Method and system for calibrating a tube scanner
A scanner instrument used for scanning tubing that is being placed into an oil well or being removed from the oil well can be calibrated during retrieval of tubing from the well. Calibrating the tube scanner includes scanning a tubing standard and comparing the data from the standard scan to the known characteristics of the standard. The relationship between the scanned data and the known characteristics can be computed. The relationship between the scanned data and the known characteristics can be used as the calibration function for the scanner. Calibrating the tube scanner can also include scanning a string of tubing segments and then adjusting the data collected. The adjustment is based upon equalizing the data peaks that occur in the scan data at the coupling joints between tube segments.
1. A method for calibrating a tubing scanner, comprising:
inserting a tubing standard;
scanning the tubing standard to produce a calibration scan;
analyzing the calibration scan;
computing a transform based on the calibration scan; and
storing the transform for application to data obtained during the scanning of tubing.
2. The method of claim 1 further comprising
optionally rotating and rescanning the tubing standard a plurality of times; and
averaging the plurality of tubing standard scans to produce the calibration scan.
3. The method of claim 1 wherein the tubing standard has a first zone for calibration of a rod sensor.
4. The method of claim 1 wherein the tubing standard has a second zone for calibration of a pitting sensor.
5. The method of claim 1 further comprising comparing the calibration scan to a stored scan and computing the transform based on differences between the calibration scan and the stored scan.
6. The method of claim 1 further comprising analyzing the calibration scan and determining a rate of scanning based on a maximum peak height and a baseline.
7. A method for scanning tubing, comprising the steps of:
scanning a tubing standard a first time with a tubing scanner to produce a first calibration scan;
storing the first calibration scan;
analyzing the first calibration scan and computing a transform based upon the first calibration scan;
storing the transform;
scanning tubing with the tubing scanner to obtain a plurality of tubing scan data;
storing the tubing scan data;
applying the transform to the tubing scan data to produced transformed tubing scan data;
storing the transformed tubing scan data; and
analyzing the transformed tubing scan data.
8. The method of claim 7 further comprising:
scanning the tubing standard a second time with a tubing scanner after the scanning of the tubing is complete;
comparing the first tubing standard scan with the second tubing scan; and
optionally correcting the tubing scan data to account for differences between the first and second calibration scans.
9. The method of claim 8 , further comprising scanning the tubing standard a plurality of times during the scanning of the tubing and computing the transform based upon all of the tubing standard scans.
10. The method of claim 7 further comprising flagging the tubing scan data if the difference between first and second tubing standard scans indicates that the tubing scanner has drifted out of calibration.
11. The method of claim 7 further comprising displaying the transformed tubing scan data.
12. The method of claim 7 further comprising determining the scan speed by comparing the first calibration scan data to a stored calibration scan.
13. The method of claim 7 further comprising:
determining the location of collars on the tubing;
recording the position of the collars;
correlating the tubing scan data to a location on the tubing.
14. The method of claim 7 wherein the scanning of the tubing produces an analog signal.
15. The method of claim 14 further comprising converting the analog signal to a digital signal.