Changes

==Stratigraphic cross sections==

==Stratigraphic cross sections==

[[file:geological-cross-sections_fig1.png|thumb|{{figure number|1}}(a) Stratigraphic and (b) structural cross sections of the Ranger Formation in the Long Beach unit of the Wilmington field, California. Sections are projected onto a north-south plane. (From Slatt et al.<ref name=pt06r122>Slatt, R. M., Phillips, S., Boak, J. M., Lagoe, M. B., 1993, Scales of geological heterogeneity of a deep-water sand giant oil field, Long Beach unit, Wilmington field, California, in Rhodes, E. G., Moslow, T. F., eds., Marine Clastic Reservoirs—Examples and Analogs: New York, Springer-Verlag.</ref>)]]

[[file:geological-cross-sections_fig1.png|thumb|300px|{{figure number|1}}(a) Stratigraphic and (b) structural cross sections of the Ranger Formation in the Long Beach unit of the Wilmington field, California. Sections are projected onto a north-south plane. (From Slatt et al.<ref name=pt06r122>Slatt, R. M., Phillips, S., Boak, J. M., Lagoe, M. B., 1993, Scales of geological heterogeneity of a deep-water sand giant oil field, Long Beach unit, Wilmington field, California, in Rhodes, E. G., Moslow, T. F., eds., Marine Clastic Reservoirs—Examples and Analogs: New York, Springer-Verlag.</ref>)]]

Stratigraphic cross sections show characteristics of correlatable stratigraphic units, such as reservoir sandstones or sealing shales. They may also be vital in understanding the timing of deformation by showing the drape of sediment over developing folds or the thickening of the section across growth faults. The following elements of cross section design are presented as if they were a sequence. In practice, however, each choice affects and is affected by the others.

Stratigraphic cross sections show characteristics of correlatable stratigraphic units, such as reservoir sandstones or sealing shales. They may also be vital in understanding the timing of deformation by showing the drape of sediment over developing folds or the thickening of the section across growth faults. The following elements of cross section design are presented as if they were a sequence. In practice, however, each choice affects and is affected by the others.

===Orientation and layout of the cross section===

===Orientation and layout of the cross section===

[[file:geological-cross-sections_fig2.png|thumb|{{figure number|2}}Schematic stratigraphic cross section along part of the north flank of the Wilmington anticline in the Long Beach unit showing log displays. Distance scale is irregular to make the cross section more compact. The left track of each log is an [[Basic open hole tools#Spontaneous potential|SP]] or [[Basic open hole tools#Gamma ray|gamma ray]] trace and the right track is a resistivity trace. (From Slatt et al.<ref name=pt06r122 />)]]

[[file:geological-cross-sections_fig2.png|300px|thumb|{{figure number|2}}Schematic stratigraphic cross section along part of the north flank of the Wilmington anticline in the Long Beach unit showing log displays. Distance scale is irregular to make the cross section more compact. The left track of each log is an [[Basic open hole tools#Spontaneous potential|SP]] or [[Basic open hole tools#Gamma ray|gamma ray]] trace and the right track is a resistivity trace. (From Slatt et al.<ref name=pt06r122 />)]]

The orientation of a cross section must be chosen to balance the need for a clear representation of the features of interest with the availability of appropriate information. In development geology, this information comes largely from well data (geophysical logs, mudlogs, and cores), but in some places, outcrops and seismic reflection data can be used to constrain interpretations (see [[Wellsite methods]], [[Wireline methods]], [[Laboratory methods]], and [[Geophysical methods]]).

The orientation of a cross section must be chosen to balance the need for a clear representation of the features of interest with the availability of appropriate information. In development geology, this information comes largely from well data (geophysical logs, mudlogs, and cores), but in some places, outcrops and seismic reflection data can be used to constrain interpretations (see [[Wellsite methods]], [[Wireline methods]], [[Laboratory methods]], and [[Geophysical methods]]).