Structural breakdown and recovery of waxy crude oil emulsion gels

Verfasser / Beitragende:
[Guangyu Sun, Jinjun Zhang]
Ort, Verlag, Jahr:
2015
Enthalten in:
Rheologica Acta, 54/9-10(2015-10-01), 817-829
Format:
Artikel (online)
ID: 605466939
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024 7 0 |a 10.1007/s00397-015-0873-8  |2 doi 
035 |a (NATIONALLICENCE)springer-10.1007/s00397-015-0873-8 
245 0 0 |a Structural breakdown and recovery of waxy crude oil emulsion gels  |h [Elektronische Daten]  |c [Guangyu Sun, Jinjun Zhang] 
520 3 |a The structural breakdown and recovery behaviors of waxy crude emulsion gels were investigated. First, the tests of stepwise increase in shear rate and hysteresis loop were carried out, and the structural breakdown process was further analyzed. Then, the structural recovery behaviors were investigated from the recoveries of apparent viscosity, storage modulus, and yield characteristics. It was found that the thixotropy of emulsion gels weakens with increasing water cut and the structural breakdown process gradually changes from solid-like brittle fracture to ductile failure. The broken-down structure of emulsion gels can only recover partially, and both the recovery rate and the recoverability are related to water cut, precipitated wax content, and pre-shear rate. To be specific, the storage modulus recovers faster with increasing water cut and decreasing precipitated wax crystals, or after pre-sheared at a higher rate, while the effects of water cut and precipitated wax on the recovery rate of yield stress are opposite. The recovery degree of both storage modulus and yield stress decreases obviously with increasing amount of wax crystals but is barely influenced by the water cut. 
540 |a Springer-Verlag Berlin Heidelberg, 2015 
690 7 |a Waxy crude  |2 nationallicence 
690 7 |a Emulsion  |2 nationallicence 
690 7 |a Gel  |2 nationallicence 
690 7 |a Structure  |2 nationallicence 
690 7 |a Breakdown  |2 nationallicence 
690 7 |a Recovery  |2 nationallicence 
690 7 |a t : Time (s)  |2 nationallicence 
690 7 |a G ′ : Storage modulus at time t (Pa)  |2 nationallicence 
690 7 |a G 0 ′ $$ {G}_0^{\prime } $$ : Storage modulus at t=0 (Pa)  |2 nationallicence 
690 7 |a G ∞ ′ $$ {G}_{\infty}^{\prime } $$ : Storage modulus at t=∞ (Pa)  |2 nationallicence 
690 7 |a t g : Characteristic gelation time (s)  |2 nationallicence 
690 7 |a d : Stretching exponent in Eq. (1) (−)  |2 nationallicence 
690 7 |a τ y : Yield stress at any rest time t after structural breakdown (Pa)  |2 nationallicence 
690 7 |a τ e : Shear stress in the equilibrium, fully broken-down state, i.e., remaining shear stress at the end of the shearing in step (2) of the yield stress recovery test (Pa)  |2 nationallicence 
690 7 |a τ y∞ : Recovered yield stress at t=∞ (Pa)  |2 nationallicence 
690 7 |a k nb : Recovery rate constant of yield stress in the Nguyen-Boger model (1/h)  |2 nationallicence 
690 7 |a K r : Coagulation rate constant in the Leong model (1/h)  |2 nationallicence 
690 7 |a S th : Area enclosed by the up curve and the down curve (Pas−1)  |2 nationallicence 
690 7 |a S up : Area determined by the up curve and the shear-rate axis (Pas−1)  |2 nationallicence 
690 7 |a S down : Area determined by the down curve and the shear-rate axis (Pas−1)  |2 nationallicence 
690 7 |a S R : Relative thixotropic area (%)  |2 nationallicence 
690 7 |a τ : Total shear stress (Pa)  |2 nationallicence 
690 7 |a γ : Total shear strain (−)  |2 nationallicence 
690 7 |a γ · $$ \overset{\cdotp }{\gamma } $$ : Shear rate (s−1)  |2 nationallicence 
