Sichuan Basin In Northern Pearl Punch Segment Glutenite Depositional System And Favorable Reservoir Prediction

There are thick layered glutenite rocks in Zhenzhuchong formation in northern Sichuan basin,but the storaging space,reservoir types and main controlling factors of glutenite reservoir is not clear at present,and the exploring effect is very poor.In this paper,on the basis of theories of sedimentary petrology,sedimentology,reservoir geology and logging geology,the author firstly carries out the studies of stratigraphic classification, stratigraphic correlation and depositional systems of Zhenzhuchong formation in researching area by observation of outcrop,description of core and interpretation of well logging data and combining with the analysis results of trace elements and spore body of paleontology. And then,the author carries out the studies in-depth about characteristics of glutenite reservoir,distribution of reservoir and main controlling factors of reservoir by taking the glutenite reservoir of Zhenzhuchong formation in Jiulongshan area as the focus.Finally,the favorable exploration areas are putted forward.By researching,the sedimentary complex of Zhenzhuchong formation in researching area can be divided into two types:one is fan,fan delta,shallow lacustrine and semi-deep lacustrine,the other is meandering river,meandering river-delta,shallow lacustrine and semi-deep lacustrine.The lithology of glutenite reservoir of Zhenzhuchong formation is consists of conglomerate rocks, glutenite rocks and sandy conglomerate rocks.The reservoir is tight,except a small amount of intergranular pores in gravel that the composition is quartz sandstone,the main storaging space is cracks whick links to various dissolved pores,which includes dissolved pore and dissolved cave of inner-gravel,dissolved pore and cave of the filling part between gravel and grave,and the hole whick is not be filled completely in the crack.The lithology of sandstone reservoir is medium to fine grained quartz sandstone, detritus quartz sandstone.The sandstone reservoir develops intergranular pores,intergranular dissolved pore,grain of die hole and dissolved pore of kaolinizationed feldspar,threrfoe,it has a certain storaging conditions.The reservoir of Zhenzhuchong formation is controlled by deposition,diagenesis and structural effect:1)reservoir is more developmental in the front of fan delta and shore-shallow lacustrine,2)compaction, pressure-solution and cementation are the important factors of pore-loss of reservoir,3)dissolution is important conditions to increase properties of the reservoir,4)crack is the important storaging space and the main infiltrating channel in the tight glutenite reservoir.The author statisticses the data of reservoir,considering2.5%as the lower limit of porosity,and drawes the thickness isoclines map of the glutenite reservoir and sandstone reservoir respectively.By this way,the regularity of distribution of the different rock reservoir on the plane is made clear.At last,The author selectes favorable exploration areas,combining with sedimentary facies,reservoir characteristics and production test data.