Abstract
A sonic-powered method is provided for horizontal directional drilling. The method includes positioning a drilling apparatus at one end of a desired path for a generally horizontal bore to be formed, and attaching a drill bit and a drill rod to a drill head. The method also includes advancing the drill bit and the drill rod into and through the ground along the desired path by advancing the drill head to move along the drill mast. A sonic oscillator of the apparatus applies sonic energy in the form of high frequency vibrations to the drill rod and the drill bit to cause the drill bit to penetrate through an underground formation in front of the drill bit along the desired path. The sonic vibrations help efficiently penetrate through different materials in underground formations. The drilling apparatus can also use sonic vibrations to install drill casings to stabilize the bore.
Claims
1. A sonic-powered method for horizontal directional drilling, comprising: positioning a drilling apparatus proximate to an entry site at one end of a desired path for a generally horizontal bore to be formed, the drilling apparatus including a sonic drill head movably mounted on a drill mast and a sonic oscillator operatively engaged with the sonic drill head; attaching a sonic drill bit and a sonic drill rod to the sonic drill head; advancing the sonic drill bit and the sonic drill rod into and through the ground along the desired path by advancing the sonic drill head to move along the drill mast, wherein the sonic oscillator applies sonic energy defined by high frequency vibrations to the sonic drill rod and the sonic drill bit to cause the sonic drill bit to penetrate through an underground formation in front of the sonic drill bit along the desired path; attaching further sonic drill rods to the sonic drill head and to at least one previously-advanced sonic drill rod(s) and repeating the advancing of the sonic drill head to continue forming a generally horizontal bore by horizontal directional drilling along the desired path until the sonic drill bit emerges at an exit site at an opposite end of the desired path, wherein the generally horizontal bore formed by the advancing along the desired path defines a pilot bore for installing a line or conduit along the desired path; attaching a sonic drill casing to the sonic drill head, the sonic drill casing being larger in diameter than the sonic drill bit and sonic drill rods; advancing the sonic drill casing into and through the ground so that the sonic drill casing surrounds the sonic drill rods and the pilot bore as the sonic drill casing is installed, wherein the sonic oscillator applies sonic energy defined by high frequency vibrations to the sonic drill casing to cause the sonic drill casing to penetrate through the underground formation(s) in front of the sonic drill casing; and attaching further sonic drill casings to the sonic drill head and to at least one previously-advanced sonic drill casing(s) and repeating the advancing of the sonic drill head to continue casing the pilot bore, thereby stabilizing the walls of the pilot bore to prevent collapse of the pilot bore and/or to prevent escape of any drilling fluids used in the pilot bore, wherein the sonic drill head alternates between advancing one sonic drill rod and then one sonic drill casing such that the majority of the pilot bore is stabilized and cased behind the sonic drill bit during the horizontal directional drilling, and wherein the sonic drill head independently and separately applies the sonic energy to the sonic drill rods or to the sonic drill casings.
2. The method of claim 1, wherein the advancing of the sonic drill bit and the sonic drill rods into and through the ground is performed without a continuous circulation of a drilling fluid to the sonic drill bit and along the pilot bore.
3. The method of claim 2, wherein the advancing of the sonic drill bit and the sonic drill rods into and through the ground is performed without circulating any drilling fluid to the sonic drill bit or along the pilot bore.
4. The method of claim 3, wherein no fluid collection trench or water recycling equipment is provided at either of the entry site or the exit site during the horizontal directional drilling.
5. The method of claim 1, wherein the desired path for the pilot bore travels through at least two different underground formations defined by differing materials to drill through, and the advancing of the sonic drill bit and the sonic drill rods into and through the ground further comprises: using the same sonic drill bit to penetrate through each of the differing materials in the at least two different underground formations.
6. The method of claim 5, wherein a single set of drilling equipment including the same sonic drill bit and a single set of drilling operation parameters is used for penetrating the pilot bore through each of the at least two different underground formations.
7. The method of claim 5, wherein one of the different underground formations is defined by sand material, and the step of advancing the sonic drill bit and the sonic drill rods further comprises: suspending sand grains of the sand material in space using transmission of sonic vibrations from the sonic drill bit and the sonic drill rods into the sand material, thereby generating a low friction environment for the sonic drill bit to advance through the sand material.
