Methods and Apparatus for Mechanical and Thermal Drilling

Abstract

Methods and apparatus for excavation of a borehole in a geological formation are provided. Such methods may include providing a thermal system capable of providing substantially hot fluid, and comprising at least one jet nozzle, providing a mechanical drilling system comprising a drill bit, directing the substantially hot fluid through the jet nozzle towards the geological formation causing an altered portion of geological formation to form, and removing the altered portion using the drill bit, thereby creating cuttings and producing a borehole in the geological formation.

What is claimed is: 
     
         1 . A method for excavation of a borehole in a geological formation, comprising:
 providing a thermal system capable of providing substantially hot fluid, and comprising at least one jet nozzle;   providing a mechanical drilling system comprising a drill bit;   directing the substantially hot fluid through the jet nozzle towards the geological formation causing an altered portion of geological formation to form; and   removing the altered portion using the drill bit, thereby creating cuttings and producing a borehole in the geological formation.   
     
     
         2 . The method of  claim 1 , wherein the drill bit and the hot fluid from the jet nozzle are simultaneously directed against the portion of the geological formation. 
     
     
         3 . The method of  claim 1 , wherein the directing step is conducting before the removing step. 
     
     
         4 . The method of  claim 1 , wherein the steps of directing the substantially hot fluid and the drilling the modified portion are sequentially alternated over a period of time. 
     
     
         5 . The method of  claim 4 , wherein the period of time is at least about 10 minutes. 
     
     
         6 . The method of  claim 1 , wherein the hot fluid exits the jet nozzle in a pulsed flow. 
     
     
         7 . The method of  claim 1 , wherein the hot fluid exits the jet nozzle in a continuous flow. 
     
     
         8 . The method of  claim 1 , wherein the hot fluid, upon exiting the jet nozzle, has a temperature between about 500° C. and about 1300° C. 
     
     
         9 . The method of  claim 1 , wherein the hot fluid is at a temperature of between about 500° C. and about 900° C. above the ambient temperature of the rock. 
     
     
         10 . The method of  claim 1 , wherein the altered portion is microfractured, macrofractured, softened, or mineralogically altered. 
     
     
         11 . The method of  claim 10 , wherein the altered portion comprises a portion between about 0.025 and 1.0 inches thick. 
     
     
         12 . The method of  claim 1 , wherein the altered portion is substantially unspallable by a thermal spallation process. 
     
     
         13 . The method of  claim 1 , further comprising introducing a flow of a cooling or lifting fluid. 
     
     
         14 . The method of  claim 13 , wherein the drilling step produces cuttings capable of being carried by the flow of the cooling fluid. 
     
     
         15 . The method of  claim 1 , wherein the substantially hot fluid is generated by a substantially flameless means. 
     
     
         16 . The method of  claim 1 , further comprising operatively connecting the thermal system to the mechanical drilling system. 
     
     
         17 . The method of  claim 1 , wherein the mechanical drilling system provides a substantially uniform nozzle stand-off distance. 
     
     
         18 . The method of  claim 1 , wherein the thermal drilling system is removed before the mechanical drilling system is introduced. 
     
     
         19 . The method of  claim 1 , wherein the mechanical drilling system comprises a hammer, rotary, slide, or coiled tube drill or reamer. 
     
     
         20 . The method of  claim 1 , wherein the removing the altered portion comprises breaking, scraping, cutting, grinding, or shearing rock, or drilling. 
     
     
         21 . The method of  claim 1 , wherein substantially hot fluid is directed substantially along an elongate central axis from the thermal system. 
     
     
         22 . The method of  claim 1 , wherein the directing the substantially hot fluid is varied so to reduce mechanical strength of selected areas of the geological formation thereby facilitating removal of the altered portion using the drill bit. 
     
     
         23 . The method of  claim 1 , wherein the thermal system comprises a catalyst. 
     
     
         24 . The method of  claim 23 , further comprising contacting one or more unreacted fluids with the catalyst to generate the substantially hot fluid. 
     
     
         25 . The method of  claim 24 , wherein the unreacted fluid comprises an oxidant. 
     
     
         26 . The method of  claim 25 , wherein the unreacted fluid comprises a fuel. 
     
     
         27 . The method of  claim 24 , wherein the contacting one or more unreacted fluids with the catalyst is substantially self-energized. 
     
     
         28 . The method of  claim 27 , wherein the fuel is an alcohol fuel. 
     
