Published September 2025, Pg. 26-31

Section: Oil and gas preparing and transportation

UOT: 622.691

DOI: 10.37474/0365-8554/2025-09-26-31

Assessment and consideration of structural stability of anomalous flows in oil gathering systems

G.G. Ismayılov Dr. in Tech. Sc. - Azerbaijan State Oil and Industry University

M.B. Adigozelova Dr. in Tech. Sc. - Azerbaijan State Oil and Industry University

F.B.Ismayılova PhD in Tech. Sc. - Azerbaijan State Oil and Industry University

Rheological investigations of various crude oils, oil blends, and water-oil emulsions show that, under certain conditions, the loss of flow stability may occur due to internal structural transformations and elastic characteristics of the system. Such systems are classified as rheologically non-equilibrium fluids, and their flow curves are generally nonlinear in nature.
In this study, it is shown that, under shear deformation, the generalized exponential-type rheological equation accounting for structural stability is analogous to the constitutive equation of Maxwell-type linear viscoelastic fluids. Based on this analogy and its extrapolation, it becomes possible to determine the structural stability coefficient. Using this approach, a functional relationship is proposed that allows estimating the structural relaxation time for structure-forming oil systems – i.e., the moment when flow begins to lose its internal structural integrity. This relaxation time characterizes the onset of rheological instability associated with the breakdown of the system’s internal structure.
Thus, the study proposes a model that, considering the structural stability under shear deformation, provides a basis for determining the structural stability coefficient by extrapolating an exponential-type generalized rheological equation analogous to the Maxwell-type viscoelastic model. Accordingly, for structure-forming crude oils, a dependency is derived to estimate the structural relaxation time, representing the time interval corresponding to the initial stage of structural disintegration of the flow.

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