Viscoelastic Behavior and Proppant Transport Properties of a New High-Temperature Viscoelastic Surfactant-Based Fracturing Fluid

Abstract

Viscoelastic surfactant (VES) fracture fluids were developed as a nondamaging alternative to conventional polymer-based fluids. However, the viscosity performance of typical VES fluids is dramatically reduced at high temperature. Therefore, these fluids are typically limited to treat relatively lowtemperature formations unless foamed with nitrogen or carbon dioxide. Recent laboratory work has shown that viscosity alone may not accurately assess proppant transport. Thus, combination of rotational and oscillatory measurements to determine the fluid viscous and elastic properties can better predict whether the fluid can be applied successfully in the field.The present study was conducted to introduce a new Gemini VES system that can gel and maintain useful viscosity up to 275°F, which can provide additional downhole benefits. Dynamic and static proppant settling tests were conducted using a high-pressure/high-temperature visualization cell to confirm the effect of elastic properties of this fluid on proppant settling. Finally, proppant settling tests were conducted with three proppant types of the same size, but different density and shape at a range of concentrations.Experimental results show that the surfactant gel behaved as an elastic material (elastic regime), where the elastic modulus (G') was dominant over the viscous modulus (G") during the tested range of frequency. This behavior gives perfect proppant transport properties. At temperature less than 225°F, Values of G= were independent of the frequency and/or shear rate values, while G" increased with increasing frequency and/or shear rate. At higher temperature, both G= and G" increased with increasing frequency and/or shear rate. This gives a good proppant-carrying capacity during dynamic conditions (mixing and injection) with a small pressure drop. The addition of an internal liquid breaker increases the viscous regime with time and temperature. When elastic regime dominates, 100% proppant suspension was confirmed for at least two hours at static and dynamic conditions and temperatures in the range of 75 to 250°F.

Recent Advances in Viscoelastic Surfactants for Improved Production From Hydrocarbon Reservoirs

“…Examples of cationic, nonionic, zwitterionic, and anionic surfactants have all been used for hydraulic-fracturing applications primarily in aqueous systems, although some examples of gelled hydrocarbon systems have been reported (Samuel 2009;Samuel et al 2014). Beginning with cationic surfactants, early studies of quaternary ammonium salts established their viscoelastic properties (Gravsholt 1976). Solutions that incorporate water, a water-soluble salt (electrolyte), and a quaternary ammonium salt have been used for drilling fluids, completion fluids, and hydraulic-fracturing fluids ).…”

“…Measurement of G 0 and G 00 can be used to determine whether a fluid is viscoelastic at a given temperature. A simple observational technique has also been described for determining whether a fluid is viscoelastic (Gravsholt 1976): Bubbles that appear during swirling of a sample will recoil when the swirling stops if the solution is viscoelastic.…”

Synthesis and characterization of a novel, pH-responsive, bola-based dynamic crosslinked fracturing fluid

“…A fracturing uid with good suspension properties is an effective way to ensure transport of a proppant to a fracture formation, and achieve high conductivity. [53][54][55] Fig. 15 shows the results of static proppant suspension tests, where BSP (0.5% BS + 0.5% CG, pH ¼ 10) fracturing uid with 30% of proppant was poured into a 100 mL in a measuring cylinder, and then heated to 65 C, and Fig.…”

Microfluidic Rheometry and Particle Settling: Characterizing the Effect of Polymer Solution Elasticity

“…Some attempts have been made in this direction for particle-free polymer solutions, however, not in the context of hydraulic fracturing, and for very basic geometrical shapes of the channel [14,15]. Fluid elasticity specifically alters the sedimentation and rotation rate of a particle, which in turn causes different cross-stream flow-induced migration behaviors, affecting the overall particle transport efficiency [15][16][17][18]. There is still a need to fully understand how to tune the properties of polymeric fluids to efficiently transport particles.…”

“…The model introduced by Stokes, however, only accounted for the shear viscosity of the fluid, and required other correction factors to be suitable under different flow conditions or fluid types. In a series of works [17,27,28], Gomma et al showed that the effective shear viscosity is not the only factor to design efficient particle transport, and the fluid elasticity, quantified via the shear modulus, also plays a significant role. Several researchers [1,23,[29][30][31][32]] conducted comprehensive experimental and numerical investigations to determine the effect of fluid elasticity on the terminal velocity of a single sphere settling in a non-Newtonian elastic fluid in order to quantify the drag coefficient.…”