Gas hydrates present a serious threat to oil and gas production efforts as they can form plugs that can block pipelines, leading to production halts and potential pipe ruptures. Kinetic hydrate inhibitors (KHIs) are cleaner, cheaper, and greener low dosage hydrate management chemicals which can prevent catastrophic hydrate plug formation in both gas and oil-dominated flow lines. However, much still needs to be known about how KHIs affect hydrate particles to enable their safe application. PVP, a model KHI, was investigated at low concentrations, ranging from 0.0005wt% to 0.01wt%, to discover its effects on hydrate interparticle force, morphology, and growth. It was found that PVP reduces interparticle force at short contact times by 40-54%, but that increased PVP concentration can artificially increase force since more unconverted water may exist at the surface for capillary bridging. PVP also affects contact force for up to an hour, well after the onset of particle sintering, reducing forces by 20-40%; however, high variability induced by the complex effects of PVP coupled with fewer trials due to the time involved in testing produced large error bars which partially obscure the observed trend. Film growth measurements were performed with different surface and aqueous concentrations of PVP, and it was discovered that PVP reduces film growth rates by 30-50% dependent more on aqueous than surface concentration. Major nucleation and growth effects were visually observed to occur at the highest concentration tested, 0.01wt% PVP, which is two orders of magnitude below the 1-3wt% KHI traditionally employed in hydrate management. Importantly, it was discovered that low concentration PVP causes major morphological changes to the hydrate particles in both short and long-term observations. As particle morphology influences interparticle force and agglomeration, it was vital to document and explain the morphological changes caused by the PVP. Images and videos of the drastic particle morphology changes in both the short term (~30 minutes) and long term (up to 2 hours) were displayed, and a mechanism by which the PVP causes the morphology changes was discussed in detail. The results of this research will impact KHI research, aiding in understanding the properties of KHIs and providing a potential morphological screening tool for KHIs, and enabling the safer and more informed application of KHIs in flow assurance, carbon capture, and hydrogen transport.

Morphology and interparticle force changes in the presence of low concentrations of model kinetic hydrate inhibitors

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