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۱Thermodynamic Investigation of the Stability of Copolymer Grafted Bentonite Nanoclays in an High Salinity Electrolyte
نویسنده(ها): ، ، ،
اطلاعات انتشار: کنفرانس بین المللی فرآورش پلیمرها، سال
تعداد صفحات: ۵
Stability of clays is one of the most important characteristics of these colloidal systems and its degree can be determined by the balance of attractive and repulsive forces acting between the colloidal particles. In this work, the stability of grafted bentonite nanoclays by different copolymers including poly (1–vinyl pyrrolidone–co–styrene) (PVP), poly(methyl methacrylate –co–methacrylic acid) (PMMA) and poly (acrylamide–co–diallyl dimethyl ammonium chloride) (PDADMAC) in a high salinity polyelectrolyte solution containing partially hydrolyzed polyacrylamide (PHPA) was investigated. Adsorption of PHPA chains onto the modified bentonite–nanoclay surfaces, according to the Langmuir isotherm mechanism, led to the stabilization of the nanoclay particles in the polyelectrolyte medium. The thermodynamic parameters including enthalpy (ΔH), entropy (ΔS), free energy (ΔG) and adsorption constant (Kn) of the interactions of organic–organic–inorganic hybrids in the nano–clay suspensions were determined by Langmuir equation using a spectrophotometer analyzer. The stability and thermodynamic studies indicated that modified PVP–nanoclay had the longest stability among the un–modified and modified nanoclays in the prepared suspensions.<\div>

۲Wellbore Stability in Shale Formation: Modeling the Effects of Polymers in the Drilling Fluids Formulation
نویسنده(ها): ، ، ،
اطلاعات انتشار: کنفرانس بین المللی فرآورش پلیمرها، سال
تعداد صفحات: ۴
A new experimental model was developed to predict the role of special polymeric additives, in the drilling fluid formulation, on the wellbore stability in shale formation. The shale formation was regarded as a non–ideal membrane and the effects of various characteristics of the added polymers were studied on the membrane reflection coefficient. The model was applied to unique field data from the Iran oil field, including clay structure, cation exchange capacity (CEC), density and porosity of the shale. The results, using various polyglycols and polyacrylamides as the polymeric additive, showed that the structure of the polymeric chains e.g. type and content of ionic segments had significant effect on their adsorption mechanism and its strength. It was concluded that increasing the molecular weight of the polymer chains decreased the rate and amount of the adsorption due to the increasing of the entanglements between the chains which in turn limited their mobility. Finally, adsorption of the polymeric material on the shale had significant impress on its performance as a membrane by increasing the shale reflection coefficient enhancing its stability during drilling process<\div>
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