The Rock Physical Properties And Reservoir Prediction Tight Sandstone In An Area

In the unconventional oil and gas resources,tight sandstone gas has great potential as the alternative energy of conventional oil and gas resources.In the process of exploration and development of tight sandstone gas,as a reservoir,the importance of relevant research is self-evident.The tight sandstone reservoir in the study area has thin single layer thickness,low porosity,strong spatial heterogeneity and low drilling success rate,which restricts the process of oil and gas exploration in this area.Therefore,this paper analyzes the rock physical characteristics and elastic parameters of the tight sandstone in the study area,and has a basic understanding.On this basis,the corresponding rock physical model is constructed,so that the later work can better carry out the quantitative prediction of the channel sand body and find the"sweet spot"area.In this paper,first of all,the target interval is analyzed by logging petrophysical analysis,and the reservoir lithology is distinguished.V_P/V_S can be used to divide the lithology of turbidite clastic rock reservoir,such as the target reservoir.The same elastic parameters,such as elastic impedance and AVO gradient,which contain longitudinal and shear wave velocity,can also be used to identify the lithology and pore fluid of the reservoir in this segment.Because of the longitudinal wave impedance On the one hand,sandstone and sandy mudstone show a high overlap,that is,only using the superposition information of P-wave amplitude can't distinguish lithology;on the other hand,according to the characteristics of the reservoir sandstone,the target reservoir can be divided into four types:gas bearing sandstone with high porosity,water saturated sandstone with high porosity,tight sandstone with high impedance and low V_p/V_sand mudstone;on the other hand,the sensitive elastic parameters of the reservoir can be determined according to the calculation results V_P/V_S??·???/??????EI(30°)are sensitive elastic parameters in distinguishing water saturated sandstone from gas bearing sandstone.After the physical analysis of the logging rock in the study area,through the comparison of theoretical calculation and logging data results,the combination model is used to quantitatively characterize the change rule of the seismic elastic properties of sandstone.For the tight sandstone,the Hashin Shtrikman upper boundary formula corrected by critical porosity is used to calculate.From the comparative analysis of the calculation results and logging results,the relationship between porosity and velocity of the target reservoir can be seen.Then,the Gassmann equation is used to fill the connected pores with fluid,and a petrophysical model based on the rock mineral,pore fluid composition and pore characteristics is constructed.The main feature of this model is that the bulk modulus of rock is organically linked with the skeleton modulus of rock,the elastic modulus of the minerals composed of rock,the elastic modulus of pore fluid,as well as the porosity and pore shape.