Evaluation of a novel controlled-released bio-acidification system for carbonate reservoirs

A novel bio-acidification system comprised by a newly enzymes and pre-acid fluid has been designed for high temperature carbonate reservoirs (90 ℃). Its characteristics were evaluated in laboratory as follows, dispersion compatibility, corrosion inhibition ability, controlled-release ability and corrosion efficiency. The results showed that the bio-acidification system has well dispersion ability, great stability and compatibility in simulated formation water. Well corrosion inhibition effect was appeared over the temperature range of 20 to 110 degree. After reacting in above 90℃ for 4 hours, the hydrogen ion concentration releasing by 20% bio-acidification system equals to that in 10% HCl solution. The dissolution rate of the acidification system to CaCO3 particle can reach 96.3% with a lasting effect of corrosion.