The main purpose of the study is the mathematical and hydrodynamic analysis of unstable flow in oil-and-gas flowlines under conditions of carbon dioxide corrosion. First of all, the analysis of existing mathematical models describing multiphase flows was conducted. Then, Multiflash was used to create a fluid model, OLGA was implemented for hydrodynamic analysis of the flow, PIPESIM provided an ability of corrosion rate calculation. However, laboratory studies of corrosion inhibitors were done and made it possible to compare experimentally calculated corrosion rates with field test data. It was approved that significant content of carbon dioxide in fluid composition and high water cut magnitudes are the main factors causing corrosion in the considered isolated system. Moreover, the effectiveness of each inhibitor was determined experimentally. In addition, possible ways to solve the pipeline corrosion problem were suggested.