Logging apparatus and method for determining absolute elemental concentrations of subsurface formations
US4810876A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 5, 1986 |
| Grant date | Mar 7, 1989 |
| Priority date | — |
| Expiry date | Sep 5, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V5/10
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Logging apparatus and methods for detecting first signals indicative of the absolute concentrations of the first category of elements in the rock matrix, for irradiating the formation with a pulse of high energy neutrons and for detecting a second signal indicative of the relative concentrations of a second category of elements in a rock matrix. The absolute and relative concentrations of a plurality of elements are determined, and this information is used to transform at least one of the relative concentrations into an absolute concentration. One of the measured absolute concentrations is for aluminum, from which correlations are used to determine the absolute concentrations of other, non-measured elements. A tool system for measuring the absolute aluminum concentration includes a californium-252 source and a gamma ray detector having a plurality of windows from which the aluminum count rate can be compensated for interference by manganese activation. A further correction to the aluminum count rate has a functional dependence on the neutron slowing down length in the formation, the formation macroscopic cross section, the borehole microscopic cross section, the bulk density of the…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.