Anisotropy orientation image from resistivity measurements for geosteering and formation evaluation
A method for providing an image of a formation surrounding a wellbore, includes: obtaining an apparent conductivity curve from main components of resistivity measurements of the formation; performing fitting for cross-components of the resistivity measurements; calculating scaling factors from the cross-component data; scaling apparent conductivity data by the calculated scaling factors; and plotting the scaled conductivity data to provide the image of the anisotropic formation. A system and a computer program product are disclosed.
1. A method for providing an image of a formation surrounding a wellbore, the method comprising:
obtaining a curve from main components of resistivity measurements of the formation;
fitting cross-components of the resistivity measurements;
calculating scaling factors from the cross-component data;
scaling apparent conductivity data by the calculated scaling factors, wherein scaling the apparent conductivity data includes scaling the apparent conductivity by either multiplying or dividing the scaling factors according to a sign of azimuthal propagation resistivity quadrature data at a zero sector; and
plotting the scaled conductivity data to provide the image of the formation.
2. The method as in claim 1 , wherein the curve comprises one of an apparent conductivity curve and a conductivity curve.
3. The method as in claim 1 , wherein the measurements are collected by at least one of a multi-component induction tool and an azimuthal propagation resistivity tool.
4. The method as in claim 1 , wherein the fitting comprises one of cosine fitting and sine fitting.
5. The method as in claim 1 , further comprising subtracting a response of one coil from a symmetric coil to provide the resistivity measurements.
6. The method as in claim 1 , further comprising averaging a response of two symmetric coils to provide the resistivity measurements.
7. The method as in claim 1 , wherein the image provides a dip angle for the formation.
8. The method as in claim 1 , wherein a color in the image is selected according to at least one of a resistivity, an orientation, a dip angle and an azimuth angle.
9. The method as in claim 1 , wherein a result of the plotting is received as an input to a geosteering apparatus.
10. The method as in claim 1 , further comprising: eliminating drift by applying results of the fitting to the curve.
11. The method as in claim 10 , wherein the drift comprises at least one of random error and systematic error.
12. The method as in claim 1 , wherein the resistivity measurements correlate to sectors of rotation for an instrument used to obtain the measurement data.
13. The method as in claim 12 , wherein the image provides at least one of anisotropy information and azimuth information.
14. The method as in claim 13 , wherein the anisotropy information comprises orientation of the anisotropy.
15. A system for imaging a formation surrounding a wellbore during a drilling procedure, the system comprising:
a drill string comprising a logging instrument comprising at least one sensor for collecting resistivity measurement data; and
a processor loaded with machine readable and machine executable instructions comprising instructions for obtaining a conductivity curve from main components of resistivity measurements of the formation; performing fitting for cross-components of the resistivity measurements; calculating scaling factors from the cross-component data;
scaling apparent conductivity data by the calculated scaling factors, wherein scaling the apparent conductivity data includes scaling the apparent conductivity by either multiplying or dividing the scaling factors according to a sign of azimuthal propagation resistivity quadrature data at a zero sector; and providing input to a geosteering device.
16. The system as in claim 15 , wherein the instrument comprises one of a multi-component induction tool and an azimuthal propagation resistivity tool.
17. The system as in claim 15 , wherein the processor is equipped to provide the input in at least one of real-time and substantially real-time.
18. The system as in claim 15 , wherein the processor is further equipped for controlling a power signal to the at least one sensor.
19. A non-transitory computer-readable medium having stored thereon a computer program product comprising computer executable instructions stored, the product comprising instructions to provide an image of a formation by:
obtaining a curve from main components of resistivity measurements of the formation;
fitting cross-components of the resistivity measurements;
calculating scaling factors from the cross-component data;
scaling apparent conductivity data by the calculated scaling factors, wherein scaling the apparent conductivity data includes scaling the apparent conductivity by either multiplying or dividing the scaling factors according to a sign of azimuthal propagation resistivity quadrature data at a zero sector; and
plotting the scaled conductivity data to provide the image of the formation.
20. The non-transitory computer-readable medium in claim 19 , further comprising instructions for outputting geosteering information.