ПРИМЕНЕНИЕ МЕТОДА УПРАВЛЕНИЯ ЭЛЕКТРОХИМИЧЕСКИМИ ПАРАМЕТРАМИ СРЕДЫ ДЛЯ СНИЖЕНИЯ СОЛЕОТЛОЖЕНИЯ

Abstract

Background Medium corrosiveness is caused by the presence of salt ions, which are directly involved in the corrosion process, causing deposition of inorganic salts on the surface of the equipment. Salt depositions often bring to reduction of the pipeline working opening and contamination of the transported/processed medium. Removal of the active salt ions from the working medium, or their inactivation, reduces significantly the rate of equipment corrosion and the amount of salt depositions. Aims and Objectives To improve the efficiency of oilfield equipment is necessary to use special techniques which reduce deposition of inorganic salts on the walls of the equipment. To this end, the following problems were solved: the factors which determined the tendency of solution to salt precipi-tation were identified, and the possibility for changing the kinetics of salt precipitation was studied using the solution prepared in the device. Methods It is necessary to develop a method of reducing the number of active salt ions to prevent corrosion failure of equipment and reduce scaling. The method must ensure the required effective removal of the active ions at low capital and working costs, and it must not contaminate the working medium. A method of controlling electrochemical parameters of the field media was developed to study disposition of solutions to salt precipitation. The essence of the method is to change the basic characteristics of the medium, such as pH and redox potential (ORP). Solution with altered characteristics added to operating environment changes the ionic composition of the medium and brings to salt transition from ion state to crystalline state with much lower activation energy and lower tendency to interaction of salts and the metal surface. Results A method was developed to reduce the amount of active ions in the working medium by adding to the medium treated water with modified electrochemical characteristics. A lab bench was designed to determine the effect of the electric field on the solution of salt ions, comprising a special unit for controlling the electrochemical parameters of environments. Liquid flow in the unit passes between two oppositely charged electrodes and is treated by the electric field. The unit facilitates separation of the liquid stream into two oppositely charged streams, i.e. anolyte and catholyte. Positively charged salt ions are dominant in one stream (the anolyte), and negatively charged ions are dominant in the other stream (catholyte). Added catholyte alkalizes the medium and shifts the redox potential (ORP) in the negative direction, while addition of analyte leads to acidification of the medium and ORP displacement to positive value. Addition to the working medium of anolyte and catholyte produced in the device changing the electrochemical parameters of liquid media, promotes electrochemical reactions, as a result of which the active calcium ions causing salt deposition are bonded as poorly soluble com-pounds. Thus obtained salt crystals are not capable to deposit on the walls of the metallic equipment because of the low energy of activation, and are removed by the fluid stream.