Changes

==Vertical permeability profiles in shoreface sandstones==

==Vertical permeability profiles in shoreface sandstones==

[[File:M91Ch6FG42.JPG|thumb|300px|42]]

[[File:M91FG108.JPG|thumb|300px|108]]

M91Ch6FG42.JPG|{{figure number|4}}Example of a sedimentological core log, Well d-2-C/94a-16, Peejay field, Canada (after Caplan and Moslow, 1999). From Shepherd, M., 2009, Sources of data, in M. Shepherd, Oil field production geology: AAPG Memoir 91, p. 49-63.

M91FG108.JPG|{{figure number|5}}The barrier bar-shoreface interval of the Brent Group reservoir in the Thistle field, UK North Sea, shows an upward-increasing permeability profile. This pattern is favorable to a high sweep efficiency (from Williams and Milne, 1991). Reprinted with permission from the Geological Society.

Shoreface sandstones characteristically show upward-increasing permeability profiles. This in turn reflects increasing grain size and better sorting higher up the shoreface profile (see also [[Figures 42]], [[108]]). A contrast in rock properties is characteristically seen between the lower and upper shoreface intervals. Upper shoreface beach facies associations generally show higher permeabilities than lower shoreface sediments. When a shoreface sand is subjected to a waterflood, the water tends to edge ahead through the high-permeability tops of these cycles by viscous forces. Gravity and capillary action will then draw the water down through the shoreface cycle into the lower units, displacing oil upward. Sweep efficiencies can be high as a result.

Shoreface sandstones characteristically show upward-increasing permeability profiles. This in turn reflects increasing grain size and better sorting higher up the shoreface profile (see also [[Figures 42]], [[108]]). A contrast in rock properties is characteristically seen between the lower and upper shoreface intervals. Upper shoreface beach facies associations generally show higher permeabilities than lower shoreface sediments. When a shoreface sand is subjected to a waterflood, the water tends to edge ahead through the high-permeability tops of these cycles by viscous forces. Gravity and capillary action will then draw the water down through the shoreface cycle into the lower units, displacing oil upward. Sweep efficiencies can be high as a result.