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

Abstract

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.

Numerical Modeling of Mud Invasion Profile Based on the Well Logging with the Shallow Depth of Investigation

“…Where R is resistivity and mf denotes the mud filtration. Sherman et al defined the J function to normalize the logging reading for the different tool [6]. The J function is ( )…”

Leg 75 Methods for Laboratory-Measured Physical Properties, Gearhart-Owen Well Logs, and the Uyeda Downhole Temperature Probe

“…Wet-bulk density is the ratio of the "mass of wet-saturated (if in situ gas is not present) formation" to its "volume," expressed as grams per cubic centimeters. The general principles of this technique, similar logging tools and their interpretation characteristics, assumptions, and precautions are discussed in Wahl et al (1964) and Sherman and Locke (1975). Additional discussion of general principles, etc., are also in Baker (1957) and Lynch (1962).…”

Effects of Invasion on the Compensated Neutron Log (Cnl) in Gas- And Liquid-Filled Formations

“…'In a previous paper, Sherman and Locke [9] discuss the effect of porosity on the depth of investigation of several neutron sondes. The experiments which were done as part of that work furnish tool response data which can be used to check the model-generated results from the present work.…”

“…Two experimental arrangements are described in Ref. (9). They both consist of a series of water tight tanks of varying diameters nested within each other.…”