The study of gas-condensate reservoirs has been a fruitful field of research in the last years because of their peculiar behaviour. Gas cycling is the recovery process of choice for gas-condensate reservoirs but this process can often not be implemented because of economic reasons. Nitrogen is a potential alternative injection gas. Nevertheless, this has also disadvantages. The application of these processes is more complex in the offshore sites.
This paper describes laboratory studies performed to evaluate the effectiveness of some gases (CO2, N2, lean natural gas) in displacing condensate from naturally fractured gas-condensate reservoirs (offshore field). Numerous hurdles had to be overcome. The experiments represented the behavior of a reservoir under HP/HT conditions, 334 °F and 8455 psia. The results of CO2 and natural depletion showed little difference in their ability to recover condensate. The natural gas raised the recovery of the light fraction, but, by contrary, the addition of N2 made evident to be less effective than the rest.
The residual saturations and condensate recovery were measured and the results are presented. The detailed analyses revealed that natural gas seems to have been more effective in recovering condensate. Under these conditions, condensate recovery will significantly increase if the lean natural gas is injected. The answers are in agreement with the simulation model.
The conclusions are relevant to the overall management of gas-condensate reservoir. These experiments will serve as a guideline to develop the long term corporate strategy to improve additional recoveries in Mexico.