LWD mineralogy/spectroscopy thermal neutron shielding
AssigneeHalliburton Energy Services, Inc.
InventorJeffrey Clayton Neely
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Abstract
A detector assembly disposed about a tubular for placement within a wellbore penetrating a subterranean formation and comprising: a gamma radiation detector disposed within a pressure housing, wherein the detector extends an axial length in a direction parallel to a central axis of the tubular; and a neutron shield disposed about a circumference of the tubular along at least the axial length of the detector, wherein the neutron shield reduces an amount of neutrons that pass from the wellbore and/or the formation through the tubular during operation of the detector assembly, while allowing transmission of gamma rays therethrough to the detector.
Claims20
A detector assembly disposed about a tubular for placement within a wellbore penetrating a subterranean formation, the detector assembly comprising:
- a gamma radiation detector disposed within a pressure housing, wherein the detector extends an axial length in a direction parallel to a central axis of the tubular;
- and
- a neutron shield disposed about a circumference of the tubular along at least the axial length of the detector, wherein the neutron shield reduces an amount of neutrons that pass from the wellbore and/or the formation through the tubular during operation of the detector assembly, while allowing transmission of gamma rays therethrough to the detector, wherein the neutron shield further comprises a shell comprised of a shell material, wherein the shell material comprises a material having a yield strength sufficient for use in the wellbore, wherein the shell comprises a plurality of shell segments positioned to provide the shell about the entire circumference of the tubular along the at least the axial length of the detector, and wherein the plurality of shell segments overlap along ends thereof when positioned to provide the shell about the entire circumference of the tubular along the at least the axial length of the detector.
A logging tool comprising a detector assembly and a tubular, wherein the detector assembly is disposed about the tubular for placement within a wellbore penetrating a subterranean formation, wherein the detector assembly comprises:
- a gamma radiation detector disposed within a pressure housing, wherein the gamma radiation detector extends an axial length in a direction parallel to a central axis of the tubular;
- and
- a neutron shield disposed about a circumference of the tubular along at least the axial length of the gamma radiation detector, wherein the neutron shield reduces an amount of neutrons that pass from the wellbore and/or the formation through the tubular during operation of the detector assembly, while allowing transmission of gamma rays therethrough to the gamma radiation detector,
- wherein the tubular comprises a drill collar, and wherein the drill collar defines a fluid flow path along an axial length of the drill collar wherein the fluid flow path is offset from the central axis of the tubular.
A method of measuring a property of material in a subterranean formation penetrated by a wellbore, the method comprising:
- placing in the wellbore a detector assembly disposed about a tubular, the detector assembly comprising:
- a gamma radiation detector disposed within a pressure housing, wherein the gamma radiation detector has an axial length in a direction parallel to a central axis of the tubular;
- and
- a gamma ray shield disposed about a portion of an outer perimeter of the pressure housing adjacent the tubular, wherein the gamma ray shield reduces an amount of gamma rays produced within the tubular that reach the gamma radiation detector, and enables azimuthal measurement;
- and
- shielding thermal neutrons from the detector while operating the detector to obtain a measure of a property of the subterranean formation.
Dependencies are inferred from the claim text.