Review on High-Temperature-Resistant Viscoelastic Surfactant Fracturing Fluids: State-of-the-Art and Perspectives

Abstract

A viscoelastic surfactant (VES) fluid is an important part of a water-based fracturing fluid. As oil and gas exploration expands into deep, high-temperature, low-permeability reservoirs, the conventional VES fracturing fluid has shown great limitations. The high-temperature-resistance mechanisms of the high-temperature-resistant VES fracturing fluids in publicly available literature were analyzed from five aspects: single-chain surfactant system, oligomeric surfactant system, counterion effect, blended surfactant system, and nano-enhanced VES system. The friction-reduction performance, sand-carrying performance, gel-breaking performance, and core-damage performance of these systems were summarized. The results show that oligomeric surfactants with a monounsaturated hydrophobic long chain (>C21) are most likely to be used for VES fracturing fluids in high-temperature reservoirs, but the loading of the surfactants is still relatively high (3–5 wt %). By reducing the repulsion among polar headgroups to effectively decrease the area of head groups, or/and penetrating into the nonpolar cores based on hydrophobic interaction to increase the average hydrophobic volume of hydrophobic tails, counterions affect the performance of VESs. The aromatic counterion salts are preferred choices for improving the temperature resistance, friction reduction, and suspended sand performance of VES fluids. The blended surfactant/synthetic polymer systems based on noncovalent interaction improve the temperature resistance of VES fluids and reduce the loading of the surfactants to a certain extent. Based on the “pseudo-cross-linking” of nanomaterials and wormlike micelles, a very small amount of nanomaterials can improve the temperature resistance of VES fluids and reduce the loading of the surfactants. The most essential and effective method to improve the temperature resistance of VES fluids for fracturing is the molecular structure design based on the packing parameter theory. However, the synthesis process or route still needs further optimization to reduce production costs. In addition, given the excellent performance of VES fluids enhanced by nanomaterials, further research should be conducted on the influence mechanism of nanomaterial type and geometric features on the performance of VESs, as well as the potential harmfulness of nanomaterials, to promote the field-scale application of nano-enhanced VES fluids.

CO2-Responsive Foam (CRF) for Mitigating CO2 Channeling in Heterogenous Reservoirs

“…This shields electrostatic repulsion between negatively charged surfactant head groups. While inorganic salts can reduce surfactant efficacy in some instances, , the interaction energy between LES and DETA in CRF significantly exceeds that between salts and surfactants, indicating that surfactant effectiveness is not compromised by salt. In such conditions, the solution can form anionic wormlike micelles that are long and flexible, and these micelles may be wound into a transient network, resulting in a high viscosity of the sample .…”

Co-Assembled Supramolecular Organohydrogels of Amphiphilic Zwitterion and Polyoxometalate with Controlled Microstructures

“…By manipulating the distinct moieties, such as hydrophilicity and hydrophobicity of building blocks, along with the types of interactions between them, and controlling assembly conditions (solvent polarity, pH, light, and temperature etc. ), devisable and multitudinous assemblies can be achieved, including micelles, vesicles, liquid crystals, and fibers [6][7][8][9]. Currently, the engineering of innovative and high-tech applications of conventional hydrogels has garnered significant interest.…”