Abstract
This paper studied a new fracturing fluid based on a supramolecular complex between associative polymer and viscoelastic surfactant (VES). The combination of VES and associative polymer synergistically enhances the viscosity several times more than that of the individual components alone. The fluid system was optimized by experimental design. The microstructure of wormlike micelle and complex formation was verified by electron microscopy. The proppant transport test in a large-scale fracture simulator showed good proppant suspension ability. After fracturing, the nano- surfactant molecule in the liquid have a high surface energy, which can play a good oil displacement effect in the crack.
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. By flooding and [1]nuclear magnetic resonance experiments results, compared to the conventional fracturing fluid and water, oil displacement efficiency can be increased by 12% to 20%, more micro-pores in the oil and gas drive for higher pressure stimulation effect for tight oil reservoir. Field application of the new fracturing fluid in 10 tight gas wells showed the enhancement of gas production over 100%. The fluid has 20% lower friction pressure than that of guar fluid. Hence, the new supramolecular fluid is an effective fracturing fluid.
Supramolecular fracturing fluid provides a new fracturing system with less formation damage to fracturing operation. This paper will be beneficial to all engineers and technologists who are currently working at tight gas stimulation applications.
