# US 11,079,513 B2 · Evaluation of formation composition using neutron induced gamma spectroscopy tools > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,079,513 B2 - Document ID: US11079513B2 - Status: Granted - Kind: B2 - Application number: 16/759,154 - Filed: 2017-11-08 - Published: 2020-10-15 - Granted: 2021-08-03 - Earliest claimed: 2017-11-08 - Assignees: Baker Hughes Incorporated - Applicants: Baker Hughes, LLC - Inventors: Bair Banzarov; Alexander Vinokurov; Toyli Anniyev; Maxim Vasilyev; Vladislav Krutko - Web page: https://patentgrep.com/patent/US11079513B2 ## CPC - G01V 5/101: {and detecting the secondary Y-rays produced in the surrounding layers of the bore hole} - G01V 5/102: {the neutron source being of the pulsed type} - G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02) ## Abstract Systems and methods for measuring formation properties in downhole operations are provided. The systems and methods include generating, at a neutron source, neutrons that are emitted into a downhole formation (302), registering, at a detector, photons generated by chemical constituents of the downhole formation (304), measuring a response of the photons registered at the detector (306), transforming, with a computing system, the measured responses of the photons registered at the detector into thermal neutron capture probabilities (308), and transforming the thermal neutron capture probabilities into weight concentrations of the chemical constituents of the downhole formation (312). ## Claims ### Claim 1 A method for measuring formation properties in downhole operations, the method comprising: generating, at a neutron source, neutrons that are emitted into a downhole formation; registering, at a detector, photons generated by chemical constituents of the downhole formation; measuring a response of the photons registered at the detector, wherein measuring the response of the photons comprises both (i) measuring capture photon energy spectra and (ii) measuring thermal neutron decay time; transforming, with a computing system, the measured responses of the photons registered at the detector into thermal neutron capture probabilities; and transforming the thermal neutron capture probabilities into weight concentrations of the chemical constituents of the downhole formation. ### Claim 2 (depends on 1) The method of claim 1, wherein the neutron source is a pulsed neutron source. ### Claim 3 (depends on 1) The method of claim 1, further comprising normalizing the thermal neutron capture probabilities to unity prior to obtaining the weight concentrations. ### Claim 4 (depends on 1) The method of claim 1, wherein the computing system comprises a surface computing element and a downhole computing element. ### Claim 5 (depends on 1) The method of claim 1, further comprising performing a drilling operation using bottomhole assembly, wherein the neutron source, the detector, and at least a part of the computing system are part of the bottomhole assembly. ### Claim 6 (depends on 1) The method of claim 1, wherein the thermal neutron capture probabilities are linear functions of elemental yields. ### Claim 7 (depends on 6) The method of claim 6, wherein the thermal neutron capture probabilities are calculated as P j = ρ ⁢ Y j - B j K j , j=1, N, wherein Yj is the yield of the j-th element, ρ is formation density, and Kj and Bj are tool sensitivity factors. ### Claim 8 (depends on 1) The method of claim 1, wherein transforming the thermal neutron capture probabilities into weight concentrations comprises representing the thermal neutron capture probabilities as functions of cross-sections. ### Claim 9 (depends on 1) The method of claim 1, further comprising at least one of measuring a thermal neutron decay time, wherein the weight concentration is calculated as W j = Σ · P j · M j N A · ρ · σ j , j=1, N, wherein Wj is the weight concentration of the j-th element, Σ is a formation macroscopic cross section of thermal neutron absorption, Pj is the thermal neutron capture probability, Mj is the molar mass, NA is the Avogadro constant, ρ is formation density, and σj is a microscopic cross section of thermal neutron absorption. ### Claim 10 A system for measuring formation properties in downhole operations, the system comprising: a neutron source configured to emit neutrons into a downhole formation; a detector configured to register photons that are generated by chemical constituents of the downhole formation; and a computing system configured to: measure a response of the photons detected by the detector; transform the measured response of the photons into thermal neutron capture probabilities; normalize the thermal neutron capture probabilities to unity prior to obtaining the weight concentrations; and transform the thermal neutron capture probabilities into weight concentrations of the chemical constituents of the downhole formation. ### Claim 11 (depends on 10) The system of claim 10, wherein the neutron source is a pulsed neutron source. ### Claim 12 (depends on 10) The system of claim 10, wherein the computing system comprises a surface computing element and a downhole computing element. ### Claim 13 (depends on 10) The system of claim 10, further comprising a bottomhole assembly for performing drilling operations, wherein the neutron source, the detector, and at least a part of the computing system are part of the bottomhole assembly. ### Claim 14 (depends on 10) The system of claim 10, wherein measuring the response of the photons comprises measuring capture photon energy spectra and measuring thermal neutron decay time. ### Claim 15 (depends on 10) The system of claim 10, wherein the thermal neutron capture probabilities are linear functions of elemental yields. ### Claim 16 (depends on 15) The system of claim 15, wherein the thermal neutron capture probabilities are calculated as P j = ρ ⁢ Y j - B j K j , j=1, N, wherein Yj is the yield of the j-th element, ρ is formation density, and Kj and Bj are tool sensitivity factors. ### Claim 17 (depends on 10) The system of claim 10, wherein transforming the thermal neutron capture probabilities into weight concentrations comprises representing the capture probabilities as functions of cross-sections. ### Claim 18 (depends on 10) The system of claim 10, the computing system further configured to measure a thermal neutron decay time, wherein the weight concentration is calculated as W j = Σ · P j · M j N A · ρ · σ j , j=1, N, wherein Wj is the weight concentration of the j-th element, Σ is a formation macroscopic cross section of thermal neutron absorption, Pj is the thermal neutron capture probability, Mj is the molar mass, NA is the Avogadro constant, ρ is formation density, and σj is a microscopic cross section of thermal neutron absorption. ### Claim 19 A method for measuring formation properties in downhole operations, the method comprising: generating, at a neutron source, neutrons that are emitted into a downhole formation; registering, at a detector, photons generated by chemical constituents of the downhole formation; measuring a response of the photons registered at the detector; transforming, with a computing system, the measured responses of the photons registered at the detector into thermal neutron capture probabilities, wherein the thermal neutron capture probabilities are linear functions of elemental yields; and transforming the thermal neutron capture probabilities into weight concentrations of the chemical constituents of the downhole formation.