Study and application of biology viscosity break ferment

In view of chemical contamination and finite viscosity break of normal fracture fluid,based on viscosity break principle of biology ferment,selected galactomannan alkali bacterium and thermophilic bacterium,developed biology ferment with viscosity break performance.Introduced properties of thermophilic bacterium DC-AW6,such as acting temperature,apply concentration,core damage,compatibility with fracturing fluid.Applied this bacterium to two wells of Yanchang oilfield and obtained success.The acting temperature of biology viscosity break ferment is 40-80 ℃,core damage is 15%-25%,breaking residua is 7%-8%,flowback ratio is 72%-75%,flowback viscosity is 1.8-2.8 mPa·s.Experiment shows it has well performance and application foreground.