Abstract
It is important to obtain such physical informations as porosity, size distribution or permeability for the evaluation of aquifers and design of a water well. These physical informations are generally obtained by soil tests or geophysical loggings. In this report, the writer studied the way of evaluation from the data of density loggings (gamma-gamma ray logging) which are most profit for working water wells. Bulk density of the strata is calculated from the value measured by density loggings. But there are some limitations against the use of calculated bulk density.
The auther concluded the the value calculated contains the error of about 15% by comparing calculated physical informations with that directly obtained by soil tests from the boring core of water wells at Osaka and Iwakuni. So, from further considerations concerning the causes of error, gamma-gamma ray logging is only applicable for evaluation of an aquifer, which is composed of sand and gravel beds of generally 2.0-2.3 g/cc in the range of bulk density.
