Method to Improve Downhole Instruments

• US 20080128166A1
• Filed: 12/05/2006
• Published: 06/05/2008
• Est. Priority Date: 12/05/2006
• Status: Active Grant

• Current Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Original Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Inventors: Forgang, Stanislav W., Gold, Randy
• Granted Patent: US 7,665,544 B2
• Time in Patent Office: Days
• US Class Current: 175/50
• CPC Class Codes: G01V 3/20 operating with propagation of electric current

Abstract

Measurements are made using a plurality of measure electrodes on a pad of a logging tool. The bias and gain of the measurements prior to A/D conversion are altered using measurements made by an additional electrode that is ahead of the measure electrodes.

Claims

1. An apparatus for evaluating an earth formation, the apparatus comprising:

(a) at least one sensor conveyed on a tool in a borehole, the at least one sensors configured to provide an associated signal indicative of a property of the formation;

(b) at least one additional sensor ahead of the at least one sensor on the tool, and

(c) circuitry configured to use an output of the at least one additional sensor to control an acquisition parameter of the signal from the at least one sensors.

2. The apparatus of claim 1 wherein the earth formation further comprises at least one of (i) a formation matrix, (ii) a formation fluid, and (iii) a borehole fluid.

3. The apparatus of claim 1 wherein the at least one sensor is selected from the group consisting of (i) an acoustic sensor, (ii) a resistivity sensor, (iii) a nuclear sensor, (iv) a pressure sensor, (v) an optical sensor and (vi) an NMR sensor.

4. The apparatus of claim 1 wherein the logging tool if configured to make measurements while being conveyed up the borehole and wherein the at least one additional sensor is above the at least one sensor.

5. The apparatus of claim 1 wherein the at least one sensor comprises measure electrodes and the associated signals comprise measure currents.

6. The apparatus of claim 1 wherein the at least one sensor comprises a plurality of sensors positioned on a pad, the apparatus further comprising a processor configured to provide an image of the formation using the signals associated with the plurality of sensors.

7. The apparatus of claim 1 further comprising a conveyance device configured to convey the tool into a borehole in the subterranean region, the conveyance device selected from the group consisting of (i) a wireline, (ii) a slickline, and (iii) a drilling tubular.

8. The apparatus of claim 6 further comprising an orientation sensor configured to make an orientation measurement.

9. The apparatus of claim 1 wherein the acquisition parameter is selected from the group consisting of (i) a bias, (ii) a gain, (iii) a logging speed, and (iv) a mode of operation.

10. The apparatus of claim 1 wherein the at least one additional sensor further comprises a plurality of additional sensors.

18. The method of claim 1 wherein controlling the acquisition further comprises altering at least one of (i) a bias, (ii) a gain, (iii) a logging speed, and (iv) a mode of operation.

11. A method of evaluating an earth formation, the method comprising:

(a) making a measurement with at least one sensor conveyed on a tool in a borehole, the measurement being indicative of a property of the formation;

(b) making at least one additional measurement using at least one additional sensor ahead of the at least one sensor on the tool; and

(c) using an output of the at least one additional sensor for controlling an acquisition parameter of an output of the at least one sensor.

12. The method of claim 11 further comprising using the measurements of the at least one sensor for determining a property of at least one of (i) a formation matrix, (ii) a formation fluid, and (iii) a borehole fluid.

13. The method of claim 11 wherein making measurements with the at least one sensor further comprises using sensors selected from the group consisting of (i) an acoustic sensor, (ii) a resistivity sensor, (iii) a nuclear sensor, (iv) a pressure sensor, (v) an optical sensor and (vi) an NMR sensor.

14. The method of claim 11 further comprising making measurements while the tool is being conveyed up the borehole with the at least one additional sensor above the at least one sensor.

15. The method of claim 11 wherein making measurements with the at least one sensor further comprise using measure electrodes and the associated signals comprise measure currents.

16. The method of claim 11 wherein making measurements with the at least one sensor further comprises positioning the at least one sensor oil a pad, the method further comprising providing an image of the formation using a signal associated with the at least one sensor.

17. The method of claim 11 further comprising conveying the tool into the borehole using a conveyance device selected from the group consisting of:

(i) a wireline, (ii) a slickline, and (iii) a drilling tubular.

19. A computer readable medium for use with an apparatus for evaluating an earth formation, the apparatus comprising:

(a) at least one sensor conveyed on a tool in a borehole, the at least one sensor configured to provide an associated signal indicative of a property of the formation; and

(b) at least one additional sensor ahead of the at least one sensor on the tool, the medium comprising instructions which;

(c) enable a processor to use an output of the at least one additional sensor to control an acquisition parameter of a signal from the at least one sensor.

20. The medium of claim 21 further comprising at least one of:

(i) a ROM, (ii) an EPROM, (iii) an EEPROM, (iv) a Flash Memory, and (v) an optical disk.