Design, Fabrication and Validation of a Laboratory Flow Loop for Hydrate Studies

摘要

The peculiar nature of the offshore environment has necessitated the need for the Oil and Gas industry to develop durable subsea technologies and better hydrate inhibitors to prevent hydrate formation and assure flow. This paper discusses the design, fabrication and validation of a laboratory flow loop for hydrate studies. The laboratory loop is a closed loop of 12meters, fabricated using 0.5inch 316 stainless steel pipe enclosed in an insulated 4inch Polyvinylchloride (PVC) pipe. The skid mounted loop was fitted with pumps, temperature gauges, pressure gauges, differential pressure transmitters, a gas mixing vessel, an inhibitor mixing vessel, and a Natural Gas cylinder. Hydrate formed in the loop when natural gas was contacted with water under suitable hydrate forming temperature and pressure conditions and was indicated by an increased loop temperature, an increased differential pressure and a decreased loop pressure. Loop Validation was done by flowing a single phase fluid of water, a single phase fluid of gas and a 2 phase fluid of gas and water in three different experimental runs respectively. Each experimental run lasted 2 hours during which temperatures and pressures around the loop were recorded every minute. Hydrate formation was observed in the experimental run conducted with the two phase fluid (gas and water) and the experimental run conducted with gas alone due to water condensing out of gas during cooling. Hydrate did not form in the experimental run conducted with single phase fluid of water. The laboratory flow loop adequately predicts hydrate formation and has been used in screening and selection of Kinetic Hydrate Inhibitors (KHI).