Assessing Hydrate Formation in a Gas Condensate Subsea Tieback Using a Transient Hydrate Simulation Tool

Abstract

Current oil prices have shifted the offshore flow assurance philosophy from "hydrate avoidance" to "hydrate management". In order to manage hydrate formation in the pipeline, not only do we need to have a good understanding of the hydrate formation process, but also a comprehensive hydrate formation predictive tool is necessary. In this work, a transient hydrate simulation tool coupled with a multiphase flow simulator, which predicts the hydrate formation rate and amount to determine hydrate slurry transportability, is applied to assess the hydrate formation risk in an offshore gas condensate subsea tieback under design stage. A simulation model is developed using the geometry, fluid properties and predicted production data from this field. This gas condensate field has an offshore separator that connects to a subsea production line. After separation, gas and liquids are transported by export lines. In this study, the hydrate formation in the production and the liquid export lines was estimated using the transient hydrate simulation tool. Simulation studies were performed to assess the hydrate plugging risk at both steady state and transient operations considering different water cuts. This simulation tool has been demonstrated to be useful in modeling hydrate management during subsea pipeline design and optimization, and can provide guidelines for safe and cost-effective hydrate management in the field.