Classifications

• • E—FIXED CONSTRUCTIONS
  • E21—EARTH DRILLING; MINING
  • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B33/00—Sealing or packing boreholes or wells
  • E21B33/10—Sealing or packing boreholes or wells in the borehole
  • E21B33/12—Packers; Plugs
  • E21B33/1208—Packers; Plugs characterised by the construction of the sealing or packing means
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH DRILLING; MINING
  • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B33/00—Sealing or packing boreholes or wells
  • E21B33/10—Sealing or packing boreholes or wells in the borehole
  • E21B33/12—Packers; Plugs
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH DRILLING; MINING
  • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B33/00—Sealing or packing boreholes or wells
  • E21B33/10—Sealing or packing boreholes or wells in the borehole
  • E21B33/13—Methods or devices for cementing, for plugging holes, crevices, or the like
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH DRILLING; MINING
  • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B33/00—Sealing or packing boreholes or wells
  • E21B33/10—Sealing or packing boreholes or wells in the borehole
  • E21B33/13—Methods or devices for cementing, for plugging holes, crevices, or the like
  • E21B33/134—Bridging plugs

Definitions

• the present invention relates to mining, and more specifically blocking off mining exploration drill holes.
• the invention has particular application for blocking off underground diamond drill exploration holes, however the product may also be applied to surface drill holes.
• diamond drill crews begin drilling from the first available underground location to allow geologists to better define the ore body so that the design of the mine can be optimised. Therefore exploration drilling usually occurs in advance of the mine development, and typically the exploration drill holes range from horizontal to downward dipping to delineate the ore body beneath and to the side of the main access.
• packer are available which are similar to the Van Ruth plug in that they are mechanical devices for plugging a drill hole. They are also referred to as Margo plugs in Canada. A packer may be made with a longer stem which would place its rubber anchor further in the hole so that it is less affected by the broken ground at the collar. Even so, the same criticisms apply as to the Van Ruth plug above; it is dangerous to use a packer to protect from rifling when subject to dynamic forces.
• Grout is a term that is used to refer to cementitious slurries used in mining which may cure to a strength similar to that of concrete (harder, but typically more brittle).
• a basic grout may be as simple as a mixture of Portland cement and water.
• Grout is mostly used for ground support in mining which involves anchoring a tendon into a hole that has been drilled in the surrounding rock for stabilisation of the strata above and around mine excavations.
• grouts tend to have additives included in addition to Portland cement, such as plasticisers to increase fluidity and reduce the hydration requirement for curing, accelerators or retarders to reduce or delay curing time, and additives to improve bond strength particularly with reinforcing steel, i.e. ground support elements.
• grout is also used to simply fill voids or prevent high pressure water inflow.
• WC ratio water/cement ratios
• Greater than 0.35 WC ratio gives a runny slurry which needs a grouting technique using a breather tube to bleed the air out.
• Less than 0.35 WC ratio gives a thick grout mix being the consistency of toothpaste in which case the operator slowly withdraws the pump delivery tube as the grout enters the hole.
• the grout with the lower WC ratio will be the stronger one.
• the present invention was developed with a view to providing a plug and method of plugging a mining drill hole that is less susceptible to the disadvantages of the prior art noted above.
• a grout plug for plugging a drill hole in a mine, the plug comprising: an elongate sleeve of porous material adapted to be received in a drill hole; a volume of dry grout material in particulate form contained in the sleeve wherein, in use, when the plug is exposed to water it mixes with the grout material to form a slurry which can seep through the porous sleeve when the plug is tamped into the drill hole to block the drill hole when the grout material cures.
• the porous sleeve is made from a water-absorbent material wherein, in use, the porous sleeve helps maintain a moist environment in the hole during curing by wicking moisture to the grout to assist with curing the grout.
• the porous sleeve is made from a lightweight, biodegradable mesh material.
• the porous sleeve is made from hessian or jute.
• the plug further comprises a liner of water-soluble material, the liner being provided within the porous sleeve for containing the grout material within the porous sleeve in its dry form and wherein, in use, when the plug is exposed to water the liner dissolves.
