Technique to verify underground targets utilizing virtual reality imaging and controlled excavation

Abstract

A system and method for locating and verifying a position of an underground target utilizes a virtual reality display to guide a cutting probe to the target. Initial coordinates of the target may be obtained from prior survey data and a vertical access borehole is excavated at the initial coordinates in a first attempt to verify the target position. If the target it not encountered at the initial coordinates, a lateral sensor is positioned within the vertical access borehole to determine three-dimensional coordinates of the target. A second borehole is then excavated by a cutting head that is guided to the three-dimensional target coordinates with the assistance of a virtual reality display that shows both the target coordinates and a real time position of the cutting head. A down-hole camera or other sensor positioned within the second borehole may verify the presence or condition of the target.

I claim: 
     
         1 . A method of excavating a borehole extending from a probe entry point to a predetermined underground target point within a formation, comprising the steps of:
 obtaining three-dimensional coordinates of the predetermined underground target point;   operating a cutting head of an excavation probe to initiate the borehole at the probe entry point;   determining a real-time three-dimensional position of the cutting head within the formation;   displaying the real-time three-dimensional position of the cutting head on a virtual reality display;   displaying the predetermined underground target point on the virtual reality display; and   directionally guiding the cutting head to the predetermined underground target point utilizing the virtual reality display.   
     
     
         2 . The method of  claim 1 , wherein the virtual reality display is provided on a visor worn by an operator of the probe cutting head. 
     
     
         3 . The method of  claim 1 , further comprising the step of operating a down-hole camera to visually verify the underground target point. 
     
     
         4 . The method of  claim 1 , wherein the step of determining the real-time three-dimensional position of the cutting head within the formation includes calculating at least one of a distance of the cutting head from the probe entry point, a directional bearing of the cutting head from the probe entry point, and an excavation angle of the borehole axis relative to a surface plane. 
     
     
         5 . The method of  claim 4 , further comprising the step of displaying the borehole axis on the virtual reality display. 
     
     
         6 . The method of  claim 1 , further comprising the step of guiding the cutting head into contact with an underground target located at the underground target point in order to verify the three-dimensional coordinates or the underground target. 
     
     
         7 . The method of  claim 6 , wherein the cutting head of the excavation probe comprises a stealth cutting head having a low angle cutting face, and wherein the step of operating the cutting head includes controlling drilling fluids applied to the low angle cutting face to prevent excess drilling fluid from damaging the underground target. 
     
     
         8 . A method of locating and verifying a position of an underground target, comprising the steps of:
 obtaining initial coordinates of a surface point positioned above the underground target;   excavating a vertical access borehole from the surface point to a target depth of the underground target;   if the vertical access borehole engages the underground target, verifying a three-dimensional position of the underground target; and   if the vertical access borehole does not engage the underground target, then performing the further steps of:
 lowering a lateral sensor into the vertical access borehole; 
 operating the lateral sensor to locate the underground target and provide three-dimensional coordinates of the underground target; and 
 excavating a second borehole extending from a second surface point toward the three-dimensional coordinates of the underground target; and 
 directing the second borehole into engagement with the underground target to verify the three-dimensional position of the underground target. 
   
     
     
         9 . The method of  claim 8 , wherein the step of directing the second borehole into engagement with the underground target includes:
 displaying the three-dimensional coordinates of the underground target on a virtual reality display;   displaying a real-time three-dimensional position of the second borehole on the virtual reality display; and   directionally guiding a probe cutting head forming the second borehole to the underground target utilizing the virtual reality display.   
     
     
         10 . The method of  claim 9 , further comprising operating a down-hole camera to visually verify a condition of the underground target. 
     
     
         11 . The method of  claim 9 , further comprising recording the three-dimensional coordinates of the underground target within a database. 
     
     
         12 . The method of  claim 9 , wherein the virtual reality display is provided on a visor worn by an operator of the probe cutting head. 
     
     
         13 . The method of  claim 9 , wherein the probe cutting head comprises a stealth cutting head having a low angle cutting face, and wherein the step of directing the second borehole into engagement with the underground target includes controlling drilling fluids applied to the low angle cutting face to prevent excess drilling fluid from damaging the underground target. 
     
     
         14 . The method of  claim 8 , wherein the lateral sensor comprises a Ground Penetrating Radar (GPR) antenna, and wherein the step of excavating the vertical access borehole utilizes a stealth cutting head that forms at least one planar wall surface within the vertical access borehole for engaging the GPR antenna. 
     
     
         15 . The method of  claim 8 , further comprising the step of verifying that at least one of the initial coordinates and the target depth of the underground target are incorrect in the event that the lateral sensor is unable to locate the underground target, and recording the false reading within a database. 
     
     
         16 . A system for locating and verifying a position of an underground target based on initial surface coordinates and a purported target depth of the underground target, comprising:
 a first drilling apparatus adapted to excavate a vertical access borehole to the purported target depth within a formation at the initial surface coordinates of the underground target;   a lateral sensor adapted to be positioned within the vertical access borehole to determine three-dimensional coordinates of the underground target within the formation;   a second drilling apparatus having a cutting head adapted to excavate a second borehole extending from a surface point toward the three-dimensional coordinates of the underground target; and   a virtual reality display adapted to display the three-dimensional coordinates of the underground target in relation to a real-time three-dimensional position of the cutting head to directionally guide the cutting head into engagement with the underground target.   
     
     
         17 . The system of  claim 16 , wherein lateral sensor comprises a Ground Penetrating Radar antenna. 
     
     
         18 . The system of  claim 16 , wherein the virtual reality display comprises a visor adapted to be worn by an operator of the second cutting head. 
     
     
         19 . The system of  claim 16 , further comprising:
 a down-hole camera adapted to be positioned within the second borehole to visually verify the underground target.   
     
     
         20 . The system of  claim 16 , wherein the first drilling apparatus includes a stealth cutting head having a low angle cutting face, the system further comprising:
 a computing device for monitoring and controlling a supply of drilling fluid directed to the low angle cutting face and an excavation chamber immediately behind the low angle cutting face of the stealth cutting head to prevent excess drilling fluid from damaging the underground target.