Thermal neutron porosity from neutron slowing-down length, formation thermal neutron capture cross section, and bulk density
US7667192B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 16, 2007 |
| Grant date | Feb 23, 2010 |
| Priority date | — |
| Expiry date | Aug 19, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V5/107
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method for determining at least one formation property calculated from neutron measurements acquired with a downhole tool includes emitting neutrons from a source in the tool into the formation, detecting neutrons with at least one detector in the downhole tool, calculating a first slowing-down length (L1) based on the detected neutrons, and deriving a second slowing-down length (L2) based on the first slowing-down length (L1). Further steps include deriving a correlation function for relating slowing-down lengths from a first tool to slowing-down lengths associated with a different source, wherein the correlation function depends on formation properties such as bulk density; and applying the correlation function to the slowing-down length of the first tool to derive the slowing-down length of the second tool. A method for determining a thermal neutron formation porosity based on a slowing-down length from epithermal neutron measurements from an electronic neutron source includes converting the slowing-down length into a computed neutron slowing-down length from thermal neutron measurements from a chemical neutron source, wherein the converting uses a correlation function that de…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.