Hydrate rheology of water-in-oil emulsions with cyclopentane

Abstract

Hydrates of natural gases are crystalline solids, composed of water and light hydrocarbon molecules that assemble in special structures under certain conditions of pressure and temperature. For most offshore production facilities, it is a major concern for the oil and gas industry, given that it can lead to a full blockage of subsea and a complete stop of petroleum flow. However, avoidance costs have grown too high, so the industry began shifting towards a risk management methodology. Within this strategy, a promising field is the evaluation of rheological properties of hydrate slurries: its full understanding can help predicting if hydrates formation will lead to a blockage, becoming a valuable tool in risk assessment of many activities. The present work is a part of this effort, employing an emulsion combined with cyclopentane (known hydrate former at atmospheric pressure) to evaluate different methods. In order to fulfill this objective, the rheological behavior of water-in-oil emulsion, with and without cyclopentane, was studied in rotational and oscillatory tests, under hydrate forming conditions. The system response to changes in thermal (minimum temperature and cooling rate) and hydrodynamic (shear) parameters was also briefly investigated.