Effect Of Porosity On Depth Of Investigation Of Neutron And Density Sondes

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Abstract Depths of investigation of a Density tool and several versions of Neutron tools hate been measured experimentally at a porosity of 22 percent in quartz sandstone. Comparisons with earlier results in 35-percent-porosity sandstone indicate little change in depth of investigation over this porosity range. The results also illustrate dependence of depth of investigation on casing and cement, neutron-source energy, relative change in hydrogen content, and presence of thermal-neutron absorbers. presence of thermal-neutron absorbers.