Improvement of heavy oil displacement efficiency by using aromatic hydrocarbon solvent

Abstract

© 2020 International Multidisciplinary Scientific Geoconference. All rights reserved. Development of heavy oil deposits increases each year, due to consumption of conventional oil reserves. However, extraction process of heavy oil faces a number of problems. The main of these problems are high density and viscosity of heavy oil as well as high content of asphaltene-resin-paraffin components, which can be precipitated. Currently, the main methods that are being used for heavy oil recovery are thermal methods, like steam assisted gravity drainage (SAGD), cyclic steam stimulation (CSS) and in-situ combustion (ISC). Another alternative is using solvent-based recovery methods, which have advantages in terms of energy effectiveness and cost efficiency. In this work, using aromatic hydrocarbon solvent is considered as an oil displacement method. Solvent o-xylene has been chosen as the research object due to its vast area of application and ability to remove organic deposits. In this work different experimental techniques were conducted to evaluate the injection of xylene for improvement heavy oil recovery. Capillary imbibition experiments of oil saturated core samples by formation water and xylene solvent were conducted in order to compare their effectiveness under standard conditions. Filtration studies under reservoir conditions were performed on a core sample model saturated with heavy oil to evaluate displacement efficiency. In addition, filtration-volumetric parameters of core samples, group and elemental composition of oil, viscosity dependence on a solvent concentration, thermal stability of solvent as well as its aggregative stability were studied. According to the obtained results, application of o-xylene in imbibition experiments (duration 7 days) helped to increase displacement efficiency from 20 % in case of water to 61 % in case of solvent. Addition of small amount of solvent to heavy oil significantly decreased its viscosity. In case of addition of 3 wt.% of solvent viscosity of heavy oil reduced more than two times from 427.18 mPa·s to 208.4 mPa·s. Compared with the basic waterflooding process, using solvent injection leads to three times increasing of oil displacement efficiency, which reaches 69 %. In addition, o-xylene showed good dissolving ability with lowest cloud number of heavy oil in its media, which is equal to 0.22. According to the laboratory studies pilot test will be performed at the Akanskoye field using studied solvent.