8. The method of claim 7, wherein another one of the different underground formations is defined by clay material, and the step of advancing the sonic drill bit and the sonic drill rods further comprises: shearing the clay material surrounding the sonic drill bit and the sonic drill rods with transmission of sonic vibrations from the sonic drill bit and the sonic drill rods into the clay material, thereby reducing friction against forward movements of the sonic drill bit and the sonic drill rods.
9. The method of claim 8, wherein another one of the different underground formations is defined by rock material, and the step of advancing the sonic drill bit and the sonic drill rods further comprises: percussively fracturing the rock material by applying sonic vibrations to the sonic drill bit to cause repeated impacts of the sonic drill bit into the rock material, thereby removing the rock material in front of the sonic drill bit and reducing friction against forward movements of the sonic drill bit and the sonic drill rods.
10. The method of claim 1, further comprising: inserting the line or conduit into the cased pilot bore and pulling the line or conduit through the pilot bore to finalize installation of the line or conduit along the desired path; and withdrawing the sonic drill casings using the drilling apparatus after the line or conduit is installed along the desired path.
11. The method of claim 1, wherein the sonic oscillator produces high frequency vibrations of up to 150 Hz in the sonic drill bit and the sonic drill rods, or in the sonic drill casings.
12. The method of claim 11, further comprising: adjusting output of the sonic oscillator such that a frequency of the high frequency vibrations applied by sonic energy on the sonic drill rods is a resonant frequency of the sonic drill rods, or such that the frequency applied on the sonic drill casings is a resonant frequency of the sonic drill casings.
13. The method of claim 1, wherein advancing the sonic drill bit and the sonic drill rods further includes turning a forward direction of the sonic drill bit with a bent sub such that the desired path of the pilot bore includes one or more turns along a length of the desired path.
14. The method of claim 1, further comprising: after the sonic drill bit emerges from the exit site to finalize formation of the pilot bore, attaching a reamer and/or a swabber to a free end defined by the sonic drill rods; and withdrawing the sonic drill rods back through the pilot bore to advance the reamer and/or the swabber along the pilot bore, wherein the sonic oscillator of the drilling apparatus continues to apply high frequency vibrations to the sonic drill rods to assist the reamer and/or the swabber to cut through the underground formations surrounding the pilot bore and thereby expand a size of the pilot bore to fit the line or conduit to be installed along the desired path.
15. The method of claim 14, further comprising: inserting the line or conduit into the expanded pilot bore and pulling the line or conduit through the pilot bore to finalize installation of the line or conduit along the desired path.
16. The method of claim 1, wherein in addition to applying sonic energy with the sonic oscillator, advancing the sonic drill bit and the sonic drill rods with the sonic drill head further comprises: applying hydraulically-generated down pressure to move the sonic drill head along a length of the drill mast towards the entry site; and slowly rotating the sonic drill bit and the sonic drill rods with the sonic drill head during movement of the sonic drill head along the length of the drill mast.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the invention.
(2) FIG. 1 is a schematic view showing a general overview of how conventional horizontal directional drilling (HDD) applications function, particularly in the pilot bore boring stage.
(3) FIG. 2A is another schematic view showing a further step in the conventional HDD drilling process, in which the pilot bore is further advanced along a desired path, with potential “frac outs” shown that may occur when using drilling fluid in HDD applications.
(4) FIG. 2B is a further schematic view showing a further step in the conventional HDD process, in which further steps of reaming and/or swabbing are being conducted.
(5) FIG. 2C is yet another schematic view showing a further step in the conventional HDD process, in which a line or conduit is being installed in the bore along the desired path.
(6) FIG. 3 is a schematic overview showing initial steps of forming a pilot bore using a sonic HDD process in accordance with embodiments of the invention.
(7) FIG. 4A is a further schematic view showing additional progress of advancing the sonic drill bit and sonic drill rods (as well as sonic drill casings) to form the pilot bore during the sonic HDD process, with the sonic drill bit penetrating through different underground formations and different materials shown by differing cross-hatchings along the desired path.
(8) FIG. 4B is a further schematic view showing a further step in the sonic HDD process, in which further steps of reaming and/or swabbing are being conducted.
