The three types of microorganisms present in oilfield reinjection water pose the most direct threat to oilfield production:
·Sulfate-Reducing Bacteria (SRB): Under anaerobic conditions, SRB metabolize to produce H2S, which directly leads to electrochemical corrosion of equipment and pipelines, causing pitting and ultimately perforation and leaks.
·Saprophytic Bacteria (TGB): They form large amounts of slime and biofilm, which adhere to pipe walls and formation pores, clogging the formation, reducing injection efficiency, and providing a habitat for anaerobic bacteria like SRB.
·Iron Bacteria (IB): They oxidize ferrous iron in water to ferric iron, forming ferric hydroxide precipitates. These precipitates, combined with biofilms, further exacerbate pipeline and formation blockages and deteriorate water quality.
Currently, oilfields widely use ultraviolet disinfection to control these three microorganisms.
Ultraviolet disinfection
In oilfield reinjection water treatment systems, ultraviolet disinfection devices are typically not used as standalone units, but rather integrated at the end of the treatment process. They serve as the final sterilization barrier before water quality refinement and injection.
Process flow: Produced water - oil/impurity removal (coagulation, flotation) → filtration (sand filtration, walnut shell filtration, etc.) → fine filtration (membrane filtration, etc.) → ultraviolet disinfection - injection well
China's petroleum and natural gas industry standard SY/T5329-2012, "Water Quality Indicators and Analysis Methods for Injection Water in Clastic Reservoirs," clearly defines microbial indicators for reinjection water in formations of varying permeability.
· Sulfate-reducing bacteria (SRB): No more than 10 cells/mL
· Saprophytic bacteria (TGB): No more than 100 cells/mL
· Iron bacteria (IB): No more than 100 cells/mL
Innovations in ultraviolet disinfection technology for oilfield reinjection water
Synergistic disinfection mode: "UV + low-dose chemical disinfectant"
As the main sterilization unit, ultraviolet rays are responsible for inactivating more than 99% of microorganisms, quickly and efficiently reducing the bacterial base number to an extremely low level at the outlet of the treatment station.
而后端仅需辅以低浓度(可能是传统用量的10%-20%需要根据管网情况确定)长效的化学抑菌剂供管网中的持续抑制能力，防止微生物复活和二次滋生。
WSH紫外明渠
WTV紫外垂直模块
ZL大型管道式紫外
CLEAR中压紫外
MOL板式臭氧发生器
UV-AOP高级氧化
D.FITE滤布滤池
