Tectonic Evolution And Its Control On Palaeo-reservoirs Of Changxing-Feixianguan Formation In Micang Mountain Area

It's an important area of oil and gas exploration in the northeast of Sichuan basin.As the development of exploration,it is necessary to research new areas and the exploration of Micang mountain structural zone become more important.In this paper,the structural character and evolution of Micang mountain structural zone are discussed by means of a large of field observations and tectonic interpretation of seismic section and the tectonic evolution history.The gas reservoir forming model in this area are revealing by combining the development characteristics of hydrocarbon source rocks,the characteristics of reservoir and the configuration of source rock and reservoir.The study shows that the main tectonic element of the Micang mountain structural zone from the core to the basin is the thrust belt,exposed fault-fold zone,blind fault-fold zone,fold zone.The Micang mountain structural zone can be divided into lower structure,middle structure and upper structure in profile,the boundary is the Precambrian shale,Silurian shale and sandy mudstone,gypsolyte of Jialingjiang formation.The tectonic evolution of Micang mountain structural zone can be divided into the following process: with continuous subsidence and deposition before Early Cretaceous,at the end of Early Cretaceous reach maximum buried depth,in the Neogene and the end of Late Cretaceous has two massive tectonic uplift.From the Late Triassic to the present in Micang mountain structural zone,the formation shortening rate is the east greater than the west and greater than the middle,the NW-SE is greater than the NE-SW.The structural lithologic gas reservoirs is the mainly gas reservoir type in Nanjiang-Tongnanba area.The small-scale palaeo reservoir just developed in jinxi 2 well?jiulong 1 well?xinheichi 1 well.The development of palaeo-reservoirs is mainly due to the weak structural deformation and the fractures during peak oil period,the migration path of source rock to the reservoir,and the poor reservoir property.The gas test shows better in Heba 1 well,the main reason is that the fault development is in the same period as the gas filling,and the original gas reservoir has not been damaged by the late reconstruction.