The model consists of a transparent plexiglass cylinder 2.5 in. (6.35 cm) in diameter and about 30 in. (76 cm) high mounted on a support stand. The cylinder contains a sand pack made of coarse, loose sand separated in the middle by 7 in. (17.8 cm) of loose fine sand. Permeability of the coarse sand is in excess of 1,000 darcys while that of the fine sand is several hundred darcys. The device was invented by me to study the behavior of gas and water flow through porous media and in particular to investigate the characteristics of conventional and deep basin types of gas traps.

Figure

The first demonstration represents the conventional trapping case. The second demonstration shows pressure/depth graphs for fluid phases to be identical with those found for the Elmworth deep basin gas traps, i.e., at the updip contact, the gas and water phase pressures are about equal as opposed to the conventional case where the gas pressure was much greater than the water pressure at the contact. Also, the downdip water column beneath the gas column is shown, in both cases, not to be in pressure continuity with the water column in the upper coarse sand column, even though there is a continuous water film wetting the sand grains through the gas-saturated coarse sand connecting the water-saturated fine sand with the water-saturated coarse sand below the gas column.

The fluid flow process through the depressured gas column from the upper water-saturated sands to the base of the gas accumulation will also be discussed.

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