STRESS WAVE DRILL
United States Patent 3840078
A method and apparatus for drilling a hole in rock. An open-ended, hardened, drilling head containing a means for creating high-intensity stress waves capable of spalling rock is utilized to drill the hole. A fluid is passed through the drilling head which removes the spalled rock from the drilling head.
US Patent References:
Method of and apparatus for forming wells
McCullough - May 1949 - 2471695
Electric boring apparatus
Murray - February 1958 - 2822148
Electric flame boring apparatus
Murray - December 1958 - 2866622
Bottom-hole turbogenerator drilling unit
Rowley - May 1962 - 3036645
SHAPED SPARK DRILL
Smith - March 1970 - 3500942
Method of and apparatus for forming wells
McCullough - May 1949 - 2471695
Electric boring apparatus
Murray - February 1958 - 2822148
Electric flame boring apparatus
Murray - December 1958 - 2866622
Bottom-hole turbogenerator drilling unit
Rowley - May 1962 - 3036645
SHAPED SPARK DRILL
Smith - March 1970 - 3500942
Inventors:
Allgood, Jay R. (Camarillo, CA)
Odello, Robert J. (Calabasas, CA)
Odello, Robert J. (Calabasas, CA)
Application Number:
05/402547
Publication Date:
10/08/1974
Filing Date:
10/01/1973
View Patent Images:
Export Citation:
Assignee:
The United States of America as represented by the Secretary of the Navy (Washington, DC)
Primary Class:
Other Classes:
175/67, 175/16, 175/17
International Classes:
E21B7/15; E21B7/18; E21B7/14; E21B7/00
Field of Search:
175/15,16,17,57,65,67
US Patent References:
Other References:
Steiger, A. J.; "Russian Electric Arc Drill Nears Oil Field Test Stage;" In rilling, March 1958, pages 106 and 107. .
Maurer, W. C.; "Themal-Spalling, Chemical Drills;" The Oil and Gas Journal, March 4, 1968, pp. 69-73. .
Sarapau, E.; "Electro-Energetic Rock Breaking Systems;" Mining Congress Journal, June 1973, pp. 44-54..
Primary Examiner:
Brown, David H.
Attorney, Agent or Firm:
Sciascia St., Richard Amand Joseph Hollis Darrell S. M. E.
Claims:
We claim
1. A stress wave drill for drilling a hole in rock comprising:
2. The drill of claim 1 wherein said second open end of said hardened drilling head is flared, thereby preventing said drill stem from jamming in the hole.
3. The drill of claim 1 wherein said means for generating stress waves is capable of controlled movement with respect to said drill pipe and said hardened drilling head about the longitudinal axis of said drill stem and said hardened drilling head.
4. The drill of claim 1 wherein said means for dividing said drill stem into a plurality of compartments comprises a single block of material dividing said drill stem into two compartments.
5. The drill of claim 1 wherein said means for generating stress waves comprises an electrohydraulic pulser.
6. The drill of claim 5 wherein said electrohydraulic pulser comprises:
7. The drill of claim 6 wherein said means for electrically insulating said electrodes includes:
1. A stress wave drill for drilling a hole in rock comprising:
2. The drill of claim 1 wherein said second open end of said hardened drilling head is flared, thereby preventing said drill stem from jamming in the hole.
3. The drill of claim 1 wherein said means for generating stress waves is capable of controlled movement with respect to said drill pipe and said hardened drilling head about the longitudinal axis of said drill stem and said hardened drilling head.
4. The drill of claim 1 wherein said means for dividing said drill stem into a plurality of compartments comprises a single block of material dividing said drill stem into two compartments.
5. The drill of claim 1 wherein said means for generating stress waves comprises an electrohydraulic pulser.
6. The drill of claim 5 wherein said electrohydraulic pulser comprises:
7. The drill of claim 6 wherein said means for electrically insulating said electrodes includes:
Description:
BACKGROUND OF THE INVENTION
1. Field of the Invention.
This invention relates, generally, to drilling a hole in rock and, more specifically, to utilizing high intensity stress waves to drill a hole in rock.
