Performance Study of Low Concentration Synthetic Polymer Fracturing Fluid for Middle-High Temperature Reservoir

In view of existed problem of plant gum fracturing fluid,a new kind of low concentration synthetic polymer fracturing fluid system for middle-high reservoir was developed. The fracturing fluid system included 0.35%—0.6% anionic synthetic polymer SKY-C100 A,which was free of water insoluble substance,0.5% —0.7% crosslinked fluid composed of cross linking agent SKY-J100 B and cross linking regulator SKY-Y100 C,0.3% clay stabilizer LYC-1,0.6% cleanup additive ZL-1 and 0.5% demulsifier KCB-1. The cross linking time of fracturing system was adjustable from 20 to 180 s. The results showed that the fracturing gel had good shear resistance and heat-resistant. Under the condition of 80—100℃,SKY-C100 A dosage of 0.35%,shearing 120 min at170 s-1(including 2 min high shearing at 1000 s-1),the viscosity of fracturing gel was still kept from 77 to 220 mPa·s;that kept about 220 mPa·s with 0.45% SKY-C100 A and 120℃;that maintained about 83 mPa·s with 0.5% SKY-C100 A and 140℃. Under the static gel breaking condition of 80℃,the residue content in gel-broken fluid was 30 mg/L within 2 h. At 80—120℃,the filtration coefficient was 1.13×10-4—3.62×10-4m/min1/2,and the damage rate to artificial core matrix was only 8.3%. Comparing with plant gum fracturing fluid,the new fracturing system did not require other pH regulator and bactericides.