The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 08, 1997
Filed:
Nov. 09, 1995
Kenneth W Winkler, Ridgefield, CT (US);
Schlumberger Technology Corportion, New York, NY (US);
Abstract
A method for determining whether a formation is subject to incipient failure are disclosed. The method comprises determining in situ a nonlinear parameter of a formation, and determining whether the nonlinear parameter and/or a derivative of that nonlinear parameter as a function of stress has a relatively large negative value in order to determine whether the formation is subject to incipient failure. In a preferred embodiment, the nonlinear parameter of the formation is a derivative of the square of the shear or compressional velocity with respect to formation stress. The nonlinear parameter of the derivative of the square of the shear velocity with respect to stress is considered to have a large negative value when it is .ltoreq.-0.1 (km/sec).sup.2/ MPa, while the nonlinear parameter of the derivative of the square of the compressional velocity with respect to stress is considered to have a large negative value when it is .ltoreq.-0.2 (km/sec).sup.2 /MPa. The derivative of the derivative of the square of the shear or compressional velocity with respect to stress is considered to have a large negative value when the derivative is .ltoreq.-0.06 (km/sec).sup.2 /(MPa).sup.2. Typically, rocks will fail if uniaxially stressed between 11-5 MPa beyond any of those points.