V.M.Fataliyev, S.A.Salimova, S.D.Maharramova
Institute of Oil and Gas of Azerbaijan National Academy of Sciences, AZ1143, Baku, F. Amirov str., 9
As a result of the analysis of thermodynamic experiments as well as field data on production wells in a number of fields in Azerbaijan and Russian, three sources of formation of dispersed liquid hydrocarbons (DLH) were detected in the pressure range above the retrograde condensation pressure: the presence of heavy end of hydrocarbons that could not be transferred into the gas phase even at high pressures; liquid phase formed as a result of condensation of the hydrocarbon system again at pressure above the retrograde condensation and liquid phase released from the system due to early condensation at higher pressure because of surface forces in the reservoir conditions. It was confirmed that the DLH in the reservoir conditions can be formed as a result of a combination of these three above-mentioned reasons. Two types of possible positions of DLH in reservoir conditions are determined. The liquid in the formation is closely linked to the surface of the rocks. This was caused by sufficiently high surface bonds as a result of adsorption of liquid molecules to the surface of grains for a long time. The high content of heavy components of hydrocarbon mixtures contributes to the weakening of the surface forces between the rock and the liquid, that causes the liquid phase to be in more free and mobile state in the formation conditions. It is noteworthy among rational methods selection for gas-condensate fields exploration necessarily to pay attention to volume of this liquid phase, its movement in formation and its extraction.