Patent Application
20250230721
This invention relates to geotechnology, and to mining and exploration in the fields of oil, gas, water, and mining. In particular, this invention relates to ground drilling.
The following discussion of the background art is intended to facilitate an understanding of the present invention only. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge as at the priority date of the application.
Various rotary and percussion drilling methods have been adopted and remain in use for the drilling of water wells, oil and gas drilling, mineral exploration, geotechnical and geothermal wells using both single circulation and dual circulation drill string configurations. These drilling methods use either water, drilling mud or fluid (liquid), or compressed air. In the case of mineral exploration, a common down hole tool for drilling medium to hard rocks comprises a down hole air operated hammer of either conventional or reverse circulation type, coupled with single or dual circulation drill strings respectively.
In some cases, down hole hammers are powered by high pressure air and in others, powered by water or a drilling liquid. In the case of reverse circulation air powered hammers commonly used in mineral exploration, the drill cuttings generated while using high pressure air pass through the hammer via a central inner tube and are delivered to surface through dual tube drill rods via an inner tube inside the drill string. An example of this technology is described in U.S. Pat. No. 4,819,746A, which discloses a reverse circulation hammer used in mineral exploration using high pressure air to power the hammer, and to remove drill cuttings through a dual tube drill string, where drill cuttings are removed from the bit face through an inner tube within the drill string.
Oil and gas wells are usually drilled using the single circulation mud rotary method as distinct from air percussion methods or dual circulation methods. Oil and gas drill strings consist of conventional single tube drill rods where drilling liquids or muds are pumped downwards through the drill string and cuttings delivered to surface via the well annulus between the drill pipe and drill hole.
Flooded Mud Dual Circulation Drilling (at times referred to as DTFR drilling) is widely used to drill larger diameter geotechnical holes and water wells. The flooded mud systems currently in use do not use fluid hammers to drill, adopting rotary methods only. A dual tube drill string is used where mud in the well annulus is ideally kept full or level with the ground surface whilst drilling. Drilling mud from the well annulus proximal to the bit face is drawn into the drill-string inner tube by the introduction of compressed air into the drill string inner tube through an air injection sub located above the drill bit. Compressed air introduced into the air injection sub creates a vacuum effect at the bit face, thus forcing drill cuttings into the inner tube for delivery to the surface through the drill string inner tube.
Where very hard rock is encountered, both conventional single circulation mud rotary and flooded mud reverse circulation rotary methods become slow and expensive. Fluid or water powered fluid percussion hammers increase penetration rates in hard rocks markedly however their use has been limited to shallow or relatively narrow wells or drill holes due to the design limitations of drill strings currently in use.
Fluid hammers currently in use are either conventional single flow fluid hammers—using single tube drill strings—or dual flow fluid hammers using dual circulation drill strings, respectively. In the case of conventional single circulation fluid hammers, drilling fluid or mud is pumped through the single tube drill pipe and through the hammer, exiting at the bit face, with cuttings delivered to surface via the well annulus.
In the case of dual circulation fluid hammers used with dual circulation drill strings, the hammer is powered by fluid pumped through a first flow path chamber between the drill pipe inner wall and the inner tube exterior wall. Cuttings are removed via the drill hole annulus with the assistance of additional fluid pumped separately through a second flow path, that is, directly down the inner tube, with the fluids from both flow paths combining at the bit face and drill cuttings delivered to surface through the well annulus. U.S. Ser. No. 14/976,641 teaches such a dual circulation fluid hammer drilling system.
In this specification, the term fluid hammer is used to describe a down hole hammer powered by a liquid, to avoid possible confusion with a down hole hammer powered by compressed air. The term “fluid” is used to describe a “liquid”, as opposed to a gas. The term water hammer used herein means a liquid or fluid powered hammer, so that the terms water hammer and fluid hammer used within this application are interchangeable and refer to the same apparatus, that is, a liquid powered hammer, as distinct from an air powered hammer.
Additionally, water when used to power a hammer may contain lubricants or certain additives to enhance hammer performance, whereupon the water may then be described as a fluid, with the term water hammer perhaps then being referred to as a fluid hammer. For the avoidance of doubt any reference herein to a water hammer or a fluid hammer shall be deemed to refer to a hammer powered by a liquid, as distinct from a hammer powered by air and any application described herein using compressed air shall be referred to as air, gas, or compressed air, as distinct from the use of the term fluid to denote air when describing a flow path through which air flows or is introduced.
