Combating Hydrate Formation in Well Flowlines

Abstract

The article details methods for the timely detection of ice plugs, which predominantly form on the side of the gas gathering station (GGS) at pipe bends, turns, and valve installations. Early detection of the problem is based on the following indicators:

• Decrease in gas flow rate at the metering station.
• Appearance of an uncharacteristic gas flow sound at the GGS.
• Pressure increases in the well lines.

For accurate localization of the formed blockage, acoustic monitoring, temperature measurement using infrared thermometers (since the temperature is significantly lower at the plug locations), and analysis of the pressure drop rate during a test line blowdown are used.

The authors provide a number of practical measures for eliminating hydrate formations:

• Sudden opening of the valve after a preliminary pressure build-up to mechanically shift and destroy the plug.
• Local heating of the problem area using a heat gun.
• Flowline blowdown (direct and reverse) to create a destructive pressure differential before and after the plug. At the same time, it is noted that these methods can provoke a dangerous water hammer.
• Two-way gas bleeding followed by thawing, which is highlighted as the safest but most time-consuming method.

A special emphasis is placed on the need for strict compliance with all health, safety, and environmental (HSE) rules and regulations when carrying out the work.