Mechanistic Study of Non Acid Chemistries in the Inhibition of Calcium Naphthenates

Abstract

The formation of oilfield calcium naphthenate deposits poses detrimental challenges for flow assurance with occurring blockage of surface equipment, scaling at the wellbore, buildup of calcium naphthenate deposits in water separators, entrapped oil in sludge's, and requiring lengthy periods of shutdown for costly removal in offshore and onshore fields. Oil field treatment of calcium naphthenate deposition is traditionally treated with the use of acid, most commonly acetic acid along with formic acid, glycolic acid, HCl, and dodecyl benzene sulfonic acid. Interfacially active chemistries provide an alternative approach to acid chemistries to mitigate the formation of calcium naphthenates with lower treatment rates, non-corrosive properties, and pH independence. This contribution presents the evaluation of three non-acid chemistries as calcium naphthenate inhibitors using a two-step process to select the best performing chemistry and understand the mechanism of inhibition to treat and prevent oilfield calcium naphthenates. Results revealed two mechanistic forms of inhibition, surface active and complexation inhibition with the latter contributing to greater calcium naphthenate inhibition.