Abstract: Aiming at the tight sandstone reservoirs in which,there is poor porous and permeability condition,large scale fracturing is the effective way to improve the development effect.Because the conventional technology of gel breaker addition amount can not satisfy the higher requirements of gel breaking,a new optimization technology of fracturing fluid gel breaking is proposed which is on the basis of considering concentration effect caused by filtration of the fracturing fluid in the formation.Through simulating the temperature field of fracture,gel breaking test under the different temperature condition and considering the gel breaking after concentration of fracturing fluid filtration,it is suggested that on the spot of large scale fracturing gel breaker addition amount should be higher than conventional amount,as to be able to ensure the gel breaking effect of the large scale fracturing,to realize the quick flowing back,decrease damage.The new gel breaking optimization is applied successfully in large scale fracturing,the technology is successfully applied in well CX491155.6 m³ fracturing,the flowback efficiency is 74.9% after 7hours opening well and flowback fluid is intensive.Testing recovery rate increase to 14×10⁴m³/d (the wellhead pressure is 22MPa) from 0.2×10⁴m³/d after perforation.The technology is popularized gradually in large scale fracturing in Weston Sichuan.

Key words: large scale fracturing, fluid condensation, gel breaking technology