In numerical simulation of hydraulic fracture propagation, tangent component of the fluid velocity generally considered to be neglected near the crack front. Then Reynolds transport theorem yields that the limit of the particle velocity coincides with the vector of the front propagation speed. We use this fact in combination with the Poiseuille-type equation, which implies that the particle velocity is always collinear to pressure gradient. We show that this specific feature of the hydraulic fracture problem may serve to simplify tracing the front propagation. The latter may be traced without explicit evaluation of the normal to the front, which is needed in conventional applications of the theory of propagating interfaces. Numerical experiments confirm that, despite huge errors in pressure and even greater errors in its gradient, the propagation speed, statistically averaged over a distance of a mesh size, is found quite accurate. We conclude that suggested method may simplify numerical simulation of hydraulic fractures driven by Newtonian and non-Newtonian fluids.

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The surface effect of acoustic anisotropy in steel and aluminum industrial alloys was experimentally detected. Changes in the integral value of acoustic anisotropy in 10–15 times were observed after removing the surface layer with a thickness of 100 microns in steel specimens and 250 microns in aluminum specimens. The correlation between distributions of acoustic anisotropy and hydrogen concentrations in surface layer of specimens was found. It was suggested that the surface effect of acoustic anisotropy occurs due to the influence of microcrack systems localized in a surface layer of metal. This result can be used to improve existing approaches to estimating of corrosion damage, fatigue, mechanical stresses and plastic deformations of technical structures by using acoustic anisotropy.

Главная цель Научно-Технического Центра «Газпром нефти» («Газпромнефть НТЦ»)повышение нефтедобычи и ее эффективности за счет внедрения новых технологий и проектных решений на месторождениях «Газпром нефти». НТЦ обеспечивает аналитическую, методическую и научно-техническую поддержку процессов разведки и добычи нефти.

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