D. W. Oliver, E. Frost, W. H. Fertl
Dresser Atlas, Dresser industries, Inc.
Houston, Texas
ABSTRACT
Carbon/Oxygen(C/0) logging has progressed from stationary to continuous measurements using a 14 MeV source in 20 kHZ pulsed neutron logging instrumentation. Spectral of count rates versus the energy distribution of gamma rays emitted during neutron in elastic scattering and neutron capture are recorded and analyzed as to the carbon, oxygen, silicon, and calcium content of potential reservoir rocks. Such information defines the oil saturation in cased wellbores, regardless of the formation water salinities, and estimates reservoir porosity and Iithology.
Instrumentation, calibration procedures, instrument response, test pit data and environmental corrections, depth of investigation, repeatability, and digital spectral analyses, are discussed in detail. Present C/O logging applications for exploration behind casing, monitoring of primary and enhanced recovery schemes, evaluation of heavy oil, tar sands, and residual oil saturation are discussed.