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rock. If these drops of oil encounter an impermeable surface
through which they cannot flow, they will continue to flow upward
along the underside of this impermeable sealing rock and collect in
traps as shown in Figure 3.3. If no traps are encountered, the oil
droplets will migrate all the way to the surface creating an oil seep.
Oil seeps (1) are quite common in areas of petroleum potential and
were used by the earliest oil prospectors to identify drilling
locations.
Oil reservoirs in the subsurface in many ways resemble
inverted ponds or lakes. Unlike ponds and lakes, however,
accumulations of hydrocarbons are contained inside the pore
spaces of solid rock.
Figure 3.3 - Reservoirs occur in places where fluids tend to
collect
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