Methods and systems for drilling boreholes

Abstract

A system for drilling a borehole according includes a drill rig and a control system. The control system receives information from the drill rig that relates to at least one drill parameter. The control system processes information relating to the drill parameter, determines whether the drill parameter is within a predetermined specification for the monitored drill parameter, chooses a hole defect mitigation routine based on the monitored drill parameter when the monitored drill parameter is outside the predetermined specification, and controls the drill rig to implement the chosen hole defect mitigation routine.

1 . A method for drilling a borehole, comprising:
 initiating a drilling phase;   monitoring a drill parameter during the drilling phase;   determining whether the monitored drill parameter is within a predetermined specification for the monitored drill parameter;   choosing a drilling phase defect mitigation routine based on the monitored drill parameter when the monitored drill parameter is outside the predetermined specification;   implementing the drilling phase defect mitigation routine; and   resuming the drilling phase.   
     
     
         2 . The method of  claim 1 , wherein monitoring a drill parameter comprises monitoring one or more drill parameters selected from the group consisting of air pressure, drill rotational speed, drill torque, drill depth, and number of drill retractions. 
     
     
         3 . The method of  claim 2 , wherein choosing a drilling phase defect mitigation routine further comprises choosing one or more drilling phase defect mitigation routines selected from the group consisting of air pressure protection, rotary stall protection, end of hole spin-out, and end of hole water control. 
     
     
         4 . The method of  claim 3 , further comprising choosing said air pressure protection routine when said monitored air pressure is outside a predetermined specification for air pressure. 
     
     
         5 . The method of  claim 4 , wherein said air pressure protection routine comprises:
 retracting a drill bit;   applying air pressure to the drill bit;   monitoring the air pressure;   resuming the drilling phase when the monitored air pressure is within the predetermined specification; and   activating a drill water injection system to unclog the drill bit when the monitored air pressure is outside the predetermined specification.   
     
     
         6 . The method of  claim 3 , further comprising choosing said rotary stall protection routine when one or both of said monitored drill rotational speed is outside a predetermined specification for rotational speed and said drill torque is outside a predetermined specification for drill torque. 
     
     
         7 . The method of  claim 6 , wherein said rotary stall protection routine comprises:
 retracting a drill bit;   rotating the drill bit; and   resuming the drilling phase with one or both of a reduced down-force and an increased rotational drill bit speed.   
     
     
         8 . The method of  claim 3 , further comprising choosing said end of hole spin-out routine when said monitored drill depth meets a predetermined specification for drill depth. 
     
     
         9 . The method of  claim 8 , wherein said end of hole spin-out routine comprises:
 retracting a drill bit to a position above a bottom of the borehole;   rotating the drill bit for a spin-out period if the drill bit was retracted two or fewer times during the drilling phase;   rotating the drill bit for a product of the spin-out period and the number of drill retractions if the drill bit was retracted 3 or more times during the drilling phase; and   retracting the drill bit from the borehole.   
     
     
         10 . The method of  claim 3 , further comprising choosing said end of hole water control routine when said monitored drill depth meets a predetermined specification for drill depth. 
     
     
         11 . The method of  claim 10 , wherein said end of hole water control routine comprises deactivating a water injection system when a drill bit is within a predetermined distance from a bottom of the borehole. 
     
     
         12 . The method of  claim 1 , further comprising performing a collaring routine after said initiating a drilling phase. 
     
     
         13 . The method of  claim 12 , wherein performing a collaring routine further comprises:
 performing a first phase collaring operation from a surface start until one or both of a penetration rate drops below a predetermined penetration rate and a drill bit reaches a maximum collaring depth; and   performing a second phase collaring operation after the penetration rate drops below the predetermined penetration rate.   
     
     
         14 . The method of  claim 1 , further comprising:
 initiating a retraction phase;   monitoring at least one drill parameter during the retraction phase;   determining whether the monitored drill parameter is within a predetermined specification for the monitored drill parameter;   choosing a retraction phase defect mitigation routine based on the monitored drill parameter when the monitored drill parameter outside the predetermined specification; and   implementing the retraction phase defect mitigation routine.   
     
     
         15 . The method of  claim 14 , wherein monitoring a drill parameter comprises monitoring one or more drill parameters selected from the group consisting of drill rotational speed, drill torque, hoist speed, and number of drill retractions. 
     
     
         16 . The method of  claim 15 , wherein choosing a retraction phase defect mitigation routine further comprises choosing one or more retraction phase defect mitigation routines selected from the group consisting of drill bit hang-up protection, torque monitoring, and hole clean-out. 
     
     
         17 . The method of  claim 16 , further comprising choosing said drill bit hang-up protection routine when one or both of said monitored drill rotational speed is outside a predetermined specification for drill rotational speed and said monitored hoist speed is outside a predetermined specification for hoist speed. 
     
     
         18 . The method of  claim 17 , wherein said drill bit hang-up protection routine comprises:
 increasing the rotational speed of a drill bit;   lowering the drill bit;   determining whether the drill bit is freed; and   raising the drill bit at a reduced hoist speed.   
     
     
         19 . The method of  claim 18 , further comprising:
 alternately applying to the drill bit a down hoist force and an up hoist force; and   activating a water injection system if the drill bit is not freed after said alternately applying down and up hoist forces.   
     
     
         20 . The method of  claim 17 , further comprising choosing said torque monitoring routine when said monitored drill torque is outside a predetermined specification for drill torque. 
     
