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US 7,609,066 B2Granted
Apparatus and method for measuring micro-resistivity anisotropy
AssigneeBaker Hughes Incorporated
InventorTsili Wang
Life of this patent
Estimating the term…
Abstract
A method for measuring anisotropy in thin-bed formations calls for placing a logging tool into a borehole in the formation and applying current to at least one set of injection electrodes and at least one set of return electrodes to measure resistivity in the formation. Resistivity measurements are used to determine aspects of thin-bed formations exposed in the borehole to the tool. The aspects include the formation azimuth angle (Θ) and the formation dip angle (θ). Typically, the measurements and determinations are completed using apparatus including a computer program product.
Claims13
A method for determining anisotropic properties in a formation, comprising:
- measuring, with respect to a coordinate system comprising an x-axis and a z-axis, a potential difference Vxx along the x-axis using a first set of electrodes disposed along the x-axis and a potential difference Vxz along the z-axis using a second set of electrodes disposed along the z-axis for excitation directed along the x-axis, and a potential difference Vzx along the x-axis using the first set of electrodes and a potential difference Vzz along the z-axis using the second set of electrodes for excitation directed along the z-axis;
- producing a tensor V comprising potential difference components Vxx, Vxz, Vzx and Vzz;
- and
- converting the tensor V to apparent resistivity R for the formation, by solving the relationship comprising
- R
- =
- (
- Vxx
- Vzx
- Vxz
- Vzz
- )
-
- (
- Kx
- /
- Ix
- Kz
- /
- Iz
- )
- ;
- where
- Kx represents a first geometric factor for the excitation directed along the x-axis;
- Kz represents a second geometric factor for the excitation directed along the z-axis;
- Ix represents a first injection current for the excitation directed along the x-axis;
- and
- Iz represents a second injection current for the excitation directed along the z-axis.
25 more elements
A method for determining anisotropic properties in a formation, comprising:
- measuring, with respect to a coordinate system comprising an x-axis, a y-axis and a z-axis, a potential difference Vxx along the x-axis using a first set of electrodes disposed along the x-axis, a potential difference Vxy along the y-axis using a second set of electrodes disposed along the y-axis and a potential difference Vxz along the z-axis using a third set of electrodes disposed along the z-axis for excitation directed along the x-axis;
- and a potential difference Vyx along the x-axis using the first set of electrodes, a potential difference Vyy along the y-axis using the second set of electrodes and a potential difference Vyz along the z-axis using the third set of electrodes for excitation directed along the y-axis;
- and a potential difference Vzx along the x-axis using the first set of electrodes, a potential difference Vzy , along the y-axis using the second set of electrodes and a potential difference Vzz along the z-axis using the third set of electrodes for excitation directed along the z-axis;
- producing a tensor V from the potential difference components Vxx, Vxy, Vxz, Vyx, Vyy, Vyz, Vzx, Vzy, and Vzz;
- and
- converting the tensor V to apparent resistivity R for the formation, by solving the relationship comprising:
- R
- =
- (
- Vxx
- Vyx
- Vzx
- Vxy
- Vyy
- Vzy
- Vxz
- Vyz
- Vzz
- )
-
- (
- Kx
- /
- Ix
- Ky
- /
- Iy
- Kz
- /
- Iz
- )
- ;
- where
- Kx represents a geometric factor of the tool for the excitation directed along the x-axis;
- Ky represents a geometric factor of the tool for the excitation directed along the y-axis;
- Kz represents a geometric factor of the tool for the excitation directed along the z-axis;
- Ix represents a first injection current for the excitation directed along the x-axis;
- Iy represents a second injection current for the excitation directed along the y-axis;
- and
- Iz represents a third injection current for the excitation directed along the z-axis.
37 more elements
A computer program product stored on machine readable media, the product comprising instructions for measuring anisotropy of a formation by making resistivity measurements, the instructions comprising instructions for:
- operating a first set of electrodes disposed along an x-axis, a second set of electrodes disposed along a-y-axis, and a third set of electrodes disposed along a z-axis wherein each set of electrodes comprises an injection electrode, a return electrode spaced therefrom and a plurality of measuring electrodes disposed therebetween;
- measuring a potential difference Vxx along the x-axis, a potential difference Vxy along the y-axis, and a potential difference Vxz along the z-axis for excitation directed along the x-axis;
- a potential difference Vyz along the x-axis, a potential difference Vyy along the y-axis, and a potential difference Vyz along the z-axis for excitation directed along the y-axis;
- and a potential difference Vzx along the x-axis, a potential difference Vzy along the y-axis, and a potential difference Vzz along the z-axis for excitation directed along the z-axis;
- producing a tensor comprising the potential differences for the first axis and the second axis to determine the potential difference V;
- and
- converting the tensor V to apparent resistivity R for the formation, by solving the relationship comprising:
- R
- =
- (
- Vxx
- Vyx
- Vzx
- Vxy
- Vyy
- Vzy
- Vxz
- Vyz
- Vzz
- )
-
- (
- Kx
- /
- Ix
- Ky
- /
- Iy
- Kz
- /
- Iz
- )
- ;
- where
- Kx represents a geometric factor of the tool for the excitation directed along the x-axis;
- Ky represents a geometric factor of the tool for the excitation directed along the y-axis;
- Kz represents a geometric factor of the tool for the excitation directed along a third axis z-axis;
- Ix represents a first injection current for the excitation directed along the x-axis;
- Iy represents a second injection current for the excitation directed along the y-axis;
- and
- Iz represents a third injection current for the excitation directed along the z-axis.
38 more elements
Dependencies are inferred from the claim text.