Process of treating oil-bearing sewage for ternary combination flooding in oil field

Abstract

The present invention discloses process of treating oil-bearing sewage for ternary combination flooding in oil field. The process includes the following steps: 1. gravitational settling of the sewage; 2. combined cyclonic and air floating treatment for oil-water separation; 3. regulating pH value of sewage and adding inorganic flocculant and organic flocculant; 4. further settling; and 5. filtering in a double filter material filter and a modified fiber ball filter. The process can treat sewage to reach the requirement for using as recirculated polymer flooding water with oil content not more than 30 mg / 1, suspended matter content not more than 30 mg / 1 and granularity midvalue not greater than 5 micron.

Description

technical field [0001] The invention relates to a process for treating oily sewage by three-element compound flooding in an oil field. Background technique [0002] With the implementation of ASP flooding, the stability of the oil-water emulsion in oily sewage was significantly enhanced, and the treatment capacity of the oily sewage treatment facilities built in the oil field was significantly reduced, and the water quality of some oily sewage treatment stations seriously exceeded the standard. [0003] The components of ternary sewage are very complex, mainly including crude oil, suspended solids (sediment, organic matter, colloid, asphaltene and paraffin and other heavy oils and colloids) that have not been separated in production, and a large amount of polymers, alkali, Chemical agents such as surfactants, these chemicals interact with oil and suspended solids in water, which increases the difficulty of oil-water separation and solid-liquid separation. [0004] The polym...

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Problems solved by technology

[0002] With the implementation of ASP flooding, the stability of oil-water emulsion in oily sewage has been significantly enhanced, and the treatment capacity of oily sewage treatment facilities built in the oil field has been significantly reduced, and the water quality of some oily sewage treatment stations has seriously exceeded the standard.

[0003] The components of ternary sewage are very complex, mainly including crude oil, suspended solids (sediment, organic matter, colloid, asphaltene and paraffin and other heavy oils and colloids) that have not been separated in production, and a large amount of polymers, alkali, Chemical agents such as surfactants, these chemicals interact with oil and suspended solids in water, which increases the difficulty of oil-water separation and solid-liquid separation

[0004] The polymer in the sewage increases the viscosity of the sewage, increases the resistance of the oil droplets to float up, and reduces the chance of collision and coalescence between each other, which also brings considerable difficulties to the separation of oil and water; in addition, its "carrying sand" effect makes the Suspended solids are not easy to separate out, and the existence of polymers is the main factor that makes it difficult to remove suspended solids in sewage

[0005] At the same time, under the combined action of alkali and polymer, the effect of conventional water treatment agents is greatly reduced, because many agents are used under neutral or acidic conditions, and some of them can undergo cross-linking reactions with polymers to form gels. In this way, not only can not reduce the content of suspended solids in sewage, but it will increase it

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