     
         29 . The method of  claim 28 , wherein the unreacted fluid comprises an alcohol fuel chosen from methanol, ethanol, propanol, or butanol. 
     
     
         30 . The method of  claim 29 , wherein the alcohol fuel is methanol. 
     
     
         31 . The method of  claim 25 , wherein the oxidant is chosen from oxygen, peroxide, peroxy compounds, permanganate and combinations thereof. 
     
     
         32 . The method of  claim 31 , wherein the oxidant is hydrogen peroxide or metal peroxide. 
     
     
         33 . The method of  claim 32 , wherein the unreacted fluid comprises an aqueous solution comprising about 10% to about 50% by weight hydrogen peroxide and about 10% to about 20% by weight methanol or ethanol. 
     
     
         34 . The method of  claim 23 , wherein the catalyst element comprises a transition metal chosen from: platinum, lead, silver, palladium, nickel, iron, cobalt, copper, chromium, cerium, vanadium, manganese, iridium, gold, ruthenium and rhodium, or mixtures or oxides or nitrides or salts thereof. 
     
     
         35 . The method of  claim 34 , wherein the catalyst element comprises platinum. 
     
     
         36 . The method of  claim 24 , wherein said contacting one or more unreacted fluids or solids with the catalyst element comprises:
 preparing the unreacted fluid outside the borehole, wherein the unreacted fluid comprises an aqueous composition comprising an oxidant and a fuel; and   transporting the unreacted fluid into the wellbore so that the composition is capable of contacting the catalyst element.   
     
     
         37 . A method of forming a borehole suitable for casing, comprising:
 directing a substantially hot fluid through a jet nozzle to a target location in a geological formation, thereby creating spalls and forming an initial borehole;   providing a mechanical reaming or drilling system; and   mechanically reaming or drilling the initial borehole to remove thermally or structurally unstable rock in the borehole to form a larger or more uniform borehole suitable for casing.   
     
     
         38 . The method of  claim 37 , further comprising installing a casing in the borehole. 
     
     
         39 . The method of  claim 37 , wherein the substantially hot fluid reduces mechanical strength of rock along the sides of the initial borehole. 
     
     
         40 . The method of  claim 37 , wherein the hot fluid, upon exiting the jet nozzle, has a temperature between about 500° C. and about 1300° C. 
     
     
         41 . The method of  claim 37 , wherein the hot fluid is at a temperature of between about 500° C. and about 900° C. above the ambient temperature of the rock. 
     
     
         42 . A method of forming a borehole suitable for casing, comprising:
 directing a substantially hot fluid through a jet nozzle to one or more target locations in a geological formation, thereby creating thermally affected rock and/or creating spalls;   providing a mechanical reaming or drilling system; and   mechanically reaming or drilling non-thermally affected rock adjacent to the target location to form a borehole suitable for casing.   
     
     
         43 . An apparatus for excavation of a borehole in a geological formation, comprising:
 a drilling system comprising a drill bit and/or a reamer; and   a thermal system comprising at least one jet nozzle, wherein the jet nozzle is operatively connected to the drill bit or reamer, and wherein the jet nozzle is adapted to direct a fluid therefrom.   
     
     
         44 . The apparatus of  claim 43 , wherein the drilling system comprises a rotary, slide, coiled or hammer drill. 
     
     
         45 . The apparatus of  claim 43 , wherein the jet nozzle is connected to the drill bit through at least one of a center ring jet linkage or a peripheral ring jet linkage. 
     
     
         46 . The apparatus of  claim 43 , wherein the thermal system comprises a plurality of jet nozzles. 
     
     
         47 . The apparatus of  claim 46 , wherein at least two of the jet nozzles are directed in different directions. 
     
     
         48 . The apparatus of  claim 43 , wherein the thermal system comprises a central axis oriented nozzle or a non-rotating peripheral gap ring nozzle. 
     
     
         49 . The apparatus of  claim 43 , wherein the drilling system comprises a tricone, PDC, TSP, drag, rotary, or hammer bit. 
     
     
         50 . The apparatus of  claim 43 , wherein the bit comprises a high temperature resistant material. 
     
     
         51 . The apparatus of  claim 43 , the jet nozzle has a substantially uniform stand-off distance from the distal end of the system. 
     
     
         52 . The apparatus of  claim 43 , wherein the thermal system comprises a substantially non-rotating structure. 
     
     
         53 . The apparatus of  claim 52 , wherein the thermal system comprises a reciprocating nozzle that varies the stand-off distance of the nozzle in a cyclical manner.