Changes

Sandstone percentage maps are [[contour]] maps that show the percentage thickness of sandstone within a gross rock interval. These can give a good indication of the sediment dispersal patterns and lateral pinch-out edges. Gross sandstone thickness maps, which are maps of the total thickness of sandstone within an interval, help determine the locations of sediment depocenters. These maps can also be used to infer depositional strike and depositional dip. Depositional strike is the dominant direction along which sedimentary bodies tend to be elongated. Depositional dip is the direction perpendicular to the depositional strike.

Sandstone percentage maps are [[contour]] maps that show the percentage thickness of sandstone within a gross rock interval. These can give a good indication of the sediment dispersal patterns and lateral pinch-out edges. Gross sandstone thickness maps, which are maps of the total thickness of sandstone within an interval, help determine the locations of sediment depocenters. These maps can also be used to infer depositional strike and depositional dip. Depositional strike is the dominant direction along which sedimentary bodies tend to be elongated. Depositional dip is the direction perpendicular to the depositional strike.

Hamilton et al.<ref name=Hamiltonetal_2002 /> described the reservoir characterization of the Tertiary deltaic sediments in the Merecure unit A reservoir interval of the Budare field in Venezuela. The gross sandstone thickness map shows a dominant east–west grain defined by elongate, thick sandstone bodies. Narrower north–south lineaments are perpendicular to this main trend. The depositional environment is interpreted as a wave-dominated delta system. North–south-oriented features interpreted as distributary channels intersect at an oblique angle with arcuate to linear oriented trends interpreted as a marine reworked delta front ([[:file:M91Ch11FG71.JPG|Figure 3]]).

Hamilton et al.<ref name=Hamiltonetal_2002 /> described the reservoir characterization of the Tertiary deltaic sediments in the Merecure unit A reservoir interval of the Budare field in Venezuela. The gross sandstone thickness map shows a dominant east–west grain defined by elongate, thick sandstone bodies. Narrower north–south lineaments are perpendicular to this main trend. The depositional environment is interpreted as a wave-dominated delta system. North–south-oriented features interpreted as [[distributary channel]]s intersect at an oblique angle with arcuate to linear oriented trends interpreted as a marine reworked delta front ([[:file:M91Ch11FG71.JPG|Figure 3]]).

Log facies maps give a sense of the internal sedimentary character of a reservoir interval.<ref name=Shelton_1972>Shelton, J. W., 1972, [http://archives.datapages.com/data/bulletns/1971-73/data/pg/0056/0008/1500/1541.htm Correlation sections and log maps in determination of sandstone trends]: AAPG Bulletin, v. 56, no. 8, p. 1541–1544.</ref> For each well, a paper copy of the gamma-ray log is trimmed to the top and base of the reservoir unit of interest and pasted on a map. Computer applications are also available to help make these displays. Log facies maps give a visual impression of how the log facies varies over the field in terms of distribution, trends, and internal bedding characteristics. The various log patterns can be mapped across the field and then tied in to a lithofacies scheme ([[:file:M91Ch11FG72.JPG|Figure 4]]). In the Budare field example from Venezuela,<ref name=Hamiltonetal_2002 /> discrete zones of log character were mapped out. Blocky log profiles are related to distributary channel and aggradational mouth bar complexes, whereas multiple, thin serrated and subtly upward-coarsening log facies are interpreted as strand plain complexes flanking the delta front.

Log facies maps give a sense of the internal sedimentary character of a reservoir interval.<ref name=Shelton_1972>Shelton, J. W., 1972, [http://archives.datapages.com/data/bulletns/1971-73/data/pg/0056/0008/1500/1541.htm Correlation sections and log maps in determination of sandstone trends]: AAPG Bulletin, v. 56, no. 8, p. 1541–1544.</ref> For each well, a paper copy of the gamma-ray log is trimmed to the top and base of the reservoir unit of interest and pasted on a map. Computer applications are also available to help make these displays. Log facies maps give a visual impression of how the log facies varies over the field in terms of distribution, trends, and internal bedding characteristics. The various log patterns can be mapped across the field and then tied in to a lithofacies scheme ([[:file:M91Ch11FG72.JPG|Figure 4]]). In the Budare field example from Venezuela,<ref name=Hamiltonetal_2002 /> discrete zones of log character were mapped out. Blocky log profiles are related to distributary channel and aggradational mouth bar complexes, whereas multiple, thin serrated and subtly upward-coarsening log facies are interpreted as strand plain complexes flanking the delta front.