Method for analyzing formation data from a formation evaluation MWD logging tool
US5091644A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 15, 1991 |
| Grant date | Feb 25, 1992 |
| Priority date | — |
| Expiry date | Jan 15, 2011 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B47/00
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
This invention relates to a method for analyzing data from a measurement-while-drilling (MWD) formation evaluation logging tool which compensates for rotations of the logging tool (along with the rest of the drillstring) during measurement periods. In accordance with this method, the received signal is broken down into a plurality of sections. In a preferred embodiment, the present invention calls for the breaking of the signal from the formation into four different sections: top, bottom, right, left. As the tool rotates, it will quickly pass through these four quadrants. Each time it passes a boundary, a counter is incremented, pointing to the next quadrant. This will allow for dividing the data into four spectra for each detector. Each of these four spectra will be obtained for 1/4th of the total acquisition time. The relative error is minimized by comparing the relative error in each spectrum and selecting a specific spectrum or by combining at least two spectra. In a gamma ray density tool having a pair of detector assemblies (e.g., long space and short space), the long space data, as well as the short space data, will have sufficient statistical significance for use in the mea…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.