Stress in formations from azimuthal variation in acoustic and other properties
AssigneeBaker Hughes Incorporated
InventorDaniel Moos
Life of this patent
Estimating the term…
Abstract
The present disclosure is related to methods and apparatuses for acoustic velocity well logging. The method may include estimating a magnitude of a principal horizontal stress in a borehole in a formation. The method may include obtaining a far field stress orientation and making a measurement of near borehole stress orientation. The present disclosure also includes an apparatus configured to be conveyed into a borehole and perform the method. Formation stresses and directions may be estimated.
Claims22
A method for characterizing an earth formation, comprising:
- obtaining at least one limited aperture measurement at frequencies greater than 20 kHz in a borehole penetrating the earth formation and obtaining a principal direction of a near field stress using the at least one limited aperture measurement;
- and
- obtaining a magnitude of a horizontal principal stress;
- using the principal direction of the near field stress and the magnitude of the horizontal principal stress for estimating a principal direction of a far field stress.
An apparatus for characterizing an earth formation comprising:
- a logging tool configured to obtain at least one limited aperture measurement at frequencies greater than 20 kHz in a borehole penetrating the earth formation;
- and
- at least one processor configured to:
- (i) estimate a principal direction of a near field stress near the borehole using the at least one limited aperture measurement;
- (ii) obtain a magnitude of a horizontal principal stress;
- and
- (ii) use the estimated principal direction of the near field stress and a magnitude of a horizontal principal stress to estimate a principal direction of a far field stress.
A method for characterizing an earth formation, comprising:
- obtaining at least one limited aperture measurement at frequencies greater than 20 kHz and obtaining a principal direction of a near field stress in a borehole penetrating the earth formation using said limited aperture measurement;
- and
- obtaining an indication of a principal direction of a far field stress in the earth formation;
- using the principal direction of the near field stress and the indication of the principal direction of the far field stress in the earth for estimating a magnitude of the horizontal principal stress using a model in which there is a gradual transition of an azimuthal direction of a fast shear mode from near the borehole to a far field.
Dependencies are inferred from the claim text.