Abstract: In order to solve the problems of Qikou sag in Dagang oilfield,such as poor reservoir properties,strong water sensitivity,complex fracture development and low success rate of fracturing operation in Sha-1 lower member,a kind of fracturing fluid with low damage and high viscosity has been developed,and it has a good compatibility with the reservoir.Based on corresponding technologies,such as sandadding timing optimization technology,preflush multistage proppant slug technology and fracturing fluid rheological property optimization technology,the fracturing fluid can be of low residue content and of good anti-swelling property.The fracturing fluid has been applied 9 times in different wells,and the construction success rate has been increased from60% to 100%,the average yield ratio has been increased from1.5 times to 10.8 times,being of obvious fracturing effect.