• the liner is in the form of an inner sleeve made from a thin film of plastics material which is separate from the porous sleeve.
• the sleeve is designed with a curved leading edge for installation to assist in guiding the grout plug into a hole of only marginally larger diameter.
• the grout plug is cylindrical or sausage shaped, and is preferably 600mm in length.
• the grout plug may be of varying outer diameters, but preferably the grout plug has an outer diameter of about 46mm, 58mm, 74mm or 94mm.
• a grout plug for plugging a drill hole in a mine, the plug comprising: an elongate sleeve of porous material adapted to be received in a drill hole; a volume of dry grout material in particulate form; and a liner of water-soluble material, the liner being provided within the porous sleeve for containing the grout material within the porous sleeve in its dry form and wherein, in use, when the plug is exposed to water the liner dissolves and the water mixes with the grout material to form a slurry which can seep through the porous sleeve when the plug is tamped into the drill hole to block the drill hole when the grout material cures.
• the porous sleeve is made from a water-absorbent material wherein, in use, the porous sleeve helps maintain a moist environment in the hole during curing by wicking moisture to the grout to assist with curing the grout.
• the porous sleeve is made from a lightweight, biodegradable mesh material.
• the porous sleeve is made from hessian or jute, which is a low cost, environmentally sustainable material.
• the liner is in the form of an inner sleeve received within the porous sleeve.
• the liner is in the form of an inner sleeve made from a thin film of plastics material which is separate from the porous sleeve.
• the liner is formed integral to the porous sleeve.
• the liner is made from polyvinyl alcohol (PVA) which is a water soluble plastic that dissolves within seconds when immersed in water.
• PVA polyvinyl alcohol
• the grout material is ordinary Portland cement. However, depending on the application various additives may be added to the grout material or cement as required, such as plasticisers, retarders, accelerators, clays, and aggregates.
• the grout material may be comprised chiefly of bentonite clay or other clay, as required.
• the grout plug is cylindrical or sausage shaped, and preferably is 600mm in length.
• a clay plug for plugging a drill hole
• the clay plug comprising: an elongate sleeve of porous material adapted to be received in a drill hole; a volume of dry clay material; a liner of water-soluble material, the liner being provided within the porous sleeve for containing the clay material within the porous sleeve in its dry form; and a substantially solid central core of low permeability, the central core running substantially the length of the plug.
• the central core comprises wood, metal, steel or cured grout.
• the clay material is bentonite or other suitable clay material.
• the clay is typically in particulate form, or other suitable form.
• a method of plugging a drill hole in a mine comprising: filling an elongate sleeve of porous material, adapted to be received in a drill hole, with a volume of dry grout material in particulate form to form a grout Plug; providing one or more of the grout plugs to a mine site ready for use in the event that a drill hole needs to be blocked; immersing one or more of the grout plugs in water for a prescribed time until the water mixes with the grout material to form a slurry; inserting the one or more wetted grout plugs in the drill hole and tamping each grout plug into the drill hole so that some of the grout material squeezes out through the porous sleeve; and allowing the grout material to cure so that the one or more grout plugs block the drill hole.
• the method further comprises the step of maintaining a moist environment in the drill hole during curing by employing a water-absorbent material to make the porous sleeve wherein, in use, the porous sleeve assists with curing the grout by wicking moisture to the grout.
• the method further comprises the step of providing a liner of water-soluble material, the liner being provided within the porous sleeve for containing the grout material within the porous sleeve in its dry form and wherein, in use, when the plug is immersed in water it is allowed to soak for the prescribed time until the liner completely dissolves.
• Figure 1 illustrates a preferred embodiment of a grout plug in accordance with the present invention
• Figure 2 is a cut-away section view of the grout plug of Figure 1 ;
• Figure 3 illustrates a first step in the process of constructing the grout plug of Figure 1 ;
• Figure 4 illustrates a second step in the process of constructing the ⁇
• Figure 5 illustrates how the grout plug in accordance with the present invention can be used to prevent rifling and venting in underground exploration drill holes
• Figures 6 and 7 illustrate a preferred method of installing the grout plugs in accordance with the present invention in a drill hole
• Figure 8 illustrates a second preferred embodiment of a clay plug in accordance with the present invention.
