Structural Deformation and Shale Gas Preservation Conditions in the Changning Area of the Southern Sichuan Basin
The Changning area is located in the southern Sichuan Basin.The shale in the Upper Ordovician Wufeng Formation and the Lower Silurian Longmaxi Formation is of high quality and exhibits favorable source-reservoir-cap conditions.During the Phanerozoic,multi-stage extension,extrusion and strike-slip deformation,along with strong uplift and denudation,resulted in very complex preservation conditions for shale gas.Based on the structural characteristics and tectonic evolution in this area,this paper examines how various structural fac-tors influence the preservation conditions of shale gas.This study also proposes a comprehensive quantitative evaluation method for assessing shale gas preservation conditions and predicts potential exploration areas.The study results show that the Changning area mainly features two groups of structures:NE-trending and NW-tren-ding.Both sets of structures are related to folds developed on the hanging wall of basement-involved fault.They formed during the Early and Late Yanshanian periods,respectively,and some NE-trending structures were mod-ified by strike-slip events during the Himalayan period.The main structural factors affecting shale gas preserva-tion conditions include the timing of tectonic transformation,uplift and denudation,stratigraphic dip,multi-scale fault-fracture systems,and the current in-situ stress direction.Based on the impact of various structural elements on the shale gas preservation,a quantitative evaluation method for assessing preservation conditions in the Changning area is proposed.The evaluation results indicate that the shale gas preservation conditions in the Jianwu syncline are the most promising,followed by the Tiangongtang anticline,Shuanglong syncline,and Luochang syncline.
Changningstructural deformationstructural evolutionWufeng Formation-Longmaxi Formationshale gas preservation condition
万方数据
维普