The use of the word “mud” in this document shall refer to the drilling fluid pumped through a drill string and present in any drill hole or well annulus during drilling operations, commonly referred to in the industry as mud
Throughout the 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.
All of the arrangements described above are challenged in situations where the cuttings have a high specific gravity or where the drilling operation is conducted in hard rock types or at greater depth or where the removal of cuttings through the well annulus in large diameter holes is constrained. It is an object of the invention to provide a drill assembly that can overcome such problems, or at least provide greater efficiency in normal drilling operations than hitherto known drill assemblies.
In accordance with one aspect of the present invention there is provided a drill assembly having at least one or preferably a plurality of drill rods connectable in series, and having a cuttings conduit to evacuate drill cuttings therealong, a liquid passage to transport drilling liquid therealong, and a gas passage to transport gas therealong; said drill rods having connectors connecting said cuttings conduit, said liquid passage, and said gas passage between connected said drill rods and maintaining fluid separation of said cuttings conduit, said liquid passage, and said gas passage from each other;
Preferably each of said drill rods comprises an outer drill rod body with a proximal connector at one end and a distal connector at an opposite end, said drill rods being connectable in a string by said proximal connector of one said drill rod and said distal connector of another said drill rod to form a connection between each of said drill rods; said connection connecting said cuttings conduit, said liquid passage, and said gas passage between connected said drill rods and maintaining separation of said cuttings conduit, said liquid passage, and said gas passage from each other.
Preferably said gas injector sub-assembly has an outer sub-assembly body with a proximal sub-assembly connector at one end and a distal drill assembly connector at an opposite end; said gas injector sub-assembly being connectable by said proximal sub-assembly connector to a said distal connector of said string to form a gas injector sub-assembly connection; said gas injector sub-assembly connection connecting said sub-assembly cuttings conduit with said cuttings conduit, said sub-assembly liquid passage with said liquid passage, and said sub-assembly gas passage with said gas passage, and maintaining separation of said cuttings conduit and said liquid passage from each other; said distal drill assembly connector communicating said sub-assembly cuttings conduit and said sub-assembly liquid passage with respective drill assembly cuttings and liquid connections.
Preferably said gas passage includes at least one spacer with a plurality of apertures therein, located between an inner wall extending around said cuttings conduit and an inside of a concentric wall extending around said inner wall defining said gas passage; and said liquid passage also includes at least one spacer with a plurality of apertures therein, located between an outside of said concentric wall and said outer drill rod body.
Preferably said inner wall is expanded at an end of said cuttings conduit, to allow connecting said inner wall of connected drill rods to join by telescoping inner walls.
Preferably said concentric wall is expanded at an end of said cuttings conduit, to allow connecting said connecting wall of connected drill rods to join by telescoping concentric walls.
In accordance with a second aspect of the present invention there is provided a drill assembly having at least one or preferably a plurality of drill rods, each of said drill rods comprising an outer drill rod body with a proximal connector at one end and a distal connector at an opposite end, a cuttings conduit to evacuate drill cuttings therealong, a liquid passage to transport drilling liquid therealong, and a gas passage to transport gas therealong; said drill rods being connectable in a string by said proximal connector of one said drill rod and said distal connector of another said drill rod to form a connection between each of said drill rods; said connection connecting said cuttings conduit, said liquid passage, and said gas passage between connected said drill rods and maintaining fluid separation of said cuttings conduit, said liquid passage, and said gas passage from each other;
Preferably said cuttings conduit extends centrally and coaxially with said outer drill rod body.
Preferably said sub assembly cuttings conduit extends centrally and coaxially with said outer sub-assembly body.
Preferably said entry sub assembly cuttings conduit extends centrally and coaxially with said stator.
Preferably said liquid passage and said gas passage extend longitudinally between said cuttings conduit and said outer drill rod body.
Preferably said sub-assembly liquid passage and said sub-assembly gas passage extend between said sub-assembly cuttings conduit and said outer sub-assembly body.
Preferably said gas passage extends concentrically around said cuttings conduit, and said liquid passage extends concentrically around said gas passage, along the inside of said outer drill rod body.
