Novel Associative Acrylamide-based Polymers for Proppant Transport in Hydraulic Fracturing Fluids

Abstract

The properties of novel polymers for proppant transport in hydraulic fracturing operations are discussed. Acrylamide based associative polymers have been synthesized using various industrial production processes. Anionic polymers investigated are acrylamide (AMD) based co- and ter-polymers functionalized with monomers such as sodium acrylate (AA), sodium acrylamido-tertiary-butyl sulfonate (ATBS) and a home-made surfactant monomer. The rheological properties of the developed polymers in different brines are evaluated and compared to commercial guar gums usually used for fracturing fluids. The viscoelastic properties as well as settling time of proppant in graduated cylinder have been evaluated. The impact of oxidizing breakers and surfactants added to increase or decrease the viscosity of solutions are reported as well. The new polymers can be used in slickwater, linear gel and cross-linked hydraulic fracturing fluid. They have the ability to carry the proppant down to the target zone. With this technology, proppant can be transported and placed into the fractures with lower concentrations of product and reduce or eliminate the need for using guar gum. Fluid viscosity can be controlled (either increased or decreased) by the addition of surfactants and broken by conventional oxidizers. Laboratory data shows that new associative polymers solutions give very high viscosity at low shear rate and a strong reversible shear thinning effect. Typically, for 3000 ppm of associative polymer, settling time of proppant is 10 times longer than for the same concentration of guar gum. In gel-based fracturing jobs, transport of proppant is generally achieved using guar gum whose viscosity may be improved by adding cross-linkers such as borate or zirconium. The polymer presented in this paper could be a total or partial alternative to guar for proppant transport whose price is subjected to harvest aleas. Results show that lower polymer concentrations are required to obtain the same or even better suspending properties. Besides, traditional oxidizing breakers could be replaced by surfactant to decrease the viscosity of the fluid once the proppant has been placed in the fractures.

Supramolecular Viscoelastic Surfactant Fluid for Hydraulic Fracturing

“…It can be seen that viscosity continues to increase with addition of VES, which is different from the maximum viscosity within a narrow range for conventional surfactants (Gaillard et al, 2013). This wider VES concentration range is easy to operate in the field.…”

“…Associative polymer combined with surfactant has been studied as fracturing fluids (Gupta et al, 2011, Gaillard et al, 2013. However, the conventional surfactant forming spherical micelle has narrow range in enhancing the viscosity and also not very efficient in enhancing the overall viscoelasticity.…”

Novel hydraulic fracturing fluids with improved proppant carrying capacity and pH-adjustable proppant deposition behavior

“…Compared with a polyacrylamide solution, a commonly used polymer solution in displacement fluids with the E a value of 6.4 kT, the activation energy for the supramolecular system is three times greater than that for polyacrylamide at the same concentration. Considering the operating temperatures at several reservoirs varying from 25 qC to 90 qC, such as the fields at Rock Spring (WY), Chaoyanggou (China), El Reno (OK) and Alberta (Canada) (Armstrong et al, 1996;Gaillard et al, 2013;Samuel et al, 2000Samuel et al, , 1999Wang et al, 2010), our supramolecular system is less sensitive to temperature and less likely to suffer from thermal gradients in natural gas and oil reservoirs. Effect of time on the viscosity was also characterized via tixotropy tests to confirm the long term reliability of the developed supramolecular dispersions at four different temperatures from 30 °C to 120 °C with increments of 30 °C (Fig.…”

“…The apparent viscosity of commercially used fracturing fluids is generally 50 to 2000 times larger than that of water (Gaillard et al, 2013). The supramolecular system described here could satisfy this viscosity range at concentrations as low as 0.5 wt.% for shear rates ranging from 0.1 s -1 to 1000 s -1 .…”

“…Technological advances in horizontal drilling and hydraulic fracturing have led to a considerable increase in U.S. oil and shale gas production in recent years (Al-Muntasheri, 2014a; Arthur et al, 2009;Gaillard et al, 2013;Jung et al, 2015). Hydraulic fracturing involves the fracturing of low permeability reservoirs to recover the natural resources trapped in the shale formations (Al-Muntasheri, 2014b; Samuel et al, 2000;Warplnskl and Laboratories, 1991).…”