1961 Middle East Regional Meeting; Dhahran, March 27–29, 1961

Gas-oil relative permeabilities of the Burgan and Wara sands can be roughly correlated with absolute permeability. Gas relative permeabilities are related to oil relative permeabilities and to capillary pressure by the Kozeny-Carman equation only if the tortuosity coefficient is considered a function of saturation and different for each absolute permeability. It must be determined empirically.

A regular relation was observed between initial water saturation and the amount of oil which can be displaced by water. This seems to be the same for Uncleaned cores taken with oil-based mud and for extracted cores. It therefore seems reasonable to assume that it also applies to the sand in situ in the reservoir. If it does, the oil recoverable by water drive can be estimated from the initial interstitial water saturation.

Initial water saturation of the Burgan and Wara sands decreases as absolute permeability increases. The residual oil saturation after water flooding also decreases with increasing absolute permeability. From this and other evidence, it appears that these sands are partially oil and partially water-wet. At low water saturations they exhibit the behaviour of water-wet sands but at higher water saturations they behave as though they were oil wet.

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