Hydrates form when water and natural gas are mixed at high pressures and low temperatures. This is a common occurrence in oil and gas pipelines and can cause significant production challenges. Years of research toward understanding hydrate occurrences and formation have resulted in industry-standard prevention methods; however, these traditional methods can sometimes prove costly for operators.
OneSubsea has developed a cost-effective hydrate management system that eliminates the uncertainties in measurement and dosage control experienced with traditional monoethylene glycol (MEG) systems. By combining industry-proven monitoring, metering, dosing, and MEG regeneration technologies, we are able to achieve target inhibition with MEG while preventing unnecessary overdoses.
The hydrate management system comprises metering on the subsea production stream and chemical injection lines as well as the most efficient MEG reclamation facility. It combines these with real-time process simulation and condition and performance monitoring into an operational system that permits the control of hydrate formation in a closed loop, open loop, or any blend in between.
This system targets a reduction in operational uncertainty and significantly lowers opex by accurately regulating the MEG dosage required to inhibit hydrate formation.
How It Works
- The hydrate management system begins topside with the Cameron PUREMEG MEG reclamation and regeneration unit.
- To regulate and accurately dose the MEG upstream, the hydrate management system employs PULSE ultrasonic chemical injection metering valves (CIMVs), which use an ultrasonic flowmeter to provide an accuracy of within 3% of the reading to directly measure the chemical injection flow rate.
- A PhaseWatcher subsea multiphase flowmeter with Vx multiphase well testing technology measures the gas rate and total water rate. An AquaWatcher water analysis sensor detects if any water is present and measures the properties of that water to determine if formation water is present and the ratio of condensed to formation water at that time. This information enables accurate control of the CIMV to inject the inhibitor amount appropriate for that well’s total water production. The AquaWatcher sensor also measures the inhibitor/water ratio, enabling verification of correct inhibitor dosing or to provide direct feedback to the PULSE CIMV to maintain a specified ratio of inhibitor to water.
- The system uses the OLGA dynamic multiphase flow simulator and the FRIEND remote surveillance and diagnostic system for condition monitoring and forecasting and management of MEG variables.