Energy Policy Act of 2005 (Ultra-deepwater and Unconventional Resources Program)
Hydrate Modeling and Flow Loop Experiments for Water Continuous and Dispersed Systems
Colorado School of Mines
University of Tulsa
Objectives of the project
Hydrates continue as the most important flow assurance problem; an order of magnitude larger than waxes/asphaltenes. The project objectives are to: (1) modify the current pressure drop modeling approach to account for a free water phase, (2) perform flow loop experiments at the University of Tulsa to identify and quantify the key parameters affecting pressure drop, (3) incorporate the pressure drop model with the growth rate model in CSMHyK-fw, (4) validate the improved CSMHyK-fw model by predicting flow loop experiments, (5) model development for water+gas and water+gas+oil (continuous and partially dispersed) systems.
Description of project, including methods to be employed
As existing oil and gas fields mature, the water holdup can be higher than 60 vol.%, which can result in free water or even an inversion from oil to water continuous emulsions. The lifetime of such fields could be extended and safety risks due to hydrate blockages of deepwater flowlines and facilities can be diminished by the optimization of inhibitor injection rates and restart procedures. A kinetic model will be developed for water continuous and dispersed systems, which will be tested, improved and validated using TU flow loop measurements over a range of flow conditions for hydrate formation and pressure drop predictions. Our previous studies have shown there is a critical need to develop an improved pressure drop model for accurate hydrate flowline predictions. The parameters of the improved pressure drop model will be optimized using flow loop data, i.e. effect of water cut, velocity (shear), liquid loading, salt content, & pressure (particle/agglomerate size). The new pressure drop model will be incorporated with the growth rate model into the new kinetic model for predicting hydrate blockages in flowlines with water continuous and dispersed systems. The improved model will be validated using flow loop experiments, which is essential to the development of the model and to provide confidence in the deployment of this model to the field.
Key deliverables associated with the project
- A new and improved validated kinetic model for water continuous and dispersed (water+gas and water+gas+oil) systems, which will serve as a flow assurance management/safety tool/program to predict when/where hydrates will form in deepwater flowlines and facilities when free water is present over a range of flow conditions
- An understanding & guidelines of the effects of operating parameters on transportability, such as, pressure drop and hydrate fractions
- Correlation of pressure drops and maximum transportable fraction
- Predictions and data as to whether the presence of an oil phase reduces transportability
- Data on whether hydrate slurries may be successfully restarted.
Principal Investigators: Carolyn Koh, Amadeu Sum, E. Dendy Sloan, Mike Volk, Emmanuel Delle-case
DOE share: $701,733
Recipient share: $175,434
Project Duration: 2 years