Errors in the Laboratory Measurement of Formation Resistivity Factor


A. E. Worthington, Chevron Oil Field Research Company

5th Formation Evaluation
Symposium of the Canadian Well Logging Society in Calgary, May 5-7,



Determination of formation resistivity factor in the laboratory involves a large number of individual measurements made under presumably known conditions. Errors in the individual measurements or unrecognized deviations in the conditions of measurement result in error in the calculated formation factor. These sources of error are identified and the resulting error in formation factor is expressed quantitatively as a function of each of the individual errors. Numerical examples are given of the errors in formation factor that result from experimental errors of the magnitude likely to be encountered under what may be termed excellent, average and fair laboratory measurement conditions and practices.