OPTIMIZATION OF THE TECHNOLOGICAL MODE OF OPERATION OF A HIGH- VISCOSITY OIL PIPELINE BY ADDING CONDENSATE TO THE FLOW

Abstract

Pipeline transportation of high-viscosity oils, characterized by higher content of high-molecular-weight hydrocarbons, paraffins and asphalt-resin substances, is complicated by abnormally high viscosity and density. The main risks of transporting such oil are related to the consequences of cooling during pipeline movement, namely:- change of technological mode parameters: restriction of flow rate and increase of operating pressure due to high friction losses along the pipe;- complications and unscheduled pipeline stops due to the deposition of asphalt-resinous paraffinic deposits (ARPD) and solidification of oil during transportation;- reduction of the time of safe pipeline stop;- high value of stranding pressure after stop, etc.These problems are particularly acute during periods of low temperatures and when the pipeline is operating in cyclic mode.One of the methods used to reduce viscosity and solidification temperature of high-viscosity oils is compounding with condensate (light oil, gas condensate) produced in nearby regions. This solution allows to improve rheo-logical properties of oil, reduce the temperature of paraffin crystallization onset, minimize the risks of the ARPD formation, increase the time of accident-free stop, reduce the pressure values at the main transportation and at the restartof liquid transportation through the pipeline after a long stop.This article considers the application of oilcondensate compounding on the example of transportation of naphthenic oil of the Russkoe field as part of the development of measures to improve and increase the operation reliability of the overground heat-insulated main oil pipeline CPF «Russkoe» – DAP «Zapolyarnoye» under various technological parameters and environ-mental conditions.The research of rheological properties of initial viscous oil, added stable condensate and their mixtures, and also the results of made hy-draulic and thermotechnical calculations, have allowed to define values of the lowest necessary and optimum ratio of pumped liquids in the mixture in various operating conditions, to find the optimum technological mode of pipeline operation.Practical significance of the made researches consists in the results of laboratory researches, calculations and variable modeling of pipeline operation after condensate addition that allow to prove efficiency of the solution and in further increase safety, and also to provide failsafe operation of existing and designing pipelines, minimizing the main risks and possible complications at transportation of high-viscosity oils, characterized by high content of high-molecular hydrocarbons, paraffins and asphalt-resinous substances.