Method for borehole measurement of formation properties
First Claim
1. A method of estimating a subsurface formation'"'"'s velocity ratio using a bottom hole assembly comprising:
- (a) generating a compressional wave having a first wavelength from said bottom hole assembly;
(b) detecting a compressional wave received signal using said bottom hole assembly;
(c) generating a shear wave having a second wavelength from said bottom hole assembly;
(d) detecting a shear wave received signal using said bottom hole assembly; and
(e) phase matching said detected compressional and shear wave received signals to determine said velocity ratio.
1 Assignment
0 Petitions
Accused Products
Abstract
The present invention is a method of estimating formation properties by analyzing acoustic waves that are emitted from and received by a bottom hole assembly. A bottom hole assembly may be deployed in a borehole to estimate formation properties. From the bottom hole assembly, a source signal may be emitted and at least one signal may be received by one or more receivers in the bottom hole assembly. Analysis of the frequency dependent characteristics of the received signal allows the estimation of the formation properties of interest, including pore pressure. The formation properties of interest may be used to monitor a wellbore pressure safety margin and to optimize drilling and weight.
98 Citations
25 Claims
-
1. A method of estimating a subsurface formation'"'"'s velocity ratio using a bottom hole assembly comprising:
-
(a) generating a compressional wave having a first wavelength from said bottom hole assembly; (b) detecting a compressional wave received signal using said bottom hole assembly; (c) generating a shear wave having a second wavelength from said bottom hole assembly; (d) detecting a shear wave received signal using said bottom hole assembly; and (e) phase matching said detected compressional and shear wave received signals to determine said velocity ratio. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
-
-
15. A method of estimating a subsurface formation'"'"'s velocity ratio using a bottom hole assembly comprising:
-
(a) generating a compressional wave having a first wavelength from said bottom hole assembly; (b) detecting a compressional wave received signal using said bottom hole assembly; (c) generating a shear wave having a second wavelength from said bottom hole assembly, said second wave length being approximately one-half of said first wavelength; (d) detecting a shear wave received signal using said bottom hole assembly; and (e) phase matching said detected compressional and shear wave received signals to determine said velocity ratio, said phase matching involves matching time intervals between said shear wave received signal and said compressional wave received signal. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22)
-
-
23. A method of continuously estimating pore pressures of a formation ahead of a bottom hole assembly, comprising the steps of:
-
(a) generating a compressional wave having a first wavelength from said bottom hole assembly; (b) detecting a compressional wave received signal using said bottom hole assembly; (c) generating a shear wave having a second wavelength from said bottom hole assembly, said second wavelength being approximately one-half of said first wavelength; (d) detecting a shear wave received signal using said bottom hole assembly; (e) phase matching said detected compressional and shear wave received signals to determine said velocity ratio, said phase matching involving matching time intervals between said shear wave received signal and said compressional wave received signal; (f) using said velocity ratio to determine effective stress of a formation ahead of said bottom hole assembly; (g) using said effective stress to determine said pore pressures of said formation ahead of said bottom hole assembly; and (h) repeating steps (a) through (g) as said bottom hole assembly moves sequentially downward through said formation.
-
-
24. A method of continuously monitoring a wellbore pressure safety margin corresponding to formation ahead of a bottom hole assembly, comprising the steps of:
-
(a) generating a compressional wave having a first wavelength from said bottom hole assembly; (b) detecting a compressional wave received signal using said bottom hole assembly; (c) generating a shear wave having a second wavelength from said bottom hole assembly, said second wavelength being approximately one-half of said first wavelength; (d) detecting a shear wave received signal using said bottom hole assembly; (e) phase matching said detected compressional and shear wave received signals to determine said velocity ratio, said phase matching involving matching time intervals between said shear wave received signal and said compressional wave received signal; (f) using said velocity ratio to determine effective stress of a formation ahead of said bottom hole assembly; (g) using effective stress to determine pore pressure of said formation ahead of said bottom hole assembly; (h) using said pore pressure to determine a wellbore pressure safety margin of said formation ahead of said bottom hole assembly; and (i) repeating steps (a) through (h) as said bottom hole assembly moves sequentially downward through said formation.
-
-
25. A method of continuously optimizing weight of drilling mud used in a drilling operation, comprising the steps of:
-
(a) detecting a compressional wave received signal using said bottom hole assembly; (b) generating a shear wave having a second wavelength from said bottom hole assembly, said second wavelength being approximately one-half of said first wavelength; (c) detecting a shear wave received signal using said bottom hole assembly; (d) phase matching said detected compressional and shear wave received signals to determine said velocity ratio, said phase matching involves matching time intervals between said shear wave received signal and said compressional wave received signal; (e) using said velocity ratio to determine effective stress of a formation ahead of said bottom hole assembly; (f) using effective stress to determine pore pressure of said formation ahead of said bottom hole assembly; and (g) using said pore pressure to specify a weight of said drilling mud which corresponds to a target wellbore pressure safety margin.
-
Specification