Formation And Distribution Of The High-quality Reservoirs Of Deep Jurassic In Taibei Sag,Tuha Basin

In order to better get knowledge of reservoir's comprehensive characters in coal-bearing strata of deep Jurassic(J₁)in Taibei Sag,Tuha Basin,based on drilling,logging and seismic data,as well as other data,this paper studied the reservoir's characters of J_1.In this paper,the sequence of J₁has been divided correctly,the basic petrology characters,physical properties,pore-throat structure,sedimentary system,diagenesis of the reservoir have been studied ahead,then the main controlsof the reservoir quality have been discussed.Based od the classification standard of high quality reservoir,the diatribution of the high-quality reservoir was predicted by overlapping some of thebasic maps.The results show that the J₁can be divided into two third-order sequences,corresponding to the Sangonghe Formation(J₁s)and Badaowan Formation(J₁b).The reservoir is mainly coarse-grained lithic sandstone with low maturity,and it is generally dense with low porosity and micro pore-throat.The porosity is obvious different in the plane structural zones and there are two secondary pore zones longitudinally.The reservoir belongs to delta front to shore-shallow lake sedimentary system.As for diagenesis characteristics,it is strongly compacted,and the cementation and the dissolution are both weak,which is mainly at the stage A of middle diagenesis.When the porosity is more than 4.5%and the permeability is more than 0.03m D,the reservoir can bear gas well,which can be used as a high-quality reservoir criterion of tight sandstone gas under the condition of physical property,The reservoir quality is mainly controlled by sedimentary provenance and rock components,sedimentary facies,diagenesis and burial modes,etc.And the high-quality reservoirs are mainly distributed in the West of Taibei Sag,Northern Piedmont belt,Shanle structural belt and Wenjisang structural belt,etc.