Effects of the Solidification of Capillary Bridges on the Interaction Forces between Hydrate Particles

摘要

The presence of unconverted water drops in bulk hydrocarbon is likely to bridge hydrate particles and cause hydrate agglomeration, leading to hydrate accumulation or bedding in oil and gas pipelines. The knowledge of the interaction forces between hydrate particles and water drops can provide critical insights into hydrate agglomeration as well as potential prevention strategies. At high subcooling, the frequent solidification of the capillary bridge between hydrate particles could significantly affect the interaction force. However, the existing classic pendular liquid bridge model with a fixed liquid volume is not adequate for this unique case. A new interaction force model is required. Based on the pendular liquid bridge model and hydrate shell theory, a modified interaction force model was developed by considering the solidification of capillary bridges. Furthermore, using a self-built micromechanical force apparatus, the cyclopentane (CyC5) hydrate-droplet adhesion forces at a temperature range from 0.5 to 6 degrees C were measured to verify the proposed model. The experiments suggest that as the temperature was increased from 0.5 to 6 degrees C, the adhesion forces first increased and then decreased. Solidification could enhance the strength of the already formed liquid bridge. However, at lower temperatures (0.5-3 degrees C), the quick solidification led to smaller particle/bridge initial contact areas and weaker adhesion forces. By accurately predicting the evolution of the capillary bridge shape/outline, the predicted adhesion forces agree well with the experimental measurements. This study can provide more insights into hydrate agglomeration. The proposed model is an important supplement to hydrate adhesion theory and could more accurately evaluate hydrate plug risks in gas-oil flowlines.