Method for estimating formation in-situ stress magnitudes using a sonic borehole tool
US5838633A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 27, 1997 |
| Grant date | Nov 17, 1998 |
| Priority date | — |
| Expiry date | Jan 27, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V1/50
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method of estimating formation in-situ stress magnitude and nonlinear constants of an earth formation traversed by a borehole includes analyzing the flexural wave dispersions for dipole sources aligned parallel and perpendicular to the maximum far-field compressive stress direction together with the Stoneley wave dispersion derived from a monopole source. In the presence of formation and borehole stresses above and beyond those in an assumed isotropic reference state, the borehole flexural and Stoneley wave velocity dispersions are also functions of the formation stresses and nonlinear constants. A multi-frequency inversion of the flexural or Stoneley wave velocity dispersions over a selected frequency band is performed to determine the uniaxial stress magnitude S and the quantities ##EQU1## where c.sub.111, c.sub.112, and c.sub.123 are the formation non-linear constants.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.