Pulsed neutron apparatus and method for using same to analyze core samples

An apparatus for analyzing a core sample obtained from a subterranean formation, comprising:

• (a) a neutron generator configured to operate in a pulsed mode and emit neutrons into the core sample, the neutrons including fast neutrons;
• (b) a plurality of detectors that includes:
• at least one gamma detector configured to estimate a gamma pulse-height spectrum that results from emitted neutrons interacting with the core sample,
• a plurality of fast neutron detectors generating at least a first count rate and a second count rate, the plurality of fast neutrons including at least:
• (i) first fast neutron detector configured to generate the first count rate by monitoring the neutron generator output and counting the number of fast neutrons coming from the neutron generator over a period of time, and (ii) a second fast neutron detector configured to generate the second count rate by counting the number of fast neutrons that are transmitted through the core sample over the period of time,
• at least one thermal neutron detector configured to generate a third count rate by counting a number of thermal neutrons over the period of time, the thermal neutrons being emitted neutrons that have been slowed down to thermal energies by passing through the core sample, and
• at least one epithermal neutron detector configured to generate a fourth count rate by counting a number of epithermal neutrons over the period of time, the epithermal neutrons being emitted neutrons that have been slowed down to epithermal energies by passing through the core sample but still have more energy than thermal neutrons;
• (c) a computed tomography scanner in which a conical beam of X-rays is aimed at the sample and an opposing detector, both of which may be rotated around the sample;
• (d) an information processing device in signal communication with the plurality of detectors and configured to separate count events on a nanosecond time scale;
• and
• (e) a transport system configured to allow relative movement between the core sample and the plurality of detectors and between the core sample and the neutron generator.