Radar plow drillstring steering
First Claim
1. A plow steering system for directional drilling, comprising:
- a set of first through fourth pressure pads distributed around the outside surface of a steering plow for placement behind a directional drilling drill bit;
an upward-looking radar antenna embedded in said first pressure pad;
a downward-looking radar antenna embedded in said second pressure pad;
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 antenna; and
a guidance control providing for steering of said directional drilling drill bit according to said real-time estimates, wherein said steering is provided by retracting and extending individual ones of said first through fourth pressure pads.
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Accused Products
Abstract
A radar-plow drillstring steering system 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 system 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 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.
21 Citations
10 Claims
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1. A plow steering system for directional drilling, comprising:
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a set of first through fourth pressure pads distributed around the outside surface of a steering plow for placement behind a directional drilling drill bit;
an upward-looking radar antenna embedded in said first pressure pad;
a downward-looking radar antenna embedded in said second pressure pad;
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 antenna; and
a guidance control providing for steering of said directional drilling drill bit according to said real-time estimates, wherein said steering is provided by retracting and extending individual ones of said first through fourth pressure pads. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification