The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 24, 1991
Filed:
May. 01, 1990
Russell C Hertzog, Missouri City, TX (US);
William A Loomis, Ridgefield, CT (US);
Peter Wraight, Missouri City, TX (US);
Schlumberger Technology Corporation, New York, NY (US);
Abstract
The porosities of subsurface earth formations surrounding a borehole are investigated using a logging tool run in the wellbore by repeatedly irradiating the formations with discrete bursts of high energy neutrons, measuring the populations of epithermal neutrons at near and far locations from the neutron source, and also measuring the rate of decay of the epithermal neutron population at a third location following each neutron burst and deriving therefrom a measurement of the epithermal neutron slowing down time. Formation porosity values derived from the near-and-far location population measurements are corrected for detector standoff effects by use, in accordance with a predetermined empirical relationship, of the epithermal slow down time measurement. Alternatively, formation porosities may be derived both from the near-and-far location measurements and from the epithermal slowing down time measurement, and the two differently-derived porosity values may be used independently to provide enhanced information of formation porosity or they may be compared to derive a standoff-corrected porosity value.