Hydrophobic guar gum derivatives prepared by controlled grafting processes - Part II: Rheological and degradation properties toward fracturing fluids applications

Introduction of polyalkoxyalkyleneamide grafts to guar gum produces new water soluble guar derivatives as described in an earlier publication.(10) In this paper, the rhelogical behavior of these products was explored in more detail at 25 and 65 degrees C. In addition, the viscosity was measured at high temperatures (90 and 120 degrees C) and pressure (150 psi) to partially simulate the down hole conditions of oil wells. Upon treatment with zirconium lactate, the cross-linked hydrophobically-modified CMG derivatives exhibited better high-temperature stability and higher gel viscosities than the corresponding CMHPG derivatives. The cross-linked gel viscosities indicate that gels will be capable of supporting a high proppant carrying capacity. To facilitate removal of the gels from the formation, the hydrophobically modified derivatives were treated with an enzyme breaker system which produced fragments capable of producing stable emulsions when extracted with toluene. Thus, the clean up process will be enhanced by emulsification of the gel fragments produced by the gel hydrolysis. The low viscosities of the linear derivatives, the rapid formation of high viscosity gels upon cross-linking and generation of emulsifiers during the gel removal suggest that these new derivatives are good candidates for fracturing fluid applications. Copyright (C) 2007 John Wiley & Sons, Ltd.