Changes

==Lowstand prograding complex traps==

==Lowstand prograding complex traps==

Siliciclastic lowstand [[Well_log_sequence_analysis#Parasequence_stacking_patterns|prograding]] complexes, imaged on seismic reflection profiles as clinoforms, are often fluvial-deltaic complexes with abundant sand in the depositional topsets (Figures 4-19 and 4-21). As the relative sea level cycle turns around from low to rising, the coarse-grained sediment supply decreases. The fine-grained sediments of the transgressive systems tract overlie the lowstand systems tract–prograding complex sand-prone facies, providing excellent top seal to the underlying sandy reservoir. If the transgressive shales are organic rich and buried in the thermal regime for kerogen [[cracking]], hydrocarbons will be generated. If the lithofacies forming the preceding shelf edge can provide lateral seal, the prograding complex reservoir facies may become charged with hydrocarbons even without structural enhancement of the trap.<ref name=ch04r16>Armentrout, J., M., Rodgers, B., K., Fearn, L., B., Block, R., B., Snedden, J., W., Lyle, W., D., Herrick, D., C., Nwankwo, B., 1997, Application of high resolution biostratigraphy, Oso field, Nigeria: Proceedings, Gulf Coast Section SEPM 18th Annual Research conference, p. 13–20.</ref>

Siliciclastic lowstand [[Well_log_sequence_analysis#Parasequence_stacking_patterns|prograding]] complexes, imaged on seismic reflection profiles as clinoforms, are often fluvial-deltaic complexes with abundant sand in the depositional topsets (Figures 4-19 and 4-21). As the relative sea level cycle turns around from low to rising, the coarse-grained sediment supply decreases. The fine-grained sediments of the transgressive systems tract overlie the lowstand systems tract–prograding complex sand-prone facies, providing excellent top seal to the underlying sandy reservoir. If the transgressive shales are organic rich and buried in the thermal regime for [[kerogen]] [[cracking]], hydrocarbons will be generated. If the lithofacies forming the preceding shelf edge can provide lateral seal, the prograding complex reservoir facies may become charged with hydrocarbons even without structural enhancement of the trap.<ref name=ch04r16>Armentrout, J., M., Rodgers, B., K., Fearn, L., B., Block, R., B., Snedden, J., W., Lyle, W., D., Herrick, D., C., Nwankwo, B., 1997, Application of high resolution biostratigraphy, Oso field, Nigeria: Proceedings, Gulf Coast Section SEPM 18th Annual Research conference, p. 13–20.</ref>

==Transgressive systems tract traps==

==Transgressive systems tract traps==