Preferably said sub-assembly gas passage extends concentrically around said sub-assembly cuttings conduit, and said sub-assembly liquid passage extends concentrically around a part of the length of said sub-assembly gas passage, along the inside of said outer sub-assembly body.
Preferably said gas passage includes at least one spacer with a plurality of apertures therein, located between an inner wall extending around said cuttings conduit and an inside of a concentric wall extending around said inner wall defining said gas passage; and said liquid passage also includes at least one spacer with a plurality of apertures therein, located between an outside of said concentric wall and said outer drill rod body.
Preferably said inner wall is expanded at an end of said cuttings conduit, to allow connecting said inner wall of connected drill rods to join by telescoping inner walls.
Preferably said concentric wall is expanded at an end of said cuttings conduit, to allow connecting said connecting wall of connected drill rods to join by telescoping concentric walls.
In accordance with a third aspect of the present invention there is provided at least one or preferably a plurality of drill rods connectable in series, and having a cuttings conduit to evacuate drill cuttings therealong, a liquid passage to transport drilling liquid therealong, and a gas passage to transport gas therealong; said drill rods having connectors connecting said cuttings conduit, said liquid passage, and said gas passage between connected said drill rods and maintaining fluid separation of said cuttings conduit, said liquid passage, and said gas passage from each other.
Preferably each of said drill rods comprises an outer drill rod body with a proximal connector at one end and a distal connector at an opposite end, said drill rods being connectable in a string by said proximal connector of one said drill rod and said distal connector of another said drill rod to form a connection between each of said drill rods; said connection connecting said cuttings conduit, said liquid passage, and said gas passage between connected said drill rods and maintaining separation of said cuttings conduit, said liquid passage, and said gas passage from each other.
Preferably said cuttings conduit extends centrally and coaxially with said outer drill rod body.
Preferably said liquid passage and said gas passage extend longitudinally between said cuttings conduit and said outer drill rod body.
Preferably said gas passage extends concentrically around said cuttings conduit, and said liquid passage extends concentrically around said gas passage, along the inside of said outer drill rod body.
Preferably said gas passage includes at least one spacer with a plurality of apertures therein, located between an inner wall extending around said cuttings conduit and an inside of a concentric wall extending around said inner wall defining said gas passage; and said liquid passage also includes at least one spacer with a plurality of apertures therein, located between an outside of said concentric wall and said outer drill rod body.
Preferably said inner wall is expanded at an end of said cuttings conduit, to allow connecting said inner wall of connected drill rods to join by telescoping inner walls.
Preferably said concentric wall is expanded at an end of said cuttings conduit, to allow connecting said connecting wall of connected drill rods to join by telescoping concentric walls.
In accordance with a fourth aspect of the present invention, there is provided, in a drill assembly having at least one or preferably a plurality of drill rods connectable in series, and having a cuttings conduit to evacuate drill cuttings therealong, and a liquid passage to transport drilling liquid therealong: a gas passage to transport gas therealong; said drill rods having connectors connecting said cuttings conduit, said liquid passage, and said gas passage between connected said drill rods and maintaining fluid separation of said cuttings conduit, said liquid passage, and said gas passage from each other;
Preferably each of said drill rods comprises an outer drill rod body with a proximal connector at one end and a distal connector at an opposite end, said drill rods being connectable in a string by said proximal connector of one said drill rod and said distal connector of another said drill rod to form a connection between each of said drill rods; said connection connecting said cuttings conduit, said liquid passage, and said gas passage between connected said drill rods and maintaining separation of said cuttings conduit, said liquid passage, and said gas passage from each other.
Preferably said gas injector sub-assembly has an outer sub-assembly body with a proximal sub-assembly connector at one end and a distal drill assembly connector at an opposite end; said gas injector sub-assembly being connectable by said proximal sub-assembly connector to a said distal connector of said string to form a gas injector sub-assembly connection; said gas injector sub-assembly connection connecting said sub-assembly cuttings conduit with said cuttings conduit, said sub-assembly liquid passage with said liquid passage, and said sub-assembly gas passage with said gas passage, and maintaining separation of said cuttings conduit and said liquid passage from each other; said distal drill assembly connector communicating said sub-assembly cuttings conduit and said sub-assembly liquid passage with respective drill assembly cuttings and liquid connections.
