| Oil and gas rich and production block more in Chang 3 oil reservoir group of Zhenbei Oilfield in Ordos Basin,but the sand body changes quickly,the construction block is small,and the study of the main factors of the reservoir storage properties is relatively weak.Therefore,it is necessary to carry out the study of the characteristics and main control factors of the Chang 3 reservoir,and provide the geological basis for the next exploration and development.Based on the theory of sedimentology,reservoir sedimentology and petroleum geology,the reservoir petrological characteristics,micro-pore structure characteristics,diagenesis and physical properties of the Chang 3 reservoir in Zhenbei area are studied comprehensively by the methods of core observation,casting slice identification,X-ray diffraction analysis,scanning electron microscopy and mercury intrusion test in this paper,and get the following conclusion.The component maturity is high and the structural maturity is medium in chang 3 reservoir of this area and the reservoir is mainly composed of feldspar sandstone in gray or light gray;the distribution of interstitial materials is uneven and mainly is silicic content,followed by water mica.The main pore types of the Chang 3 are mainly intergranular pores,followed by feldspar pores.The average pore radius of Chang 3 is 142.1?m,the average throat radius is 1.68?m,the main throat radius is 2.15?m,mainly is large hole-fine throat type,followed by large holes-micro-laryngeal type.The diagenetic types experienced by the reservoir are: compaction,cementation and dissolution.Cementation mainly is siliceous cementation,followed by water mica cementing.The dissolution is the main effect of forming secondary interstice.Diagenetic facies divided into I class Coarse sandstone weak compaction phase,II class Kaolinite cementation dissolution pore phase,III class Fine sandstone residual intergranular pore phase and ? class Dense cemented phase four diagenetic phase.The diagenetic evolution stage is mainly in the A period of late diagenetic stage.The study of physical properties in this area shows that: The average permeability of the reservoirs of Chang 31,Chang 32 and Chang 33 is 3.37×10-3?m2,4.15×10-3?m2,4.09×10-3?m2,the average porosity of the reservoir is 12.95%,12.84%,12.42%.Permeability is mainly due to the different small pore structure between each small layer,the reservoir of the Chang 3 belongs to the low porosity-low permeability reservoir.On the whole,the reservoir of the Chang 3 is mainly controlled by the sedimentary facies,followed by diagenetic facies.The sedimentary facies control the distribution of reservoir properties from the macroscopic level,and the physical properties of the delta plain are better than those of the delta front,as a overall performance,the physical properties of the branch river and underwater diversion channel physical properties are better.Main development in the diversion channel is Coarse sandstone weak compaction phase?Water mica <4,Carbonate <4,The sedimentary facies are thick?and the physical properties is best,distributed in the west of Z291-Z299-Z448-Z231.followed by the reservoir properties which is developmented in underwater distributary channel?Dissolved hole relative content> 40%?and mainly distributed in the near of Tongchuan. |
PDF Full Text Request