2. Description of the Prior Art.
Some prior art drills utilize cavitational drilling techniques. Cavitation is a phenomenon whereby under certain conditions cavities form and violently collapse within a liquid. A shock wave results from the cavitation and may cause considerable mechanical damage to neighboring solid surfaces. Cavitation is induced in a drilling liquid by any suitable technique such as by the generation of acoustic energy. The cavitation threshold is a function of the physical properties of the liquid. The shock wave pressure is a function of the cavitation threshold. Hence, the shock wave pressure is not easily controlled or varied. Liquids having differing physical properties are necessary for creating different shock wave pressures. Since the shock wave pressure necessary to cause spalling of rock varies with the physical properties of the rock, the cavitation method may require different liquids for different rock in order to effect spalling. Also, the range of shock wave pressures achievable by cavitation is limited by the physical properties of the liquid. Thus, certain types of rock are incapable of being spalled by cavitation.
Currently most rock drilling is done by rotary drag bits or percussion bits. In both of these methods a bit made of hardened steel or other hard material scrapes or impacts against the rock until the rock material is disintegrated into a powder. The efficiency of such drills is very low. The rate of drilling and the cost increases greatly for hard formations and deep holes. In addition, the power lost in transmitting power to the rock reaches significant proportions.
The explosive drill, which is currently an operational alternative to rotary-percussion methods, is greatly restricted in application due to the high cost of explosive pellets.
SUMMARY OF THE INVENTION
The general purpose of this invention is to provide a stress wave drill for drilling rock whose shock wave pressure is easily controlled and varied, that does not require different liquids for different rock, whose shock wave pressure is not limited in range, that is highly efficient, and that is more economical to operate than prior art drills. To achieve these significant advantages, one embodiment of the present invention provides an open-ended, hardened, drilling head containing an electro-hydraulic pulser. The electrohydraulic pulser creates high-intensity stress waves capable of spalling the rock. These high-intensity stress waves are transmitted to the surface of the rock by a liquid which also serves as a carrier to remove spalled rock from the borehole.
Accordingly, one object of the present invention is to provide an easily controllable stress wave capable of spalling rock.
Another object of the present invention is to provide an easily variable stress wave capable of spalling rock.
Another object of the present invention is to provide a wide range of stress waves capable of spalling rock.
Another object of the present invention is to provide a highly efficient drill.
Another object of the present invention is to provide a highly economical drill.
Another object of the present invention is to provide a faster drilling rate.
Another object of the present invention is to provide drilling rates that are relatively independent of rock properties.
Another object of the present invention is to increase the percentage of total power of a drill that is transmitted to the rock.
Other objects and a more complete appreciation of the present invention and its many attendant advantages will develop as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings in which like reference numerals designate like parts throughout the figures thereof and wherein
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top view of a specific embodiment of the present invention.
FIG. 2 is a front elevation of the specific embodiment of FIG. 1.
FIG. 3 is a top view of a specific embodiment of the present invention.
FIG. 4 is a front elevation of the specific embodiment of FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Turning to FIGS. 1 and 2, numeral 10 designates a drill stem. Attached to one end of drill stem 10 is an open-ended, hardened, drilling head 12. Hardened drilling head 12 is flared slightly to prevent jamming of drill stem 10 in the borehole 14. Hardened drill head 12 must be capable of withstanding the stress waves generated by electrohydraulic pulser 16 without cracking or breaking.
