Research On Sedimentary System And Oil-bearing Properties Of The Southern Part Of Jurassic Qigu Formation In Junggar

The southern part of Junggar Basin consists of Beisantai bulge and Jimusaer sag, the areaof which is about 4,500 square kilometers, and experiences four periods strongly tectonicmovement (late Hercynian movement, Indosinian movement,Yanshan movement andHimalayan movement) and five periods of reservoir-forming (The hydrocarbon source rocksof Permian of the hydrocarbon-generating and accumulation stages from the late Triassic toearly Jurassic, first scene in final Jurassic Xishan Kiln of Yanshan movement, the second actof Yanshan movement in late Jurassic, the third act of Yanshan movement in Cretaceousperiod and the Himalayan movement period). It develops four kinds of trap includingLithologic type, stratigraphic type, fault block type and paleogeomorphology type. The maintype is lithologic reservoir.There is a problem of systematic and refinement deficient in the study of sedimentaryfacies and sedimentary system in the southern part of Junggar Basin. Existing distribution ofsedimentary system can only reflect the macro feature of basin evolution. Because qualitativestudy is less to the quantitative study of sedimentary and sedimentary system, the furtherincreasing accuracy study to sedimentary system is necessary. The cognition to thedistribution of sedimentary system is key element which affects oil-gas exploration.The aim of this dissertation is analyzing the sedimentary facies and sedimentary faciespattern in Qigu formations Jurassic system, determing the favorable reservoir facies belt,summarizing the rule of skeleton sandbodies distribution, and analyzing oiliness of aimhorizon.This study analyses the sedimentary facies model and type of Qigu Formations based ongeology drilling, logging, rock debris material, besides that we gain delineation of scope ofplane sedimentary facies by analyzing single-well sedimentary facies of key location anddepositional framework of well connection in Qigu Formations. We gain discriminant of source direction in lithologic reservoir on the basis of the heavy mineral assemblage and thecontour map of ratio of sandstone thickness and bedthickness. We predict the special locationof advantageous sandstone and porosity log curves of reservoirs.The sedimentary system of Jurassic Qigu Formation in the southern part of JunggarBasin is channel delta facies and shallow lake sedimentary facies, and the main sedimentaryfacies is the front delta phase. The sedimentary rock of objective zone experienced manyperiods of river system superposition. Mudstone, silty sandstone, sandstone, andconglomerate as sedimentary rocks are interactive deposition. Channel sandstone areabundant, and constitute conditions of lithologic oil-gas reservoir.