The Reservoir Characteristics And Favorable Area Forecas Of Chang2 Yanchang Formation Zhiluo Area

The exploration area of Zhiluo Oil field is located in Fuxian,Shaanxi Province.The study area is about 1168.7 square kilometers,And the tectonic location belongs to the southeastern part of the Shanbei slope of the Ordos Basin.At present,the exploration of Chang2 is very limitation,and the degree of exploration and development is not uniform,and have entered the period of high water content.The contradiction of production is becoming more and more prominent,the natural decline beyond 20%.In order to ensure the stability of the oil field production area,need to find out the favorable area in Chang2 formation outside the developed block as soon as possible.In this paper,according to the sedimentary geology,sequence stratigraphy,petroleum geology,reservoir geology,geophysics and geochemistry and so on,as a guide.Based on the understanding of the regional area,As the beginning of studying sedimentary facies and sandbody distribution,this paper analyzes the structure of the main target layer,the reservoir characteristics and the control factors of oil and gas accumulation,the relationship between reservoir and reservoir cover,so as to clarify the oil and gas enrichment geological conditions in the study area,forecast favorable reservoir distribution area and provid the target for oilfield exploration and development.Chang2 formation in the study area has a gentle structure is low and slow latitudinal nose-shaped uplifts based on west-east dip monocline which is based on the west tilted.In the Chang2 sedimentary period,the study area mainly developed delta-front facies.Through core observation,casting thin film,scanning electron microscopy,find that the main type of sandstone is minute and mintueness granular feldspathic litharenite and lithicarkose.The dominating pore types are feldspar dissolution and inter-granular pore,with sorting better,sub-angular grinding round.The reservoir property is poor,and it belongs to low and low porosity and ultra-low permeability Reservoir.The results of microscopic experiments such as cast sheet,scanning electron microscope and X-ray diffraction show that the diagenetic type is mainly mechanical compaction,cementation,metasomatism and dissolution.And sandstone of Chang2 reservior is already at mid-diagenetic stage A.Delta front underwater distributary channel sand body is the main reservoir sandstone.On the basis of the sedimentation,the late diagenesis on reservoir physical property of sandstone's impact is good or bad,which complicate the reservoir performance.The distribution of source rock,sedimentary effects,reservoir physical properties and tectonic action are the main factors controlling oily oil,and the oil control factors and oil test data are summarized.The Chang2~1 and Chang2~2 sublayers were selected to predict the favorable area of Class ? exploration 3,and favorable area of Class ? exploration 4,and provide a reliable geological basis for the follow-up exploration and development work in the study area.