Abstract
The viscoelastic surfactant (VES) fluids have been used in stimulation of low permeability oil and gas reservoir due to their low formation damage. The physical association and entanglement of wormlike like micelle gives viscoelastic properties, which gives similar properties as polymer. However, conventional viscoelastic surfactant fluids were used at much higher concentration than that of traditional polymer guar fluids. The more effective VES fluids that performed at lower concentration are unmet needs to be filled. Hence, new cationic Gemini viscoelastic surfactants with connecting spacer were studied. The Gemini surfactants have higher surface activity than that of conventional surfactants. Critical micelle concentration of Gemini surfactants is 10 times lower than that of conventional surfactants. Fluids of Gemini surfactants gave the desired viscosity by forming gel structure at lower concentration than that of conventional surfactants. The viscosity of new Gemini VES fluid can be maintained above 50 cps at 1% under 120 °C and shear rate of 100 s-1. The fluid is shear stable at the temperature for 2 hours. The dynamic rheological properties of the new VES fluid showed highly elastic properties, which elastic moduli G’ is higher than loss moduli G’ ‘at angular frequency 0.1 rad/s below 100 °C. It showed good proppant suspending properties. The solvent with high polarity has less effect on fluid viscosity than that of solvent with low polarity. The Gemini VES gel can be broken down upon contacting and mixing with hydrocarbons or dilution with formation brine. The Gemini VES gel is a better alterative fluid for low damaging hydraulic fracturing.
