Reverse action auger

The present invention provides an improved auger for use in drilling holes in the earth. The auger has a helical flight which is wound in a direction opposite to the normal direction of rotation of the auger. Thus an auger which is to be rotated in a clockwise manner has its flight directed in a counterclockwise manner. As the auger enters the earth with its clockwise rotation the tailings created thereby encounter a downhole force created by the reverse flight and they are forced outwardly from the auger so that they enter natural fissures or porous zones of the earth along the wall of the hole. No tailings reach the surface of the earth to create environmental problems. When water is used, as in drilling deeper as for seismic exploration, the water and tailings enter the wall of the hole and create a form of cement which prevents wall collapse. Drilling is faster and more economical, with fewer breakdowns, than with conventional augers.

The present invention relates in general to the drilling of the earth and 
in particular to an improved auger for such drilling. 
BACKGROUND OF THE INVENTION 
It is conventional to use an auger when drilling into the earth whether the 
hole to be produced is shallow as for a post hole, or deep, as for a well 
or for seismic exploration. For such conventional drilling the flight of 
the auger has its helix oriented in the same direction as the rotation of 
the auger. Thus a drill or auger which rotates in the clockwise direction 
has a right-hand or clockwise flight. With this type of conventional auger 
the flight tends to pull the auger down into the earth and the material 
(tailings) removed from the hole is forced up the auger to the surface by 
the flight. If the auger becomes clogged by the material it is necessary 
to lift the auger from the hole for cleaning. As the hole becomes deeper 
and/or dense material such as clay is encountered it becomes progressively 
more difficult to remove the auger for cleaning. Also the hole wall tends 
to continuously collapse, making removal of the auger more difficult, 
making drilling more difficult or possibly resulting in a broken auger. 
When drilling bore holes for seismic exploration or when drilling deeper, 
as for a well, it is conventional to use a drill string made up of a 
plurality of lengthsdrilling mud passes downwardly through the drill 
string to the drill bit secured to the downhole end of the lowermost drill 
steel so as to lubricate and cool the drill bit and to help carry the 
tailings upwardly to the surface. The same problems resulting from 
clogging of the auger, as discussed above, apply to drill strings as well. 
When drilling for seismic exploration or for wells there is an even greater 
problem, represented by the talings and mud brought to the surface by the 
auger. The tailings and mud are distributed about the hole on the surface 
and are considered to be unacceptable by many enviromental protection 
agencies or groups. The tailings and mud, especially if chemically treated 
as is often the case, can damage lakes and streams. Chemically treated mud 
can also leak into underground streams unknown to the operators, and if 
the streams discharge into lakes or rivers it is often impossible to 
determine the sorurce of the pollution. A large sub-industry has developed 
recently solely for the purpose of cleaning up drilling sites and this of 
course increases greatly the cost of a drilling operation. 
SUMMARY OF THE INVENTION 
The present invention overcomes the problems enumerated above by providing 
a drill steel or auger in which the flight is directed oppositely to the 
direction of auger rotation. Thus in the present invention an auger or 
drill steel which rotates in a clockwise direction has a left-hand, or 
counter-clockwise flight. 
Such an auger at first appears to be unworkable since the flight is 
applying forces which would tend to remove the auger from the hole. 
However, when dealing with a drill string, for example, which has a 
separate bit at the downhole end, it is in fact the bit, rather than the 
flight, which cuts into the earth. A downhole directed weight is applied 
by the drill rig and hence the drill string will enter the earth and will 
bore a hole as desired. Water may be forced down the hollow drill string 
as in conventional drilling to exit at the bit, keeping the bit cool and 
lubricated. The water mixes with the tailings in the vicinity of the drill 
bit, as is conventional. However, the reversed flight now applies 
essentially a downhole force to the tailings and, since they cannot move 
upwardly in the hole they are in fact forced in a generally radial 
direction against the walls of the hole. The tailings and the mud created 
thereby under the back (downhole) pressure created by the flight are 
forced into the natural fissures, cracks or porous zones of the 
surrounding earth and the surrounding earth absorbs both the water and the 
tailings or mud. Nothing reaches the surface. 
The present invention provides many advantages over the prior art. When the 
water and tailings are forced in to the material surrounding the hole a 
strong tight wall of a consistency not unlike cement is created. This 
greatly reduces the tendency towards collapse of the bore wall, which 
collapse would trap a conventional drill steel causing it to break. Should 
the bore wall collapse with the present invention the reversed flight 
would try to screw the drill string out of the hole. By doing this the 
forces created actually crush the collapsed material reducing the partical 
size and making it easier for that material to be forced back into the 
bore wall. Drilling can then continue without fear of drill steel 
breakage. 
Most importantly, as indicated above, no tailings or mud reach the surface. 
This of course means that every hole will be clean at the surface and 
there will be no environmental problems. Also it is not necessary to use 
chemically treated water and the amount of water required is considerably 
less since recirculation to the surface is avoided. 
