DRILLING ROD AND DRILLING METHOD
A drill rod for reverse circulation drilling, the drill rod including a first outer tube having an first end adapted to receive a rotational force to transfer the rotational force to the first drill bit and a second end adapted to receive a first drill bit, and a first inner tube adapted to be inserted in the outer tube to define an annulus to allow fluid flow from the first end of the outer tube to the second end of the outer tube, the inner tube having a first end and a second end, the second end being adapted to receive a second drill bit, wherein the inner tube is releasably inserted within the outer tube. An inner string for a drill rod, and method for casing a borehole also are disclosed.
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This application claims the benefit of Australian Patent Application No. 2012905255, filed on Dec. 3, 2012, the disclosure of which is incorporated herein in its entirety by reference.
TECHNICAL FIELDThe present invention relates to methods and apparatus for drilling boreholes.
The invention has been devised particularly, although not necessarily solely, in relation to methods and apparatus for conducting reverse circulation drilling.
BACKGROUND ARTThe following discussion of the background art is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgement or admission that any of the material referred to is or was part of the common general knowledge as at the priority date of the application.
Air rotary drilling methods are used to create in relative short periods of times boreholes in the ground. Reverse drilling is an example of an air drilling method.
Reverse drilling (RC drilling) is typically used for recovering samples from the ground into which the borehole is drilled. This method uses a hollow rod that has an inner tube fitted inside it. The air is delivered to a bit through a side entry swivel and through a gap between the drill rod and inner tube (also called annulus). The samples of the soil that is being drilled are delivered via the air to the surface. The samples pass through the centre of the bit into the inner tube for delivery to the surface. At the surface the samples are passed through a top swivel and into a cyclone where the samples are separated from the air. The advantages of RC drilling is that it is possible to obtain accurate samples from the bottom of the borehole that are not contaminated by the side walls of the hole which have been drilled. This is because the sample is delivered to the surface via the inner tube.
Typically, after having drilled the hole it desirable to obtain a representation of the stratigraphic formation of the ground into which the hole has been drilled. The stratigraphic formation of the ground is conducted by lowering into the hole a probe to analyse the composition of the soil of the side walls of the hole.
Prospecting of the side walls of the borehole to obtain a representation of the stratigraphic formation of the ground is typically conducted by extracting the outer rod and the inner tube from the borehole after the borehole has been drilled. After the extraction of the outer rod and the inner rod the borehole needs to be cased. This can be done via a casing such as a tube which is lowered into the hole after removal of the drill rod (the inner tube and the outer tube).
Typically, casing a borehole is a cumbersome process. This is particularly true in view that to design a appropriate casing it is necessary to take into account, for example, the subsurface data such as formation pressures, strengths and makeup of the subsurface.
It is against this background that the present invention has been developed.
SUMMARY OF INVENTIONAccording to a first aspect of the invention there is provided a drill rod for reverse circulation drilling, the drilling rod comprising an outer tube having an upper end adapted to receive a rotational force to rotate the outer tube and a lower end adapted to receive the drill bit to transfer the rotational force to the drill bit and in fluid communication with the drill bit, and an inner tube adapted to be inserted in the outer tube, wherein the inner tube is releasably attached within the outer tube.
Preferably, the inner tube being in fluid communication with the drill bit,
Preferably, the inner tube comprises first and second end portions, the first and second end portions comprising means to centre the inner tube within the outer tube. This allows to locate the inner tube coaxially with respect to the outer tube.
Preferably, the means to centre the inner tube within the outer comprises a plurality of protrusions extending radially outward from the circumference of the first and second end portions. In this manner, the arrangement of protrusions defines a spacer which allows defining an annulus between the inner tube and the outer tube. The annulus being in fluid communication with the drill bit to provide fluid such as air to the bottom of the borehole that is being drilled.
Preferably, the protrusions are arranged in a spaced apart arrangement around the circumference of first end second end portions such as to define a plurality of clearances, each of the clearances being located between neighbouring protrusions. The clearances allow fluid flow longitudinally within the annulus defined between the outer tube and the inner tube.
In one arrangement there are two clearances located opposite to each other and two vertical flat surfaces located opposite to each other, the two clearances being located between neighbouring protrusions and the two flat surfaces located between neighbouring protrusions.