Preferably said gas passage includes at least one spacer with a plurality of apertures therein, located between an inner wall extending around said cuttings conduit and an inside of a concentric wall extending around said inner wall defining said gas passage; and said liquid passage also includes at least one spacer with a plurality of apertures therein, located between an outside of said concentric wall and said outer drill rod body.
Preferably said inner wall is expanded at an end of said cuttings conduit, to allow connecting said inner wall of connected drill rods to join by telescoping inner walls.
Preferably said concentric wall is expanded at an end of said cuttings conduit, to allow connecting said connecting wall of connected drill rods to join by telescoping concentric walls.
In accordance with a fifth aspect of the present invention, there is provided a method of drilling a bore hole comprising providing a drill assembly having at least one or preferably a plurality of drill rods connectable in series, each of said drill rods having a cuttings conduit connectable in series to evacuate drill cuttings therealong, a liquid passage connectable in series to transport drilling liquid therealong, and a gas passage connectable in series to transport gas therealong; said drill rods having connectors connecting said cuttings conduit, said liquid passage, and said gas passage between connected said drill rods and maintaining fluid separation of said cuttings conduit, said liquid passage, and said gas passage from each other;
Preferably, in said method, each of said drill rods comprises an outer drill rod body with a proximal connector at one end and a distal connector at an opposite end, said drill rods being connectable in a string by said proximal connector of one said drill rod and said distal connector of another said drill rod to form a connection between each of said drill rods; said connection connecting said cuttings conduit, said liquid passage, and said gas passage between connected said drill rods and maintaining separation of said cuttings conduit, said liquid passage, and said gas passage from each other.
Preferably, in said method, said gas injector sub-assembly has an outer sub-assembly body with a proximal sub-assembly connector at one end and a distal drill assembly connector at an opposite end; said gas injector sub-assembly being connectable by said proximal sub-assembly connector to a said distal connector of said string to form a gas injector sub-assembly connection; said gas injector sub-assembly connection connecting said sub-assembly cuttings conduit with said cuttings conduit, said sub-assembly liquid passage with said liquid passage, and said sub-assembly gas passage with said gas passage, and maintaining separation of said cuttings conduit and said liquid passage from each other; said distal drill assembly connector communicating said sub-assembly cuttings conduit and said sub-assembly liquid passage with respective drill assembly cuttings and liquid connections.
Preferably, in said method, said gas passage includes at least one spacer with a plurality of apertures therein, located between an inner wall extending around said cuttings conduit and an inside of a concentric wall extending around said inner wall defining said gas passage; and said liquid passage also includes at least one spacer with a plurality of apertures therein, located between an outside of said concentric wall and said outer drill rod body.
Preferably, in said method, said inner wall is expanded at an end of said cuttings conduit, to allow connecting said inner wall of connected drill rods to join by telescoping inner walls.
Preferably, in said method, said concentric wall is expanded at an end of said cuttings conduit, to allow connecting said connecting wall of connected drill rods to join by telescoping concentric walls.
In accordance with a sixth aspect of the present invention, there is provided a method of drilling a bore hole comprising providing a drill assembly having a drill rig rotary head located outside said bore hole, driving a drill string having a drilling component at a distal end thereof, said drill string being formed of a plurality of drill rods connectable in series as drilling proceeds; injecting liquid from a first rotary connector located proximal to said drill rig rotary head, through a liquid passage along said drill string to drill assembly; ejecting cuttings from said drill assembly through a cuttings conduit extending along said drill string; injecting gas under pressure through a second rotary connector located proximal to said drill rig rotary head, through a gas passage along said drill string to a location adjacent to said drill assembly proximal to the end of said drill string where said gas under pressure is introduced into said cuttings conduit to assist in evacuating the cuttings and liquid slurry along said cuttings conduit.
In all of the above described arrangements the cuttings conduit evacuates cuttings from the drilling component, up the drill string formed by the drill rods to be delivered usually to the surface of the drilling operation, counter current to the liquid and gas which are delivered via the liquid passage and the gas passage respectively down the drill string. The drilling component may be a drill bit or a drill bit with a hammer mechanism, and the liquid is delivered to the drill bit, where cuttings are entrained and evacuated toward the entry of the sub-assembly cuttings conduit and/or the cuttings conduit.
