PRODUCTION

Factors affecting performance of crude oil wax-control additives

Lab studies define application procedures that can reduce effectiveness of pour-point depressant chemicals on crude oils and what can be done about it

John S. Manka and Kim L. Ziegler, The Lubrizol Corp.

Crude oil producers have used pour-point depressants (PPDs) with great success for several decades. However, chemical wax-control packages can be plagued by crude-oil specificity, large package treating rates, and waxy components that can be hard to apply.

This article discusses what factors affect the performance of crude oil wax-control additives and what contributes to crude-oil “specificity,” as will be defined. This study investigated effects of the wax-control additives’ polymer backbone, pendant chains and molecular weight on cold-flow performance. The impact of solvents used, the extent of the packages’ dilution and the effect of proper additive dosing is addressed.

Concluding comments summarize the study, noting in particular that effective mixing of the additive into the crude oil has a great effect on PPD performance. And specificity can be overcome by using mixtures of depressants to be able to treat a broad range of crude-oil wax distributions.