Study of the Gas Hydrate Anti-agglomerant Performance of a Series of n-Alkyl-tri(n-butyl)ammonium Bromides

Plugging of flow lines by gas hydrates is a costly and challenging problem for the oil and gas industry. One of the options available is the injection of anti-agglomerant (AA) low-dosage hydrate inhibitor (LDHI). LDHIs are injected in much lower concentration and amount in comparison to thermodynamic hydrate inhibitors (THIs). Quaternary ammonium surfactants currently dominate the AA market. In this paper, we report the first systematic study of laboratory tests on single-tail quaternary tributylammonium bromide surfactants for their ability to prevent structure II gas hydrate agglomeration in high-pressure rocker cells. The effect on AA performance by varying the alkyl chain length from 8 to 18 carbon atoms and the effect of salinity have been investigated. It was shown that there is an optimum alkyl tail chain length for the anti-agglomerating efficacy of this surfactant class and that increased salinity improves the AA performance. The performance of the AAs could also be further improved by the addition of the anionic surfactant, sodium dodecyl sulfate (SDS), particularly at low salinity.