(9) FIG. 4C is yet another schematic view showing a further step in the sonic HDD process, in which a line or conduit is being installed in the bore along the desired path.
(10) FIG. 5A is a detail view of the sonic drill bit and the foremost sonic drill rod and sonic drill casing as these separately/independently penetrate through a first underground formation (e.g., such as one made of sand material) along the desired path, and as noted at detail circle 5A in FIG. 4A.
(11) FIG. 5B is a detail view of the sonic drill bit and the foremost sonic drill rod as these penetrate through a second underground formation (e.g., such as one made of rock material) along the desired path, and as noted at detail circle 5B in FIG. 4A.
(12) FIG. 5C is a detail view of the sonic drill bit and the foremost sonic drill rod as these penetrate through a third underground formation (e.g., such as one made of clay material) along the desired path, and as noted at detail circle 5C in FIG. 4A.
(13) FIG. 6A is a top view that schematically illustrates the exemplary sonic HDD process in another embodiment, specifically to show turns that may be formed when advancing the sonic drill bit and sonic drill rods along the desired path.
(14) FIG. 6B is a side view that schematically illustrates another example of the sonic HDD process, such as a vertical profile of the pilot bore formed in the FIG. 6A example.
(15) FIG. 7 is a detail side view of the sonic drill bit and a foremost sonic drill rod and sonic drill casing upon initial insertion into the ground at the entry site when starting the sonic HDD process.
DETAILED DESCRIPTION
(16) An improved horizontal directional drilling (“HDD”) process for installing utility line(s) for one or more services is provided in accordance with the following description. Notably, the inventors have applied use of a sonic drill to the HDD process to enhance the reliability and efficiency of this HDD process. Using the sonic drill allows for various geological formations to be successfully cut through and penetrated during formation of the bore hole with no changes necessary in the drilling equipment, with corresponding increases in speed of advancing the sonic drill bit along the desired path for the utility lines to be installed. To this end, variations in the underground geological formation along the desired borehole path can be handled when using sonic-powered HDD methods without causing significant delay and reconfiguration of the drilling equipment during the process. Additionally and unexpectedly, such bore hole formation is accomplished without need for circulation of drilling fluid, or alternatively, with only a minimized amount of drilling fluid use. The HDD using sonic energy is capable of generating accurate bore hole paths for utility line installation without the known risks and technical problems encountered as a result of trench-digging or use and containment of significant amounts of drilling fluid during the HDD process.
(17) As set forth generally above, the inventors of this application have now applied sonic drilling to the HDD context. Generally, a sonic drilling method uses a sonic drill head which includes a mechanism for vibrating a drill pipe or drill string/rod. One preferred mechanism for generating the vibrations is an oscillator mounted on the drill and adapted to transmit sinusoidal pressure waves through the drill pipe to thereby create a cutting action at the bit face. The oscillator may include, for example, one or more pairs of rotating weight elements contained within cavities such that counter-rotations of the weight elements relative to one another (e.g., one clockwise and another counterclockwise within the cavities) generates a high frequency vibration, such as up to 150 Hz, that is transmitted and applied to the drill string and therefore also to the sonic drill bit at the leading end of the drill string. A pneumatic isolation system may be used to insulate the remainder of the sonic drill head and rig from this energy so that it can be directed for maximum effect on the drill string.
(18) The sonic frequency energy or vibrations generated by the oscillator are controlled by the drill operator to be generally what's called a resonant frequency for the underground formation being bored through at the sonic drill bit. To this end, when the sonic energy applied coincides with a natural frequency of the drill string, resonance occurs and this results in a maximum amount of energy transfer to the leading end of the sonic drill bit. The drill string and sonic drill bit are also slowly rotated during this process to help evenly distribute the energy and resulting impact on the sonic drill bit face. The advancement of the sonic drill head along the drill mast is performed in this embodiment by hydraulic down pressure created by flowing hydraulic fluid (on the drilling rig) to a hydraulic feed cylinder while also slowly applying rotation to the drill string and the aforementioned sonic energy. As with the percussive drilling method noted above, the sonic drill bit face may include carbide cutting bits that operate to cut through and remove material from in front of the sonic drill bit as a result of the rotation and application of sonic frequency energy. The resonant energy applied to the drill string also tends to suspend the soil or ground formation immediately adjacent the drill string, which minimizes friction applied against forward movements of the drill string as the sonic drill bit advances. The specific operation of sonic energy on various types of underground formations is described further below.
