Method of downhole neutron monitoring

Patent · Tue Apr 16 04:00:00 EDT 1991

OSTI ID:5090353

Czirr, J B

This patent describes a method of downhole monitoring neutrons emanating from a pulsed-type neutron source, the neutron source having beam-on and beam-off time periods and positioned in a downhole apparatus. It comprises using an oxygen containing scintillating material in a detector to monitor neutrons from the neutron source by generating scintillator light as a function of electrons and gamma rays emitted from the product of the {sup 16}O (n,p) reaction, the neutron source emitting neutrons having energies greater than 11 MeV; positioning the detector in the downhole apparatus and within a borehole surrounded by a formation to be studied; reducing the effects of background gamma radiation from the {sup 16}O (n,p) reaction occurring in the formation surrounding the detector; by: setting the bias level of the detector to an energy level of at least 6.7 MeV; and after setting the bias level, and during the beam-off time period of the neutron source, measuring the combined energy deposition within the scintillating material from both the electrons and the gammas which equals or exceeds the 6.7 MeV bias level, the scintillating material generating scintillator light corresponding to the combined energy deposition; converting the generated scintillator light to an electrical signal; and using the electrical signal to record the flux of the neutrons from the neutron source.

• Assignee: NOV; EDB-91-158372; NOV-91-023141
• Patent Number(s): US 5008067; A
• Application Number: PPN: US 7-492395
• OSTI ID: 5090353
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
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& Exploration
03 NATURAL GAS
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& Exploration
DESIGN
DETECTION
EQUIPMENT
EXPLORATORY WELLS
GEOLOGIC DEPOSITS
MEASURING INSTRUMENTS
MINERAL RESOURCES
MONITORS
NATURAL GAS DEPOSITS
NEUTRON DETECTION
NEUTRON LOGGING
NEUTRON MONITORS
NEUTRON-GAMMA LOGGING
PETROLEUM DEPOSITS
RADIATION DETECTION
RADIATION MONITORS
RADIOACTIVITY LOGGING
RESOURCES
WELL LOGGING
WELL LOGGING EQUIPMENT
WELLS