Evaluation of Effects of Selected Wax Inhibitors on Paraffin Deposition

摘要

Deposition from decane solutions of model paraffins such as n-C_(24)H_(50) (C24), and n-C_(36)H_(74) (C36), as well as a mixture of n-alkanes (C21 to C45) was examined with and without chemical wax deposition inhibitors. The device used to produce the deposits investigated was a "Cold Disk" Wax Deposition Apparatus (CoDWaD) capable of producing field like deposits with relatively small volumes of oil in minutes. It was found that most of commercial wax inhibitors tested can decrease the deposition of low molecular weight paraffins (C34 and below), while having little effect on the wax deposition for high molecular weight paraffin (C35-C44). In many cases, although the total amount of wax formed on the cold plate was reduced, the absolute amount of deposition for high molecular wax was actually increased. Therefore, the net effect of many commercial inhibitors is to make even harder wax under the tests conditions studied here. One intriguing result was that the addition of an oleic imidazoline corrosion inhibitor improved the performance of two wax inhibitors tested. It was also observed that there are subtle differences in inhibitor performance depending on whether the test solutions are binary mixtures, synthetic wax mixtures, or crude oil.