川北元坝西须二下亚段气藏构造控藏研究OA

Focusing on the Lower Subsection of Xu-2 Member in Western Yuanba area of Northern Sichuan Basin,this study analyzes its structural and evolutionary characteristics as well as the hydrocarbon accumulation process during critical periods.Rearch indicates that source rocks are well developed in the Lower Subsection of Xu-2 Member,forming a self-sourced and self-reservoired gas reservoir.During the Middle Jurassic,hydrocarbons mi-grated into the not-yet-fully compacted reservoirs of the Lower Subsection of Xu-2 Member,resulting in the forma-tion of paleo-gas reservoirs characterized by a northwest-high and southeast-low structural configuration,with the main part of Western Yuanba Area situated on the southern slope.From the Late Jurassic to the Early Cretaceous,increased reservoir compaction hindered internal gas migration,allowing the paleo-gas reservoirs to persist and de-velop abnormally high-pressure gas accumulations.In the Late Cretaceous,uplift significantly altered the regional structure,resulting in the formation of southern slope of the Jiulongshan structure.This structural transformation preserved gas reservoirs in elevated positions while facilitating the migration of gas from lower positions to higher el-evations.The interplay between paleo-present structural evolution and source rocks is a critical factor influencing hydrocarbon accumulation in the Lower Subsection of Xu-2 Member in Western Yuanba Area.The paleo-high and present-high areas represent the most favorable zones for hydrocarbon accumulation,whereas the paleo-low and present-low areas are the least favorable.