Preferably, the flat surfaces are adapted to be gripped by jaws of a gripping tools such as a spanner tool. This allows applying a rotational force to the inner tube as well as holding and moving the inner tube.
Preferably, each protrusion protrudes substantially perpendicularly from the circumference of the end portions defining first and second surfaces which extend radially outward from the circumference of the end portions.
Preferably, the first surface comprises a horizontal surface and the second surface comprises an inclined surface.
Preferably, the horizontal surface comprises a flat surface, adapted to support the jaws of the gripping tool. This allows holding and moving longitudinally the inner tube within the outer tube.
In a particular arrangement there are a plurality of inner tubes adapted to be attached together to define an extended inner tube adapted to be received by an extended outer tube comprising a plurality of outer tubes adapted to be attached together to define the extended outer tube.
Preferably, each of the first end portions of each inner tube comprises means for attaching the second end portions of an inner tube adjacent to the each inner tube.
Preferably, the first end portion comprises a female junction and the second end portion comprises a male junction adapted to be received by the female junction.
Preferably, the female junction comprises an inner thread and the male junction comprises an outer thread for screwing the female and male junction together after insertion of a portion of the male junction into a portion of the female junction.
In a particular arrangement, the drill rod comprises a first inner tube adapted to be attached within the outer tube at the bottom of the borehole.
Preferably, the first inner tube is adapted to receive the extended inner tube which is releasably attached within the outer tube.
Preferably, the drill rod further comprises first and second end portions adapted to be attached to each other, the second end portion being adapted to be attached to the first inner tube and the first end portion being adapted to be attached to the extended inner tube which is releasably attached within the outer tube.
Preferably, the first and second end portions are adapted to be releasably attached to each other.
Preferably, the first and second end portions are adapted such that a relative large force needs to be applied in order to attach (or unattach) the first and second end portions together.
Preferably, the first and second end portions comprise means to impede rotational movement between the second end portion and the first end portion.
Preferably, the means to impede rotational movement comprise at least one leg extending from the first end portion and a plurality of lugs located in a spaced apart relationship around the second end portion defining a lug arrangement, the lug arrangement being adapted to receive the at least one leg.
According to a second aspect of the invention there is provided an inner tube of a drill rod for reverse circulation drilling, the inner tube being adapted to be releasably inserted in an outer tube, wherein the inner tube comprises first and second end portions, the first and second end portions comprising means to centre the inner tube within the outer tube.
Preferably, the means to centre the inner tube within the outer tube comprises a plurality of protrusions extending radially outward from the circumference of the first and second end portions of the inner tube.
Preferably, the protrusions are arranged in a spaced apart arrangement around the circumference of first end second end portions such as to define a plurality of clearances, each of the clearances being located between neighbouring protrusions.
In one arrangement there are there are two clearances located opposite to each other and two vertical flat surfaces located opposite to each other, the two clearances being located between neighbouring protrusions and the two flat surfaces located between neighbouring protrusions.
Preferably, the flat surfaces are adapted to be gripped by jaws of a gripping tool such as a spanner tool.
Preferably, each protrusion protrudes substantially perpendicularly from the circumference of the end portions defining first and second surfaces which extend radially outward from the circumference of the end portions.
Preferably, the first surface comprises a horizontal surface and the second surface comprises an inclined surface.
Preferably, the horizontal surface comprises a flat surface, adapted to support the jaws of the gripping tool.
According to a third aspect of the invention there is provided an end portion for an inner tube for a drill rod for reverse circulation drilling, the inner tube being adapted to be releasably inserted in an outer tube, wherein the end portion comprises means to centre the inner tube within the outer tube.
Preferably, the means to centre the inner tube within the outer tube comprises a plurality of protrusions extending radially outward from the circumference of the end portion.
Preferably, each protrusion protrudes substantially perpendicular from the circumference of the end portion defining first and second surfaces which extend radially outward from the circumference of the end portion.
Preferably, the first surface comprises a horizontal surface and the second surface comprises an inclined surface.
In an arrangement, the end portion comprises a female junction comprising an open end having an inner thread.
In an alternative arrangement, the end portion comprises a male junction having an open end comprising an outer thread adapted to screw onto the thread of the inner thread of the female junction.
