Method for estimating permeability from multi-array induction logs

摘要

An improved method of estimating formation permeability is provided. Essentially, the improved method of the present invention combines a mud cake build-up/invasion model and a fully implicit near-well bore model from which radial formation resistivities can be computed and compared with log-observed values. The permeability used to compute the radial formation resistivities is varied until the computed radial formation resistivities match with the log-observed values. The improved method does not require core samples. Specifically, by using a multi-array induction log in combination with the porosity log, a petrophysical analysis of the formation is carried out and a calculated conductivity or resistivity log is provided. The calculated log values are compared with the measured log values obtained from the multi-array induction log. An automatic parameter estimation procedure is employed and the permeability, irreducible water saturation, residual gas saturation, capillary entrance pressure, and capillary correlation parameter values are adjusted in the petrophysical analysis until the calculated log values compare favorably with the measured log values. When the calculated values compare favorably with the measured log values, the permeability value is obtained.