The Research On Sedimentary Microfacies And Forcasting Perspective Of Chang6Reservoir In Baliangou And Jinzhuang Areas, Nanniwan Oilfield

This paper studies the Chang61-Chang63of Chang6oil reservoir beds of Yanchangformation in Baliangou and Jinzhuang aears in Nanniwan oilfield. Taking sedimentology、geological logging and reservoir geology as guidance, many modern analysis are used tosystematically research stratigraphic sequence and source analyses of the bed of interest basedon the study of geological background and divisions of substratums. The types of sedimentarymicrofacies are divided on the basis of lithological characteristics, fossils and logging facies.The paper predicts the character and trend of the distribution of the skeletal sand body, anddiscusses the relationship between microfacies and reservoir、oil and gas distribution. Finally,six favourable areas of oil and gas are presented.It is concluded that that Chang6oil-bearing formation in the studied area is interpreted tobe a river-dominated delta deposited in lacustrine environment, consisting of underwaterdistributary channel, interdistributary bay, front santsheet and natural levee. The underwaterdistributary channel sand bodies constitute the dominated reservoir. By the influence of rivercourse, underwater distributary channel distributes alternating with interdistributary bay whichforms the principal source-reservoir-seal assemblage mode. The sedimentation forms thefoundation of sandstone reservoir, decides its clastic constituents, texture, and controls thedistribution of sand body. The reservoir sand body of Chang61is well developed to Chang62;the pore texture type is influenced by diagenesis which mainly forms plenty of secondarypores. The underwater distributary channel sand bodies which should be the main destinationsof exploration of this area in the near future is not merely good physical property, it is alsofavourable places for hydrocarbon accumulation.