Preferably, in the arrangement of the female junction the horizontal surface defined by the protrusions faces towards the open end having the inner thread.
Preferably, in the arrangement of the male junction the inclined surface defined by the protrusions faces towards the open end having the outer thread.
Preferably, the male junction comprises an extended portion adapted to be received by the open end of the female junction. The extended portion facilitates alignment of the female and male junction prior screwing of the male and female junction.
According to a fourth aspect of the invention there is provided a junction for joining first and second tubes, the junction comprising first and second end portions adapted to be attached to each other, the second end portions being adapted to be attached to the first tube and the first end portion being adapted to be attached to the second tube which is releasably attached within the outer tube.
Preferably, the second tube comprises the inner tubes in accordance with the second aspect of the invention.
Preferably, the first and second end portions are adapted to be releasably attached together.
Preferably, the first and second end portions are adapted such that a relative large force needs to be applied in order to attach (or unattach) the first and second end portions to each other.
Preferably, the first and second end portions comprise means to impede rotational movement between the second end portion and the first end portion.
Preferably, the means to impede rotational movement comprise at least one leg extending from the second end portion and a plurality of lugs located in a spaced apart relationship around the first end portion, the lugs defining a lug arrangement being adapted to receive the at least one leg.
According to a fifth aspect of the invention there is provided a tool comprising a handle and a head attached to the handle, the head comprising an indentation adapted to receive a tube, the indentation having an inner edge comprising a flange which at least partially surrounds the inner edge, wherein the flange is adapted to receive a first surface of at least one protrusion protruding from the circumference of a tube to secure the tube to the tool.
Preferably, the tube comprises the inner tube in accordance with the second aspect of the invention.
Preferably, the indentation is adapted to receive the at least one protrusion of the tube to allow application of a rotational force to the tube
According to a sixth aspect of the invention there is provided a drill rod for reverse circulation drilling, the drilling rod comprising a first outer tube having an first end adapted to receive a rotational force to transfer the rotational force to the first drill bit and a second end adapted to receive a first drill bit, and a first inner tube adapted to be inserted in the outer tube to define an annulus to allow fluid flow from the first end of the outer tube to the second end of the outer tube, the inner tube having a first end and a second end, the second end being adapted to receive a second drill bit, wherein the inner tube is releasably inserted within the outer tube.
Preferably, the drill rod further comprises a coupling for transferring the rotational force to the second drill bit, the coupling adapted to releasably couple the first inner tube to the first outer tube.
Preferably, the coupling comprises a drive sub and a driven gear, the drive sub being releasably attached to the first outer tube and the driven gear being releasably attached to the first inner tube, the drive sub being adapted to releasably couple the inner tube to the outer tube
Preferably, the drive sub is releasably attached to the first end of the first outer tube and the driven gear being releasably attached to the first end of the first inner tube.
Preferably, the drill rod further comprising a seal between the second end of outer tube and the second end of the inner tube to impede fluid from exiting the annulus and the second end of the inner tube comprising at least one port to allow fluid to flow from the annulus into the inner tube to form a vacuum so as to transport soil samples into the inner tube to a location distal from the first and second drill bits.
Preferably, the at least one port comprises an angled port to direct the fluid in a direction opposite to the first and second drill bits.
Preferably, the first inner tube comprises a protruding structure to centre the inner tube within the outer tube.
Preferably, the centring structure comprises a plurality of protrusions extending radially outward from the circumference of the first and second ends, the protrusions being arranged in a spaced apart arrangement around the circumference of the first end second ends.
Preferably, the drill rod further comprises a plurality of clearances between neighbouring protrusions and a plurality of surfaces between neighbouring protrusions, the clearances being located opposite to each other and the surfaces being located opposite to each other.
Preferably, the drill rod further comprises further comprising a plurality of second inner tubes adapted to be sequentially attached to each other and to the driven gears, and a plurality of second outer tubes adapted to be sequentially attached to each other and to the drive sub.
Preferably, each of the second inner tubes comprises the centring structure for centring the inner tube within the outer tube.
According to a seventh aspect of the invention there is provided an inner string of a drill rod for reverse circulation drilling, the inner string comprising an inner tube, the inner tube being adapted to be releasably inserted in an outer tube, the inner tube and the outer tube defining an annulus between the inner and outer tube.
