Wax deposition mechanisms and the effect of emulsions and carbon dioxide injection on wax deposition: Critical review

Abstract

Wax deposition inside the tubing walls endures being a critical operational challenge faced by the petroleum industry. The build-up of wax deposits may lead to the increase of pumping power, as well as the decrease of flow rate or, even, to the total blockage, with production losses and high operational costs. The current paper is a critical review of the main deposition mechanisms involved in wax deposition. Most of wax deposition models regard molecular diffusion as the dominant wax deposition mechanism. However, there are other deposition mechanisms which can also play a role. As most oil fields produce water along with crude oil, the deposition process for oil-water emulsions has also been investigated. Furthermore, carbon dioxide injection effects upon wax appearance temperature along its current applications onto wells have been reviewed. Having a total awareness of the wax deposition mechanisms background is the key factor to prevent the wax precipitation and control the deposition of solid wax crystals.