Communications: directive radio wave systems and devices (e.g. – Transmission through media other than air or free space
Reexamination Certificate
2002-11-04
2003-10-14
Gregory, Bernarr E. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Transmission through media other than air or free space
C342S061000, C342S070000, C342S175000, C342S194000, C342S195000, C342S196000, C702S002000, C702S006000, C702S009000, C175S024000, C175S026000, C324S332000
Reexamination Certificate
active
06633252
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates generally to directional drilling of boreholes in coal seams, and more specifically to steering mechanisms, radars and control systems for drilling horizontal boreholes in coal deposits.
2. Description of the Prior Art
The production of coal and methane depends upon the environment of the original coal bed deposit, and any subsequent alterations. During burial of the peat-coal swamp, sedimentation formed the sealing mudstone/shale layer overlying the coal bed. In deltaic deposits, high-energy paleochannels meandered from the main river channel. Oftentimes, the channels scoured through the sealing layer and into the coal seam.
High porosity sandstone channels often fill with water. Under the paleochannel scour cut bank, water flows into the face and butt cleats of the coal bed. Subsequent alterations of the seam by differential compaction cause the dip, called a roll, to occur in the coal bed. Faults are pathways for water flow into the coal bed.
Drilling into the coal bed underlying a paleochannel and subsequent fracking can enable significant flows of water to enter. The current state of the art in horizontal drilling uses gamma sensors in a measurements-while-drilling (MWD) navigation subsystem to determine when the drill approaches a sedimentary boundary rock. But if sandstone is protruding into the coal, such as results from ancient river bed cutting and filling, then the gamma sensor will not help. Sandstone does not have significant gamma emissions, so this type of detection is unreliable. Drilling within the seam cannot be maintained when the seam is not bounded by sealing rock.
Methane diffusion into a de-gas hole improves whenever the drillhole keeps to the vertical center of the coal seam. It also improves when the drillhole is near a dry paleochannel. Current horizontal drilling technology can be improved by geologic sensing and controlling of the drilling horizon in a coal seam.
One present inventor, Larry G. Stolarczyk, has described methods and equipment for imaging coal formations in geologic structures in many United States patents. Some of those patents are listed in Table I, and are incorporated herein by reference.
TABLE I
Patent No.
Issued
Title
4577153
Mar. 18, 1986
Continuous Wave Medium Frequency Signal
Transmission Survey Procedure For Imaging
Structure In Coal Seams
4691166
Sep. 01, 1987
Electromagnetic Instruments For Imaging
Structure In Geologic Formations
4742305
May 03, 1988
Method For Constructing Vertical Images Of
Anomalies In Geological Formations
4753484
Jun. 28, 1988
Method For Remote Control Of A Coal Shearer
4777652
Oct. 11, 1988
Radio Communication Systems For
Underground Mines
4879755
Nov. 07, 1989
Medium Frequency Mine Communication
System
4968978
Nov. 06, 1990
Long Range Multiple Point Wireless Control
And Monitoring System
4994747
Feb 19, 1991
Method And Apparatus For Detecting
Underground Electrically Conductive Objects
5066917
Nov. 19, 1991
Long Feature Vertical Or Horizontal
Electrical Conductor Detection Methodology
Using Phase Coherent Electromagnetic
Instrumentation
5072172
Dec. 10, 1991
Method And Apparatus For Measuring The
Thickness Of A Layer Of Geologic Material
Using A Microstrip Antenna
5087099
Feb. 11, 1992
Long Range Multiple Point Wireless Control
And Monitoring System
5093929
Mar. 03, 1992
Medium Frequency Mine Communication
System
5121971
Jun. 16, 1992
Method Of Measuring Uncut Coal Rib
Thickness In A Mine
5146611
Sep. 08, 1992
Mine Communication Cable And Method For
Use
5181934
Jan. 26, 1993
Method For Automatically Adjusting The
