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Abstract:
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In gas -condensate reservoirs , gas productivity declines due to the increasing accumulation of liquids in the near wellbore region as the bottom -hole pressure declines below the dew point pressure . This phenomenon occurs even in reservoirs containing lean gas -condensate fluid . Various methods were addressed to remediate the productivity decline , for example , fracturing , gas injection , solvent injection and chemical treatment . Among them , gas injection techniques have been used as options to prevent retrograde condensation by vaporizing condensate and /or by enhancing condensate recovery in gas -condensate reservoirs . It is of utmost importance that the behavior of liquid accumulation near the wellbore should be described properly as that provides a better understanding of the productivity decline due to the originated from impaired relative mobility of gas .
In this research , several gas injection techniques were assessed by using compositional simulators . The feasibility of different methods such as periodic hot gas injection and gas reinjection using horizontal wells were assessed using different reservoir fluid and injection conditions . It is shown that both the temperature and composition of the injection fluids play a key role in the remediation of productivity and condensate recovery . The combined effect of these parameters were investigated and the resulting impact on gas and condensate production was calculated by numerical simulations in this study . Design parameters pertaining to field development and operations including well configuration and injection /production scheme were also investigated in this study along with the above parameters .
Based on the results , guidelines on design issues relating gas injection parameters were suggested . The various simulation cases with different parameters helped with gaining insight into the strategy of gas injection techniques to remediate the gas productivity and condensate recovery . |