(19) Exemplary embodiments of combining the concepts of sonic drilling with an HDD operation are shown in the views of FIGS. 3 through 7, contrasted with the more generic views of standard HDD operation as previously shown. FIG. 3 shows a general overview of the setup for a drill site using sonic HDD. In this Figure, a track-mounted mobile sonic drill rig 40 (also referred to as a drilling apparatus 40 herein), which may specifically be a “Terra Sonic 150 Compact Crawler” commercially available from Terra Sonic of Marietta, Ohio, has been modified to operate in an HDD mode of operation. As with conventional HDD rigs, the sonic drill rig 40 moves a sonic drill head 42 along an angled drill mast 44 as shown so that a sonic drill bit 46 and a drill string made up of a series of sonic drill rods 48 (also known as drill steel) can be advanced through the ground in a substantially and/or completely horizontal manner. It will be understood that a bent sub (not shown in detail) is also connected between the sonic drill bit 46 and the foremost sonic drill rod 48 to allow for steering thereof, described further below. The sonic drill head 42 of the sonic drill rig 40 in FIG. 3 includes an oscillator (not shown) as described above and therefore applies high frequency sonic energy to cause drilling action and advancement of the sonic drill bit 46 and drill string. A storage rack of further sonic drill rods 48 would be positioned in close proximity to where the sonic drill rig 40 is operating so that as pieces of the sonic drill rod 48 are advanced into the ground, additional portions can be added and then advanced by longitudinal movement of the sonic drill head 42 along the drill mast 44. Such sonic drill rods 48 or portions can be manually positioned for connection to the existing drill string and the sonic drill head 42 or alternatively an automated lift and positioning system (not shown) can be used. This process of advancing the drill string and inserting a new drill string portion/member repeats until the pilot bore 50 has been drilled along the entirety of the desired path.
(20) Moreover, the sonic HDD process may also advantageously include installation of sonic drill casings 49 (first seen in FIG. 4A) as well along the pilot bore 50. The sonic drill casings 49 are of a larger diameter than the size of the sonic drill bit 46 and can be advanced so as to remain only a few feet behind the operations of the sonic drill bit 46, although this positioning is not shown in the highly-schematic views provided in FIGS. 3 through 4C. The sonic drill casings 49 are installed using the same application of sonic energy/vibrations and slow rotations with the sonic drill head 42 (e.g., the sonic drill head 42 independently applies vibrations, rotation, and advancement movement to either the drill string (sonic drill rods 48) or to the sonic drill casings 49). Once installed, the sonic drill casings 49 solidify the pilot bore 50 to prevent any collapse thereof while also preventing any possibility of a “frac out” when drilling fluids are to be used in the process. It will be understood that in embodiments where sonic drill casings 49 are used in this manner, the process of advancing the drill string will alternate between securing a new sonic drill rod section to the sonic drill head 42 and advancing the sonic drill bit 46 and sonic drill rods 48, and securing a new sonic drill casing section to the sonic drill head 42 and then advancing the sonic drill casings 49. The storage rack described above may contain both sonic drill rods 48 and sonic drill casings 49 for ease and convenience of this alternating advancement to produce a “cased” pilot bore 50.
(21) What can be seen in FIG. 3 is that the sonic drill bit 46 and sonic drill rods 48 have been advanced using the sonic drill rig 40 so as to penetrate into the ground at an entry site 52, as shown by the movement arrows in this FIG. 3. As will be described in further detail below (and also shown specifically in FIG. 7), no trench or pit is needed to be dug at the entry site 52 because the sonic HDD process does not require continuous circulation (or even any circulation, in some embodiments) of drilling fluid along the pilot bore 50. The sonic drill bit 46 moves at an angle downwardly until a depth of the desired generally horizontal path is reached, at which point the sonic drill bit 46 advances generally horizontally under the ground, and this permits the pilot bore 50 to traverse underneath environmental features such as sensitive areas (where trenches cannot be dug) or a river, as specifically shown in FIG. 3. It is also shown in FIG. 3 that the underground areas where the sonic drill bit 46 and the sonic drill rods 48 move through may be defined by various underground formations having different materials, an example of which will be described further below. The sonic HDD process allows for the same sonic drill bit 46 and drilling methodology to be used to successfully form the pilot bore 50 through each of these underground formations and materials.