The liquid may be a drilling fluid such as a drilling mud or may be water, which is pumped down the liquid passage.
The gas may be air, particularly supplied under pressure/as compressed air, which is supplied down the gas passage. The compressed air is introduced into the cuttings being evacuated from the drilling component, through ports connecting the gas passage to the cuttings conduit in the gas injector sub-assembly (connecting the sub-assembly gas passage to the sub-assembly cuttings conduit), from where it assists in lifting the drilling cuttings up the cuttings conduit, and assists in drawing the cuttings from the cutting surfaces of the drilling component.
Generally, the drilling component is of a greater diameter than the diameter of the drill string (the diameter of each drill rod or the diameter of the cuttings conduits), resulting in an anulus around the drill string (the well annulus), which would normally be flooded with water/mud during the drilling operation.
The invention provides a triple tube drill rod system comprising one or more drill rods which when coupled together form a drill string having three separate fluid paths, each performing a specific function.
The up-hole end of the drill string is attached to a drill rig rotary head having a hollow spindle and the down hole end the drill string is attached to the drilling component, which may be either a reverse circulation rotary drill bit, reverse circulation hole opening bit assembly, a conventional water or fluid hammer or a reverse circulation water or fluid hammer.
The triple tube, triple circulation drill string according to the invention has advantages over existing single circulation or dual circulation drill string systems, including but not limited to more rapid penetration rates in hard rocks and more effective removal of drill cuttings, especially in large diameter wells where rapid and effective removal of cuttings can occur through the cuttings conduit/drill string inner tube when assisted by compressed air pumped into the sub-assembly injector cuttings conduit in the gas injector sub-assembly. The combination of high-pressure water ejected at the drill bit face plus the vacuum effect created by compressed air pumped into the gas injector sub-assembly, assisted by static pressure from mud or drilling fluid in the annulus surrounding the outer drill bodies (between the bored hole and the drill string) acting downwards, results in highly effective cuttings removal through the cuttings conduits of the serially joined drill rods.
While it is most preferred that the gas passage is arranged concentrically around the central cuttings conduit, and the liquid passage is arranged concentrically around the gas passage, in an alternative embodiment the liquid passage could be arranged concentrically around the central cuttings conduit, and the gas passage could be arranged concentrically around the liquid passage. In further alternative arrangements separate multiple ducts may be provided for the liquid passages and/or separate multiple ducts may be provided for the gas passages. For reasons of balance primarily, it is most preferred that the cuttings conduit is arranged centrally within the drill rods.
In order to provide a better understanding, preferred embodiments of the present invention will be described, by way of example only, with reference to the accompanying drawings, in which:
Referring to
In
Referring to
Above the drill rig rotary head 41 (see
The invention resides in the arrangements provided in the entry sub-assembly 39, the drill rods 33, and the gas injector sub-assembly 27. The arrangements of the drill body 15 and drill bit 11 located below the gas injector sub-assembly 27, and the drill rig rotary head 41, air blow-down injector 43, and deflector assembly 45 located above the entry sub-assembly 39, are conventionally used in normal ground and rock drilling.
Referring to
Referring to
The drilling assembly has initially one drill rod 33, and as drilling proceeds, a number of drill rods 33 connected together. Referring generally to
Referring to
The coaxial tube 57 forming the separation between the gas passage 61 and the liquid passage 59 has a male fitting 63 at the top forming part of the proximal connector 35 and a female connector 65 with embedded o-ring seals 67 at the bottom forming part of the distal connector 31. The o-ring seals 67 seal the gas passage 61 from the liquid passage 59.
Referring also to
The arrangement of the o-ring seals 67 and 73 in the respective tube joins maintains fluid separation of the cuttings conduit 49, gas passage 61, and liquid passage 59, from each other. The connectors 69 and 71, and 63 and 65 provide for passage of drill cuttings, gas, and drilling liquid between connected drill rods 33.
Referring to
Drilling liquid, such as water is pumped down from the entry sub-assembly 39 liquid passage, through the connected drill rods 33 liquid passages 59 and through the gas injector sub-assembly 27 liquid passage 93, from where is proceeds to the drill bit 11.
