Abstract: There are some differences in characteristics of lithology,physical property,pore texture and sensitive minerals between granite reservoir and conventional reservoir,so the damage mechanisms of the granite reservoir are different from conventional reservoir.By utilizing such research methods as Scanning Electron Microscope,Cast Thin Section etc,the damage mechanisms of granite reservoirs are systematically analyzed,and the effective protection measures of granite reservoirs are explored.The study results indicate that the main damage mechanisms of granite reservoirs are solid invasion,stress sensitivity and water blocking;in"five types of sensitivity"damage,acid sensitivity and salt sensitivity are main damage types,the other sensitive damage are relatively weak.Combining the literature investigation with damage mechanisms study results,the underbalanced drilling technology is believed to be the best choice to exploit granite reservoirs,if the underbalanced drilling technology is integrated with nonstraight well technology,the multiple fractures in granite reservoirs can be crossed,so the better productivity can be achieved.Low pressure bridge plug technology can not plug the macroscopic fractures and big size fractures,but the fractures those width is less than 50 microns can be effectively plugged and the part of productivity is protected.

Key words: granite, reservoir, fracture, damage, underbalanced drilling, bridge plug