(22) Further steps of the sonic HDD process are shown with reference to FIGS. 4A through 4C. In FIG. 4A, the sonic drill bit 46 and the sonic drill rods 48 have continued to be advanced by the sonic drill rig 40 through most of the desired path, e.g., the sonic drill bit 46 in FIG. 4A is moving at an angle upwardly so as to emerge at an exit site 54 as also shown in FIG. 4B. Also shown in FIG. 4A, the sonic drill casings 49 have been installed over the sonic drill rods 48 along at least a portion of the pilot bore 50. It will be understood that when such sonic drill casings 49 are installed, they are typically installed in alternating sequence (contrary to what is shown in FIG. 4A for consistency with later FIG. 5A, described below) so that a substantial entirety of the pilot bore 50 is “cased” except for the couple of feet that the sonic drill bit 46 and sonic drill rods 48 project beyond a free end of the sonic drill casings 49. During the movement along the desired path to form the pilot bore 50, the sonic drill bit 46 and sonic drill rods 48 (as well as sonic drill casings 49) are advanced through at least two different underground formations located in this schematic view at different portions under the river shown. As set forth in further detail below, the different underground formations are defined by different materials, such as sand material at a first underground formation 56, rock material at a second underground formation 58, and clay material at a third underground formation 60. The sonic HDD process may cut through more or fewer variations of underground formations when making the pilot bore 50, depending on local geology and surface structure. The specifics of cutting through these different underground formations 56, 58, 60 are described further below with reference to detail views at FIGS. 5A through 5C, the detail circles being shown for reference in FIG. 4A.
(23) The advancing movement of the sonic drill bit 46 and sonic drill rods 48 (and optionally the sonic drill casings 49) is shown by the movement arrows along the pilot bore 50 in FIG. 4A. After emerging from the exit site 54, which again does not require digging a trench or collection pit for drilling fluids, the sonic HDD process may continue in some embodiments by attaching one or more of a reamer 62 (also known as a back-reamer) or swabber to the free end of the drill string where the sonic drill bit 46 was connected. The advancing movements of the sonic drill rods 48 with the sonic drill rig 40 are repeated in reverse then, which withdraws the sonic drill rods 48 back through the pilot bore 50 section-by-section as shown by movement arrows in FIG. 4B. Where sonic drill casings 49 are also installed at the pilot bore 50, the sonic drill casings 49 are withdrawn in front of the typically-larger reamer 62 so as to not interfere with the further expansion of the bore, and this is shown by the location of the sonic drill casings 49 relative to the reamer 62 in FIG. 4B. Such withdrawal of the sonic drill rods 48 also moves the reamer 62 and/or swabber through the pilot bore 50 as shown at the bottom of FIG. 4B. The reamer 62 is configured to further cut through the underground formations to expand the diameter or size of the bore along the desired path, and such cutting is enhanced by the continued application of sonic energy with the sonic oscillator along the drill string. During this same movement or withdrawal step, the method may also include inserting the line or conduit 64 into the pilot bore 50 along the desired path, such as by having the line or conduit 64 be secured behind the reamer 62 to therefore follow into the pilot bore 50 as shown by the movement arrows in FIG. 4C. Once the reamer 62 and the line or conduit 64 have emerged again at the entry site 52, the sonic HDD process is complete with the line or conduit 64 fully installed along the desired path, which in this illustrated example is generally horizontally underneath a body of water like a river. Because no drilling fluid or only a minimal amount of drilling fluid is needed thanks to the application of sonic vibrations, there is no risk of “frac outs” or other environmental hazards during this process. Furthermore, the sonic HDD process installs the line or conduit 64 quickly regardless of the variations that may be present in underground formations and materials to be penetrated through.
(24) In one alternative, where the sonic drill casings 49 are sufficiently large in size so that the line or conduit 64 to be installed can fit through the sonic drill casings 49, the step of pulling the reamer 62 or a swabber back through the desired path is not necessary. To this end, in such alternative embodiments the sonic HDD process can be completed by pulling (with the sonic drill rods 48) the line or conduit 64 back through the pilot bore 50 that remains “cased” by the sonic drill casings 49, and then the sonic drill casings 49 are thereafter removed following the finalized installation of the line or conduit 64.