Cutting Drum Position Of A Resource Cutting
Machine
5188426
Feb. 23, 1993
Method For Controlling The Thickness Of A
Layer Of Material In A Seam
5260660
Nov. 09, 1993
Method For Calibrating A Downhole Receiver
Used In Electromagnetic Instrumentation For
Detecting An Underground Conductor
5268683
Dec. 07, 1993
Method Of Transmitting Data From A
Drillhead
5301082
Apr. 05, 1994
Current Limiter Circuit
5408182
Apr. 18, 1995
Facility And Method For The Detection And
Monitoring Of Plumes Below A Waste
Containment Site With Radiowave
Tomography Scattering Methods
5474261
Dec. 12, 1995
Ice Detection Apparatus For Transportation
Safety
5686841
Nov. 11, 1997
Apparatus And Method For The Detection And
Measurement Of Liquid Water And Ice Layers
On The Surfaces Of Solid Materials
5769503
Jun. 23, 1998
Method And Apparatus For A Rotating Cutting
Drum Or Arm Mounted With Paired Opposite
Circular Polarity Antennas And Resonant
Microstrip Patch Transceiver For Measuring
Coal, Trona And Potash Layers Forward, Side
And Around A Continuous Mining Machine
RE032563
Dec. 15, 1987
Continuous Wave Medium Frequency Signal
Transmission Survey Procedure For Imaging
Structure In Coal Seams
RE033458
Nov. 27, 1990
Method For Constructing Vertical Images Of
Anomalies In Geological Formations
There are a number of conventional ways directional drills use to steer in a desired direction. One involves placing the drill bit and its downhole motor at a slight offset angle from the main drillstring. The whole drillstring is then rotated to point the offset angle of the drill bit in the direction the operator wants the borehole to head. Another method involves an articulated joint or gimbal behind the drill bit and its downhole motor and using servo motors to angle the joint for the desired direction.
SUMMARY OF THE PRESENT INVENTION
Briefly, a radar-plow drillstring steering embodiment of the present invention comprises a steering plow and a measurements-while-drilling instrument for mounting just behind the drill bit and downhole motor of a drill rod. The instrument includes a radar connected to upward-looking and downward-looking horn antennas and a dielectric-constant sensor. The steering plow includes four pressure pads radially distributed around the outside surface and their associated servo motors. A coordinated control of the pressure pads allows the steering plow to push the drillstring and drill bit up-down-left-right. The antennas and sensor are embedded in respective ones of the pressure pads and are used to electronically and non-invasively probe a coal seam to locate its upper and lower boundary layers. The dielectric-constant sensor provides 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 radio communication uses the drillstring as a transmission line and F
1
/F
2
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.
An advantage of the present invention is that a drillstring steering plow is provided for directional drilling.
Another advantage of the present invention is that a drillstring steering plow is provided that keeps radar sensing antennas in intimate contact with the media.
A further advantage of the present invention is a drillstring steering system is provided that can be self-guided and is relatively insensitive to groundwater.
These and other objects and advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiment which is illustrated in the various drawing figures.
REFERENCES:
patent: 4297699 (1981-10-01), Fowler et al.
patent: 4430653 (1984-02-01), Coon et al.
patent: 4545017 (1985-10-01), Richardson
patent: 4577153 (1986-03-01), Stolarczyk
patent: 4691166 (1987-09-01), Stolarczyk
patent: RE32563 (1987-12-01), Stolarczyk
patent: 4742305 (1988-05-01), Stolarczyk
patent: 4753484 (1988-06-01), Stolarczyk
patent: 4777652 (1988-10-01), Stolarczyk
patent: 4814768 (1989-03-01), Chang
patent: 4879755 (1989-11-01), Stolarczyk et al.
patent: 4916400 (1990-04-01), Best et al.
patent: RE33458 (1990-11-01), Stolarczyk
pate
Stolarczyk Gerald L.
Stolarczyk Larry G.
Gregory Bernarr E.
Main Richard B.
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