Overall field settings like dip of 80, partial water drive, permeability of less than 50md and with 350 API oil make Field - A in Western India an ideal choice for gas injection. Non-availability of hydrocarbon / non-hydrocarbon gas makes air injection a preferred alternative. Viability of air injection process in laboratory was established through displacement tests in 1.83m long & 100mm diameter combustion tube using synthetic and natural core at IRS, ONGC.

In view of limitations of laboratory generated oil reactivity data for carrying out prediction in STARS, following workflow was adopted to estimate recovery from air injection.

  • Predicting recovery by immiscible gas injection

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      Pressure maintenance and Immiscible displacement

  • Predicting Volumetric Sweep Efficiency

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      From miscible Gas Injection. It is felt that Miscible process mimics closely air injection as both these processes have displacement efficiency of more than 90%

  • Predicting Recovery by Air Injection

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      Integrating immiscible flue gas with Nelson & McNeil derived profile after considering volumetric sweep from miscible gas displacement process. Air injection has the potential to enhance recovery from 19% to 62%.

Keywords:
air injection, displacement efficiency, nelson, feasibility, recovery factor, oil rate, efficiency, flood, gas flood, enhanced recovery
Subjects:
Improved and Enhanced Recovery, Gas-injection methods
Copyright 2010, Society of Petroleum Engineers
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