Radiant energy – Geological testing or irradiation – Well testing apparatus and methods
Patent
1987-10-05
1992-07-07
Fields, Carolyn E.
Radiant energy
Geological testing or irradiation
Well testing apparatus and methods
250266, 250270, G01V 510
Patent
active
051285410
ABSTRACT:
A borehole logging method for determining thermal neutron decay characteristics of a formation surrounding the borehole, comprises the following steps. The formation surrounding the borehole is irradiated from a location within the borehole with a burst of neutrons and indications of the concentration of the diffusing thermal neutrons are detected in at least three time gates following the burst of neutrons. Corresponding count rate signals in response to the detected neutrons are produced. Thereafter, the count rate signals are combined in a predetermined manner to separate a characteristic of the thermal neutron decay rate of the formation from associated neutron diffusion characteristics which are monotonically decreasing with time. The steps of irradiating, detecting and combining are then repeated at different depth locations within the borehole and a recording of the rate of decay of thermal neutrons as a function of borehole depth is produced.
REFERENCES:
patent: 4445033 (1984-04-01), Preeg et al.
patent: 4721853 (1988-01-01), Wraight
patent: 4947040 (1990-08-01), Mahdavi et al.
Steinman et al., "Dual-Burst Thermal Decay Time Logging-Principles", SPE 15437, 1986.
Locke et al., "Computed Departure Curves for the Thermal Neutron Decay Log", SPWLA 16th Annual Logging Sym., Jun. 4-7, 1975.
Polyachenko, "The Theory of Nonstationary Diffusion of Thermal Neutrons in a Two-Substance, Infinite Medium with a Cylindrical Dividing Surface", IZV Geophys. Ser. 1964, pp. 532-541.
Rezvanov, "Results of Statistical Modelling of Problems of Pulsed Neutron-Neutron Logging with Epithermal Neutrons", Izv., Earth Physics No. 3, 1970, pp. 105-110.
S. Locke, Private Communication, "A Refined Scale Factor Measurement for TDT Sondes", Schlumberger-Doll Research Center, Patent Memo, Jun. 29, 1972.
Mahdavi Mehrzad
Olesen Jean-Remy
Steinman Donald K.
Summerfield George C.
Bouchard John H.
Fields Carolyn E.
Garrana Henry N.
Schlumberger Technology Corporation
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