Method and Apparatus for Fluid Influx Detection While Drilling

• US 20070144740A1
• Filed: 12/14/2006
• Published: 06/28/2007
• Est. Priority Date: 12/16/2005
• Status: Active Grant

• Current Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Original Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Inventors: Deo, Padmakar, Guo, Pingjun
• Granted Patent: US 7,804,060 B2
• Time in Patent Office: Days
• US Class Current: 166/254.200
• CPC Class Codes: E21B 47/11 using tracers; using radioactivity
• CPC Class Codes: G01V 5/102 the neutron source being of the pulsed type
• CPC Class Codes: G01V 5/104 and detecting secondary Y-rays as well as reflected or back-scattered neutrons

Abstract

A C/O ratio is determined using measurements of inelastically scattered gamma rays with a pulsed neutron source. Combined with look-up tables, the C/O measurement is used as an indicator of formation fluid influx into wellbore such as gas kick.

Claims

1. A method of detecting a presence of a second fluid from an earth formation into a borehole containing a first fluid, the method comprising:

(a) conveying a logging tool into the borehole;

(b) irradiating the earth formation with a source thereof on the logging tool;

(c) measuring radiation resulting from interaction of the irradiation with nuclei in the borehole at at least one detector; and

(d) estimating from the measured radiation the presence of the second fluid in the borehole.

2. The method of claim 1 wherein irradiating the earth formation further comprises using a pulsed neutron source.

3. The method of claim 1 wherein measuring the radiation further comprises measuring inelastic gamma rays.

4. The method of claim 3 further comprising estimating a C/O ratio from the measured radiation.

5. The method of claim 4 wherein estimating the presence of the second fluid further comprises detecting a change in the C/O ratio.

6. The method of claim 1 wherein the first fluid is selected from the group consisting of:

(i) a water-based mud, and (ii) an oil-based mud.

7. The method of claim 1 wherein the second fluid is selected from the group consisting of:

(i) water, (ii) oil, and (iii) gas.

8. The method of claim 1 wherein the earth formation is selected from the group consisting of:

(i) a sandstone, and (ii) a carbonate.

9. The method of claim 1 further comprising:

(i) measuring additional radiation resulting from interaction of the irradiation with nuclei at at least one additional detector, and

(ii) estimating from the measured radiation and the measured additional radiation at least one of;

(i) a formation density, (ii) a formation porosity, and (iii) a formation composition.

10. The method of claim 1 further comprising conveying the logging tool into the borehole on a conveyance device selected from:

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

11. An apparatus for detecting a presence of a second fluid from an earth formation into a borehole containing a first fluid, the apparatus comprising:

(a) a logging tool configured to be conveyed into the borehole;

(b) a source of the radiation on the logging tool configured to irradiate the earth formation;

(c) at least one detector on the logging tool configured to measure radiation resulting from interaction of the irradiation with nuclei in the borehole; and

(d) a processor configured to estimate from the measured radiation the presence of the second fluid in the borehole.

12. The apparatus of claim 11 wherein source of radiation further comprises a pulsed neutron source.

13. The apparatus of claim 11 wherein the at least one detector is further configured to measure inelastic gamma rays.

14. The apparatus of claim 13 wherein the processor is further configured to estimate a C/O ratio from the measured radiation.

15. The apparatus of claim 14 wherein the processor is further configured to estimate the presence of the second fluid by detecting a change in the C/O ratio.

16. The apparatus of claim 11 wherein the first fluid is selected from the group consisting of:

(i) a water-based mud, and (ii) an oil-based mud.

17. The apparatus of claim 11 wherein the second fluid is selected from the group consisting of:

(i) water, (ii) oil, and (iii) gas.

18. The apparatus of claim 11 wherein the earth formation is selected from the group consisting of:

(i) a sandstone, and (ii) a carbonate.

19. The apparatus of claim 11 further comprising:

(i) at least one additional detector configured to measure additional radiation resulting from interaction of the irradiation with nuclei, and

wherein the processor is further configured to estimate from the measured radiation and the measured additional radiation at least one of;

(i) a formation density, (ii) a formation porosity, and (iii) a formation composition.

20. The apparatus of claim 11 further comprising a conveyance device selected from:

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

21. A computer-readable medium for use with an apparatus for detecting a presence of a second fluid from an earth formation into a borehole containing a first fluid, the apparatus comprising:

(a) a logging tool configured to be conveyed into the borehole;

(b) a source of the radiation on the logging tool configured to irradiate the earth formation; and

(c) at least one detector on the logging tool configured to measure radiation resulting from interaction of the irradiation with nuclei in the borehole;

the medium comprising instructions which enable a processor to;

(d) estimate from the measured radiation the presence of the second fluid in the borehole.

22. 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.