Drillstring radar

• US 6,778,127 B2
• Filed: 11/04/2002
• Issued: 08/17/2004
• Est. Priority Date: 03/28/2001
• Status: Expired due to Fees

• Current Assignee: Gerald L. Stolarczyk, Larry G. Stolarczyk
• Original Assignee: Gerald L. Stolarczyk, Larry G. Stolarczyk
• Inventors: Stolarczyk, Gerald L., Stolarczyk, Larry G.
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US10/287,041
• Publication Number:
  US 20030102995A1
• Time in Patent Office: 652 Days
• Field of Search: 342/21, 342/22, 342/61, 342/70, 342/71, 342/118, 342/127-146, 342/194-197, 299/1.05, 299/1.1, 299/1--, 299/3, 299/4, 299/5, 299/6, 299/10-18, 324/323, 324/332, 324/333-344, 324/629, 324/637, 324/642, 324/644, 702/9, 175/24, 175/25, 175/26, 175/27, 175/40, 175/41, 175/42, 175/43, 175/44, 175/45
• US Class Current: 342/22
• CPC Class Codes: F41H 11/12 Means for clearing land minefields; Systems specially adapted for detection of landmines
• CPC Class Codes: G01S 13/885 for ground probing prospecting or detecting using electromagnetic waves G01V3/12
• CPC Class Codes: G01V 3/12 operating with electromagnetic waves operating with millimetre waves G01V8/005
• CPC Class Codes: G01V 3/30 operating with electromagnetic waves

Abstract

A drillstring radar comprises a measurements-while-drilling instrument for mounting just behind the drill bit and downhole motor of a drill rod. The instrument includes a radar system connected to upward-looking and downward-looking horn antennas. These are used to electronically probe the interface of a coal seam with its upper and lower boundary layers. A dielectric constant sensor is included to provide corrective data for the up and down distance measurements. Such measurements and data are radio communicated to the surface for tomographic processing and user display. The instrument also includes a navigation processor and drill bit steering controls. The radio communication uses the drillstring as a transmission line and F1/F2 repeaters can be placed along very long runs to maintain good instrument-to-surface communication. A docking mechanism associated with the instrument and its antenna array allows the instrument to be retrieved back inside the drillstring with a tether should the drill head become hopelessly jammed or locked into the earth.

Claims

1. A drillstring radar system, comprising:

an upward-looking radar antenna for mounting to a directional-drilling drillstring behind a steerable drillhead;

a downward-looking radar antenna for mounting to said directional-drilling drillstring behind said steerable drillhead,

a ground-penetrating radar transceiver connected to each of the upward-looking and downward-looking radar antennas, and providing for return signal attenuation and phase shift measurements, and for providing from said measurements real-time estimates of the distances transmitted radar signals traveled before being reflected back to a respective antennae; and

a guidance control providing for steering said drillhead according to said real-time estimates;

wherein, said real-time estimates are fetched from a calibration table that has in-phase (I) and quadrature-phase (Q) return-signal amplitude measurements as inputs.

2. The system of claim 1, further comprising:

a dielectric-constant sensor associated with the upward-looking and downward-looking radar antennas and providing corrective data to said real-time estimates of the distances provided by the ground-penetrating radar transceiver.

3. The system of claim 1, further comprising:

a docking mechanism for remote disconnection of the ground-penetrating radar transceiver from said directional-drilling drillstring; and

a tether for causing the docking mechanism to release the ground-penetrating radar transceiver and allowing it to be withdrawn from within the length of said drillstring.

4. The system of claim 1, further comprising:

a docking mechanism for remote automatic connection of the ground-penetrating radar transceiver to said directional-drilling drillstring with the aid of hydraulic pumping to shuttle it to a distal end.

5. The system of claim 1, further comprising:

a user display for providing tomographic images of a coal bad to an operator from data provided by the ground-penetrating radar transceiver.

6. The system of claim 5, further comprising:

a signal repeater located along said drillstring between the user display and the ground-penetrating radar transceiver and providing for extended communication between them.

7. The system of claim 1, further comprising:

a navigation processor connected to sense the course taken by said directional-drilling drillstring and for providing information to the guidance control.

8. The system of claim 1, further comprising:

a hydroelectric generator for receiving a hydraulic flow through said drillstring and for powering the ground-penetrating radar transceiver.

9. The system of claim 8, further comprising:

a magnetic clutch for coupling in mechanical power to the hydroelectric generator collocated with the ground-penetrating radar transceiver inside an explosion-proof enclosure.

10. The system of claim 1, further comprising:

an inductive coupler for supporting a radio communication along said drillstring acting as a transmission line.

11. A method or drilling, comprising:

using a radar antenna mounted to a directional-drilling drillstring behind a steerable drillhead to radar-scan surrounding rock, and to collect in-phase (I) and quadrature-phase (Q) return-signal amplitude measurements;

finding the depth to a boundary rock interface by operating a ground-penetrating radar transceiver connected to the radar antenna, and deriving from said I and O return-signal amplitude measurements boundary rock interface depth estimates fetched from a calibration table.

12. A method of drilling, comprising:

using an upward-looking radar antenna mounted to a directional-drilling drillstring behind a steerable drillhead to radar-scan above, and to collect in-phase (I) and quadrature-phase (Q) return-signal amplitude measurements;

using a downward-looking radar antenna mounted behind said steerable drillhead to radar-scan below, and to collect I and Q return-signal amplitude measurements;

finding the depth to a boundary rock interface by operating a ground-penetrating radar transceiver connected to each of the upward-looking and downward-looking radar antennas, and deriving from said I and Q return-signal amplitude measurements boundary rock interface depth estimates fetched from a calibration table.

13. The method of claim 12, further comprising:

steering said drillhead according to said real-time estimates with a guidance control.

14. The method of claim 12, further comprising:

manipulating radar frequencies from said ground-penetrating radar transceiver for best transmission penetration and receiver sensitivity on-the-fly as different kinds of media and objects are inspected.