Clathrate Hydrate-Solid Surface Adhesive Shear Strength Measurements on Carbon Steel Surfaces

Area of Science:

• Petroleum Engineering
• Materials Science
• Chemical Engineering

Background:

• Hydrate plugs in oil and gas flowlines pose risks of equipment damage and personnel injury due to detachment.
• Understanding hydrate-solid adhesive shear strength is crucial for safe depressurization procedures.

Purpose of the Study:

• To quantify the hydrate-solid adhesive shear strength under various conditions.
• To investigate the influence of subcooling, surface roughness, and wettability on hydrate plug adhesion.

Main Methods:

• Used a force meter with a cylindrical probe to measure dislodging force for model THF hydrate plugs.
• Employed profilometry to assess pipe surface roughness and contact angle measurements for wettability.
• Tested hydrate plugs on pristine, sanded, and corroded carbon steel pipe surfaces.

Main Results:

• Subcooling significantly impacts hydrate-solid adhesive shear strength, with mixed failure observed at high subcooling.
• Surface roughness and wettability influence adhesion; corroded and sanded surfaces showed greater strength than pristine surfaces.
• Wenzel wetting mode and mechanical interlocking likely contribute to increased adhesion on rougher, more wettable surfaces.

Conclusions:

• Hydrate plug adhesion is strongly dependent on operational conditions like subcooling and pipe surface characteristics.
• Optimizing flowline surface properties and managing subcooling can mitigate risks associated with hydrate plug detachment.