Determination of stress characteristics of earth formations
US7042802B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Sep 18, 2003 |
| Grant date | May 9, 2006 |
| Priority date | — |
| Expiry date | Apr 12, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V1/50
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method for determining the maximum and minimum horizontal stresses of formations surrounding a borehole includes the following steps: suspending a logging device in the borehole; transmitting sonic energy from the logging device to establish flexural waves in the formations; receiving, at the logging device, sonic energy from the flexural waves, and producing, from the received sonic energy, measurement signals at a number of frequencies; determining, at the number of frequencies, the fast and slow flexural wave velocities in the formations, to obtain fast and slow flexural velocity dispersions; establishing a model of formation stresses in which stresses of a loaded state are represented by the sum of an omnidirectional hydrostatically loaded mean reference stress, a vertical stress perturbation, and maximum and minimum horizontal stress perturbations; establishing an inversion model that includes inputs from the fast and slow flexural velocity dispersions and also includes unknown horizontal perturbations of the model of formation stresses; deriving, from the inversion model, estimates of the maximum and minimum horizontal stress perturbations; and determining, from the estimat…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.