Oil field re-injection water microbiological treatment

Abstract

The improved process of treating oil field effluent for reinjection features aerobic biochemical treatment and subsequent filtering. The microbes for the aerobic biochemical treatment include Bacillus cereus, Corynebacterium, Bacillus subtilis and Pseudomonas alcaligenes, and the inflow water has pH value controlled in 6-9. The process can reach oil field water injection standard, including oil not more than 2 mg / l, SS not more than 1 mg / l and grain size mid value not greater than 1 micron. The present invention has the advantages of simple technological process, low cost, stable treating effect, no secondary pollution, etc., and is especially suitable for use in oil field.

Description

technical field [0001] The invention relates to the improvement of the oilfield produced water treatment reinjection method, in particular to an oilfield reinjection water treatment process which adopts obligate microorganisms combined with flora biological treatment and combines physical filtration treatment. Background technique [0002] Oil extraction is accompanied by a large amount of produced water. For example, in 2005, my country's crude oil output was 181.5 million tons, which produced more than 900 million tons of produced water. However, the oil production process requires a large amount of water to be re-injected into the formation to save water resources. At least 90% of the produced water is required. % above for re-injection. The oilfield produced water has: high oil content, up to 200-1000mg / l; complex composition, in addition to crude oil, it also contains fatty acids, surfactants, oil displacement agents, demulsifiers, viscosity reducers, corrosion inhibitor...

AI Technical Summary

Problems solved by technology

This method mainly uses physical and chemical treatment as pretreatment. Not only is the treatment process long, the process is complicated, the floor area is large, the investment is high, the maintenance workload is heavy, and the operating cost is high. It is also difficult to stably meet the reinjection water standard.

[0008] It can be seen from the above that at present, various improved physical and chemical methods are basically used for the treatment of oilfield produced water, and it is difficult to stably treat them to the standard of reinjection water.

[0009] In the 4th issue of "China Water Supply and Drainage" in 2003, the "biochemical method for treating high-temperature and high-salt oilfield produced water" disclosed that although it proposed to treat oilfield produced water with microorganisms (undisclosed specific microbial strains) contact oxidation combined with precipitation technology, it can only be used for production The COD in the effluent is degraded, and the oil removal effect is not disclosed. The treated effluent can only meet the (GB8978-1996) secondary discharge standard, and still cannot be used for reinjection water

This method is only applicable to new projects, resulting in high investment costs, and is not suitable for low-cost transformation of existing physical and chemical treatment equipment in oil fields

After practical application, due to the relatively few bacterial strains used, the synergistic effect is limited, and the bacterial strains need to be frequently supplemented, which brings inconvenience to practical application; and with the increasingly complex composition of oilfield produced water, its adaptability is relatively insufficient, which will cause inconsistent treatment effects, thus Add difficulty to subsequent processing

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