EM-guided drilling relative to an existing borehole

Patent metadata

Field	Value
Publication number	US-9732559-B2
Application number	US-52655208-A
Country	US
Kind code	B2
Filing date	Jan 18, 2008
Priority date	Jan 18, 2008
Publication date	Aug 15, 2017
Grant date	Aug 15, 2017

Abstract

Parallel drilling systems and methods suitable for drilling wells for steam-assisted gravity drainage (SAGD). In some method embodiments, a tilted-antenna tool gathers azimuthally-sensitive electromagnetic signal measurements. Such measurements enable accurate measurement of inter-well distance and direction, thereby providing, the necessary information for drilling accurately-spaced wells having reduced vulnerability to “short-circuits” that inhibit effective reservoir exploitation. In some other method embodiments, a tilted-antenna tool transmits azimuthally non-uniform signals as it rotates. The attenuation and azimuthal variation detected by one or more receivers enables accurate direction and distance determination. The transmitter and receiver antennas can in some cases be combined into a single tool, while in other cases the transmitters and receivers are placed in separate wells to increase detection range.

First claim

What is claimed is:

1. A parallel drilling method that comprises:
gathering azimuthally-sensitive measurements of electromagnetic signals while drilling a new borehole near an existing borehole, said measurements being indicative of a formation resistivity; and
steering a drill string along a path at a substantially constant distance from the existing borehole, wherein the drill string includes both transmit and receive antennas for making the azimuthally-sensitive measurements, and determining the substantially constant distance based at least in part on the formation resistivity measurements.

2. The method of claim 1 , wherein the distance is less than 10 meters and constant to within +/−0.5 meters.

3. The method of claim 1 , wherein the new borehole is positioned vertically above or below the existing borehole.

4. The method of claim 1 , wherein the existing borehole is cased with a conductive casing.

5. The method of claim 1 , wherein a conductive fluid is present within the existing borehole.

6. The method of claim 1 , wherein the drill string includes a tool having at least one tilted antenna in the bottom hole assembly.

7. The method of claim 1 , wherein the azimuthally-sensitive measurements are indicative of a three-dimensional resistivity profile around the new borehole.

8. The method of claim 1 , wherein the azimuthally-sensitive measurements are geosignals indicative of an azimuthal direction towards a conductive object.

9. The method of claim 1 , wherein said steering includes:
processing the azimuthally-sensitive measurements downhole to determine control signals for steering the drill string in a manner that minimizes a difference between measured and programmed distance values.

10. A parallel drilling system that comprises:
a steerable drill string that includes a tool having at least one tilted transmitter antenna,
wherein the tool comprises at least one receive antenna, gathers formation resistivity measurements acquired using the receive antenna and determines distance to an existing borehole based at least in part on the formation resistivity measurements.

11. The system of claim 10 , wherein the drill string includes a downhole processor that determines steering control signals to direct the drill string along a path parallel to the existing borehole.

12. The system of claim 10 , wherein tool determines a signal indicative of a direction to the existing borehole.

13. The system of claim 10 , wherein the measurements include measurements of signal attenuation as a function of azimuthal angle.

14. The system of claim 10 , wherein the measurements include measurements of signal phase shift as a function of azimuthal angle.

15. The system of claim 10 , further including an array of at least two receivers in the existing borehole.

16. The system of claim 10 , further comprising a surface computer that enables a driller to monitor said distance and responsively steer the drill string along a path at a constant distance and direction from the existing borehole.

17. A parallel drilling method that comprises:
transmitting an azimuthally non-uniform electromagnetic signal from a source in a drill string while creating a new borehole; and
detecting the signal with at least two receivers in an existing borehole to determine distance from the existing borehole to the source, said signal being indicative of a formation resistivity and said distance being determined based at least in part on said formation resistivity.

18. The method of claim 17 , further comprising steering the drill string to direct the new borehole along a path that parallels the existing borehole.

19. The method of claim 17 , wherein the source includes at least one tilted transmitter antenna.

20. The method of claim 19 , wherein the tilted transmitter antenna rotates to transmit the signal in different azimuthal directions.

21. The method of claim 20 , wherein the signal includes information regarding the azimuthal orientation of the source.

22. The method of claim 17 , further comprising determining a direction between the existing borehole and the source.

23. The method of claim 22 , further comprising communicating the distance and direction measurement to a surface computer.

24. The method of claim 23 , further comprising displaying a representation of the existing borehole relative to the new borehole to enable the driller to steer the new borehole parallel to the existing borehole.

Assignees

• Bittar Michael S
• Halliburton Energy Services Inc

Inventors

• Bittar Michael S

Classifications

• E21B47/0228 Primary

  using electromagnetic energy or detectors therefor · CPC title

• E21B7/046 Primary

  horizontal drilling (drilling with mechanical conveying means E21B7/003) · CPC title

• E21B47/02216

  Fixed Constructions · mapped topic