Study On The Characteristic Of Petrology And Diagenesis Of The Reservoir In The4Th Member Of Xu Jia He Formation In Upper Triassic Of Sichuan Foreland Basin

Guided by the theory of geology and sedimentology of reservoir,after referring and reading a great quantity of references, combinated the field data and indoor analysis and test result, we studied the petrology and diagensis character of the4th Member of Xu jia he Formation in Upper Triassic of Sichuan in different tectonic zonation,and discussed the main type and character and effect on the reservoir. Then set up the model of the form and evolvement of reservoir, divided the diagenetic facies, studied the regulartion of distribution and the relation to reservoir. Finally, make clear the controlling factors on development of reservoir.The lithology the4th Member of Xu jia he formation reservoir is mainly the continental clastic rocks with high textural maturity and low compositional maturity. The lithology in every tectonic zonation are feldspathic litharenite、lithic sandstone, and a small quantity of lithic quartz sandstone and arkose quartzite and quartz sandstone.The physical property of reservoir is bad because it is low-porosity, low-permeability and special low-porosity, special low-permeability The pore of reservoir are intergranular pore, intragranular pore, basis pore and fracture, and most of them are intergranular pore and intragranular pore. The pore configuration of reservoir is less as a whole.The4th Member of Xu jia he formation reservoir has throughed many complicate diagenesis. Compaction, pressure solution and cementation reduce pore, dissolution and tectonic disruption increase pore. Diagenetic stage of Xu jia he formation reservoir presenily is at middle diagenesis A to B substage. The depression basin belt in sichuan basin western, foreland slope and uplifted zone north is at middle diagenesis B substage,foreland slope, uplifted zone south and transition zone is at middle diagenesis A substage. The deep buried front downwarped basin belt with local area can reach late diagenesis stage.According to the control of reservoir pore formation and evolution of the main diagenesis-we divided the diagenetic facies of the4th Member of Xu jia he formation reservoir into compacted facies. calcitic cementing facies, chiorite cementing facies. silicic cementing facies, dissolution and kaolinite cementing facies. The best reservoir physical property is chlorite cementing facies, better are dissolution and kaolinite cementing facies, the worse are silicic cementing facies, calcitice cementing facies and the strong-compacted facies.The physical property of reservoir is multiple influenced by original component of sediment, deposition, diagensis and tectonism. Sedimentation partly decide the original components and rock structure of the reservoir and diagenesis, controlling the reservoir distribution scope on macroscopic; Diagenesis decide the reservoir pore structure, and finally decide the physical property of reservoir.