Coreflooding experiments have been performed using 1 metre long, sandstone cores and a synthetic, six component (C1, C2, C3, C5, C8 and C16) gas condensate fluid, with a dewpoint close to 4,500 psia. The efficiency of equilibrium gas injection for the mobilisation of liquid condensate has been examined under both high and low interfacial tension (IFT) conditions. The volume of liquid recovered and the composition of both phases have been monitored throughout each experiment and the results used to validate a compositional simulator.

Under conditions of maximum liquid dropout and high IFT (σ ≈ .92 mN/m), an average of 6.5% volume of liquid condensate was mobilised in an equilibrium gas injection in a horizontal core, resulting in reduced recovery of the heavier components of the fluid. An improved recovery of 17.2% was obtained in the vertical injection.

Under conditions of low IFT (σ ≈ .04 mN/m) however, 24.1% of the liquid was recovered during injection in a horizontal core and 51.6% of liquid was recovered with vertical injection, giving a much increased yield of the heavier ends.

The recovery efficiency in a straight depletion on a horizontal core to abandonment pressure averaged 18.8%. This is much lower than for the low tension gas injection.

These results are in agreement with other recent studies concerning the influence of IFT and the effects of gravity on gas condensate flow.

Keywords:
composition, enhanced recovery, complex reservoir, fluid dynamics, liquid, flow in porous media, water saturation, experiment, gas injection, liquid mobility
Subjects:
Reservoir Fluid Dynamics, Improved and Enhanced Recovery, Unconventional and Complex Reservoirs, Flow in porous media, Gas-condensate reservoirs
Copyright 1993, Society of Petroleum Engineers
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