High Active, Dispersion Based Paraffin Inhibitors for Subsea Applications

Abstract

Abstract Production of waxy crude oils can be challenging due to increased viscosity, restart issues and wax deposition. Due to a decrease in solubility of high molecular weight paraffins in waxy crude oils with decreasing temperature, paraffins precipitate and deposit on pipeline walls or form a 3-dimensional network in which liquid oil becomes trapped. Even for crude oils with low to moderate wax content, where viscosity and restart issues may not be a critical factor, deposition could be a huge problem when (subsea) flowlines are being affected and flow restricted. Among other options available, chemical treatment with pour point depressants and / or paraffin inhibitors is used to impede wax related problems. Specific high molecular weight polymers, changing the wax crystallization process are commonly used as the active components in these pour point depressants and paraffin inhibitors. The products are formulated in solvents to allow for easy pumping and injection. To achieve interaction with crystallizing paraffins, functional groups of the polymers are similar to wax and as such the polymers themselves are difficult to dissolve. Particularly for application in deepwater, subsea or cold climates, low active formulations are used which require high dose rates. To overcome these typical problems, dispersion based products have been used for a number of years. High active dispersion base products have been successfully applied in land based operations as well as topsides offshore. New developments in formulating dispersion based PPDs and Paraffin Inhibitors has resulted in products suitable for subsea injection. One of these new environmentally friendly developments was proposed for inhibiting wax deposition in a subsea tieback in the Norwegian sector of the North Sea. Following lab evaluations that confirmed the performance of the product, the product has been successfully applied through a subsea injection line. This paper will discuss development, practical application and benefits of such products.