Drainage Capillary-Pressure Functions and the Influence of Connate Water

Abstract

Drainage capillary-pressure functions oi reservoir rock-fluid-fluid systems OCTOBER. 1974 .497 SOCIETY OF PET ROLS1" M ES GIXKERS JO I R\,\L

Development and Optimization of Gas-Assisted Gravity Drainage (GAGD) Process for Improved Light Oil Recovery

“…They observed that the presence of connate water is critical for achieving very low oil residual saturations during gravity drainage floods, under high gas-oil capillary pressures, irrespective of whether or not the oil spreads on water in the presence of gas. Interestingly, Dumore and Schols (1974) attribute the achievement of low residual oil saturations to possible 'film flow'. This appears to contradict their previous inference that the oil spreading need not occur in presence of gas, and that the contribution of oil from film flow in secondary gas caps is negligible.…”

“…Reservoir water saturation, both connate (bound) and free (mobile), has been found to influence the oil recovery characteristics of many enhanced recovery processes (Dumore and Schols, 1974;Hagoort, 1980;. From a gas injection point of view, oil recovery rates (and efficiency), especially during the injection of a watersoluble solvent (such as CO 2 ), have been found to be directly related to the free water saturation in the reservoir .…”

“…Sparse experimental data available on the topic yielded a wide variety of conflicting conclusions (Dumore and Schols, 1974;Kantzas et al, 1988;Nahara et al, 1990;Skauge et al, 1994;. Nahara et al (1990), based on centrifugal gas-oil displacements, report that gas-oil relative permeabilities are unaffected by the presence of water, as long as the water is immobile.…”

“…Nahara et al (1990), based on centrifugal gas-oil displacements, report that gas-oil relative permeabilities are unaffected by the presence of water, as long as the water is immobile. On the other hand, Dumore and Schols (1974) showed that the presence of immobile connate water in Bentheim sandstones result in extremely low residual oil saturations during gravity drainage, irrespective of the gas/oil IFT values (that affect the gas-oil relative permeabilities).…”

Improved efficiency of miscible CO2 floods and enhanced prospects for CO2 flooding heterogeneous reservoirs. Final report, April 17, 1991--May 31, 1997

“…The free-fall gravity drainage, which is representative of gas injection into a depleted fractured reservoir, has been investigated by Le~erett,~" Stahl et a p 2 Cardwell and Pars0ns,2'~ Nenniger and St~rrow,"~ Templeton and Niel~en;~' Dumore and Schols, 260 Unlike forced gravity drainage, free-fall gravity drainage cannot be modeled using a Buckley-Leverett approach because flow rate is not prespecified. A survey of the literature reveals four mathematical models that have been developed for describing the process of free-fall gravity drainage of equilibrium fluids.…”