Reservoir Fluid Identification in Chang 6 Member in Southern Ordos Basin
The Chang 6 member in the southern Ordos Basin is a typical low porosity and low permeability reservoir.It is difficult to identify the properties of reservoir fluid,which restricts the efficient development of the oil reservoir.First,the type of reservoir rocks is clarified through reservoir petrology analysis.The reservoir's physical property characteristics are determined through core observation and core physical property analysis.The experimental analysis results are combined with logging data,and the core and analysis data are sorted out.The reservoir porosity and interval transit time parameters may be obtained,and the porosity interpretation model of logging by interval transit time is established.The relationship between permeability and porosity,per-meability and micropotential/microgradient ratio is analyzed,and a permeability interpretation model is estab-lished.Based on the core observation,oil test,and trial production results,the relationship between porosity,permeability,and reservoir oil-bearing probability is analyzed to determine the lower limit of effective reservoir physical properties.The cross plot of interval transit time and resistivity is established,and the fluid may be identified combined with Fisher discriminant method.The results show that the lower limits of lithology and oil-bearing probability for the effective reservoirs in Chang 6 member are fine sandstone and oil spot grade;the lower limits of porosity and permeability are 7.4％and 0.1×10-3μm2,respectively;the resistivity of oil-wa-ter layer,poor reservoir,and oil reservoir is greater than 20Ω·m,and the interval transit time is greater than 230μs/m;the cross plot of interval transit time and resistivity is applied to identification of Chang 6 reservoir fluid,with the comprehensive accuracy of 78.7％,and the accuracy of stratified identification of 85.3％,88.5％and 91.7％for Chang 61,Chang 62 and Chang 63,respectively.Using Fisher discriminant method,the compre-hensive correct rate of reservoir fluid is 86.3％.
万方数据
维普
