Retrograde condensation of heavy hydrocarbons in the bottomhole zone

Abstract

The relevance of the conducted research is due to the practical lag of the oil and gas industry of Ukraine in the implementation of advanced technologies for the development of gas condensate fields with significant condensate reserves and, accordingly, low actual condensate recovery factors compared to the world level. Currently, Ukraine's economy needs not only to stabilize but also to increase hydrocarbon production levels in order to meet its needs through domestic production. To develop optimal ways to increase the efficiency of production of explored reserves, a study was conducted using digital modeling. The processes of retrograde condensation of liquid hydrocarbons in the bottomhole zone of a reservoir were studied on the basis of a sectoral model of a gas condensate reservoir. Based on the research, it was found that the reservoir properties of the formation and the technological modes of production wells significantly affect the efficiency of condensate production. The lower the permeability of the reservoir, the greater the depression on the formation to ensure the specified hydrocarbon production rates. This results in the creation of a significant pressure drop in the bottomhole zone of the reservoir, which causes intensive processes of retrograde condensation of liquid hydrocarbons. According to the results of the studies, it was found that at a reservoir permeability of 3 mD, the radius of the bottomhole zone saturated with condensed hydrocarbons is 16.5 m, at a permeability of 5 mD - 13.5 m, at a permeability of 10 mD - 11.1 m, and at a permeability of 50 mD - 6.6 m. The saturation of the pore space with condensed hydrocarbons near the wellbore, depending on the permeability of the reservoir, is 34.1%, 33.6%, 30.6% and 24.8%, respectively. Given the above, it can be concluded that the lower the reservoir permeability, the greater the pressure drop in the bottomhole zone of the formation and, accordingly, the saturation of the pore space with condensed hydrocarbons, and thus the greatest losses of liquid hydrocarbons. To increase the efficiency of the extraction of residual condensate reserves, it is necessary to take measures to prevent or slow down the processes of condensate loss in reservoir conditions.