Fig. 3.31. Diagram showing permeability variations and trends in sand bodies. Channels often have upward
fining grain-size profiles, so permeability may decline upward within a channel. Barrier sands often have
upward-coarsening grain-size profiles, so they often show an upward increase in permeability. On a regional
scale channels will tend to trend down the paleoslope, whereas barrier bars will parallel it. These permeability variations affect the flow of petroleum and other fluids, and may control the locus of precipitation of certain types of mineral deposit.
100
g
r
._~
a
E
~
\
0
Delta
~.
tAIluvium ""~istributary
channel)~'~
0
,
I ~
I
i
200
400
600
Length of shale layer (m)
Fig. 3.32. Graph of shale layer length against frequency (%). This shows that shale layers, and thus permeability barriers, increase in continuity from nonmarine to marine deposits. Note, however, the wide range of
values in deltaic deposits. (Modified from Weber, 1982.)
fining grain-size profiles, so permeability may decline upward within a channel. Barrier sands often have
upward-coarsening grain-size profiles, so they often show an upward increase in permeability. On a regional
scale channels will tend to trend down the paleoslope, whereas barrier bars will parallel it. These permeability variations affect the flow of petroleum and other fluids, and may control the locus of precipitation of certain types of mineral deposit.
100
g
r
._~
a
E
~
\
0
Delta
~.
tAIluvium ""~istributary
channel)~'~
0
,
I ~
I
i
200
400
600
Length of shale layer (m)
Fig. 3.32. Graph of shale layer length against frequency (%). This shows that shale layers, and thus permeability barriers, increase in continuity from nonmarine to marine deposits. Note, however, the wide range of
values in deltaic deposits. (Modified from Weber, 1982.)