The Researching Of The Characteristic And Main Controlling Factors Of Chang-9's Oil Reservoir In Jiyuan Area

Jiyuan area is located in the northwest of Ordos Basin,although the high production of Chang-9 formation reservoir have discovered in some wells,the reservoir controlling factors are complex,distribution pattern of oil and water is not clear,which restrict the further exploration and development.Therefore,it is of great practical significance to carry out an in-depth research of reservoir characteristics and reservoir forming controlling factors in the study area.Based on the deposition kinetics and diagenesis and mineralization theory,sequence stratigraphy,tectonic sedimentology as theoretical guidance,making full use of logging data,core observation,scanning electron microscope,cast thin section,carbon and oxygen isotope,mercury,nuclear magnetic resonance,porosity and permeability under overburden pressure and a series of modern analysis and testing means,which carry out systematically reservoir characteristics and accumulation for Chang-9 formation.The results show that: Chang-9 formation of the study area is mainly controlled by the northeast,northwest of the two control resource system,developed delta front and plain subfacies,the main sedimentary microfacies are underwater distributary channel and distributary bay.Chang-9 reservoir mainly belongs to low-pore and micro-throat type,mid-pore and micro-throat type reservoir.according to the movable fluid saturation,Chang-9 formation mostly belongs to I class reservoir,followed by II class reservoirs.Chang-9 oil resource comes from Chang-7 resource rocks,the vertical dredging system is mainly cracks,dredging dynamic hydrocarbon generated overpressure,the resistance are rapillary force and net buoyancy;the horizontal dredging system is sand formation,the driving force is hydrocarbon generating overpressure and net buoyancy.The resistance is rapillary force.the west of the study area is mainly lithologic structural reservoir,while the Eastern isMainly lithological reservoir.Chang-7 high-quality resource rocks provides oil resource and accumulation of driving power for Chang-9 reservoir,fracture,cracks and high-quality reservoir formation of effective allocation makes migration pathwayfor the oil,The oil and gas rich area is controlled by the dredging system relative development zone of the reservoir,and the reservoir heterogeneity controls the oil and gas accumulation position,while the late diagenesis influences and indicates the distribution of oil and gas.