Electrohydraulic pulser 16 comprises a solid block of electrical Electrode material 18. A high voltage electrode 20 extends through insulating material 18 and projects into the space inside drilling head 12. Two ground electrodes 22, located adjacent to high voltage electrode 20, also extend through insulating material 18 and project into the space inside drilling head 12. Solid block 18 prevents short circuiting of the discharge between electrodes 20 and 22. Electrodes 20 and 22 are enclosed in electrical insulation 24 inside drill stem 10. The description and operation of electrohydraulic pulser 16 is promulgated in detail in Browne, Allen and Schrom, Electrohydraulics, Science Journal, March 1968. ELECTRODE support material 26 supports and protects the electrodes 20 and 22 from impact with spalled rock being carried out of the borehole 14 by fluid 28. Gasket 30 enables electro-hydraulic pulser 16 to rotate within drill stem 10 and drilling head 12. Gasket 30 forms a fluid-tight seal between electrohydraulic pulser 16 and drill stem 10 and drilling head 12.
Referring to FIGS. 3 and 4, fluid 28 enters drill stem 10 via inlet port 34 and leaves drill stem 10 via outlet port 36. The direction of flow of fluid 28 is indicated by arrows 32. Fluid 28 serves as a carrier for spalled rock. Loose rock spalled by electrohydraulic pulser 16 is carried from the bottom of borehole 14 to outlet port 36, located near the top end of drill stem 10. Thus, the inside diameter of outlet port 36 must be large enough to pass the largest piece of spalled rock that will be produced by electrohydraulic pulser 16. The fluid 28 may be recycled through the drill provided the spalled rock is first removed therefrom. Electrohydraulic pulser 16 in conjunction with gasket 30 divides drill stem 10 in two compartments 38 and 40. Of course, a plurality of compartments of various shapes are possible. The only requirement being that the compartments do not interrupt the fluid flow.
Shock waves from electrohydraulic pulser 16 travel through fluid 28 to the rock face 42. These stress waves load the face 42 which spalls on rebound. Rock particles spalled from the face 42 are removed by fluid 28 circulating through drill stem 10 and drilling head 12. The high-intensity stress waves generated by electrohydraulic pulser 16 are typically of microsecond duration. It is noted that electrohydraulic pulser 16 is but one means for generating high-intensity stress waves.
Obviously many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described herein.
1. Field of the Invention.
This invention relates, generally, to drilling a hole in rock and, more specifically, to utilizing high intensity stress waves to drill a hole in rock.
2. Description of the Prior Art.
Some prior art drills utilize cavitational drilling techniques. Cavitation is a phenomenon whereby under certain conditions cavities form and violently collapse within a liquid. A shock wave results from the cavitation and may cause considerable mechanical damage to neighboring solid surfaces. Cavitation is induced in a drilling liquid by any suitable technique such as by the generation of acoustic energy. The cavitation threshold is a function of the physical properties of the liquid. The shock wave pressure is a function of the cavitation threshold. Hence, the shock wave pressure is not easily controlled or varied. Liquids having differing physical properties are necessary for creating different shock wave pressures. Since the shock wave pressure necessary to cause spalling of rock varies with the physical properties of the rock, the cavitation method may require different liquids for different rock in order to effect spalling. Also, the range of shock wave pressures achievable by cavitation is limited by the physical properties of the liquid. Thus, certain types of rock are incapable of being spalled by cavitation.
Currently most rock drilling is done by rotary drag bits or percussion bits. In both of these methods a bit made of hardened steel or other hard material scrapes or impacts against the rock until the rock material is disintegrated into a powder. The efficiency of such drills is very low. The rate of drilling and the cost increases greatly for hard formations and deep holes. In addition, the power lost in transmitting power to the rock reaches significant proportions.
The explosive drill, which is currently an operational alternative to rotary-percussion methods, is greatly restricted in application due to the high cost of explosive pellets.
SUMMARY OF THE INVENTION
The general purpose of this invention is to provide a stress wave drill for drilling rock whose shock wave pressure is easily controlled and varied, that does not require different liquids for different rock, whose shock wave pressure is not limited in range, that is highly efficient, and that is more economical to operate than prior art drills. To achieve these significant advantages, one embodiment of the present invention provides an open-ended, hardened, drilling head containing an electro-hydraulic pulser. The electrohydraulic pulser creates high-intensity stress waves capable of spalling the rock. These high-intensity stress waves are transmitted to the surface of the rock by a liquid which also serves as a carrier to remove spalled rock from the borehole.