Preferably, the inner tube comprises first and second ends, the first and second ends comprising centring structure for centring the inner tube within the outer tube,
Preferably, the drill string further comprises driven gear having an end attached to the first end of the inner tube, the driven gear being adapted to receive a rotational force from the outer tube for rotation of a drill bit attached to the second end of the drill bit.
Preferably, the driven gear is adapted to releasably couple the inner tube to the outer tube.
Preferably, the drill string further comprises at least one additional inner tube comprising a centring structure for centring the inner tube within an outer tube, the driven gear having an opposite end attached to the additional inner tube.
Preferably, the second end of the inner tube comprises at least one port to allow fluid to flow from the annulus into the inner tube to define a vacuum at a location adjacent the second end of the inner tube.
Preferably, the at least one port comprises an angled port.
According to an eight aspect of the invention there is provided a drill rod for reverse circulation drilling, the drill rod comprising a first outer tube having an first end adapted to receive a rotational force to transfer the rotational force to the first drill bit and a second end adapted to receive a first drill bit; a first inner tube adapted to be inserted in the outer tube to define an annulus to allow fluid flow from the first end of the outer tube to the second end of the outer tube, the inner tube having a first end and a second end, the second end being adapted to receive a second drill bit; and a seal means between the second end of outer tube and the second end of the inner tube to impede fluid from exiting the annulus and the second end of the inner tube comprising at least one port to allow fluid to flow from the annulus into the inner tube to form a vacuum so as to transport soil samples into the inner tube to a location distal from the first and second drill bits.
Preferably, the at least one port comprises an angled port to direct the fluid in a direction opposite to the first and second drill bits.
According to a ninth aspect of the invention there is provided a drill rod for reverse circulation drilling, the drill rod comprising a first outer tube having an first end adapted to receive a rotational force to transfer the rotational force to the first drill bit and a second end adapted to receive a first drill bit; a first inner tube adapted to be inserted in the outer tube to define an annulus to allow fluid flow from the first end of the outer tube to the second end of the outer tube, the inner tube having a first end and a second end, the second end being adapted to receive a second drill bit; and a coupling for transferring the rotational force to the second drill bit, the coupling adapted to releasably couple the first inner tube to the first outer tube, wherein the coupling is releasably attached to the inner and outer tubes.
Preferably, the coupling comprises a drive sub and a driven gear, the drive sub being releasably attached to the first outer tube and the driven gear being releasably attached to the first inner tube, the drive sub being adapted to releasably couple the inner tube to the outer tube
Preferably, the drive sub is releasably attached to the first end of the first outer tube and the driven gear being releasably attached to the first end of the first inner tube.
According to an tenth aspect of the invention there is provided a drill rod, the drill rod comprising a first outer tube having an first end adapted to receive a rotational force to transfer the rotational force to the first drill bit and a second end adapted to receive a first drill bit, and a first inner tube adapted to be releasably inserted within the outer tube.
According to an eleventh aspect of the invention there is provided a drill rod for reverse circulation drilling, the drilling rod comprising a first outer tube having an first end adapted to receive a rotational force to transfer the rotational force to the first drill bit and a second end adapted to receive a first drill bit; a first inner tube adapted to be inserted in the outer tube to define an annulus to allow fluid flow from the first end of the outer tube to the second end of the outer tube, the inner tube having a first end and a second end, the second end being adapted to receive a second drill bit; and a seal means between the second end of outer tube and the second end of the inner tube to impede fluid from exiting the annulus and the second end of the inner tube comprising at least one port to allow fluid to flow from the annulus into the inner tube to form a vacuum so as to transport soil samples into the inner tube to a location distal from the first and second drill bits.
Preferably, the at least one port comprises an angled port to direct the fluid in a direction opposite to the first and second drill bits.
According to an twelfth aspect of the invention there is provided a method for casing a borehole after drilling thereof, the method comprising the steps of:
-
- inserting at least one first inner tube in an outer tube having a lower end adapted to receive a first drill bit, the inner tube having a lower end adapted to receive a second drill bit;
- releasably coupling the inner tube to the outer tube to transfer rotational force from the outer tube to the second drill bit;
- drilling the borehole using the outer tube incorporating the inner tube; and
- extracting the inner tube from the outer tube.
