Changes

Structure maps show [[Contours|lines of equal elevation or depth]] for a selected [[Markers|marker horizon]] ([[:file:subsurface-maps_fig1.png|Figure 1]]) (see [[Evaluating structurally complex reservoirs]]). Mean sea level is a useful reference datum. Commonly contoured horizons are top of zone or top of net pay. Control points are provided by surveyed wells and can be supplemented by [[seismic interpretation]]s, especially offshore. In highly developed fields, typically onshore, sufficient well control might exist to allow [[geostatistical interpolation]] between control points.

Structure maps show [[Contours|lines of equal elevation or depth]] for a selected [[Markers|marker horizon]] ([[:file:subsurface-maps_fig1.png|Figure 1]]) (see [[Evaluating structurally complex reservoirs]]). Mean sea level is a useful reference datum. Commonly contoured horizons are top of zone or top of net pay. Control points are provided by surveyed wells and can be supplemented by [[seismic interpretation]]s, especially offshore. In highly developed fields, typically onshore, sufficient well control might exist to allow [[geostatistical interpolation]] between control points.

[[file:subsurface-maps_fig2.png|thumb|{{figure number|2}}Structure of the base of the Humber unconformity (top of the Brent Group), Dunlin field, U.K. Northern North Sea mapped with 1979 and 1989 vintage data. Contours are marked in ft subsea × 100; contour interval is 100 ft. (From <ref name=pt06r16>Braithwaite, C. I. M., Marshall, J. D., Holland, T. C., 1989, Improving recovery from the Dunlin field, U., K. Northern North Sea, in Formation Evaluation and Reservoir Geology: 64th Annual Technical Conference of the Society of Petroleum Engineers, San Antonio, TX, Oct. 8–11, SPE 19878, 18 p.</ref>.)]]

[[file:subsurface-maps_fig2.png|thumb|{{figure number|2}}Structure of the base of the Humber unconformity (top of the Brent Group), Dunlin field, U.K. Northern North Sea mapped with 1979 and 1989 vintage data. Contours are marked in ft subsea × 100; contour interval is 100 ft. (From Braithwaite et al.)<ref name=pt06r16>Braithwaite, C. I. M., Marshall, J. D., Holland, T. C., 1989, [https://www.onepetro.org/conference-paper/SPE-19878-MS Improving recovery from the Dunlin field, U., K. Northern North Sea, in Formation Evaluation and Reservoir Geology]: 64th Annual Technical Conference of the Society of Petroleum Engineers, San Antonio, TX, Oct. 8–11, SPE 19878, 18 p.</ref>]]

===Fault planes===

===Fault planes===