- Sometimes called “Steam Field”, the Geothermal Flowline Systems consist of insulated steel infield flowlines connecting production wells to power generation facilities and then carrying slightly cooled reservoir fluids back to injection wells back into the reservoir.
- The size and scope of these flowlines would be a function of whether distributed power generation at each well pad was selected or whether a central power plant was selected. Construction access considerations and vegetation clearance and drainage are important aspects of the design.
- Due to large thermal expansions as temperatures increase from ambient to the temperature of the contained fluids, these lines would need to have expansion loops and bends to allow the lines to expand and contract. Detailed stress models and calculations are required to ensure integrity. Flowline supports need to consider both static and thermal loads and be able to incorporate flowline movements/deflections where required. Depending on topography, there might be liquid holdups and surges during start-up and shutdowns to be considered.
- With hot, often corrosive fluids in these lines, corrosion and material selection is important.
- There are multiple insulation technologies for these flowlines ranging from coatings to wrapped insultation with metallic covers.
- Scaling can be an issue in wells and these flowlines as the produced fluids experience chemical reactions due to changes in temperature and pressure. Mineral scaling can occur in certain circumstances involving carbonates, silica polymorphs, metal compounds (oxides, hydroxides, sulphides, sulphate), and clays. Pressure and temperature changes can result in precipitates that have the potential to scale in wells and surface facilities. Integrated flow assurance modelling is required to ensure these flow assurance issues are able to be managed, either with maintaining certain pressure or temperature envelope limits or by the injection of chemical treatments in the fluid to mitigate the tendency to precipitate or scale.
