Abstract: Fracturing fluid acts as pressure transfer and proppant carrier during the process of fracturing. However, polymer-based fracturing fluid will damage the payzones or even cause production decline of wells due to incomplete degradation of polymer in it. Surfactant molecules are made up of hydrophilic head group and lipophilic tail group, which become micelle by coalescence when dissolved in water. The viscoelastic surfactant fracturing fluid with some salinity is known as clean fracturing fluid for its little damage to fractures and absence of polymer residue. In general, such a fluid doesn't break till mixing with crude oil and gas in reservoirs without adding gel breaker. But this study shows that the viscoelastic fracturing fluid can not break when mixing with natural gas, so gel breaker has to be added for gas well fracturing. A suitable macromolecular gel breaker is presented in this paper.

Key words: fracturing fluid, surfactant, viscoelastic property, micelle