The gas injector sub-assembly 27 proximal sub-assembly connector 85 is configured the same as the proximal connector 35 of the drill rods 33, so as to be connectable to the distal connector 31 of a drill rod 33, while maintaining fluid separation of the cuttings conduit gas passage and liquid passage from each other, and allowing passage of gas and drilling liquid from the connected drill rod 33 to the gas injector sub-assembly 27.
The distal drill assembly connector 87 is configured to attach to the drill body 15 and drill bit 11 (or percussive hammer mechanism as the case may be). The distal drill assembly connector 87 also includes embedded o-ring seals 101 in a female end 103 of the cuttings conduit 51 to seal the cuttings conduit from the liquid passage 93.
Referring to
Referring to
The housing 115 is in two parts, secured together by bolts 125 and nuts 127 spaced circumferentially around a flange formed in the separate parts of the housing 115. O-ring seals 129 seal off the rotating parts 131 of the entry sub-assembly 39 from the housing 115, in order to contain gas forced under compression into the gas inlets 117.
Still referring to
In the housing 115 of the entry sub-assembly 39, extending around circumferentially and connecting with the gas inlets 117 is a circumferential gas passage 139. Four ducts 141 are located in the rotating parts 131 to communicate gas under pressure from the circumferential gas passage 139 to the gas passage 135.
Referring also to
Referring also to
O-ring seals 159 are provided on a boss 161 located on the top of the coaxial tube 133 in order to provide a seal between the liquid passage 143 and the gas passage 139.
O-ring seals 163 are provided on a boss 165 located on the outside of the wear tube pipe 107, to seal off the gas passage 135 at the top of the entry sub-assembly 39.
The embodiment shown in
The embodiment shown in
The embodiment shown in
When compared to conventional single flow fluid hammers, the use of the entry sub-assembly 39, the drill rods 33 and the gas injector sub-assembly 27 of the invention has the advantage of allowing clean drilling fluid to be specifically directed to power a fluid hammer 181 independently of the other fluid paths, thus minimising abrasion and wear normally resulting from the use of more abrasive recycled drilling mud as used in single flow fluid systems when coupled to a fluid hammer.
The embodiment shown in
When used with a hole opening assembly 191, the entry sub-assembly 39, the drill rods 33 and the gas injector sub-assembly 27 of the invention provides advantages including but not limited to more rapid and effective cuttings removal via the drill string central cuttings conduit due to the combined simultaneous effect of high pressure fluid exiting at the drill bit faces together with compressed air pumped down from into the entry sub-assembly 39, and through the drill rods 33 to the gas injector sub-assembly 27, where the compressed air is injected entrained cuttings in the cuttings conduit, and static downward pressure from drilling fluid in the upper and lower annulus 201 and 199 forcing cuttings into and through the centre of the hole opening device and through the drill string central inner tube to surface. This compares advantageously with prior art arrangements single or dual flow drill string systems when drilling large diameter holes, which require considerably more fluid volume, time and energy to remove drill hole cuttings via the well annulus.
In all of the above described arrangements the central cuttings conduit evacuates cuttings from the drilling component, up the drill string formed by the drill rods to be delivered to the surface of the drilling operation, counter current to the liquid and gas which are delivered via the liquid passage and the gas passage respectively down the drill string. The drilling component may be a drill bit or a drill bit with a hammer mechanism, and the liquid is delivered to the drill bit, where cuttings are entrained and evacuated toward the entry of the sub-assembly cuttings conduit and/or the cuttings conduit.
The liquid may be a drilling fluid such as a drilling mud or may be water, which is pumped down the liquid passage.
The gas may be air, particularly supplied under pressure/as compressed air, which is supplied down the gas passage. The compressed air is introduced into the cuttings being evacuated from the drilling component, through ports connecting the gas passage to the cuttings conduit in the gas injector sub-assembly (connecting the sub-assembly gas passage to the sub-assembly cuttings conduit), from where it assists in lifting the drilling cuttings up the cuttings conduit, and assists in drawing the cuttings from the cutting surfaces of the drilling component.
