High-Throughput Testing of Kinetic Hydrate Inhibitors

Abstract

The formation of clathrate hydrates is considered to be a major flow assurance problem in offshore oil and gas lines. Kinetic hydrate inhibitors (KHIs) are used for hydrate prevention, with their efficiency assessed by techniques that are a bottleneck for new materials development in this area. Efficient design of high-performance advanced materials requires a thorough understanding of the structure–property relationships that is currently hindered by conventional evaluation protocols. A cost-effective method for the rapid, parallel screening of potential KHIs is desirable, which preferably does not involve handling of highly pressurized and potentially flammable/explosive fuel gases. We have developed a novel high-throughput KHI ranking method based on its inhibition performance of Structure II (sII)-forming cyclopentane (c-C 5 ) hydrate under atmospheric pressure. Ice seeding was used to induce the nucleation of c-C 5 hydrate to save time, so the method focuses on the growth inhibition performance (as opposed to the nucleation inhibition performance) of a KHI. Comparison of some commercial KHIs [Luvicap 21W ( N -vinylpyrrolidone: N -vinylcaprolactam 2:1 copolymer), Luvicap 55W ( N -vinylpyrrolidone: N -vinylcaprolactam 1:1 copolymer), polyvinylpyrrolidone (PVP), poly( N -isopropylacrylamide) (PNIPAM), and polyacrylamide (PAM)] was made using this new screen, which has been validated against conventional rocking cell measurements. The observed efficacy performance ranking of these KHIs was Luvicap 21W ≥ Luvicap 55W > PNIPAM ≥ PVP > PAM. This ranking was in reasonable agreement with the rocking cell data that gives the ranking Luvicap 55W > Luvicap 21W > PNIPAM > PVP > PAM. This method enabled parallel screening of multiple KHIs with major advantages in time, instrument complexity, safety, and material. We propose that this method could serve as a useful first screening method for identifying promising candidates for more rigorous testing.