Estimating sigma log beyond the measurements points
US8521435B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 9, 2010 |
| Grant date | Aug 27, 2013 |
| Priority date | — |
| Expiry date | Jul 29, 2031 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V11/00
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The present disclosure relates to a method to determine the capture cross-section of a subsurface formation at a desired depth in the formation. A database of Sigma values for known lithologies, porosities, and salinities is provided, and multiple Sigma measurements are obtained from a downhole logging tool. Within the database, Sigma values are interpolated to determine the respective depths of investigation of the multiple Sigma measurements. A monotonic function is fitted to the multiple Sigma measurements at the determined depths of investigation, and the capture cross-section of the subsurface formation at any desired depth in the formation is determined using the fitted function. Similarly, a system to determine the capture cross-section of a subsurface formation at a desired depth in the formation and/or a depth of invasion of drilling fluids is also disclosed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.