The composition of acid/oil interface in acid oil emulsions
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ORIGINAL PAPER
The composition of acid/oil interface in acid oil emulsions Yulia M. Ganeeva1 · Tatiana N. Yusupova1 · Ekaterina E. Barskaya1 · Alina Kh. Valiullova1 · Ekaterina S. Okhotnikova1 · Vladimir I. Morozov1 · Lucia F. Davletshina2 Received: 21 November 2019 © The Author(s) 2020
Abstract In well stimulation treatments using hydrochloric acid, undesirable water-in-oil emulsion and acid sludge may produce and then cause operational problems in oil field development. The processes intensify in the presence of Fe(III), which are from the corroded surfaces of field equipment and/or iron-bearing minerals of the oil reservoir. In order to understand the reasons of the stability of acid emulsions, acid emulsions were prepared by mixing crude oil emulsion with 15% hydrochloric acid solutions with and without Fe(III) and then separated into free and upper (water free) and intermediate (with water) layers. It is assumed that the oil phase of the free and upper layers contains the compounds which do not participate in the formation of acid emulsions, and the oil phase of the intermediate layers contains components involved in the formation of oil/ acid interface. The composition of the oil phase of each layer of the emulsions was studied. It is found that the asphaltenes with a high content of sulfur, oxygen and metals as well the flocculated material of protonated non-polar oil components are concentrated at the oil/acid interface. In addition to the above, in the presence of Fe(III) the Fe(III)-based complexes with polar groups of asphaltenes are formed at the acid/oil interface, contributing to the formation of armor films which enhance the emulsion stability. Keywords Acid emulsions · Ferric cations · Acid/oil interface · Asphaltenes · Resins · Waxes · Oil paramagnetic particles · Fe(III)-based complexes
1 Introduction During well operations, reservoir porosity and permeability of bottomhole rock deteriorate as a result of clay swelling, mineral scaling, asphaltene and wax deposition, formation of high viscosity water-in-oil emulsions, etc. To improve wellto-reservoir connectivity and restore rock permeability in the bottomhole formation zone, well stimulation treatments with various acids are used. However, the use of acid is accompanied by a number of negative consequences (Fredd and Fogler 1998). During acid treatment there is an interaction of Edited by Yan-Hua Sun * Yulia M. Ganeeva [email protected] 1
Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center, Russian Academy of Sciences, Arbuzov str. 8, Kazan 420088, Russian Federation
Gubkin Russian State University of Oil and Gas (National Research University), Leninsky Prospekt 65, Moscow 119991, Russian Federation
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acid with the rock, in which significant quantities of soluble and insoluble inorganic products capable of precipitating and clogging the reservoir pores can form, thereby reducing the rate of production wells and the intake capacity of injection wells. In addition, a serious danger is also posed by the prod
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