Preferably, the method further comprises the steps of inserting a pipe within the outer tube and extracting the outer tube.
Further features of the present invention are more fully described in the following description of several non-limiting embodiments thereof. This description is included solely for the purposes of exemplifying the present invention. It should not be understood as a restriction on the broad summary, disclosure or description of the invention as set out above. The description will be made with reference to the accompanying drawings in which:
In accordance with the present embodiment of the invention, there is provided a drill rod 10 to conduct, for example, RC drilling. The drill rod 10 comprises an inner tube 12 and an outer tube 14. The inner tube 12 is adapted to be inserted in the outer tube 14 to define an annulus 16 (see
Referring to
The ports 120 traverse the wall 122 of the inner tube 12 in such a manner that the air flow forms a vacuum at the bit face. This vacuum allows lifting of the soil samples. In the arrangement shown in
Furthermore, there is provided seal means for impeding the air from flowing through the gap defined between the drill bit of the outer tube 14 and the inner tube 12. The seal means close the gap between the drill bits 92 and 94 so as to direct the air through the ports 122 and into the inner tube 12.
We refer now to
In an alternative arrangement, instead of maintaining the outer string rod 13 within the borehole to maintain the integrity of the borehole it is possible to insert a pipe 90 (see
The inner string rod 11 comprises (1) a plurality of inner tubes 12 sequentially attached as shown in
Further, the inner string 11 is rotatably coupled to the outer string rod 13. This allows simultaneous rotation of the inner string rod 11 and the outer string rod 13 during drilling of the borehole. In an arrangement in accordance with the present embodiment of the invention, the rotational force is transferred from the swivel of the drilling rig to the outer string rod 13 and the outer string rod 13 transfers the rotational force to the inner string rod 11. The rotational force is transferred via a coupling.
In a particular arrangement, the coupling comprises a drive sub 96 and a driven gear 98. The drive sub 96 and the driven gear 98 are adapted to be attached, respectively, to the upper end of the first outer tube 14a and the upper end of the first tube 12a. Furthermore, the drive sub 96 and the driven gear 98 are adapted to be coupled together so as to transfer the rotational force from the outer string 13 to the inner string 11.
The drive sub 96 comprises a cylindrical body. The cylindrical body comprises an end having an inner threaded and an opposite end having an exterior thread. The end having the inner thread is adapted to be attached to the upper end of the first outer tube 14a. The opposite end is adapted to be either (1) rotatably attached to the swivel for rotation of the drive sub 96 and the first outer tube or (2) attached to the additional outer tube 14b (see
The driven gear 98 comprises a cylindrical body adapted to be attached to the upper end of the first inner tube 12a. The cylindrical body comprises an end having an inner threaded and an opposite end having an exterior thread. The end having the outer thread is adapted to be attached to the upper end of the first inner tube 12a. The opposite end is adapted to be attached to the second additional outer tube 12b (see
The driven gear 98 comprises a plurality of protrusions 106 arranged in a spaced apart relationship around the outer circumference of the first inner tube 14. The protrusions 106 are adapted to be received by the locking area 104 of the drive sub 96 of the first outer tube 14a.
As mentioned earlier, the drive sub 96 is adapted to be coupled to the driven gear 98 of the first inner tube 12a to transfer the rotational force. The drive sub 96 is also adapted to enable uncoupling of the driven gear 98 to allow extraction of the inner string 11 from the outer string 13 after completion of the drilling process.
The coupling is accomplished when the first inner tube 12a is inserted into the first outer tube 14a. As the inner tube 12a is inserted into the outer tube 14a the protrusions 106 slide into the channels 102. To couple the inner tube 12a and outer tube 14a, the protrusions 106 are received by the locking area 104 of the drive sub 96. This is accomplished, by rotating the inner tube 12a so that the protrusions 106 are driven into the locking area 104. To uncouple the inner tube 12a from the outer tube 14a, the inner tube 12a is rotated—in the opposite direction than during the coupling process—so as to extract the protrusions 106 from the locking area 104 and the channels 102. In this manner, the inner tube 12a may be selectively coupled and uncoupled from the outer tube 14a.
