A New Breakthrough in Oilfield Produced Water Treatment: CDFU Integrated Flotation and Cyclone Technology Drives Industry Transformation
According to the World Energy Outlook 2023 report, as the global energy mix gradually shifts toward low carbon, overall oil demand from the road transport sector is expected to fall by more than 50% by 2050. The share of renewable energy is expected to rise from 55% in 2021 to about 70% in 2050. Nevertheless, over the next decade or so global oil consumption will remain broadly stable, and oil will continue to play a key role in the global energy system.
As the world's largest energy consumer and a major driving force of demand growth, China is in a phase of economic structural transition. At present, China accounts for about 26% of global total energy consumption and 35% of net global energy consumption growth. This reality means that, in order to safeguard energy supply security and improve the national energy layout, China still needs to keep advancing oil exploration and development over the next decade.
Figure 1. Changes in oil demand under three different scenarios
However, as domestic oil extraction continues to deepen, more and more “three-low” reservoirs (low output, low permeability, low abundance) are gradually brought into development, and tertiary oil recovery processes such as polymer flooding are widely used, causing marked changes in the water quality characteristics of oilfield produced water: higher viscosity, intensified emulsification and finer suspended solids, with the overall water quality becoming more complex. If treated produced water is reinjected into the formation without meeting standards, it may cause pore plugging in the reservoir, which not only increases the difficulty of subsequent water injection operations but also reduces crude oil recovery efficiency.
Effective purification of produced water has therefore become a key challenge constraining the sustainable development of the industry throughout the oil production process. Conventional treatment methods cover gravity settling, air flotation, centrifugal separation, filtration and coalescence, while more advanced technologies include ultrafiltration, activated carbon adsorption and biological treatment. Faced with increasingly complex water quality conditions, a single treatment process can hardly meet actual needs any more, and an integrated treatment model in which multiple technologies work together has become an inevitable direction of development.
Over the past decades, many research institutions and enterprises around the world have carried out continuous R&D on compact produced water treatment technologies under the concept of “high-efficiency unit technologies and integrated process combinations”. Among them, compact flotation unit (CFU) technology has attracted wide attention.
SINOKLE has successfully combined ultra-fine bubble generation technology, dissolved gas flotation technology, coalescence technology and integrated flotation-cyclone treatment technology to develop a new generation of oil production wastewater treatment equipment, CDFU (Cyclonic Dissolved Gas Flotation Unit). Targeting the characteristics of fluid mass transfer and heat transfer processes, it uses CFD numerical simulation of fluid mechanics, thermodynamics, heat transfer and mass transfer, and applies physical-chemical equilibrium or conservation equations that describe the limiting performance of the process to carry out numerical simulation, thereby achieving a precise description of process design, structural optimisation, engineering scale-up and flow control.
Figure 2. Process flow diagram of a typical application case
CDFU integrates multiple technologies into one unit, achieves an oil removal rate above 90% and SS removal above 85%, operates under pressure in a closed system, and is safe, environmentally friendly, skid-mounted, automated and digitalised. Besides oilfield produced water treatment, it has already been applied in pressure flowback water, landfill leachate, oily firefighting wastewater, medical wastewater and many other fields.
CDFU unit application project cases