690 7 |a λ : Scaled structural parameter, varying between the values of 0 for the completely broken-down structure and 1 for the fully developed structure (−)  |2 nationallicence 
690 7 |a G 0 : Shear modulus of the completely structured material (λ=1) (Pa)  |2 nationallicence 
690 7 |a γ e : Elastic strain of the continuous network structure (−)  |2 nationallicence 
690 7 |a Δ k : Structure-dependent consistency ( Pa s n 1 $$ \mathrm{Pa}\ {\mathrm{s}}^{n_{\kern0.2em 1}} $$ )  |2 nationallicence 
690 7 |a k : Completely unstructured consistency ( Pa s n 1 $$ \mathrm{Pa}\kern0.35em {\mathrm{s}}^{n_{\kern0.2em 1}} $$ )  |2 nationallicence 
690 7 |a n 1 : Kinetic index describing the viscous stress's dependence on shear rate (−)  |2 nationallicence 
690 7 |a p 1, p 2 : Dimensionless parameters related to the viscoelastic property (−)  |2 nationallicence 
690 7 |a n 2 : Positive dimensionless constant (−)  |2 nationallicence 
690 7 |a a : Kinetic constant for structure buildup (s−1)  |2 nationallicence 
690 7 |a b : Kinetic constant for shear-induced breakdown (Pa−msm−1)  |2 nationallicence 
690 7 |a ϕ : Rate of energy dissipation, defined as ϕ = τ γ ̇ $$ \phi =\tau \dot{\gamma} $$ in the simple shear flow (Pas−1)  |2 nationallicence 
690 7 |a m : Dimensionless constant (−)  |2 nationallicence 
690 7 |a s : A characteristic time in the elasto-viscoplastic thixotropic model (Eq. 5) with the value of 1s (s)  |2 nationallicence 
690 7 |a τ y0 : Yield stress when the gel structure breaks down for the first time (Pa)  |2 nationallicence 
690 7 |a τ y1h, τ y4h, τ y8h : Yield stresses when gel structure yields for the second time after rest for 1, 4, and 8h, respectively (Pa)  |2 nationallicence 
700 1 |a Sun  |D Guangyu  |u National Engineering Laboratory for Pipeline Safety / Beijing Key Laboratory of Urban Oil and Gas Distribution Technology, China University of Petroleum (Beijing), 18 Fuxue Road, Changping District, 102249, Beijing, China  |4 aut 
700 1 |a Zhang  |D Jinjun  |u National Engineering Laboratory for Pipeline Safety / Beijing Key Laboratory of Urban Oil and Gas Distribution Technology, China University of Petroleum (Beijing), 18 Fuxue Road, Changping District, 102249, Beijing, China  |4 aut 
773 0 |t Rheologica Acta  |d Springer Berlin Heidelberg  |g 54/9-10(2015-10-01), 817-829  |x 0035-4511  |q 54:9-10<817  |1 2015  |2 54  |o 397 
856 4 0 |u https://doi.org/10.1007/s00397-015-0873-8  |q text/html  |z Onlinezugriff via DOI 
898 |a BK010053  |b XK010053  |c XK010000 
900 7 |a Metadata rights reserved  |b Springer special CC-BY-NC licence  |2 nationallicence 
908 |D 1  |a research-article  |2 jats 
949 |B NATIONALLICENCE  |F NATIONALLICENCE  |b NL-springer 
950 |B NATIONALLICENCE  |P 856  |E 40  |u https://doi.org/10.1007/s00397-015-0873-8  |q text/html  |z Onlinezugriff via DOI 
950 |B NATIONALLICENCE  |P 700  |E 1-  |a Sun  |D Guangyu  |u National Engineering Laboratory for Pipeline Safety / Beijing Key Laboratory of Urban Oil and Gas Distribution Technology, China University of Petroleum (Beijing), 18 Fuxue Road, Changping District, 102249, Beijing, China  |4 aut 
950 |B NATIONALLICENCE  |P 700  |E 1-  |a Zhang  |D Jinjun  |u National Engineering Laboratory for Pipeline Safety / Beijing Key Laboratory of Urban Oil and Gas Distribution Technology, China University of Petroleum (Beijing), 18 Fuxue Road, Changping District, 102249, Beijing, China  |4 aut 
950 |B NATIONALLICENCE  |P 773  |E 0-  |t Rheologica Acta  |d Springer Berlin Heidelberg  |g 54/9-10(2015-10-01), 817-829  |x 0035-4511  |q 54:9-10<817  |1 2015  |2 54  |o 397