Estimating formation stress using borehole monopole and cross-dipole acoustic measurements: theory and method
US6098021A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 15, 1999 |
| Grant date | Aug 1, 2000 |
| Priority date | — |
| Expiry date | Jan 15, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V1/50
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A system and method to determine an in-situ stress field based on borehole acoustic monopole and cross-dipole measurements. A radially polarized monopole shear-wave is generated in a borehole. It is then determined whether the shear-wave has split into two shear-waves. If it has, the difference in velocities between the two split shear-waves is used to determine the stress induced anisotropy around and near the borehole. The difference in velocities of cross-dipole shear-waves and the direction of the fast shear-wave are measured and used to determine the magnitude of the maximum shear stress and the maximum stress orientation of the geologic formation. Furthermore, a method of determining the stress-velocity coupling coefficients from laboratory measurements as well as through field measurement calibration is disclosed. The effect of borehole pressure on the field measurement calibration method of determining the stress-velocity coupling coefficients is taken into account. Additionally disclosed is a method for defining a stress indicator that is related to stress-caused rock deformation. This stress indicator can be used to determine if rock failure is impending and is useful in …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.