Gamma-ray spectroscopy tool environmental effects

Conference · Wed Sep 01 04:00:00 EDT 1982 · Soc. Pet. Eng. AIME, Pap.; (United States)

OSTI ID:5467949

Schweitzer, J S; Hertzog, R C; Manente, R A

An analysis of inelastic and capture gamma-ray spectra, obtained from reactions induced by 14 MeV neutron irradiation of the formation, provides a valuable determination of formation elemental yields. These yields can be used to infer oil saturation, water salinity, porosity, and lithology of the formation. However elements present in the formation may also be present in the casing, cement, and borehole fluid. To obtain accurate formation elemental concentrations, the contribution of these elements in the borehole to the measured signal must be accounted for in the final interpretation of the spectral data. Many different borehole and formation conditions have been investigated in the laboratory to clarify the underlying effects on the spectral response to changes in borehole geometry and elemental composition. The results of this investigation permit a more accurate interpretation to be made from the carbon, oxygen, hydrogen, silicon, calcium, iron, chlorine, and sulfur concentrations obtained from a Weighted-Least Squares (WLS) analysis of inelastic and capture gamma-ray spectra. The combination of various measured elemental yields to infer formation properties independent of the borehole environment can now be made with greater accuracy. Certain underlying physical properties have been clarified permitting a successful analysis of log data under conditions not previously investigated.

• Research Organization: Schlumberger-Doll Research
• OSTI ID: 5467949
• Report Number(s): CONF-820927-
• Conference Information: Journal Name: Soc. Pet. Eng. AIME, Pap.; (United States) Journal Volume: SPE11144
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
58 GEOSCIENCES
580203 -- Geophysics-- Geophysical Survey Methods-- (1980-1989)
BENCH-SCALE EXPERIMENTS
CHEMICAL COMPOSITION
CORRECTIONS
DATA ANALYSIS
ENVIRONMENTAL EFFECTS
EXPLORATORY WELLS
GAMMA SPECTRA
GAMMA SPECTROMETERS
GAMMA SPECTROSCOPY
LITHOLOGY
MEASURING INSTRUMENTS
NEUTRON LOGGING
NEUTRON-GAMMA LOGGING
OIL SATURATION
PHYSICAL PROPERTIES
POROSITY
RADIOACTIVITY LOGGING
RESERVOIR ROCK
SALINITY
SATURATION
SPECTRA
SPECTRAL RESPONSE
SPECTROMETERS
SPECTROSCOPY
WELL LOGGING
WELLS