Electromagnetic Ranging Source Suitable for Use in a Drill String

Patent metadata

Field	Value
Publication number	US-2016177705-A1
Application number	US-201414891558-A
Country	US
Kind code	A1
Filing date	Jul 18, 2014
Priority date	Jul 18, 2014
Publication date	Jun 23, 2016
Grant date	—

Abstract

An electromagnetic ranging source embodiment includes: a tubular body having a circumference; a ferromagnetic core conforming to the tubular body and extending at least halfway around the circumference to define a gap with circumferentially-spaced poles; one or more current-carrying windings around the core to induce a magnetic field between the poles; and a downhole power source that drives the one or more current-carrying windings. A method embodiment includes: equipping a first drill string with such an electromagnetic ranging source; extending a first borehole with the first drill string; assembling a second drill string with sensors; and drilling a second borehole while using said sensors to guide the second drill string relative to the first borehole.

First claim

What is claimed is:

1 . An electromagnetic ranging source that comprises:
a tubular body having a circumference; a ferromagnetic core conforming to the tubular body and extending at least halfway around the circumference to define a gap with circumferentially-spaced poles; one or more current-carrying windings around the core to induce a magnetic field between the poles; and a downhole power source that drives the one or more current-carrying windings, wherein the ranging source provides a time-varying magnetic field as a ranging beacon to guide drilling of a second well relative to a first well.

2 . The ranging source of claim 1 , wherein the tubular body comprises a non-magnetic steel.

3 . The ranging source of claim 1 , wherein the gap extends no more than 90° of the circumference.

4 . The ranging source of claim 3 , wherein the gap has a circumferential dimension of at least 2 cm.

5 . The ranging source of claim 1 , wherein the gap has a long dimension parallel to an axis of the tubular body.

6 . The ranging source of claim 1 , wherein the gap has a long dimension that is angled with respect to an axis of the tubular body.

7 . The ranging source of claim 6 , wherein the core is angled with respect to the axis of the tubular body.

8 . The ranging source of claim 1 , wherein the downhole power source provides pulsed or alternating current.

9 . The ranging source of claim 1 , wherein the downhole power source is a flow-powered electrical generator.

10 . The ranging source of claim 1 , wherein the tubular body forms part of a drill string.

11 . An electromagnetic ranging method that comprises: deploying a first drill string in a first borehole the first drill string comprising an electromagnetic ranging source having a ferromagnetic core conforming to a circumference of a tubular body and extending at least halfway around the circumference to define a gap with circumferentially-spaced poles, the source further having one or more current-carrying windings around the core to induce a magnetic field between the poles, wherein the ranging source provides a time-varying as a ranging beacon;
deploying a second drill string with sensors in a second borehole; determining distance or direction between the first drill string and the second drill string based on magnetic field measurements obtained by the sensors in response to the ranging beacon; and extending the second borehole based on the determined distance or direction.

12 . The method of claim 11 , further comprising causing a downhole power source to drive the one or more current-carrying windings with pulsed or alternating current.

13 . The method of claim 11 , further comprising circulating a fluid through the first drill string, thereby powering a downhole electrical generator that is coupled to the one or more current-carrying windings.

14 . The method of claim 11 , further comprising rotating the first drill string to modulate the magnetic field.

15 . The method of claim 11 , wherein said drilling a second borehole includes intersecting the first borehole.

16 . The method of claim 15 , wherein prior to their performance, said assembling and drilling were contingent upon occurrence of a well-control problem in the first borehole.

17 . The method of claim 15 , further pumping a kill fluid into the first borehole via the second borehole.

Assignees

• Halliburton Energy Services Inc

Inventors

• Derr Doug
• Cuthbert Andrew J
• Hess Joe E

Classifications

• E21B47/022

  of the borehole, e.g. using geomagnetism · CPC title

• E21B47/024

  of devices in the borehole (determining slope or direction of the borehole E21B47/022) · CPC title

• G01V3/18 Primary

  specially adapted for well-logging · CPC title

• G01V3/28

  using induction coils · CPC title

• E21B7/04

  Directional drilling · CPC title