Claims
- 1. A method for determining the horizontal resistivity and vertical resistivity of an earth formation, the earth formation being penetrated by a borehole, comprising:(a) developing an inversion model for various earth formations; (b) deploying an induction tool in said borehole, said tool having a longitudinal axis, a transmitter array comprised three mutually orthogonal transmitter antennae, at least one of the antenna being oriented parallel to said tool longitudinal axis, and a receiver array offset from the transmitter array, said receiver array being comprised of three mutually orthogonal receiver antennae, the receiving array sharing a common orientation with said transmitter array; (c) activating said transmitter antenna array and measuring electromagnetic signals values induced in said receiving array antennae, including resistive and reactive components of said signal values; (d) determining an azimuth angle for said tool; (e) calculating secondary signal values signals as a function of said measured signal values and said azimuth angle; and (f) simultaneously determining said horizontal resistivity, vertical resistivity and a dip angle as a function of selected resistive and reactive components of said secondary signals by minimizing error utilizing said inversion model.
- 2. The method of claim 1, wherein said azimuth angle is calculated as a function of said electromagnetic signals in said receiver array antennae perpendicular to said tool longitudinal axis, relative to a direction of said horizontal resistivity and said vertical resistivity.
- 3. The method of claim 1, wherein step (f) further includes the simultaneous determination of a dip angle.
- 4. The method of claim 1, wherein said secondary signal values are calculated by rotating said measured signals values through a negative of said azimuth angle.
- 5. The method of claim 2, wherein step (f) further includes the simultaneous determination of a dip angle.
- 6. The method of claim 3, wherein said dip angle is calculated as a function of said secondary values for said electromagnetic signals for a receiver antenna parallel to said tool longitudinal axis with respect to said vertical resistivity.
Parent Case Info
This application claims the benefit of U.S. Provisional Application No. 60,336,996 filed Dec. 3, 2001, the entire disclosure of which is hereby incorporated by reference.
US Referenced Citations (12)
Foreign Referenced Citations (1)
Number |
Date |
Country |
527089 |
Jun 1992 |
EP |
Provisional Applications (1)
|
Number |
Date |
Country |
|
60/336996 |
Dec 2001 |
US |