Preferably, the drive sub 96 and the driven gear 98 are screwed, respectively, onto the upper end of the first outer tube 14a and the upper end of the first inner tube 12a. In this preferred arrangement the drive sub 96 and driven gear 98 are located at a location relatively distal to the drill bits 92 and 94. For example, the drive sub 96 and driven gear 98 are located at a distance of 4 meters from the drill bits 92 and 94. The fact that the drive sub 96 and driven gear 98 are located distal to the drill bits 92 and 94 avoids contamination of the drive sub 96 and driven gear 98 during the drilling process.
We refer now to
Referring now to
Referring back to
As shown in
The second section 38 comprises an area having a plurality of protrusions 44. The protrusions 44 are arranged in a spaced apart arrangement around the circumference of the end portions 20 and 22. Each of the protrusions 44 extends radially outward from the circumference of the end portions 20 and 22. In the particular arrangement shown in the figures, the protrusions 44 extend beyond the circumference of the opened ends 24 and 26 such that the protrusions 44 are adapted to centre the inner 12 within the outer tube 14. In this manner, the arrangement of protrusions 44 defines a protruding structure to centre the inner 12 within the outer tube 14 defining the annulus 16 located between the inner tube 12 and the outer tube 14.
Further, the protrusions 44 are configured and arranged around the circumference of the opposite end 32 such that at least two clearances 46 are defined between the protrusions 44. In the particular arrangement shown in the figures, there are two clearances 46a and 46b located opposite to each other and there are defined two flat surfaces 48 between adjacent protrusions. The flat surfaces 48 are also opposite with respect to each other (see
Referring back to
As will be described with respect to the method of operation of the drill rod 10 in accordance with the present embodiment of the invention, the flat surface 50 facilitates holding and moving longitudinally the inner tube within the outer tube 12. This allows extraction of the inner tube 12 from the outer tube 14 as well as holding the inner tube 12 to avoid the inner tube 12 from falling into the outer tube 14 during, for example, joining of the inner tubes 12.
The flat surface 50 of the female end 20 faces opposite to the open end 24 of the female end 20. The flat surface 50 of the male end 22 faces opposite to the open end 26 of the male end 22. This particular arrangement of the flat surfaces 50 and 52 guarantees that both surfaces 50 and 52 faces towards the bottom of the hole. This is particularly advantageous in view that it allows, as mentioned earlier, holding and moving longitudinally the inner tube within the outer tube 12.
Holding and moving the inner tube 12 as well as joining inner tubes 12 together is accomplished via a snapper tool 60 (see
As mentioned above, the end portions 20 and 22 allows joining together inner tubes 12 to extend the overall length of the inner tube 12 as the drilling progresses and the depth of the borehole increases.
In particular,
As was explained before, in accordance with the present embodiment of the invention, the inner tubes 12 may be extracted from the outer tube 14. This is particularly advantageous in view that it allows the outer tube 14 to function as a casing for the borehole to allow prospecting probes to be lowered into the borehole. The process of extracting the inner tubes 12 is accomplished, for example, by grabbing the inner tubes 12 with the snapper tool and raising the inner tube 12 out of the outer tube 14. In a particular arrangement, the inner tubes 12 may be grabbed by the jaws 62 of the snapper tool 60 at the first section 26 adjacent the flat surface 50 of either the female end 20 or male end 22. In this manner, the flat surface 50 provides a support surface facilitating extraction of the inner tubes 12 when force is applied to the snapper tool 60 to move longitudinally the inner tube 12 out of the outer tube 14.
In particular,
As shown in
Furthermore, the indentation 66 comprises a flange 68. In the particular arrangement shown in the
We refer now to
The drilling process starts by drilling the earth surface using the first and inner rod 12a and 14a. However, typically boreholes require to be of considerable more depth than the length of the inner and outer tube 12a and 14a. To drill boreholes of considerable more depth than the length of the inner and outer tube 12a and 14a it is necessary to join additional drilling rods 12 and 14 so as to extend the drilling string 11 and 13. The process of joining additional rods 12 and 14 is know as running the drill string into the well hole (also called borehole).
The running of the drill string into the well hole or the extracting of the drill string out of the well hole is performed using a tower-like structure (also called derrick). The derrick is located adjacent to the well hole during running of the drill string into the well hole
Typically, the derrick extends vertically from the well hole. The derrick comprises the drilling lines, pulleys and apparatus that allow running and extracting the drill string into and out of the well hole. The derrick also comprises the swivel for applying torque to the drill bits during drilling of the well hole.
