Measurement of Three Phase Relative Permeability during Gravity Drainage using CT Scanning

Abstract

TX 75083-3836, U. S. A., fax et-972-952.9435. AbstractWe measured three phase relative permeabilities for gravity drainage using a dual-energy medical CT scanner modified to scan vertical cores, Independent measurements of two saturations as a function of time and distance along the length of the core were made from which relative permeabilities were found. Three phase (air/oil/water) gravity drainage experiments were performed on systems with different spreading coefficients and at different initial conditions. Experiments were run on both consolidated and unconsolidated porous media. The results were compared to measurements of three phase flow in capillary tubes, micromodels and to predictions from network modeling.We find that at low oil saturation k,. N S; for hexane and octane as the oil phase. This functional form of relative permeability is consistent with the drainage of oil layers, wedged between the water and gas in crevices of the pore space. For decane, which is non-spreading, the layer drainage regime was not observed. At higher oil saturations kro -+ S: with a x 4 for spreading and non-spreading systems. Within the scatter of the experimental data, oil and water relative permeability are functions only of their own saturations and independent of initial conditions.

The Impact of Tides on the Capillary Transition Zone

“…The fluctuations in saturation seen in the experiments are real and are probably due to minor heterogeneities in packing leading to heterogeneities in the water saturation. Similar fluctuations in water saturation were seen by Sahni (1998) and reported in Di Donato et al (2006) when monitoring air-water gravity drainage using CT scanning to measure water saturation versus depth.…”

Prediction of Gas Injection Performance for Heterogeneous Reservoirs

“…Gravity drainage is also relatively easy to study experimentally and its analysis avoids consideration of hysteresis e ects, which can bevery signi cant in three-phase ow. 5, 6 Sahni et al 7 used CT scanning to measure oil and water relative permeability during three-phase gravity drainage in water-wet media and studied the e ect of spreading coe cient. Zhou et al 8 performed three-phase gravity drainage in sandpacks that were mixtures of oil-wet and water-wet grains.…”

“…From the measured saturation distribution, the oil water, gas oil and gas water capillary pressures can beinferred. 7 The capillary gradients are greatest near the bottom of the column where they equal the gravitational gradient, but are small compared to the gravitional gradient near the top of the column where the saturation is roughly constant with position. The calculation of permeabilities can thus bedone by ignoring the capillary pressures if it is performed over a region were the saturation data satis es the above condition.…”

“…This CT method and the calculation of permeabilities from the data are described in greater detail in Sahni et al 7 The core holders were standard Hassler-type with an overburden uid water at 50 psi and a rubber sleeve. The sand was packed into the rubber sleeve of diameter 7.6 cm and length 67 cm.…”

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

“…(Sahni, et al, 1998) and radioactive tracer technique (Naylor and Frorup, 1989) indicate a lack of saturation shock in free gravity drainage experiments. Buckley-Leverett shock ) is formed by a mechanism of self-sharpening of the displacing fluid.…”