Development of hydrate inhibition monitoring and initial formation detection techniques
Abstract
Prevention of gas hydrate blockages is a major challenge posed to the petroleum
industry because uncontrolled formation of hydrate may result in plugging of transport
pipelines, causing considerable production loss and personnel safety hazard. Injection
of hydrate inhibitors is the most common option to prevent hydrate formation.
In current industrial practice the dosage of hydrate inhibitor is estimated and injected
upstream without much downstream measurements. Therefore, hydrate blockages are
still encountered in the oil and gas industry due to lack of any hydrate monitoring
measures against unexpected changes.
In this thesis, novel techniques have been developed for monitoring hydrate inhibition
and detecting early signs of hydrate formation based on downstream sample analysis
and online measurements. The main achievements of this study can be categorised as
follow:
1. Hydrate Inhibition Monitoring Techniques: Three techniques, i.e.
conductivity-velocity (C-V) technique, water activity technique and water
content technique, have been developed for determining optimising inhibitor
injection rates
2. Initial Hydrate Formation Detection Techniques: The main objective of
detecting early signs of hydrate formation is to give the operators adequate time
to prevent hydrate formation and start remediation actions. Two techniques
including the onset of hydrate formation and compositional change have been
developed for detecting initial hydrate formation
3. Development of prototypes: Following the above fundamental studies,
prototypes of the CV and water activity methods have been developed
The development of hydrate inhibition monitoring and early hydrate formation
detection techniques opens a novel flow assurance approach for the oil and gas
industry. The developed hydrate monitoring techniques like the C-V technique, water
activity and content techniques can be used to optimise hydrate inhibitor injection. In
the near future, further development of the investigated early hydrate formation
detection techniques like gas compositional change technique could provide an
effective measure to minimise the risk of hydrate blockage.