Organochlorine compounds are undesirable components of oil. Under certain conditions they can form chloride salts and hydrochloric acid, which are sources of corrosion of equipment. Organochlorine compounds can form or get into oil both at the production stage and during its processing. In principle, organochlorine compounds in oils can be divided into two groups: natural (native) and technogenic. This article describes studies with modeling in reservoir conditions of interaction of the multicomponent system ‘oil-reservoir water – core-drilling mud/chemical reagent’. The components of the multicomponent system (oil, reservoir water, core, drilling mud, chemical reagent) are studied. The presence of components, which potentially can lead to generation organochlorine compounds or catalyst reaction of generation organochlorine compounds, is identified. The methodology of providing of model experiments is described. The possibility of organochlorine compounds formation under high oxidative potential of the medium is considered. The mechanism of the chlorination reaction involving active (molecular) chlorine is proposed. The thermodynamic calculations with using standard reduction-oxidation potentials are presented. Conditions of the process of generation significant amount of active (molecular) chlorine are calculated depend on nature of oxidant, concentration of chloride ion and pH. It has been shown that with increasing acidity of reservoir waters, a number of substances capable to oxidize chloride ion with the formation of molecular chlorine grow. These conditions can be realized both during acid treatment of wells and as a result of certain reduction-oxidation processes that occur with the formation of acids. Moreover, some oxidizing agents, for example, persulfate ions, are capable to generate molecular chlorine at any pH value. The performed calculations allow to make an approximate assessment of the conditions for the generation of chlorine in an acidic environment. To predict the processes of organochlorine compounds formation it is necessary to provide a detailed study of the systems ‘core - formation water - oil - reagents / drilling fluids’.
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