Accordingly, one object of the present invention is to provide an easily controllable stress wave capable of spalling rock.
Another object of the present invention is to provide an easily variable stress wave capable of spalling rock.
Another object of the present invention is to provide a wide range of stress waves capable of spalling rock.
Another object of the present invention is to provide a highly efficient drill.
Another object of the present invention is to provide a highly economical drill.
Another object of the present invention is to provide a faster drilling rate.
Another object of the present invention is to provide drilling rates that are relatively independent of rock properties.
Another object of the present invention is to increase the percentage of total power of a drill that is transmitted to the rock.
Other objects and a more complete appreciation of the present invention and its many attendant advantages will develop as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings in which like reference numerals designate like parts throughout the figures thereof and wherein
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top view of a specific embodiment of the present invention.
FIG. 2 is a front elevation of the specific embodiment of FIG. 1.
FIG. 3 is a top view of a specific embodiment of the present invention.
FIG. 4 is a front elevation of the specific embodiment of FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Turning to FIGS. 1 and 2, numeral 10 designates a drill stem. Attached to one end of drill stem 10 is an open-ended, hardened, drilling head 12. Hardened drilling head 12 is flared slightly to prevent jamming of drill stem 10 in the borehole 14. Hardened drill head 12 must be capable of withstanding the stress waves generated by electrohydraulic pulser 16 without cracking or breaking.
Electrohydraulic pulser 16 comprises a solid block of electrical Electrode material 18. A high voltage electrode 20 extends through insulating material 18 and projects into the space inside drilling head 12. Two ground electrodes 22, located adjacent to high voltage electrode 20, also extend through insulating material 18 and project into the space inside drilling head 12. Solid block 18 prevents short circuiting of the discharge between electrodes 20 and 22. Electrodes 20 and 22 are enclosed in electrical insulation 24 inside drill stem 10. The description and operation of electrohydraulic pulser 16 is promulgated in detail in Browne, Allen and Schrom, Electrohydraulics, Science Journal, March 1968. ELECTRODE support material 26 supports and protects the electrodes 20 and 22 from impact with spalled rock being carried out of the borehole 14 by fluid 28. Gasket 30 enables electro-hydraulic pulser 16 to rotate within drill stem 10 and drilling head 12. Gasket 30 forms a fluid-tight seal between electrohydraulic pulser 16 and drill stem 10 and drilling head 12.
Referring to FIGS. 3 and 4, fluid 28 enters drill stem 10 via inlet port 34 and leaves drill stem 10 via outlet port 36. The direction of flow of fluid 28 is indicated by arrows 32. Fluid 28 serves as a carrier for spalled rock. Loose rock spalled by electrohydraulic pulser 16 is carried from the bottom of borehole 14 to outlet port 36, located near the top end of drill stem 10. Thus, the inside diameter of outlet port 36 must be large enough to pass the largest piece of spalled rock that will be produced by electrohydraulic pulser 16. The fluid 28 may be recycled through the drill provided the spalled rock is first removed therefrom. Electrohydraulic pulser 16 in conjunction with gasket 30 divides drill stem 10 in two compartments 38 and 40. Of course, a plurality of compartments of various shapes are possible. The only requirement being that the compartments do not interrupt the fluid flow.
Shock waves from electrohydraulic pulser 16 travel through fluid 28 to the rock face 42. These stress waves load the face 42 which spalls on rebound. Rock particles spalled from the face 42 are removed by fluid 28 circulating through drill stem 10 and drilling head 12. The high-intensity stress waves generated by electrohydraulic pulser 16 are typically of microsecond duration. It is noted that electrohydraulic pulser 16 is but one means for generating high-intensity stress waves.
Obviously many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described herein.