Changes

==Species distribution and oxygen concentration==

==Species distribution and oxygen concentration==

Lagoe<ref name=ch17r54>Lagoe, M., B., 1987, The stratigraphic record of sea-level and climatic fluctuations in an active-margin basin: the Stevens Sandstone, Coles Levee area, California: Palaios, vol. 2, no. 1, p. 48–68., 10., 2307/3514572</ref> recognizes four biofacies of benthic foraminiferal species in the upper Miocene Stevens Sandstone of the southern San Joaquin Valley He demonstrates that the biofacies distribution was largely controlled by changes in oxygen concentration caused by fluctuations in the position and intensity of low-oxygen water within the oxygen minimum zone.

Lagoe<ref name=ch17r54>Lagoe, M., B., 1987, The stratigraphic record of sea-level and climatic fluctuations in an active-margin basin: the Stevens Sandstone, Coles Levee area, California: Palaios, vol. 2, no. 1, p. 48–68., 10., 2307/3514572</ref> recognizes four biofacies of benthic foraminiferal species in the upper Miocene [[Stevens Sandstone]] of the southern [[San Joaquin Valley]]. He demonstrates that the biofacies distribution was largely controlled by changes in oxygen concentration caused by fluctuations in the position and intensity of low-oxygen water within the oxygen minimum zone.

In the figure below, biofacies associations reflect different and distinctive populations living in different paleoenvironments. Biofacies are arranged from left to right in order of inferred increasing oxygen concentration. The stratigraphic distribution strongly suggests systematic shifts in oxygen concentration.

In the figure below, biofacies associations reflect different and distinctive populations living in different paleoenvironments. Biofacies are arranged from left to right in order of inferred increasing oxygen concentration. The stratigraphic distribution strongly suggests systematic shifts in oxygen concentration.

==Distribution of palynomorph types==

==Distribution of palynomorph types==

Whittaker et al.<ref name=ch17r95>Whittaker, M. F., Giles, M., R., Cannon, S., J., C., 1992, Palynological review of the Brent Group, UK sector, North Sea, in Morton, A., C., Haszeldine, R., S., Giles, M., R., Brown, S., eds., Geology of the Brent Group: Geological Society Special Publication 61, p. 169–202.</ref> provide an industrial example in the Brent Group (Jurassic), North Sea, in which the distribution of palynomorph types is used to infer the depositional environments and extent of delta progradation during brief intervals of the Jurassic. The figure below illustrates the nonmarine (fluvial and marsh), lagoon, barrier, and marine environments and the interpreted sediment transport direction (large arrow) during one time interval. This information can help identify regions of greater potential for fluvial reservoir sands.

Whittaker et al.<ref name=ch17r95>Whittaker, M. F., Giles, M., R., Cannon, S., J., C., 1992, Palynological review of the Brent Group, UK sector, North Sea, in Morton, A., C., Haszeldine, R., S., Giles, M., R., Brown, S., eds., Geology of the Brent Group: Geological Society Special Publication 61, p. 169–202.</ref> provide an industrial example in the [[Brent Group]] (Jurassic), [[North Sea]], in which the distribution of palynomorph types is used to infer the depositional environments and extent of delta progradation during brief intervals of the Jurassic. The figure below illustrates the nonmarine (fluvial and marsh), lagoon, barrier, and marine environments and the interpreted sediment transport direction (large arrow) during one time interval. This information can help identify regions of greater potential for fluvial reservoir sands.

Oboh<ref name=ch17r67>Oboh, F., E., 1992, Multivariate statistical analysis of palyno debris from the Middle Miocene of the Niger Delta and their environmental significance: Palaios, vol. 7, p. 559–573., 10., 2307/3514869</ref> develops a paleoenvironmental model of Middle Miocene reservoir units from the Niger Delta, which uses palynomorphs and organic matter to interpret more precisely the depositional environments. This improves the understanding of the lateral continuity of the reservoir and its susceptibility to diagenetic changes.

Oboh<ref name=ch17r67>Oboh, F., E., 1992, Multivariate statistical analysis of palyno debris from the Middle Miocene of the Niger Delta and their environmental significance: Palaios, vol. 7, p. 559–573., 10., 2307/3514869</ref> develops a paleoenvironmental model of Middle Miocene reservoir units from the Niger Delta, which uses palynomorphs and organic matter to interpret more precisely the depositional environments. This improves the understanding of the lateral continuity of the reservoir and its susceptibility to diagenetic changes.

==Integrated paleoenvironmental interpretation==

==Integrated paleoenvironmental interpretation==

Figure 17-20 shows an integrated paleoenvironmental interpretation of the E2.0 reservoir (Middle Miocene, Niger Delta). Lithofacies range from pebbly sandstones (S1) to mudstones (M2). The palynofacies are composed of the following substances:

Figure 17-20 shows an integrated paleoenvironmental interpretation of the E2.0 reservoir (Middle Miocene, [[Niger Delta]]). Lithofacies range from pebbly sandstones (S1) to mudstones (M2). The palynofacies are composed of the following substances:

* Wood and amorphous organic matter

* Wood and amorphous organic matter