Waxy Gels with Asphaltenes 2: Use of Wax Control Polymers
journal contributionposted on 16.12.2015, 15:38 by Jack F. Tinsley, Justin P. Jahnke, Douglas H. Adamson, Xuhong Guo, Devang Amin, Robert Kriegel, Rajesh Saini, Heather D. Dettman, Robert K. Prud’home
The effect of asphaltenes on the effectiveness of wax control polymers was studied using a model waxy oil and a set of polymers with controlled crystalline and polar/aromatic content. The effect of crystalline content was examined with a set of maleic anhydride copolymers with alkyl appendages of different lengths. Different polar and/or aromatic functionalities were incorporated into the maleic anhydride copolymers (MAC) and poly(ethylene butene) polymers to probe potential interactions with the asphaltenes. The performance of the polymers was measured by testing their effect upon precipitation temperature, gelation temperature, and yield stress. Some polymers provided little or no benefit. Others had significant effects, reducing precipitation temperatures up to 1.9 °C, gelation temperatures up to 37 °C, and yield stresses up to 2200-fold for solutions of 8 wt % wax. Polymer efficacy was almost entirely determined by the crystalline functionality incorporated into the polymer rather than the presence of polar functionality designed to target interactions with the asphaltenes. The performance of the polymers is attributed to the ability of the polymers to coprecipitate with the wax. Comparison with previously published results using the same wax showed that the selectivity of the MACs was strongly affected by wax concentration, not because the quantity of wax overwhelmed the polymer, but because the range of wax precipitation temperatures increased above that of the polymer. Comparison of the effect of polymers in solutions with and without asphaltenes showed that asphaltenes had different effects on polymer performance, depending on the property being measured (precipitation temperature, gelation temperature, or yield stress).