Synthesis and Evaluation of Polymeric Additives as Flow Improvers for Indian Crude Oil

Abstract

Transportation of crude oil near or below its pour point requires a deep understand-ing of crude oil chemistry, its rheological properties, and operating conditions. Out ofall the methods available for pumping waxy crude oil, use of pour point depressant (PPD) is preferred economically. Optimization of PPD dosages can affect cost savings. Present study deals with the synthesis of copolymers of maleic anhydride and esters of n-alkyl alcohols with oleic acid and methacrylic acid. The resulted copolymers were esterified with two moles of fatty alcohol (C19H36O3). They were characterized by IR spectroscopy and their molecular weights were determined by GPC. These polymeric diesters with pen-dant fatty chains were evaluated for their efficiency as pour point depressants and flow improvers on crude oil from Gandhar oil field (Gujarat, India). The polymeric diesters of oleic acid series were found to be more effective and depress the pour point of the crude oil up to 9oC with 500 ppm of doses. The rheological properties of the crude oil such as apparent viscosity, plastic viscosity, and yield values were also studied using Fann V-G meter. The virgin crude oil above the pour point temperature was found to behave as Newtonian fluid and at the pour point it shows Bingham plastic behaviour. Different doses (100, 500, and 1000 ppm) of synthesized polymeric additives were examined at different temperatures with the crude oil to evaluate pour point depressants and to study the dependence of shear rate on its shear stress and viscosity. The additives of polymeric diesters (DO series) were evaluated as PPD and rheological modifiers. The mechanism of pour point depression and viscosity reductions are also discussed.