(25) Now turning with reference to FIGS. 5A through 5C, the detail views showing how the same sonic drill bit 46 and drilling operations are used for the different underground formations 56, 58, 60 are shown in detail. In these illustrations, it will be understood that the sonic drill bit 46 is shown generally schematically, but in slightly more detail than in prior views. When a sand-based first underground formation 56 is encountered by the sonic drill bit 46 as shown in FIG. 5A, the sonic vibrations cause sand grains to suspend in space to allow for a generally frictionless or friction-light environment to advance along the desired path (as shown by the movement arrow). This type of movement may be referred to as “suspension advancement” of the sonic drill bit 46 and the sonic drill rods 48. Also visible in FIG. 5A, such sand-based formations are also where following the sonic drill bit 46 with installation of sonic drill casings 49 (a frontmost one shown in this Figure) help solidify and stabilize the pilot bore 50 within the soft formation. When a rock-based second geological formation 58 is encountered by the sonic drill bit 46 as shown in FIG. 5B, repeated impacts of the carbide cutting bits percussively fracture and remove rock material to allow advancement (as shown by the movement arrow), while again reducing frictional damping forces along the length of the drill string. When a clay-based third subsurface formation 60 is encountered by the sonic drill bit 46 as shown in FIG. 5C, the clay material is sheared using the sonic energy and this allows for reduced frictional damping forces along the length of the drill string following the sonic drill bit 46, thereby allowing for advancement as shown by the movement arrow in this view. In each of FIGS. 5B and 5C, it can be seen that the sonic drill rods 48 can advance without much friction because the sonic drill bit 46 used is slightly larger in diameter size than the sonic drill rods 48 (and/or the bent sub behind the sonic drill bit 46), for example, the sonic drill bit 46 in one embodiment can be about 5 inches in diameter and the sonic drill rods 48 are 3.5 inches in diameter, leaving a small gap about the periphery of the sonic drill rods 48. No reconfiguration is generally necessary of the equipment or of the operations of the sonic drill rig 40 when transitioning between these different types of underground geological formations, as each is automatically handled well by the application of sonic energy, thereby eliminating pauses and delays that may be encountered when using conventional HDD processes in the same context. Moreover, the borehole remains open and has good stability even without circulating drilling fluid to reinforce bore walls as a result of transmitting sonic energy/vibrations along the drill string, which allows for the unexpected result of true “dry” HDD being possible. These various benefits of sonic-powered HDD work both during initial pilot bore drilling as well as the subsequent reaming (and optional swabbing) passes through the desired path. Other types of materials and underground formations can also be handled by the sonic HDD process similarly, as these three are provided as exemplary embodiments only.
(26) Another embodiment for the sonic HDD process is shown in FIGS. 6A and 6B, this being reflective of some testing done during proof-of-concept work for this process. In FIG. 6A, it can be seen that the advancing of the sonic drill bit 46 and the sonic drill rods 48 done by the sonic drill rig 40 includes turning a forward direction of the sonic drill bit 46 (e.g., using the bent sub) in a couple of places so as to follow a desired path for the pilot bore 50 that includes one or more turns. A bore path with two turns is shown from above in the example of FIG. 6A. The vertical profile of this test is shown in FIG. 6B, where it can be seen that the horizontal elevation of the pilot bore 50 can be adjusted as needed to follow the desired path as well as the lateral turns visible in FIG. 6A. The sonic drill casings 49 were also used in this test but have been omitted from the views here for simplicity.
