Method and apparatus for neutron logging using a position sensitive neutron detector
AssigneeSchlumberger Technology Corporation
InventorsLibai Xu, Kevin S McKinny, Cornelis Huiszoon, Christian Stoller
Life of this patent
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Abstract
A neutron logging tool includes a neutron source and at least one position sensitive thermal or epithermal neutron detector. The logging tool further includes an electronic controller configured to estimate the axial location of detected neutrons. Measurement of the axial neutron flux distribution enables other formation and borehole parameters such as formation porosity and sensor standoff to be computed. In logging while drilling embodiments, a borehole caliper may also be computed form the axial neutron flux distribution.
Claims25
A neutron logging tool comprising:
- a downhole logging tool body;
- a neutron source;
- a position sensitive neutron detector, an axis of which is substantially parallel with an axis of the tool body;
- and
- a controller configured to determine axial locations of neutrons detected by the position sensitive neutron detector, determine an axial neutron flux distribution based upon the axial locations of the detected neutrons, and to distribute the axial neutron flux distribution into a plurality of predetermined axial bins, each of the bins including neutron counts at a range of corresponding axial positions.
A method for making a neutron logging measurement in a subterranean borehole, the method comprising:
- (a) deploying a neutron logging tool in a borehole, the neutron logging tool including a neutron source and a position sensitive neutron detector configured to determine an axial position of detected neutrons;
- (b) using the neutron detector to measure an axial neutron flux distribution;
- and
- (c) distributing the axial neutron flux distribution into a plurality of predetermined axial bins, each of the bins including neutron counts at a range of corresponding axial positions.
Dependencies are inferred from the claim text.