Gas Hydrate In Pipelines

(image courtesy of the Minerals Management Service)

Conditions of pressure and temperature leading to hydrate formation are often found in pipelines. Secondary conditions such as high gas velocity, agitation and the formation of a nucleation site may also help form hydrates.

Hydrate formation is undesirable because the crystals might cause plugging of flow lines, valves and instrumentation. This can reduce line capacity and cause physical damage to pipelines and equipment.

Flow assurance is a significant issue for deepwater oil and gas operations and concerns have been raised that for the production of gas from hydrate the flow assurance issues could prevent commercialization. Flow assurance is one of the major issues for deepwater conventional gas deposits and industry is spending millions of dollars per day to both inhibit the formation of hydrate in pipelines and mitigate or remove it once unwanted hydrate has formed. Slugs or blockages may appear and can sometime move. Whether the blockages are in-place or moving, the effect will cause either pressures to rise or pumping to become more difficult on the upstream side of a blockade or pressure will drop on the downstream side of a blockage. Pressure drop is currently the primary manner of detecting hydrate formation although other methods, primarily acoustic, are in development for limited application. Avoidance and risk management are hydrate management techniques.