Effect of naphthenate precipitation on dynamic force between clathrate hydrate-water interface

Abstract

Hydrate plugging effect in a submarine oil transportation pipeline can cause significant economic and environmental losses on offshore oil production industry. This work investigates the effect of naphthenic acid and naphthenate on the dynamic force acting on a clathrate hydrate at a water-oil interface. The adhesion force acting on the hydrate with various concentrations of naphthenic acid is measured by z-directional microbalance. The addition of naphthenic acid in the oil phase reduces the adhesion force acting on the hydrate from the lowered interfacial tension between the hydrate particle and aqueous phase. With the basic solution, the precipitate layer of calcium naphthenate is formed at the water-oil interface. The precipitate layer blocks the contact between the hydrate particle and aqueous phase, and the anti-adhesive force pushing on the hydrate probe is induced. In this case, the precipitated calcium naphthenate acts like an anti-agglomerant that inhibits the agglomeration of hydrate particles. These findings imply that the crude oil of high acidity may alleviate the agglomeration of hydrate particles in the oil pipeline by inducing naphthenate formation.