Introduction - Cased-Hole Log Analysis and Reservoir Performance Monitoring - page 4

Modern Production Logging Tools
Modern production logging tools may be categorized in three general groups as
making measurements of:
Formation properties through casing and/or tubing
Fluid type, fl ow rate, and movement within the casing/tubing vicinity
The status of the completion string
Well bore
OIL ZONE
Cone
WATER
Fig. 1.3 Water coning across bedding planes. Reprinted with permission of the Petroleum
Engineer International from Cesak and Schultz (1956)
Tools for Formation Properties
Tools that measure formation properties from within a completed well include:
Pulsed neutron logs: (TDT, NLL, TMD)
Gamma ray logs: (GR)
Natural gamma spectra logs: (NGT)
Inelastic gamma logs: (IGT)
Carbon/oxygen logs: (C/O, GST)
All have a common characteristic; they depend on interactions of nuclear parti-
cles (neutrons) and/or radiation (gamma rays) that have the ability to pass through
steel casing.