Overview of nuclear oil well logging measurements
- Western Atlas Logging Services, Houston, TX (United States)
Nuclear oil well logging measurements are an essential part of the oil exploration process where various sensors are lowered in boreholes penetrating oil reservoirs to determine the location and amount of hydrocarbon. Four nuclear sensors are of primary importance: gamma-ray density, neutron porosity, natural gamma ray, and pulsed neutron capture measurements. Gamma-ray density measurements consist of a {sup 137}Cs gamma-ray source and two gamma-ray detectors placed at different spacings from the source. Gamma rays recorded in the detectors as a result of backscattering from nuclei of earth formations are used to measure the formation bulk density. Neutron porosity measurements consist of an Am-Be neutron source and two {sup 3}He neutron detectors at different spacings from the source. The ratio of the count rate of the two detectors is a function of the neutron slowing-down and thermal diffusion processes and is used to measure the formation liquid-filled porosity. Natural gamma-ray tools measure the spectral response of the natural radioactivity of underground formations from which formation lithology can be identified. Pulsed-neutron capture tools use a pulsed 14-MeV neutron generator and two gamma-ray detectors at different spacings from the source. The gamma-ray response of the detectors measured as a function of time following the source burst is proportional to the thermal neutron capture cross section of the formation that is used to measure the formation water saturation.
- OSTI ID:
- 552699
- Report Number(s):
- CONF-971125-; ISSN 0003-018X; TRN: 97:005809-0404
- Journal Information:
- Transactions of the American Nuclear Society, Vol. 77; Conference: 1997 American Nuclear Society (ANS) winter meeting, Albuquerque, NM (United States), 16-20 Nov 1997; Other Information: PBD: 1997
- Country of Publication:
- United States
- Language:
- English
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