During drilling the bit and drill steel will encounter layers of different 
density and porosity. When drilling in unconsolidated material the 
porosity is high and the tailings are coarse. However the high porosity 
means that the coarser tailings are readily accepted. Similarly in granite 
or other consolidated material where the porosity is less the tailings 
will be very fine and may still enter the surrounding material to form a 
solid bore wall. 
In summary of the above, therefore, the present invention may be broadly 
defined as providing an auger for use in drilling into the earth under 
rotative movement in one direction of rotation, the auger having a helical 
flight extending from one end to the other, the flight being defined as a 
helix winding in a direction opposite to said one direction of rotation. 
Additionally, the present invention defines a length of drill steel for use 
in drilling into the earth under rotative movement in one direction, the 
drill steel comprising: an elongated cylindrical drill stem having means 
at each end for connecting the drill steel to adjacent lengths of drill 
steel or to a drill bit, and a helical auger flight extending from one end 
of the drill stem to the other end thereof, the flight being secured to 
the outer surface of the drill stem and winding therealong in a direction 
opposite to said one direction of rotation.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 of the drawings shows the reverse action auger 10 of the present 
invention in terms of its constituent components. The auger 10 is 
illustrated as made up of a stem pipe 12 typically cut to the appropriate 
length from 2 inch diameter 4041 hot rolled tubing and having a wall 
thickness of 0.375 inches. This leaves a central bore along the tubing in 
the order of 11/4 inches. At each end the stem pipe is provided with means 
for attaching each length of pipe to an adjacent length, a coupler or a 
drill bit. Typically a box end fitting will be provided at each end of the 
stem pipe, the box end 14 for the upper end having a female failing thread 
16 and the box end 18 for the lower end having a male failing thread 20. 
The box ends are also formed (machined) from 2 inch diameter X 0.375 inch 
wall 4041 hot rolled tubing so as to smoothly mate with the stem pipe 
itself. The box ends are in turn welded into the drill stem pipe 12 to 
establish the full length of the auger. Lengths of 3, 5, 10 or 15 feet are 
conventional. 
The significant component of the auger of the present invention is the 
reverse action flight 22 which, as is seen in FIG. 1 is wrapped down the 
pipe in a direction opposite to the direction of pipe rotation as shown by 
the arrow A. The flight is made from 1/2 by 1/4 inch flat bar stock 
wrapped and welded in a spiral manner along and to the outer surface of 
the stem pipe in what is shown as a left hand helix. It is suggested that 
the helix be formed on 4 inch centers although that dimension is not 
critical. 
A mechanism for drill stem breakout has not been shown but it is understood 
that any of the accepted types, such as the Sewel or the Top drive, could 
be used. 
FIG. 2 shows a drill string 24 made up of a plurality of individual stem 
pipes or lengths of drill steel. The scale of FIG. 2 is expanded with 
respect to the drill string and compressed with respect to the earth 
formations to aid in full comprehension of the processes involved. 
The drill string 24 is connected at the top to a drill rig (not shown) 
which applies rotative torque to achieve clockwise rotation as shown by 
the arrow A, and which also applies a downhole force to the drill string 
and thereby to the rotary bit 26 connected to the downhole end of the 
lowermost length of drill steel. The rig also pumps water down through the 
hollow interior of the drill string 24 (arrows B), the water exiting 
through appropriate openings or holes 28 in the drill bit 26 (arrows C) at 
the bottom of the hole. So far everything is completely conventional. 
As the drill string rotates clockwise (arrow A) the water issuing from the 
drill bit (arrows C) encounters a high back pressure (arrows D) caused by 
the reverse thrust of the flight 22. There is very little clearance 
between the outer edge of the flight and the bore hole wall since the 
diameter of the drill bit is substantially equal to the overall diameter 
of the auger and hence there is little chance for the tailings or residue 
created by the drill bit to work their way upwardly past the flights. As a 
result of the back pressure generated by the flights the tailings and 
water are forced into natural fissures or porous zones in the earth 
formaton (arrows E) and the porosity of the formations absorbs both the 
water and the tailings. This action creates a tight wall in the earth 
formations along the bore wall having a consistency not unlike cement 
which tends to prevent any collapsing of the bore wall. An unchecked wall 
collapse could trap a drill string in the hole causing fracture of the 
string as it rotates and binds in the collapsed material. With the present 
invention, even if there should be a collapse of the wall, the reverse 
action flights would tend to try to screw the drill string out of the 
hole, alleviating the forces which would tend to break a conventional 
drill string since the conventional drill string would still be trying to 
advance into the hole. Furthermore, the action of the reverse flight in 
effect further crushes any collapsed material making it finer and thus 
making it easier for the finer crushed material to be forced into the wall 
of the hole. Drilling can continue as if no collapse had occurred. 
One particular advantage to the present invention as seen from FIG. 2 is 
that there is little or no chance for tailings to reach the surface, a 
problem as enumerated previously with conventional drilling systems. Even 
if tailings and water do migrate up the bore hole they will be constantly 
subjected to the downhole forces applied by the reverse action flights and 
eventually they will encounter a formation of sufficient porosity to 
accept them. Also, the longer the tailings remain in the borehole the more 
they will be crushed by the flights and the easier it will be for the 
crushed tailings to enter natural fissures in the earth formations. Since 
no tailings reach the surface the ecological damage to the environment is 
absolutely minimized, the drilling area being unscarred by tailings and/or 
mud. Also, since there is no cleanup required when drilling is complete 
the overall costs are reduced, making the drilling operation more 
economical. When the operator is ready to leave the drill site all he has 
to do is plug the hole (conventional) and move on to the next site. 
