Results analysis of non-miscible condensate displacement by nitrogen and carbon dioxide

Full miscibility conditions of nitrogen and carbon dioxide with typical gas-condensate fluids with potential condensate yield of liquid hydrocarbons 100, 300 and 500 g/m3 have been researched. In case of significant reservoir energy depletion and low reservoir pressures, that is common for final stages of the field development, full miscibility cannot be achieved for none of these gases. Application of carbon dioxide is preferable, because on the earliest stages of the development gives a chance to achieve full multi-contact miscibility at pressures that are below the initial reservoir pressure. The effectiveness of the nitrogen and carbon dioxide injection for the displacement of the dropped-out condensate have been analyzed in case of maximum depletion of the reservoir energy, when reservoir pressure is equal to the pressure of maximum liquid drop-out. Usage of carbon dioxide allows increase of condensate recovery factor by 7% in comparison to nitrogen for the reservoir fluids with a high potential condensate yield (500 g/m3).