While estimating reservoir permeability from log porosity is considered to be an ev- eryday occurence, no one technique has been adopted universally. The relationship between these two parameters varies from one reservoir to the next. It has been recognized that the Free Fluid Index from the Nuclear Magnetic Log (NML’) is the key to overcoming this problem in some reservoirs. Since core permeability is the standard by which log-derived permeability will be measured, a successful transform must match core over a wide range of applications. While laboratory work has sug- gested that this is plausible, a relationship has not been established due to a lack of field data.