Generally, the drilling component is of a greater diameter than the diameter of the drill string (the diameter of each drill rod or the diameter of the cuttings conduits), resulting in an anulus around the drill string (the well annulus), which would normally be flooded with water/mud during the drilling operation. This provides a static downward pressure, which assists in moving drill cuttings toward the cuttings conduit.
The invention provides a triple tube drill string system comprising one or more drill rods which when coupled together form a drill string having three separate fluid paths, each performing a specific function.
The up-hole end of the drill string is attached to a drill rig rotary head having a hollow spindle and the down hole end the drill string is attached to the drilling component, which may be either a reverse circulation rotary drill bit, reverse circulation hole opening bit assembly, a conventional water or fluid hammer or a reverse circulation water or fluid hammer.
The triple tube, triple circulation drill string according to the invention has advantages over existing single circulation or dual circulation drill string systems, including but not limited to more rapid penetration rates in hard rocks and more effective removal of drill cuttings, especially in large diameter wells where rapid and effective removal of cuttings can occur through the cuttings conduit/drill string inner tube when assisted by compressed air pumped into the sub-assembly injector cuttings conduit in the gas injector sub-assembly. The combination of high-pressure water ejected at the drill bit face plus the vacuum effect created by compressed air pumped into the gas injector sub-assembly, assisted by static pressure from mud or drilling fluid in the annulus surrounding the outer drill bodies (between the bored hole and the drill string) acting downwards, results in highly effective cuttings removal through the cuttings conduits of the serially joined drill rods.
This triple tube drill string system provides added flexibility when compared to other prior art systems through being able to alter or direct fluid flow for a number of additional applications such as flushing and clearing down-hole blockages by pumping water or drilling fluid directly down the central cuttings conduit or by introducing grout into a well if required. In the event a hammer is in use this allows grouting without the grout having to pass through the hammer internals.
In the event that a well exuding undue pressure at depth requires an injection of high-density mud or drilling fluid to kill the well, or an injection of lost circulation material is required to be pumped into a lost circulation zone, the triple tube drill string system allows the injection of the necessary fluids directly through the central cuttings conduit.
The triple tube drill string system provides rapid delivery of cuttings to the surface through the central cuttings conduit, in both small and large diameter holes when compared to prior art single and dual circulation systems. In prior art systems where cuttings are moved to surface from the bit face outside the drill string via the well annulus, fluid when exiting the bit face under high pressure undergoes a rapid loss of velocity and pressure when exiting the drill string into the well annulus, the well annulus being a much larger cross-sectional area and volume, resulting in the drill cuttings taking longer to reach surface than when the drill cuttings are removed through the central cuttings conduit.
During drill rod connections between downward advances during the drilling process, especially when low viscosity drilling fluid is in use, cuttings produced from each advance are required to be removed from or suspended in the drill hole prior to making connections, otherwise cuttings may settle around the bottom hole assembly and cause the drill string to become stuck. Removal of drill cuttings prior to drill rod connections is faster and more efficient through the triple tube drill string system due to the higher velocity at which cuttings travel to surface through the more confined central cuttings conduit.
The advantages conferred by the triple tube drill string system also apply to current flooded mud dual circulation systems using prior art dual tube drill strings, especially in large diameter and/or deeper wells. The use of the triple tube drill string system provides superior clearance of drill cuttings through the positive flushing at cutting faces from high pressure liquid pumped through the liquid passage of the joined string components, providing more effective clearing of cuttings from the bit or cutting faces when compared to flooded mud dual circulation systems, where no fluid is pumped through the bits or cutting faces. Effective removal of large volumes of, at times, coarse, heavy cuttings is critical and removal thereof more rapid and effective by means of the triple tube drill string system where the liquid passage of the connected components provides positive flushing at the cutting faces of bits and down hole assemblies plus the triple tube drill string system facilitates rapid removal of cuttings through the central cuttings conduit, with lift of the drill cuttings entrained in drilling liquid enhanced by injected air introduced at the gas injector sub-assembly into the central cuttings conduit, which also provides a lower pressure at the drill bit face, assisting in evacuating cuttings therefrom.
It should be appreciated that the scope of the invention is not limited to the specific embodiments described herein, and the skilled addressee will understand that changes may be made to these embodiments without departing from the spirit and scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021903466 | Oct 2021 | AU | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/AU2022/051176 | 10/3/2022 | WO |
