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公开(公告)号：US10139518B2
公开(公告)日：2018-11-27
申请号：US15177427
申请日：2016-06-09
发明人： Michael Lynn Evans
IPC分类号： G01V5/10
摘要： A method for determining a corrected neutron gamma density of a formation includes emitting neutrons into a formation using a neutron source to generate gamma-rays. Additionally, the method includes detecting a first count rate of gamma-rays and a gamma-ray spectrum using at least a gamma-ray detector of the downhole tool. The method also includes detecting a second count rate of neutrons using a neutron detector. The method includes using a processor to perform a gamma-ray spectroscopy analysis on the formation based on the gamma-ray spectrum and determining a correction based on results of the gamma-ray spectroscopy analysis. The method includes applying the correction to the first count rate or the second count rate and determining a neutron gamma density of the formation based on a first corrected count rate of gamma-rays or a second corrected count rate of neutrons. The method also includes outputting the determined density of the formation.
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公开(公告)号：US20170176634A1
公开(公告)日：2017-06-22
申请号：US14974135
申请日：2015-12-18
发明人： Michael Lynn Evans
IPC分类号： G01V5/10
摘要： Methods and devices for determining accurate neutron-gamma density (NGD) measurements of a broad range of formations. The NGD measurements may be obtained by emitting neutrons into a formation such that some of the neutrons inelastically scatter off elements of the formation and generate inelastic gamma rays. Inelastic gamma rays that return to the downhole tool may be detected. Additionally, fast neutron signals may be directly measured with a fast neutron detector. Some characteristics of certain formations are believed to affect the fast neutron transport of the formations. Thus, if a formation has one or more of such characteristics, a correction may be applied to a count rate of inelastic gamma rays from which the neutron-gamma density (NGD) may be determined.
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公开(公告)号：US10162079B2
公开(公告)日：2018-12-25
申请号：US15422782
申请日：2017-02-02
IPC分类号： G01V5/10
摘要： Systems, methods, and devices for determining a neutron-gamma density (NGD) measurement of a subterranean formation that is accurate in both liquid- and gas-filled formations are provided. For example, a downhole tool for obtaining such an NGD measurement may include a neutron generator, a neutron detector, two gamma-ray detectors, and data processing circuitry. The neutron generator may emit neutrons into a formation, causing a fast neutron cloud to form. The neutron detector may detect a count of neutrons representing the extent of the neutron cloud. The gamma-ray detectors may detect counts of inelastic gamma-rays caused by neutrons that inelastically scatter off the formation. Since the extent of the fast neutron cloud may vary depending on whether the formation is liquid- or gas-filled, the data processing circuitry may determine the density of the formation based at least in part on the counts of inelastic gamma-rays normalized to the count of neutrons.
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公开(公告)号：US20170357027A1
公开(公告)日：2017-12-14
申请号：US15177427
申请日：2016-06-09
发明人： Michael Lynn Evans
IPC分类号： G01V5/10
摘要： A method for determining a corrected neutron gamma density of a formation includes emitting neutrons into a formation using a neutron source to generate gamma-rays. Additionally, the method includes detecting a first count rate of gamma-rays and a gamma-ray spectrum using at least a gamma-ray detector of the downhole tool. The method also includes detecting a second count rate of neutrons using a neutron detector. The method includes using a processor to perform a gamma-ray spectroscopy analysis on the formation based on the gamma-ray spectrum and determining a correction based on results of the gamma-ray spectroscopy analysis. The method includes applying the correction to the first count rate or the second count rate and determining a neutron gamma density of the formation based on a first corrected count rate of gamma-rays or a second corrected count rate of neutrons. The method also includes outputting the determined density of the formation.
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公开(公告)号：US20170146684A1
公开(公告)日：2017-05-25
申请号：US15422782
申请日：2017-02-02
IPC分类号： G01V5/10
摘要： Systems, methods, and devices for determining a neutron-gamma density (NGD) measurement of a subterranean formation that is accurate in both liquid- and gas-filled formations are provided. For example, a downhole tool for obtaining such an NGD measurement may include a neutron generator, a neutron detector, two gamma-ray detectors, and data processing circuitry. The neutron generator may emit neutrons into a formation, causing a fast neutron cloud to form. The neutron detector may detect a count of neutrons representing the extent of the neutron cloud. The gamma-ray detectors may detect counts of inelastic gamma-rays caused by neutrons that inelastically scatter off the formation. Since the extent of the fast neutron cloud may vary depending on whether the formation is liquid- or gas-filled, the data processing circuitry may determine the density of the formation based at least in part on the counts of inelastic gamma-rays normalized to the count of neutrons.
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