Kinetic Hydrate Inhibitor Studies for Gas Hydrate Systems: A Review of

Review pubs.acs.org/EF

Kinetic Hydrate Inhibitor Studies for Gas Hydrate Systems: A Review of Experimental Equipment and Test Methods Wei Ke† and Malcolm A. Kelland*,‡ †

Department of Petroleum Engineering and ‡Department of Mathematics and Natural Sciences, Faculty of Science and Technology, University of Stavanger, NO-4036 Stavanger, Norway ABSTRACT: Kinetic hydrate inhibitors (KHIs) have been studied, developed, and used in the oil and gas industries for more than two decades. The main active ingredients in commercial KHI formulations are water-soluble polymers. When dosed at low concentrations (0.1−2.0 wt % active chemical), they are able to retard the gas hydrate formation process and facilitate reliable oil and gas transportation. A considerable amount of research effort on KHI technologies has contributed to an abundance of KHI knowledge, applications, and tailor-made solutions. Whereas previous reviews have concentrated on the chemistry of KHIs, this review article has a particular emphasis on the experimental equipment, hydrate detection tools, and test methods commonly applied in KHI investigations. The underlying mechanisms of KHIs are still not fully understood. The major hypotheses proposed in the literature and supporting experimental and computational evidence are also reviewed.

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INTRODUCTION Gas hydrates are crystalline, nonstoichiometric clathrate inclusion compounds. At the microscopic level, they are composed of hydrogen-bonded water molecules as hosts and gas molecules entrapped in the water cavities as guests. They are not chemical compounds because no strong chemical bonds exist between the water and gas molecules. Generally, high pressures and low temperatures are required for their stable existence. The gas molecules able to be enclathrated into the water lattices are usually small (