(27) With reference to FIG. 7, a beginning of the sonic HDD process with the sonic drill rig 40 is shown, with drillers preparing the lead element of the drill string (sonic drill rod 48) and the sonic drill bit 46 for initial insertion into the entry site 52 of the desired path or bore. As shown in this and the other views, an entry pit does not need to be dug at this jobsite because there is no need to use and reclaim a large amount of drilling fluids when using sonic in combination with sonic HDD. To this end, the drilling described in this process is successfully done “dry,” meaning without drilling fluids. The sonic drill head 42 then proceeds to advance the sonic drill bit 46 and the sonic drill rods 48 into the ground along the desired path as described above, the advancement being done as a result of the application of sonic energy at high frequencies to fluidize and penetrate the underground formations in front of the sonic drill bit 46 as well as pull down force applied by movement of the sonic drill head 42 down the length of the drill mast 44. The sonic drill head 42 is then used to connect to and advance a sonic drill casing 49 into the ground so as to surround the sonic drill rod 48 as shown behind the sonic drill bit 46, and thereby to case the pilot bore 50 for the advantageous reasons explained above. Additional sonic drill rods 48 and sonic drill casings 49 are added for each pass of the sonic drill head 42 along the drill mast 44, with the sections being manually or automatically moved from the storage rack near the entry site to the sonic drill rig 40. The generally “dry” and reliable operation of the sonic HDD process is accomplished thanks to the combination of applying hydraulically-generated down pressure to move the sonic drill head 42 along the drill mast 44, slow rotations of the sonic drill bit 46 and sonic drill rods 48 with the sonic drill head 42, and application of sonic vibrations of up to 150 Hz, specifically applied in many circumstances to be adjusted to a resonant frequency of the sonic drill rods 48.
(28) During some initial testing of the sonic-powered HDD process conducted by the inventors and referred to above, a generally horizontal bore path located 8 to 10 feet underground was successfully cut along over a 900 foot path length using the sonic drill rig 40, with at least two turns in the bore path as viewed in the example of FIG. 6A. In this testing, the accurate positioning and location of the sonic drill bit 46 was verified in some locations by digging a small trench to locate the current position of the sonic drill bit 46, but this confirmation of sonic drill bit position was only performed in testing because the downhole tracking elements (sonde) are not presently capable of reliably functioning in the context of sonic energy drilling applications. The bore path in testing was cut using sonic drilling and therefore no drilling fluid was necessary for the cutting/boring process. Thus, the use of a sonic powering by a sonic drill rig allows for successful HDD operations without as much equipment and space being necessary. In addition, several problems associated with use of drilling fluids in HDD are avoided, including less environmental damage caused by “frac outs” of drilling fluid at points between the entry and exit points of the desired path, and no issues presented with regard to sourcing the fluid, high consumption rates and recycling of the fluid, and/or freezing of fluids in certain drilling environments. Furthermore, the use of sonic energy causes forward advancement of the sonic drill bit faster than conventional HDD processes and rigs. These increases in speed reduce the overall time each pass of the sonic drill head along the drill mast takes, allowing for quicker installation and drilling of the bore hole.
(29) Each of the sonic drill bit 46, the sonic drill rods 48, the sonic drill casings 49, and sonic drill head 42 in these examples is custom-tailored sonic equipment that is made to withstand the vibrations and use in this setting. For example, the sonic drill bit 46 is threaded onto the sonic drill rods 48 and the sonic drill rods 48 are threaded together with connection threads that can transmit sonic energy and not be disengaged unintentionally by such vibrational energies. The sonic drill bit 46 as shown most clearly in the schematics of FIGS. 5A-5C and 7 includes a front face with carbide cutting tips and a tapered cylindrical profile behind the front face, but it will be appreciated that this sonic drill bit 46 is just one design for accomplishing the sonic HDD process.
(30) In summary, the use of a sonic drill and/or sonic energy assist on a HDD operation greatly improves the efficiency and predictability of using HDD technology for installation of utility line(s). The sonic powered HDD process causes less environmental harm, via both reduced consumption and fouling of water and/or drilling fluid as well as eliminating the risk of frac outs, while avoiding the need for additional equipment and pits at the jobsites associating with handling the drilling fluids. That reduces the space required while also lowering costs and makes drilling jobsites safer overall. The sonic powered HDD process successfully and quickly penetrates through many different types of underground formations and transitions between formations that may be encountered, especially along particularly long desired bore paths. With at least these technical benefits in combination, utility and drilling companies can better predict costs and timing of projects so as to avoid unnecessary disruptions to project timelines and the local area around the installation site.
(31) While the invention has been illustrated by a description of various embodiments, and while these embodiments have been described in considerable detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope of the Applicant's general inventive concept.
