Flow Assurance: Hydrate Monitoring and Early Warning Systems

Currently, hydrate inhibitors are injected at the upstream end of pipelines, based on the calculated/measured hydrate phase boundary, water cut, worst pressure and temperature conditions, and the amount of inhibitor lost to the non-aqueous phases. In general, no means of controlling and monitoring are available along the pipeline and/or downstream to assess the degree of inhibition. In many cases, high safety margins are used to account for the uncertainties in the above parameters and minimise the gas hydrate risks. However, despite all these efforts, hydrates do form that can have considerable economic and safety impacts.

The main objectives of this project are:

  1. developing methods for determining the hydrate safety margin, and
  2. developing techniques for detecting initial hydrate formation in pipelines.

The first goal is to ensure that the system is adequately inhibited against hydrate formation and that inhibitor injection is optimised. The second goal is to develop a warning system should hydrate start to form (prior to hydrate build up and pipeline blockage). The feasibility phase of this project began in early 2004 with support from a major E&P company with promising results. The current phase of the project, with support from 7 major oil and gas production companies, began in August 2005 for a period of two years.