Changes

Correlation sections that will be used for establishing sandstone body geometry should have a depositionally flat datum (such as a [[bentonit]]e bed, marine shale bed, or laterally persistent limestone). Sections should be oriented parallel and perpendicular to [[depositional strike]], if known, and represent as straight a line as possible given well density and placement.

Correlation sections that will be used for establishing sandstone body geometry should have a depositionally flat datum (such as a [[bentonit]]e bed, marine shale bed, or laterally persistent limestone). Sections should be oriented parallel and perpendicular to [[depositional strike]], if known, and represent as straight a line as possible given well density and placement.

The only sedimentologically significant correlation horizons are those that approximate time lines within and between sandstone bodies. This style of correlation requires an understanding of the succession of depositional environments and intervening unconformable surfaces. It often leads to nonparallel and nonhorizontal correlations. For example, in shoreface systems, time lines denoted by shale or silt breaks between shingled shoreface sheets and lenses are inclined in a seaward (depositional dip) direction (Figure 2).

The only sedimentologically significant correlation horizons are those that approximate [[time lines]] within and between sandstone bodies. This style of correlation requires an understanding of the succession of depositional environments and intervening [[Unconformities|unconformable surfaces]]. It often leads to nonparallel and nonhorizontal correlations. For example, in [[shoreface]] systems, time lines denoted by shale or silt breaks between shingled shoreface sheets and lenses are inclined in a seaward ([[depositional dip]]) direction (Figure 2).

[[file:lithofacies-and-environmental-analysis-of-clastic-depositional-systems_fig2.png|thumb|{{figure number|2}}Gamma ray correlation (dip section) of a series of prograding shoreface sandstones. Note the imbricate nature of the sandstone bodies and the “non-layer cake” nature of the correlations.]]

[[file:lithofacies-and-environmental-analysis-of-clastic-depositional-systems_fig2.png|thumb|{{figure number|2}}Gamma ray correlation (dip section) of a series of prograding shoreface sandstones. Note the imbricate nature of the sandstone bodies and the “non-layer cake” nature of the correlations.]]