Extending the length of the drill string is accomplished by detaching the upper end of the drill string from the swivel which provides the torque to the drill strings 11 and 13 formed by the inner and outer rods 12 and 14 that are within the borehole.
Prior detachment of the drill pipe from the swivel the drill string is fastened to the rotary table to impede that the drill string falls into the well hole. This is accomplished via a spanner 108 which extends perpendicularly from the derrick to the drilling string formed by the inner and outer rods 12 and 14. The spanner 105 is adapted to be displaced between a contracted condition and an extended condition. In the extended condition the spanner 105 secures the drill string to the rotary table 110.
After detachment of the drill string (defined by the inner and outer string 11 and 13) from the swivel, the swivel is lifted up along the derrick in order to add an additional inner and outer tubes 12 and 14 to the drill string. Lifting the swivel allows separating the swivel from the upper end of the drill string. This allows creating a clearance between the swivel and the upper end of the drill string to locate additional inner and outer tubes 12 and 14 to the upper end of the drill string. At this stage the additional outer rod 14—incorporating the additional inner rod 12—is located parallel to the derrick and lifted such that the additional inner and outer rods 12 and 14 are located above the tubes 12 and 14 to which the additional tubes 12 and 14 to be attached.
In order for the outer rod 14—incorporating the inner rod 12—be lifted without the inner rod 12 falling out of the outer rod it is necessary to temporary fasten the inner rod 12 to the outer rod 13. This accomplished via a threaded bracket 112—see
Referring now back to
Once the desired depth of the borehole has been reached the inner string 11 may be extracted from the outer string 13. This is accomplished by raising the inner string and separating the inner tubes 12 from each other—see
To separate the inner tubes 12 from each other, the inner string needs to be secured to the rotary table. This accomplished via the spanner 108 and an accessory spanner 113. The accessory spanner 113 is adapted to be mounted on the spanner 108—see
After removal of the inner string 11, the outer string 13 may be left inside the borehole. Alternatively, as was mentioned earlier, a pipe 90 may be introduced into the outer string and the outer string 13 may be extracted from the borehole in such a manner that the pipe 90 remains within the borehole. In an arrangement, the pipe 90 is kept as within the borehole acting as a casing to, for example, conduct analysis of the composition of the earth formation traversed by the borehole or for further drilling operation to extract, for example, core samples from the earth formation by lowering a core drill through the pipe 90 for generating a core sample. This is particular useful during diamond drilling.
In the previously described particular arrangement the inner string is releasably attached within the outer string.
In particular, the first inner tube 12a of the inner string is releasably coupled to the drive sub 96 to allow transfer of rotational force from the outer string 13 to the inner string 11. Alternatively, the first inner tube 12a may be fixed to the outer tube 14a.
In the particular arrangement shown in
The junctions 70 and 72 are adapted to be attached together in order to join the inner tube 12a and the inner tube 12 together. The junctions 70 and 72 comprise internal seals which are adapted so that a relative large force is required to push the male junction 72 into the female junction 70. This arrangement impedes that the female and male junctions 70 and 72 be pulled apart easily. Also, the male junction 72 comprises lugs 74 and 76 defining a lug arrangement which stops the male junction 72 from turning when a rotational force is applied, for example, to the inner tubes 12b and 12c during assembly of the extended inner tube 12. This allows the junctions 20 and 22 to be tightened with a relative large force.
The male junction 72 comprises a first section 82 and a second section 84. The first section 82 is of reduced diameter with respect to the second section 84. The second section 84 is adapted to receive the second portion 78 of the female junction 70. And, as mentioned before, there are provided seals adapted so that relative large force is required to join together the female and male junctions 70 and 72 together.
Further, the male junction 72 comprises legs 80a and 80b which extend from the second section 84. The legs 80 are adapted to be received between the lugs 74 of the female junction 70. This can be seen in
Referring back to
Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention.
Further, it should be appreciated that the scope of the invention is not limited to the scope of the embodiments disclosed.
Throughout this specification, unless the context requires otherwise, the word “comprise” or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.
