Polymer-free fluid for fracturing applications

Polymer residues that stay in the fracture after fracturing can limit the t reatment effectiveness. A new and easy-to-prepare, surfactant-based polymer -free fluid, ClearFRAC(TM), that consists of a quaternary ammonium salt der ived from a long-chain fatty acid is described. In brine, it builds fluid v iscosity and viscoelasticity due to the formation of highly entangled worm- like micelles. The micelles have a gross structure similar to a polymer cha in. Since the viscosity of the fluid depends on the nature of micelles, the fluid can be broken by changing this micellar structure. The breaking occu rs when the fluid is exposed to hydrocarbons or diluted with formation wate r. Therefore, conventional breakers are not required, and the produced ail or gas can act as breakers for this fluid system. The structural characteristics of this viscoelastic surfactant-based fluid to its chemical and physical properties are correlated in this article. Str ucture, rheology, fluid loss, and conductivity of this surfactant fluid tog ether with its case histories are presented.