLE with internationally advanced technical levels. It creatively combines cyclonic centrifugal separation, ultrafine bubble generation and dissolved air flotation to achieve efficient, comprehensive removal of multiple pollutants from refractory wastewater. It is a new-generation, domestically pioneered, high-efficiency, compact, enclosed, pressurized flotation technology that rapidly and efficiently separates waste oil, emulsified oil and suspended solids.

4. Screw Press: Float Scum Dewatering and Reflux

The float scum generated by CDOF and CDFU enters the screw press for dewatering, and the discharged wastewater re-enters the collection tank. This stage forms an internal reflux loop within the process: dewatering creates no new external discharge burden, and the reduced scum volume facilitates subsequent handling.

5. Filter: Produced Water Meets Re-Mixing Requirements

The CDFU produced water enters the filter, and the filtered water can satisfy re-mixing (re-injection) use requirements.

6. Stage and Responsibility Overview

7. Engineering Form

The entire process adopts skid-mounted equipment that can be deployed on vehicles to operate at the wellsite, and the filtered water meets re-mixing use requirements.

Conclusion

Viewed stage by stage, the division of labor in this process is very clear: settling for coarse removal, oxidation for gel-breaking, flotation for oil and solids removal, dewatering and reflux, filtration and reuse. Each stage solves only one class of problem, and together they form a complete flowback fluid treatment chain.