# US 11,906,691 B2 · Method for improving neutron interpretations in subsurface formations > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,906,691 B2 - Document ID: US11906691B2 - Status: Granted - Kind: B2 - Application number: 17/050,141 - Filed: 2019-04-22 - Published: 2021-07-29 - Granted: 2024-02-20 - Earliest claimed: 2018-04-23 - Assignees: Schlumberger Technology Corporation - Applicants: Schlumberger Technology Corporation - Inventors: Paul R. Craddock; Laurent Mosse; Jeffrey R. Miles; Andrew E. Pomerantz - Web page: https://patentgrep.com/patent/US11906691B2 ## CPC - G01V 5/10: using neutron sources {(neutron generating tubes H05H5/00; neutron sources using isotopes G21G4/00)} - E21B 49/00: Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells - G01N 21/3563: for analysing solids; Preparation of samples therefor - G01N 33/241: {for hydrocarbon content} - G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02) - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract Embodiments of the present disclosure are directed towards a method for improving neutron interpretations in a subsurface formation. Embodiments may include estimating mineral concentrations and kerogen concentrations at one or more depths in the subsurface formation and determining kerogen properties at one or more depths in the subsurface formation. Embodiments may further include calculating mineral properties at one or more depths in the subsurface formation and calculating a neutron-based log response to a rock matrix based upon, at least in part, the kerogen properties and the mineral properties at one or more depths in the subsurface formation by subtracting. ## Claims ### Claim 1 A method for improving neutron interpretations in a subsurface formation comprising: deploying a neutron tool directly in a borehole traversing the formation; logging the formation using the neutron tool; estimating mineral concentrations and kerogen concentrations at one or more depths in the subsurface formation; estimating kerogen properties at the one or more depths in the subsurface formation; calculating mineral properties at the one or more depths in the subsurface formation by summing a plurality of individual mineral abundances solved by infrared spectroscopy, wherein each of the plurality of individual mineral abundances is multiplied by a respective mineral property; calculating a neutron-based log response to a rock matrix based upon, at least in part, the kerogen properties and the mineral properties at the one or more depths in the subsurface formation by subtracting a contribution from the rock matrix associated with the kerogen properties and the mineral properties from a total neutron response measured by the neutron tool when logging the formation; and generating and delivering an output to a reservoir tool to alter operation of the reservoir tool, wherein the generated output is based at least in part on an interpretation of the neutron-based log response. ### Claim 2 (depends on 1) The method according to claim 1, wherein estimating the mineral concentrations and the kerogen concentrations is based upon, at least in part, a diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis of at least one sample from the subsurface formation. ### Claim 3 (depends on 1) The method according to claim 1, wherein estimating the kerogen properties includes estimating from an infrared spectrum measured by a diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis of at least one sample from the subsurface formation. ### Claim 4 (depends on 1) The method of claim 1, further comprising: refining the neutron-based log response using one or more of nuclear magnetic resonance, resistivity and dielectric dispersion. ### Claim 5 (depends on 1) The method of claim 1, wherein at least one of the kerogen properties and the mineral properties include one or more of thermal neutron porosity and hydrogen index. ### Claim 6 (depends on 1) The method of claim 1, wherein at least one of the kerogen properties and the mineral properties include one or more of macroscopic thermal neutron absorption cross section and fast neutron scattering cross section. ### Claim 7 (depends on 1) The method of claim 1, further comprising: performing an interpretation of the neutron-based log response, wherein the interpretation is based upon, at least in part, a porosity. ### Claim 8 (depends on 1) The method of claim 1, further comprising: performing an interpretation of the neutron-based log response, wherein the interpretation is based upon, at least in part, a volumetric solution using properties of kerogen and minerals. ### Claim 9 (depends on 1) The method according to claim 1, wherein estimating the kerogen properties includes using an infrared spectrum measured by an attenuated total reflection or a transmission Fourier transform infrared spectroscopy. ### Claim 10 A system for improving neutron interpretations in a subsurface formation comprising: a computing system including at least one processor configured to estimate mineral concentrations and kerogen concentrations at one or more depths in the subsurface formation based at least on a formation characterization obtained by utilizing a neutron log obtained by deploying a neutron tool into a borehole traversing the formation, the at least one processor further configured to determine kerogen properties at the one or more depths in the subsurface formation and to calculate mineral properties at the one or more depths in the subsurface formation by summing a plurality of individual mineral abundances solved by infrared spectroscopy, wherein each of the plurality of individual mineral abundances is multiplied by a respective mineral property, the at least one processor further configured to calculate a neutron-based log response to a rock matrix based upon, at least in part, the kerogen properties and the mineral properties at the one or more depths in the subsurface formation by subtracting a contribution from the rock matrix associated with the kerogen properties and the mineral properties from a total neutron response measured by the neutron tool when obtaining the neutron log, and the at least one processor further configured to generate and deliver an output to a reservoir tool to alter operation of the reservoir tool, wherein the generated output is based at least in part on an interpretation of the neutron-based log response. ### Claim 11 (depends on 10) The system according to claim 10, wherein the mineral concentrations and kerogen concentrations are estimated, at least in part, with a diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis of at least one sample from the subsurface formation. ### Claim 12 (depends on 10) The system according to claim 10, wherein the kerogen properties are estimated, at least in part, from an infrared spectrum measured by a diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis of at least one sample from the subsurface formation. ### Claim 13 (depends on 10) The system of claim 10, further comprising: refining the neutron-based log response using one or more of nuclear magnetic resonance, resistivity, and dielectric dispersion. ### Claim 14 (depends on 10) The system of claim 10, wherein at least one of the kerogen properties and the mineral properties include one or more of thermal neutron porosity and hydrogen index. ### Claim 15 (depends on 10) The system of claim 10, wherein at least one of the kerogen properties and the mineral properties include one or more of macroscopic thermal neutron absorption cross section and fast neutron scattering cross section. ### Claim 16 (depends on 10) The system of claim 10, further comprising: performing an interpretation of the neutron-based log response, wherein the interpretation is based upon, at least in part, a porosity. ### Claim 17 (depends on 10) The system of claim 10, further comprising: performing an interpretation of the neutron-based log response, wherein the interpretation is based upon, at least in part, a volumetric solution using properties of kerogen and minerals. ### Claim 18 (depends on 10) The system according to claim 10, wherein estimating the kerogen properties includes using an infrared spectrum measured by an attenuated total reflection or a transmission Fourier transform infrared spectroscopy.