Method for borehole measurement of formation properties
First Claim
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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.
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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.
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Citations
25 Claims
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1. A method of estimating a subsurface formation'"'"'s velocity ratio using a bottom hole assembly comprising:
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(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)
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15. A method of estimating a subsurface formation'"'"'s velocity ratio using a bottom hole assembly comprising:
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(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 the 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)
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23. A method of continuously estimating the pore pressures of formations 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 wave length 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 involves the matching time intervals between said shear wave received signal and said compressional wave received signal;
(f) using said velocity ratio to determine the effective stress of a formation ahead of said bottom hole assembly; and
(g) using said effective stress to determine said pore pressures of said formations ahead of said bottom hole assembly;
repeating steps (a) though (g) as said bottom hole assembly moves sequentially downward through said formations.
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24. A method of continuously monitoring the wellbore pressure safety margin corresponding to formations ahead of a bottom hole assembly, comprising the steps of generating a compressional wave having a first wavelength from said bottom hole assembly;
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(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 wave length 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 the matching time intervals between said shear wave received signal and said compressional wave received signal;
(e) Using said velocity ratio to determine the effective stress of a formation ahead of said bottom hole assembly;
(f) Using effective stress to determine the pore pressure of said formation ahead of said bottom hole assembly;
(g) Using said pore pressure to determine the wellbore pressure safety margin of a formation ahead of said bottom hole assembly; and
(h) repeating steps (a) though (h) as said bottom hole assembly moves sequentially downward through said formations.
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25. A method of continuously optimizing the weight of drilling mud used in a drilling operation, comprising the steps of:
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(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 wave length 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 the matching time intervals between said shear wave received signal and said compressional wave received signal;
(e) using said velocity ratio to determine the effective stress of a formation ahead of said bottom hole assembly;
(f) using effective stress to determine the 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.
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Specification