Method and apparatus for determining the respective contributions of borehole and earth formation in gamma ray spectroscopy
US5105080A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 2, 1991 |
| Grant date | Apr 14, 1992 |
| Priority date | — |
| Expiry date | Apr 2, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V5/101
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A apparatus and an apparatus for determining the respective contributions in spectroscopy measurements of the borehole and the earth formations surrounding the borehole, derived from the detection of gamma rays resulting from the collisions of neutrons with atoms of the formation or the borehole. From gamma rays from a near and far detector, and established, at each depth, responses (e.g. elemental yields) representative of the values of an unknown in the borehole and in the formation. The far detector response is plotted against the near detector response. From the plot and from known conditions of the detection, is derived a closed curve characteristic of the relative contributions of the borehole and the formation in the responses. For each depth, the respective values of the unknown are derived from the position on the plot of the couple of responses for that depth, with respect to the closed curve. For instance, on a plot of C/(C+O) yields, the curve is a parallelogram two concurrent sides of which form a coordinate system; the coordinates of each response corresponds to the values of the unknown respectively for the formation and the borehole.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.