     
         21 . The method of  claim 20 , wherein said torque monitoring routine comprises:
 performing said hole clean-out routine;   retracting a drill bit from the borehole;   resuming the drilling phase; and   performing an end of hole spin-out routine.   
     
     
         22 . The method of  claim 16 , further comprising choosing said hole clean-out routine when one or more of said monitored drill retractions is outside a predetermined specification for drill retractions, said monitored hoist speed is outside a predetermined specification for hoist speed, and said monitored drill torque is outside a predetermined specification for drill torque. 
     
     
         23 . The method of  claim 22 , wherein said hole clean-out routine comprises:
 lowering a drill bit to a position above a bottom of the borehole;   rotating the drill bit for a spin-out period if the drill bit was retracted two or fewer times during the drilling phase;   rotating the drill bit for a product of the spin-out period and the number of drill retractions if the drill bit was retracted at least 3 times during the drilling phase; and   retracting the drill bit from the borehole.   
     
     
         24 . A system for drilling a borehole, comprising:
 a drill rig comprising a drill, an air injection system, and a water injection system;   a control system operatively associated with said drill rig, said control system receiving information from said drill rig relating to at least one drill parameter, controlling said drill rig, storing program steps for program control, and processing data;   said control system processing information relating to the drill parameter, determining whether the drill parameter is within a predetermined specification for the monitored drill parameter, choosing a hole defect mitigation routine based on the monitored drill parameter when the monitored drill parameter is outside the predetermined specification, said control system controlling said drill rig to implement the chosen hole defect mitigation routine.   
     
     
         25 . The system of  claim 24 , wherein said hole defect mitigation routine comprises at least one drilling phase defect mitigation routine and at least one retraction phase defect mitigation routine. 
     
     
         26 . The system of  claim 25 , wherein said drilling phase defect mitigation routine comprises one or more selected from the group consisting of air pressure protection, rotary stall protection, end of hole spin-out, and end of hole water control. 
     
     
         27 . The system of  claim 26 , wherein said control system monitors one or more drill parameters selected from the group consisting of air pressure, drill rotational speed, drill torque, drill depth, and number of drill retractions. 
     
     
         28 . The system of  claim 27 , wherein said control system implements said air pressure protection routine when said monitored air pressure is outside a predetermined specification for air pressure. 
     
     
         29 . The system of  claim 27 , wherein said control system implements said rotary stall protection routine when one or both of said monitored drill rotational speed is outside a predetermined specification for rotational speed and said drill torque is outside a predetermined specification for drill torque. 
     
     
         30 . The system of  claim 27 , wherein said control system implements said end of hole spin-out routine when said monitored number of drill retractions during the drilling phase is outside a predetermined specification for number of drill retractions. 
     
     
         31 . The system of  claim 27 , wherein said control system implements said end of hole water control routine when said monitored drill depth exceeds a predetermined specification for drill depth. 
     
     
         32 . The system of  claim 27 , wherein said retraction phase defect mitigation routine comprises one or more selected from the group consisting of drill bit hang-up protection, torque monitoring, and hole clean-out. 
     
     
         33 . The system of  claim 32  wherein said control system monitors one or more drill parameters selected from the group consisting of drill rotational speed, drill torque, hoist speed, and number of drill retractions. 
     
     
         34 . The system of  claim 33 , wherein said control system implements said drill bit hang-up protection routine when one or both of said monitored drill rotational speed is outside a predetermined specification for drill rotational speed and said monitored hoist speed is outside a predetermined specification for hoist speed. 
     
     
         35 . The system of  claim 33 , wherein said control system implements said torque monitoring routine when said monitored drill torque is outside a predetermined specification for drill torque. 
     
     
         36 . The system of  claim 33 , wherein said control system implements said hole clean-out routine when one or more of said monitored drill retractions is outside a predetermined specification for drill retractions, said monitored hoist speed is outside a predetermined specification for hoist speed, and said monitored drill torque is outside a predetermined specification for drill torque. 
     
     
         37 . A method for drilling a borehole, comprising:
 monitoring a drill parameter;   using the monitored drill parameter to draw a conclusion about a borehole characteristic;   choosing a defect mitigation routine based on the borehole characteristic; and   implementing the defect mitigation routine.   
     
     
         38 . The method of  claim 37 , wherein monitoring a drill parameter is conducted during a drilling phase. 
     
     
         39 . The method of  claim 38 , wherein monitoring a drill parameter comprises monitoring one or more drill parameters selected from the group consisting of air pressure, drill rotational speed, drill torque, drill depth, and number of drill retractions. 
     
     
         40 . The method of  claim 39 , wherein choosing a defect mitigation routine further comprises choosing one or more defect mitigation routines selected from the group consisting of air pressure protection, rotary stall protection, end of hole spin-out, and end of hole water control. 
     
     
         41 . The method of  claim 37 , wherein monitoring a drill parameter is conducted during a retraction'phase. 
     
     
         42 . The method of  claim 41 , wherein monitoring a drill parameter comprises monitoring one or more drill parameters selected from the group consisting of drill rotational speed, drill torque, hoist speed, and number of drill retractions. 
     
     
         43 . The method of  claim 42 , wherein choosing a defect mitigation routine further comprises choosing one or more retraction phase defect mitigation routines selected from the group consisting of drill bit hang-up protection, torque monitoring, and hole clean-out.