Claims
1. A drill rod for reverse circulation drilling, the drill rod comprising a first outer tube having an first end adapted to receive a rotational force to transfer the rotational force to the first drill bit and a second end adapted to receive a first drill bit, and a first inner tube adapted to be inserted in the outer tube to define an annulus to allow fluid flow from the first end of the outer tube to the second end of the outer tube, the inner tube having a first end and a second end, the second end being adapted to receive a second drill bit, wherein the inner tube is releasably inserted within the outer tube.
2. A drill rod according to claim 1 further comprising a coupling for transferring the rotational force to the second drill bit, the coupling adapted to releasably couple the first inner tube to the first outer tube.
3. A drill rod according to claim 2 wherein the coupling comprises a drive sub and a driven gear, the drive sub being releasably attached to the first outer tube and the driven gear being releasably attached to the first inner tube, the drive sub being adapted to releasably couple the inner tube to the outer tube
4. A drill rod according to claim 3 wherein the drive sub is releasably attached to the first end of the first outer tube and the driven gear being releasably attached to the first end of the first inner tube.
5. A drill rod according to claim 1 further comprising a seal between the second end of outer tube and the second end of the inner tube to impede fluid from exiting the annulus and the second end of the inner tube comprising at least one port to allow fluid to flow from the annulus into the inner tube to form a vacuum so as to transport soil samples into the inner tube to a location distal from the first and second drill bits.
6. A drill rod according to claim 5 wherein the at least one port comprises an angled port to direct the fluid in a direction opposite to the first and second drill bits.
7. A drill rod according to claim 1 wherein the first inner tube comprises a protruding structure to centre the inner tube within the outer tube.
8. A drill rod according to claim 7 wherein the protruding structure comprises a plurality of protrusions extending radially outward from the circumference of the first and second ends, the protrusions being arranged in a spaced apart arrangement around the circumference of the first end second ends.
9. A drill rod according to claim 8 further comprising a plurality of clearances between neighbouring protrusions and a plurality of surfaces between neighbouring protrusions, the clearances being located opposite to each other and the surfaces being located opposite to each other.
10. A drill rod according to claim 3 further comprising a plurality of second inner tubes adapted to be sequentially attached to each other and to the driven gears, and a plurality of second outer tubes adapted to be sequentially attached to each other and to the drive sub.
11. A drill rod according to claim 10 wherein each of the second inner tubes comprises the protruding structure for centring the inner tubes within the outer tubes.
12. An inner string of a drill rod for reverse circulation drilling, the inner string comprising an inner tube, the inner tube being adapted to be releasably inserted in an outer tube, the inner tube and the outer tube defining an annulus between the inner and the outer tube.
13. An inner string according to claim 12 wherein the inner tube comprises first and second ends, the first and second ends comprising a protruding structure for centring the inner tube within the outer tube,
14. An inner string according to claim 12 further comprising a driven gear having an end attached to the first end of the inner tube, the driven gear being adapted to receive a rotational force from the outer tube for rotation of a drill bit attached to the second end of the drill bit.
15. An inner string according to claim 14 wherein the driven gear is adapted to releasably couple the inner tube to the outer tube.
16. An inner string according to claim 14 further comprising at least one additional inner tube comprising a protruding structure for centring the additional inner tube within an additional outer tube, the driven gear having an opposite end attached to the additional inner tube.
17. An inner string according to claim 12 wherein the second end of the inner tube comprises at least one port to allow fluid to flow from the annulus into the inner tube to define a vacuum at a location adjacent the second end of the inner tube.
18. An inner string according claim 17 wherein the at least one port comprises an angled port.
19. A method for casing a borehole after drilling thereof, the method comprising the steps of:
- inserting at least one first inner tube in an outer tube having a lower end adapted to receive a first drill bit, the inner tube having a lower end adapted to receive a second drill bit;
- releasably coupling the inner tube to the outer tube to transfer rotational force from the outer tube to the second drill bit;
- drilling the borehole using the outer tube incorporating the inner tube; and
- extracting the inner tube from the outer tube.
20. The method according to claim 19 further comprising the steps of inserting a pipe within the outer tube and extracting the outer tube.
Type: Application
Filed: Dec 3, 2013
Publication Date: Jun 12, 2014
Applicant:
Inventor: Harley Bruce HOLLIER (Kalgoorlie)
Application Number: 14/095,719
International Classification: E21B 17/00 (20060101);