Challenges and Limitations of Traditional Oilfield Produced Water Treatment Processes

1. Process Flow

2. Process Disadvantages

2.1. Poor Oil-Water Separation Efficiency:

Due to the suboptimal concentration of added chemicals or temperature during the sedimentation process, the oil-water separation effect may not meet the required standards. Inadequate cleaning of the inclined plate tank and failure to meet the required standards for clear water control result in oil and mechanical impurities remaining in the produced water, increasing the difficulty of subsequent treatments. 

2.2. Equipment Corrosion and Clogging Issues:

The high content of sulfides and bacteria in produced water leads to severe corrosion of wastewater treatment equipment, shortening the service life of the equipment. If calcium carbonate precipitation is not treated in time, it can form hard lime scale, which can block pipelines over time, reduce the flow of produced water, and affect the normal operation of the equipment. 

2.3. Insufficient Treatment Efficiency: 

As the volume of produced water increases, the treatment capacity becomes insufficient, necessitating an expansion of the treatment system, which leads to higher investment and operating costs. Delays in oil recovery in oil tanks lead to clogged screens, which further affect oil-water separation efficiency. In filtration tanks, the compaction of the filter media reduces filtration efficiency and impacts water quality standards.

2.4. Environmental Pollution Issues:

The treatment of produced water generates a large amount of oily sludge. Due to insufficient sludge reinjection capacity, there is a risk of delayed sludge treatment, posing environmental and safety hazards. If the treated water does not meet the standards, discharging it directly into the environment can lead to soil and water contamination, which affects the ecological environment. 

2.5. Technical Limitations:

For heavy oil produced water, its high viscosity makes both extraction and treatment difficult. Although high-pressure steam extraction methods can be used for heavy oil, the main challenge in treating produced water lies in its high oil content, which complicates wastewater purification. For low-permeability oil produced water, formation blockage is a major issue. To optimize treatment technology, it is necessary to adjust the filtration membrane coefficient for low-permeability oil, which increases both technical difficulty and costs. 

Polymer-driven produced water contains high-molecular polymers, which increase the viscosity of the water, making it difficult to separate oil from water, thus further complicating the treatment process.