Molecular Insights About Gas Hydrate Formation

TLDR: In this article, the effect of three low molecular weight di-acids, namely oxalic acid, malonic acid and succinic acid on synthetic natural gas hydrate formation kinetics was investigated.

Abstract: At present, gas hydrates are the most abundant source of methane on the earth and could be a promising option in the context of climate change and energy challenges in the upcoming years. It is estimated that nearly 20,000 trillion cubic meters of methane gas is trapped in the naturally existing gas hydrate reserves. This amount will be sufficient to fulfill the energy requirements for centuries, even if 20–30% of methane is recovered by using recently developed technologies. Although gas hydrates have immense energy potential on the one hand, gas hydrate plugging, on the other hand, is one of the major industrial challenges that can cause huge economic losses. The increasing energy demand has led to drilling of deeper oil wells and has increased the length of transmission lines. The problems associated with hydrate formation have gained more attention from both researchers and industries. The current methods of combating gas hydrate plugging involve the use of methanol and ethylene glycol in a large concentration, which usually shifts the three-phase boundary region from hydrate stability region and prevents hydrate plugging. However, a large portion of these chemicals ends up in the gas stream. In such scenarios, the use of kinetic hydrate inhibitors (KHIs) becomes attractive, since these additives are required in low concentrations. The KHIs delay the nucleation of hydrate or decrease the kinetics of gas hydrate formation or both can occur simultaneously. In this work, we have reported the effect of three low molecular weight di-acids, namely oxalic acid, malonic acid and succinic acid on synthetic natural gas hydrate formation kinetics. The di-acids were tested at two molar concentrations of 0.01 and 0.05 M at 3.0 MPa and 273.15 K. The hydrate former gas consumption and induction time data are reported, and discussion on the nature of results is also presented in this work.