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Author: search.filters.author.Gareche, MouradHas files: No

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    Rheological and flow behavior of water-in-oil Pickering emulsions stabilized with organo-hectorite clay
    (Elsevier, 2021) Boutheina, Merad; Bekkour, Karim; Pierre, François; Gareche, Mourad
    The rheological and flow behaviors of Pickering emulsions are studied as a function of their water concentration. The studied emulsions are water-in-gasoil inverse emulsions stabilized with organo-hectorite clay. An in-line emulsion preparation was performed and a novel emulsification system was used. The emulsification system was tested and confirmed before performing pipe-flow measurements. A stress-controlled rheometer was used to study the rheological behavior of organoclay stabilized inverse emulsions. It was found that the emulsions exhibited a shear thinning with yield stress non-Newtonian rheological behavior and that the flow curves were well correlated using the Herschel-Bulkley model. Pressure loss and axial velocity measurements were studied to investigate the pipe-flow behavior of the emulsions. Axial velocity of the fluids was measured using an Ultrasonic Pulsed Doppler Velocimeter. It was shown that, up to 50 wt% water mass concentration, an exponential increase of yield stress and viscosity values is noticed, and the phase inversion point is not reached. In the range of the applied flow rates, turbulence took place only in the case of the lowest water cut (0 wt%). The Herschel-Bulkley rheological parameters were used to simulate the pipe-flow behavior of the studied fluids, and showed a satisfactory correlation with the in-line measurements. Furthermore, wall shear stress and velocity profiles were used to study the short-, medium-, and long-term stability of the emulsions
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    Thermal gelation of partially hydrolysed polyacrylamide/polyethylenimine mixtures using design of experiments approach
    (Elsevier, 2019) Ghriga, Mohammed Abdelfetah; Hasanzadeh, Mahdi; Gareche, Mourad; Lebouachera, Seif El Islam; Drouiche, Nadjib; Grassl, Bruno
    Polyethylenimine crosslinked polymer gels are gaining a huge interest in conformance control applications in oilfields. They are used to reduce the production of undesirable fluids (water & gas) by blocking the fractures that connect injection and production wells. In this paper, a statistical analysis on the thermal gelation of well characterized reactants namely partially hydrolysed polyacrylamide (PHPA) (Mw = 5.1 million Daltons and hydrolysis degree = 6%) and polyethylenimine (PEI) (Mw = 19.2 kilo Daltons and branching degree = 59%), was conducted using response surface methodology (RSM). A four factor doehlert matrix was employed in designing the experiments and evaluating the gelation time as function of salinity (0–8 g/L NaCl), polymer (PHPA) and crosslinker (PEI) concentrations, temperature (70 °C–90 °C) and their corresponding combinations. As a result, the gelation time was found to strongly vary with salinity, temperature and PHPA concentration following a nonlinear mathematical model. The analysis of variance (ANOVA) of this model revealed its significance in a 95% confidence level against experimental data. In a second part, an experimental investigation was carried out to understand the interaction between PHPA and PEI. To do so, the viscosity variations of analogue mixtures prepared with low molecular weight (Mw) polymers, such as polyacrylamide (PAM) and polyacrylic acid (PAA), were monitored using capillary viscometry at different conditions of temperature, pH and reaction time. The PAM/PEI mixtures showed a remarkable viscosity increase at typical pH of around 10 when cured at 80 °C. While, the PAA/PEI mixtures underwent precipitation at pH of around 6 revealing the strong interaction between PAA and PEI at this condition