The work is devoted to the study of the rheological behavior of proppant carrier fluids used for hydraulic fracturing (HF) technology in order to increase oil recovery, including from hard-torecover oil and gas reserves, in a wide range of deformation rates using viscometers of various designs. Rheological properties were studied for proppant carrier fluids based on guar and Surfogel grade D, (type 70–100, produced by JSC “Polyex”) with comparable shear rate 128 s–1. Quasistatic experiments to determine the values of the dynamic viscosity of the liquids under study were carried out using a falling ball viscometer (according to the Stokes method). Using an original viscometer, consisting of two coaxial cylinders (rotary rheometer), the dynamic viscosity of surfogel was investigated in a wide range of shear rates. The viscoelastic properties of surfactants were studied using a Physica MCR501 rheometer, which has a plane-to-plane measuring system and allows rheological studies in rotational and oscillatory modes. A comparison of the rheological properties of fluids based on the guar and the viscoelastic surfactant is carried out and it is established that a fluid based on the viscoelastic surfactant has a higher dynamic viscosity and does not lose its elastic properties, which is an certain advantage over a fluid based on the guar.

The study focuses on the rheological behavior of a fluid based on a viscoelastic surfactant (Surfogel grade D, type 70-100, produced by JSC “Polyex”) in wide range of strain rates. This fluid is used for hydraulic fracturing technology as a proppant-carrying and proppant-retaining fluid in order to enhance oil recovery, including those with hard-to-recover oil and gas reserves. Quasi-static experiments to determine the values of the dynamic viscosity of the fluids under study were carried out using a falling ball viscometer (according to the Stokes method). The viscoelastic properties of fluids were studied using a Physica MCR501 rheometer with a cone-plane measuring system and an original rheometer with coaxial cylinders measuring system. The rheological properties of the fluid with the addition of proppant were studied using a Rheolab QS rheometer with a measuring system of the type of coaxial cylinders. The analysis of the rheological properties of fluids based on a viscoelastic surfactant has been carried out, and it has been established that fluids based on a viscoelastic surfactant has stable rheological properties over the entire range of strain rates, including fluid with proppant concentration up to 20%.

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The work is devoted to the study of the formation of tangential discontinuities of glycerol parameters under shear load. The studies were carried out using a modified coaxial cylinder viscometer. The experiment was inspired by the work of Ya. I. Frenkel, in which it was noted that “… liquids, being condensed media, should exhibit effects that are more characteristic of solids than gases …”, while the thermodynamic and kinetic properties should be determined by structural “variables”, traditional for both “liquid” and solid state. These studies will further help in explaining the anomalous momentum transfer regimes caused by the mechanisms of instability that are realized under the conditions of the “decay” of multiple metastable states, usually observed under intense (dynamic and shock-wave) loading in liquids and solids.

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