Experiments with an auger according to the present invention have shown its 
worth. For example, in a 12 hour shift using conventional right-hand 
augers, a crew is considered efficient if 25 to 30 seismic exploration 
holes of about 60 feet in depth can be produced. Using augers in 
accordance with the present invention (left-hand augers) the same crew was 
able to produce over 65 seismic exploration holes in a 12 hour shift. Thus 
it is seen that by avoiding the problems associated with conventional 
augers it is possible to greatly increase the drilling efficiency and to 
benefit as well from the environmental advantages obtainable therewith. 
FIGS. 2 and 4 are intended to show the other components which are 
conventionally known and are used with the present invention. FIG. 3 shows 
a drill string 30 made up of a plurality of lengths 32 of drill steel made 
in accordance with the present invention each having a reverse action 
flight 22. These lengths are typically 5, 10 or 15 feet in length and the 
flights are oriented such that the lower end of one flight will run 
smoothly into the upper end of the flight of the subjacent drill steel 
when the two steels are firmly mated together. At the top a "cheater" 
length of 3 feet is used, the cheater taking up the space between the rig 
and the surface of the ground, thereby making the depth of the hole easy 
to calculate by adding up the lengths of drill steel used. The cheater 
also takes the main downhole wear and is cheaper to replace than other 
longer lengths. 
Item 36 is a coupler which is used only if an oversize drill bit, such as 
38 is used. For example, if a normal 31/2 inch diameter bit is used, a 
coupler is not required. However, if a 41/2 inch diameter bit is used than 
a coupler such as 36 would be inserted between the bit 38 and the 
lowermost end of the downhole drill steel. The drill bits of course are 
commercially available standard bits. 
Should a drill string become trapped in the hole (less likely with the 
present invention than with conventional augers) then an overshot as shown 
in FIG. 4 would be used. First of all the string would be reverse rotated 
to break the connection between the trapped steel and the untrapped string 
portion. In this regard, should a length become trapped the action of the 
auger according to the present invention makes it very easy to break a 
connection since, when trapping does occur the string tends to screw 
itself out of the hole and no additional forces are applied to the 
threaded connections between adjacent lengths of drill steel. With 
conventional augers when a length becomes trapped the continued rotation 
tends to drive the string deeper into the hole and this has the effect of 
tightening the threaded connections, making it more difficult to break the 
connection between the trapped length and the rest of the drill string. 
When the untrapped length of drill steel has been removed from the hole an 
overshot as shown in FIG. 4 is connected to the lowermost end of the 
untrapped length. The overshot is essentially a coupler, such as 40, 
having a female box thread 42 in one end thereof and a male threaded 
member, such as a tap 44 at the other end thereof. An annular plate 43 is 
welded to the coupler body 41 intermediate the ends thereof and a helical 
spring member 46, having a right hand thread is welded to the coupler body 
41 and the plate 43 so as to extend downwardly below the overshot 40. The 
spring 46 has a constant diameter along its length and its inside diameter 
is slightly greater than the outside diameter of an auger flight. In use 
the overshot member 40 is connected via the thread 42 to the male thread 
of the lowermost length of untrapped steel and is lowered into the bore 
hole. The spring 46 will engage and center itself around the outer edge of 
flight 22 of the uppermost end of the trapped length and thus centers the 
overshot 40 with respect to the trapped drill steel. Continued downward 
movement brings the tap into engagement with the female box end of the 
trapped length and rotation of the drill string allows the tap to thread 
itself into the uppermost end of trapped steel so that a stong connection 
is made. The trapped length can then be pulled from the hole. 
In the event that loose soil or soft ground has fallen from the wall of the 
bore hole during the process of retrieving the trapped length, such debris 
will pass outward between the coils of the spring 46 as it rotates 
downwardly into the bore hole. 
It is understood that the foregoing description provides the best mode of 
effecting the present invention, but that variations therein could occur 
to a skilled person in the art. For example while the invention has been 
described in terms of drill steel having an auger flight applied to a 
hollow drill stem it is clear that the advantages of the present invention 
would also accrue to other augers such as those used for the preparation 
of post holes, wherein a solid central shaft is used. The reverse action 
of the auger flight would force the dug earth outwardly so that it is 
compacted against or enters into the earth surrounding the hole, thereby 
eliminating the tailings which would otherwise accumulate at the surface. 
Such tailing are especially burdensome to the person drilling holes in a 
lawn since the tailings if left for a day or so can destroy the grass, and 
since the homeowner usually does not have a disposal site for the tailings 
close to hand. These problems would be eliminated by an auger constructed 
with a reverse flight in accordance with the present invention. Thus the 
protection to be afforded the present invention should be determined from 
the claims appended hereto.