Abstract

This paper studied a new fracturing fluid based on a supramolecular complex of associative polymer and vsicoelastic surfactant. The crosslink complex gel was based on weak physical attractive forces such as van der waals, hydrogen bonding and electrostatic interaction between associative polymer and wormlike micelle of viscoelastic surfactant. The fluid contained surfactant ten times less than that of conventional viscoelastic surfactant fracturing fluid. The combination of viscoelastic surfactant and associative polymer synergistically enhances the viscosity ten times more than that of the individually components alone. The fluid system was optimized by experimental design. The microstructure of wormlike micelle was verified by cryo-transmission electron microscopy. The fluid is shearing-stable at high temperature for 1 hour. The dynamic rheological properties of the new VES fluid showed high viscoelasticity, in which elastic moduli is higher than loss moduli at angular frequency 0.1 rad/s. The proppant transport test in a large-scale fracture simulator showed good proppant suspension ability. The fluid has 50% lower formation damage than that of conventional guar. The fluid was prepared with less additives and formed gel instantly which can be mixed on the fly in the field. The gel can be completely broken with almost no residue. Field application of the new fracturing fluid in a gas field showed the enhancement of gas production over 100%. The fluid has 20% lower friction pressure than that of guar fluid. Hence, the new supramolecular viscoelastic surfactant gel is an effective fracturing fluid with less formation damage.

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