ELECTRICAL DIRECTIONAL CONTROL OF AN ELECTROCRUSHING DRILL
CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the benefit of the filing of U.S. Provisional Patent Application No. 63/220,781 , entitled “ELECTRICAL DIRECTIONAL CONTROL OF AN ELECTROCRUSHING DRILL”, filed on July 12, 2021, the entirety of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION Field of the Invention (Technical Field)
The present invention is related to electrical directional control of pulsed power electrocrushing drills.
Background Art
Note that the following discussion may refer to a number of publications and references. Discussion of such publications herein is given for more complete background of the scientific principles and is not to be construed as an admission that such publications are prior art for patentability determination purposes.
SUMMARY OF THE INVENTION (DISCLOSURE OF THE INVENTION')
One or more embodiments of the present invention comprise an apparatus for controlling a direction of an electrocrushing drill, the apparatus comprising an electrocrushing drill bit comprising a plurality of electrode sets, each electrode set comprising one or more electrodes; one or more capacitors configured to energize at least one of the electrode sets; and one or more transformers configured to pulse charge the one or more capacitors. In one or more configurations, the one or more capacitors preferably comprise a plurality of capacitors, one or more of the plurality of capacitors each corresponding to an electrode set. In one of those configurations, the one or more transformers preferably comprise a separate transformer corresponding to each capacitor, and the apparatus preferably comprises one or more switches, each switch preferably corresponding to a transformer. Each switch is preferably capable of switching a voltage of between approximately 5 kV and approximately 75 kV, and is optionally capable of switching a voltage greater than approximately 75 kV. Each switch is preferably capable of switching a peak current of between approximately 1 kA and approximately 10 kA. In another of those configurations, the one or more transformers preferably comprise a transformer configured to pulse charge any or all of the plurality of capacitors, and the apparatus preferably comprises one or more switches, each switch connecting the transformer to each capacitor. Each switch is preferably capable of switching a voltage of between approximately 50 kV and approximately 300 kV, and is optionally capable of switching a voltage greater than approximately 300 KV. Each switch is preferably capable of switching a peak current of between approximately 1 kA and approximately 10 kA.
In a different configuration, the one or more capacitors are each configured to energize any or all of the plurality of electrode sets, and the one or more transformers comprises a transformer for pulse charging the one or more capacitors. This apparatus preferably comprises a plurality of switches, each switch connecting one or more of the one or more capacitors to each electrode set. Each switch is preferably capable of switching a voltage of between approximately 50 kV and approximately 300 kV, and is optionally capable of switching a voltage greater than approximately 300 KV. Each switch is capable of switching a peak current of between approximately 1 kA and approximately 25 kA.
One or more other embodiments of the present invention are methods for controlling a direction of an electrocrushing drill, the methods comprising providing an electrocrushing drill bit with a plurality of electrode sets, each electrode set comprising one or more electrodes; connecting a first transformer to a pulsed power supply; the first transformer pulse charging a first capacitor; and the first capacitor energizing a first electrode set, thereby increasing excavation adjacent to the first electrode set and steering the electrocrushing drill bit in a direction opposite the first electrode set.
One method of changing a drilling direction preferably comprises disconnecting the first transformer from the pulsed power supply; connecting a second transformer to the pulsed power supply; the second transformer pulse charging a second capacitor; and the second capacitor energizing a second electrode set, thereby increasing excavation adjacent to the second electrode set and steering the electrocrushing drill bit in a direction opposite the second electrode set. Another method of changing the drilling direction preferably comprises disconnecting the first capacitor from the first transformer; connecting a second capacitor to the first transformer; the first transformer pulse charging the second capacitor; and the second capacitor energizing a second electrode set, thereby increasing excavation adjacent to the second electrode set and steering the electrocrushing drill bit in a direction opposite the second electrode set. Yet another method of changing the drilling direction preferably comprises disconnecting the first capacitor from the first electrode set; connecting the first capacitor to a second electrode set; and the second capacitor energizing the second electrode set, thereby increasing excavation adjacent to the second electrode set and steering the electrocrushing drill bit in a direction opposite the second electrode set.
Objects, advantages and novel features, and further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated into and form a part of the specification, illustrate the practice of embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating certain embodiments of the invention and are not to be construed as limiting the invention. In the drawings:
FIG. 1 shows a six electrode electrocrushing bit suitable for directional drilling. In a six electrode bit, the electrodes are preferably wired in three adjacent pairs as shown.
FIG. 2 shows a schematic for the Multiple Pulsed Power Systems Directional Drilling Strategy of the present invention for driving sets of electrodes on the bit of FIG. 1. Each pulsed power system drives an electrode set to provide directional steering capability.
FIG. 3 shows the schematic for the Distributed Capacitor Directional Drilling Strategy of the present invention.
FIG. 4 shows a schematic for the Distributed Switching Directional Drilling Strategy of the present invention. DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
FIG. 1 shows a six electrode electrocrushing drill bit suitable for directional drilling. Such a bit is more completely described in U.S. Patent Nos. 8,172,006, 7,416,032, and 10,060,195, incorporated herein by reference. Any number of electrodes, in a variety of arrangements and form factors, may be used. The high voltage electrodes receive high-voltage pulses, and the ground structure provides current return. The drill bit preferably comprises electrodes that are wired in adjacent pairs; thus, for the exemplary six electrode bit shown in FIG. 1 , there are three sets of electrode pairs. In order to electrically steer such a drill, the bit preferably comprises at least three sets of electrode pairs across the bit face. High-voltage, high current pulses are preferably applied separately to the three electrode sets at different repetition rates to steer the drill. If the repetition rate is high on one set of electrodes relative to the other electrode sets, the drill will steer toward the side of the ground structure or ring opposite the high repetition rate electrode set. This is because the excavation rate is higher where the repetition rate is higher. There may be only one, two, or any other number of electrodes in each set. Embodiments of the present invention comprise strategies for providing this difference in repetition rates. Three such exemplary strategies are detailed as follows.
