(152b) Risk-Based Estimation of Hydrate Blockage Risk in Oil and Gas Flowlines

The numerical simulation of gas hydrate formation in oil and gas flowlines has traditionally employed the coupling between advanced hydrate reaction models with a multiphase transportability framework. In recent years, the Hydrate Flow Assurance Simulation Tool (HyFAST) has been developed as an open framework, where laboratory-based hydrate growth and transportability models are paired with a simplified hydrodynamic model to describe the frictional pressure loss due to hydrate growth in multiphase flow. This presentation introduces the third generation of the tool, which incorporates a critical new feature: the frictional pressure loss due to hydrate slurry formation or wall deposition is coupled within the momentum balance across the flowline. This accomplishment means that HyFAST 3 is able to estimate the risk of hydrate blockage based on flowline velocity approaching zero. To our knowledge of the field, HyFAST 3 is the first global flowline simulation tool to connect hydrate-based frictional pressure loss to flow velocity; as a consequence, the tool does not require rules of thumb to assign a risk category to the amount of hydrate in the system. This presentation will demonstrate how this novel risk assessment method may be deployed in the industry, which may be coupled with laboratory characterisation to determine the maximum allowable hydrate fraction in the system without increasing the risk of hydrate blockage.