The Effect of composition on n-alkane deposition

Abstract

n-Alkanes are known to be the major component of deposits found in subsea oil pipelines, which can cause significant problems in petroleum transportation. In this work, a coldfinger apparatus is used to simulate the deposition of n-alkanes for both monodisperse and polydisperse systems. Proper coldfinger operating conditions and experimental methods are developed. The results show that for monodisperse systems, both the percent of wax in the deposit and deposit mass increase with system cloud point. However, for binary systems cocrystallization occurs the mass of the deposit and the wax percent of the deposit decrease drastically for systems with comparable cloud points, in spite of doubling the total wax in the system. For binary systems where cocrystallization does not occur, the presence of the less soluble component enhances deposition of the more soluble component, while the deposit mass and the total wax percent remain approximately the same. For n-alkane deposition with stearic acid, n-alkane deposition can be significantly reduced even though stearic acid is present in small amounts.