The use of polymer agents in the reduction of hydrodynamic drag for heavy oil

Abstract

ransneft-Sever JSC, Ukhta, Russian Federation Conventional Drag-Reducing Agents (DRAs) based on higher alpha-olefin polymers do not always prove efficient for heavy oils, largely due to polymer solubility. Heavy oils have a high content of polar hetero-atomic (oxygen, sulphur, nitrogen, phosphorus) compounds which determine their solvent power to specific macromolecules. Higher alpha-olefin polymers are non-polar compounds of the paraffin series, and therefore, they experience collapse around the oil wax-appearance temperature (WAT), i.e. they fail to dissolve in liquid hydrocarbons due to thermodynamic and/or kinetic reasons. Another unfavourable factor is the high asphaltene content in heavy oil, which inhibits the dissolution of non-polar macromolecules by adsorbing them on the surface of polymer chips. Because good polymer solubility in liquid hydrocarbon is required for the Toms effect, these two factors appear most likely to be the cause of the reduced effectiveness in heavy oils of conventional DRAs. In order to improve affinity for these oils, polar groups such as carboxyl or aromatic substituents containing benzene nuclei with a dynamic π -electron system should be added to the polymer. A small number of ionic bonds may also be added to the polymer chain. Generally, the molecular architecture of DRA should be selected having specific pumping facilities in mind. This article discusses laboratory technology for DRA based on polar acrylic polymers, and describes its commercial form. It presents the laboratory equipment used to make qualitative predictions for the efficiency of various DRA in heavy oils.