The first strategy, referred to herein as the Multiple Pulsed Power Systems Directional Drilling Strategy and shown in FIG. 2, comprises three separate pulsed power systems that each operate one of three sets of electrodes, ES1 , ES2, and ES3. Primary capacitor Cp1 is charged by the pulsed power system charging system (not shown). In one operational example, when primary switch Sp1 is closed, it connects capacitor Cp1 to transformer T 1. This creates a high voltage pulse on the output side of transformer T1 to pulse charge capacitor C1 to the desired output voltage. As the voltage rises on capacitor C1 from the charge current being delivered by transformer T1 , the voltage also rises across first electrode set ES1. This rising voltage, with the stored energy in capacitor C1 , enables the bit electrodes in ES1 to excavate the rock on the ES1 side of the bit. By increasing the repetition rate of the pulsed power system driving electrode set ES1 relative to the pulsed power system’s driving second electrode set ES2 and third electrode set ES3, the drill is steered preferentially toward the side of the bit opposite the ES1 set of electrodes. In other words, it preferentially excavates the rock on ES1 side of the bit, which causes the drill to steer towards the bit section opposite the ES1 electrodes. The Multiple Pulsed Power Systems Directional Drilling Strategy switches are preferably capable of switching from about 5 kV to about 75 KV, or even higher. The peak current is preferably from approximately 1 kA to approximately 10 kA. The second strategy, referred to herein as the Distributed Capacitor Directional Drilling Strategy and shown in FIG. 3, uses a separate output capacitor for each of the three sets of electrodes similar to the Multiple Pulsed Power Systems Directional Drilling Strategy, but all of the output capacitors are driven by a single primary circuit and transformer. Preferably high-voltage, moderate current switches are placed between the output of pulse transformer T and each of the three sets of output capacitors C1 , C2, and C3. Primary switch SP connects primary capacitor CP with pulse transformer T. First electrode set ES1 of the bit is fed by capacitor C1 and connected to the pulse transformer by switch S1. Second electrode set ES2 of the bit is fed by capacitor C2 and connected to the pulse transformer by switch S2. Third electrode set ES3 of the bit is fed by capacitor C3 and connected to the pulse transformer by switch S3. Primary capacitor CP is charged by the pulsed power system charging system (not shown). When primary switch SP is closed, it connects capacitor CP to transformer T. This creates a high voltage pulse on the output side of transformer T. When a particular set of electrodes, such as ES1 , is to be fired to produce excavation on that side of the bit, then switch S1 for electrode set ES1 is activated so that the output capacitor C1 for ES1 is pulse charged. With switch S1 closed, and switches S2 and S3 open, capacitor C1 is pulse charged to the desired output voltage. As the voltage rises on capacitor C1 because of the charge current being delivered by transformer T, the voltage also rises across first electrode set ES1. This rising voltage, with the stored energy in capacitor C1 , then enables the first electrode set ES1 to excavate the rock on the ES1 side of the bit. Operating switch S1 at a higher repetition rate than switches S2 and S3 preferentially excavates the rock on the ES1 side of the bit, which causes the drill to steer towards the bit section opposite the ES1 electrodes. Increasing the repetition rate of any output switch relative to the other two switches will cause the drill to steer towards the side of the bit opposite the high repetition rate electrode set, thereby providing electronic directional control of the drill. The Distributed Capacitor Directional Drilling Strategy switches are preferably capable of switching from about 50 kV to about 300 KV, or even more. The peak current is preferably from approximately 1 kA to approximately 10 kA.
The third strategy, referred to herein as the Distributed Switching Directional Drilling Strategy and shown in FIG. 4, comprises a single output capacitor CO that is charged from transformer T and three sets of switches, S1 , S2, and S3, that connect the output capacitor to the individual electrode sets ES1 , ES2, and ES3. For example, if it is desired to fire first electrode set ES1 , then switch S1 that connects the output capacitor CO to first electrode set ES1 will be activated. As the voltage rises across output capacitor CO, the voltage also rises across first electrode set ES1. This rising voltage, coupled with the energy stored in capacitor CO, then produces excavation at electrode set ES1. By increasing the repetition rate of any output switch relative to the other two switches, it will cause the drill to steer towards the side of the bit opposite the high repetition rate electrode set, thereby providing electronic directional control of the drill. The Distributed Switching Directional Drilling Strategy may require significantly higher peak current switch capability than the Distributed Capacitor Directional Drilling Strategy. The Distributed Switching Directional Drilling Strategy switches are preferably capable of switching from about 50 kV to about 300 KV, or even more. The peak current is preferably from approximately 1 kA to approximately 25 kA.
Wherever a single capacitor is referenced above, a plurality of capacitors may be used, because it is often most expedient to operate capacitors in series to gain better voltage capability, or in parallel to gain better current capability. Similarly, wherever a single switch is referenced above, a plurality of switches may be used in order to provide the current carrying capability and/or voltage standoff capability for the specific application.
Note that in the specification and claims, “about” or “approximately” means within twenty percent (20%) of the numerical amount cited. As used herein, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a functional group” refers to one or more functional groups, and reference to “the method” includes reference to equivalent steps and methods that would be understood and appreciated by those skilled in the art, and so forth.
Although the invention has been described in detail with particular reference to the disclosed embodiments, other embodiments can achieve the same results. Variations and modifications of the present invention will be obvious to those skilled in the art and it is intended to cover all such modifications and equivalents. The entire disclosures of all patents and publications cited above are hereby incorporated by reference.