Multi-Functional Flow Assurance Inhibitors : Three Birds With One Stone?

Abstract

Abstract Due to the presence of produced water, several fouling problems such as gas hydrates and scale, as well as corrosion can occur in unprocessed subsea production flow lines. Several treatment chemicals often need to be injected simultaneously at the well head into these flow lines. Among them are hydrate, scale, and corrosion inhibitors. However, some combinations of these chemicals can be antagonistic. We have investigated the possibility to combine all three properties into one molecule. We used kinetic hydrate inhibitor (KHI) polymers as the developmental starting point for use in cold flow lines with low to medium gas hydrate subcooling potential. We focussed on maleic-based polymers as they offer a low cost - high performance solution with great flexibility to also incorporate functionality for scale and corrosion inhibition. A set of low molecular weight maleic homo- and copolymers were synthesized and synergists added to improve the CO2 corrosion inhibition performance. The KHI performance was determined in high pressure steel rocking cells, scale calcite inhibition in static jar and dynamic tube blocking test equipment and sweet corrosion inhibition in a CO2 bubble test cell. The difficulties of achieving the "triple", three different inhibitors in one molecule, will be highlighted.