Thermodynamic, Rheological, and Electrical Properties of Hydrate Inhibitors: Implications for Natural Gas Production and Flow Assurance

This work studies the relationship between the thermodynamic, rheological, and electrical characteristics of gas hydrate inhibitors dissolved in water. It explores how inhibitors might be used to address flow assurance issues and enhance the output of methane from hydrate reservoirs. Several models are available in the literature that predict the thermodynamic properties of the inhibitors and additives. However, they still have limitations when it comes to forecasting thermodynamic parameters in the presence of polymers, binary solutions, and mixtures. This study aims to establish a universal correlation between the rheology of inhibitor aqueous solutions and their inhibition effects. Thermodynamic hydrate inhibitors (THIs) and kinetic hydrate inhibitors (KHIs) are the primary types of inhibitors used. Common THIs are electrolytes like KCl, NaCl, CaCl2, and other nonelectrolytes such as methanol, PEG 200, PEG 400, and PEG 600. The viscosity of chemical inhibitors in water-based materials may govern the effectiveness of hydrate inhibition. Several experiments were performed to understand and develop a correlation between the rheology of inhibitor aqueous solutions and the thermodynamic inhibition of gas hydrates. The temperature depression (Delta T-Depression) data of the hydrate were obtained from the existing literature. Delta T-Depression data were compared with measured rheology at shear rates of mu(1) = 30 s(-1) and mu(2) = 66 s(-1). The viscosity measurement was conducted at 4 degrees C, the typical temperature of natural gas hydrate reservoirs. In order to provide more comprehensive data, the electrical characteristics of the aqueous solutions were measured and recorded. The rheological-thermodynamic/electrical-thermodynamic model can be developed by comparing Delta T-Depression, viscosity, and electrical data/information. Additionally, a study was conducted to examine whether the nanoparticles altered the viscosity and electrical conductivity of the base fluids. The findings from the study will be highly valuable for production from hydrate reservoirs and flow assurance investigations.