For establishing a good log petrophysical model and evaluating productivity of tight sandstone gas reser-voir in Tabamiao area of Ordos basin accurately

NMR porosity data of Section 3 of the wells were compared with the core porosity values for 14 cores.A linear relationship was observed.A comparison between the NMR permeability and core permeability gave similar result.This indicates a linear relationship between the porosity and permeability from NMR log and conventional log.Using the NMR porosity and permeability and conventional log data

accurate conventional log porosity model and permeability model were established.As NMR log avoids the non-parallelism of depths with conventional log and the pore-permeability model established by incontinuous core data causes no error

the new models are more appropriate for the porosity and permeability estimation of the gas formation.