Effect of water saturation on oil recovery by near-miscible gas injection
- Univ. of Houston, TX (United States)
During gas injection, bypassing of oil is common due to gravitational, viscous, and/or heterogeneity effects. The oil in the bypassed regions can be recovered through enhanced flow and mass transfer between the bypassed region and the injectant gas. Previously, experiments in our laboratory have been carried out to evaluate the effects of phase behavior and capillary crossflow in near-miscible gasfloods, however these studies were conducted in the absence of water. In this paper, we evaluate the effects of water saturation on oil bypassing and the rate of mass transfer from the bypassed zones. Injectant gases are first-contact miscible (FCM), multicontact miscible (MCM), or near-miscible with the bypassed oil. Gasfloods are conducted in different orientations with different levels of water saturation. Mass transfer experiments are carried out at to isolate and investigate mass transfer mechanisms. Results indicate that oil recovery from vertical, near-miscible gasfloods is not influenced by water saturation level. Horizontal gasfloods showed evidence of less gravity override in the presence of water. The mass transfer experiments showed that recovery increases with enrichment and is reduced by the presence of water. Effective diffusion coefficients are estimated as a function of water saturation and enrichment.
- OSTI ID:
- 468138
- Report Number(s):
- CONF-961003--
- Country of Publication:
- United States
- Language:
- English
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