• a preferred embodiment of grout plug 10 in accordance with the invention comprises an elongate sleeve 12 of porous material adapted to be received in a drill hole (see Figure 5).
• the porous sleeve 12 contains a volume of dry grout material 14 in particulate form.
• the plug 10 When the plug 10 is exposed to water it mixes with the grout material 14 to form a slurry which can squeeze through the porous sleeve when the plug is tamped into the drill hole. In this way the grout plug 10 can be used to block the drill hole once the grout material 14 cures.
• the grout plug 10 further comprises a liner 16 of water-soluble material.
• the liner 16 is provided within the porous sleeve 12 for containing the grout material 14 within the porous sleeve 12 in its dry form.
• the liner 16 dissolves and the water mixes with the grout material 14 to form a slurry.
• the slurry can seep through the porous sleeve when the plug 10 is tamped into the drill hole to block the drill hole when the grout material cures.
• the porous sleeve 12 is made from a water-absorbent material wherein, in use, the porous sleeve 12 helps maintain a moist environment in the hole during curing by wicking moisture to the grout material 14 to assist with curing the grout.
• the porous sleeve 12 is made from a lightweight, biodegradable mesh material.
• the porous sleeve 12 is made from hessian or jute, which is a low cost, environmentally sustainable material. In the described embodiment 18oz hessian is employed to make the porous sleeve 12.
• the liner 16 is in the form of an inner sleeve received within the porous sleeve 12.
• the liner 16 is made from a thin film of plastics material which is separate from the porous sleeve 12.
• the liner 16 is formed integral to the porous sleeve 12.
• the liner 16 is made from polyvinyl alcohol (PVA) which is a water soluble polymer that dissolves within seconds when immersed in water.
• PVA polyvinyl alcohol
• the grout material 14 is ordinary Portland cement. However depending on the application various additives may be required such as plasticisers, retarders or accelerators, and aggregates.
• a currently preferred process of manufacturing the grout plugs 10 will now be described with reference to Figures 1 to 4.
• a rectangular, elongate sheet of hessian or jute material 14 is cut and folded in half length ways as shown in Figure 3. Then the open side and one end of the sheet 14 is stitched together along the stitch line 18 as shown in Figure 4.
• the resulting sleeve 12 is turned inside out to conceal the hem.
• the sleeve 12 is designed with a curved leading edge 26 for installation to assist in guiding the grout plug 10 into a hole of only marginally larger diameter.
• the plug 10 still needs to be capable of installation even where the hole may have surface irregularities through deviation or broken ground.
• the PVA liner 16 is formed in a similar way, either by stitching or heat welding along the open side and one end to form an inner sleeve.
• the PVA liner 16 is not turned inside out. Assembly is simple and involves inserting the PVA liner 16 into the hessian or jute sleeve 12 and filling it with the dry grout powder 14 (and the central core if the configuration requires, as discussed below for the second embodiment 40) .
• the grout plugs preferably have a bulk density after filling with grout of 1.5 - 2.5g/cc, more preferably about 1.9g/cc. This is driven by the need for the grout plug to retain its shape for installation, and to maintain a low watencement ratio on immersion. Both sleeves 12 and 16 are then wire tied or cable tied at the open tail end, resulting in the completed grout plug 10 as shown in Figures 1 and 2.
• the completed grout plug 10 is cylindrical or sausage shaped and typically is manufactured in lengths of 600mm, with an outer diameter of about 46mm (allowing a tolerance of about 2mm within a drill hole with 48mm inside diameter, and allowing for bit wear and irregularities within the hole).
• the grout material extrudes through the hessian sleeve 12 to engage more fully with the hole and make up the hole diameter.
• the outer diameter of the porous sleeve 12 may be selected to suit the nominal drill hole size. Colour-coded hessian may be used to clearly identify different diameter plugs for ease of use for the various standard diameter drill holes.
• the grout plugs 10 will nominally be 2mm smaller in diameter than the new bit size for each of the standard sizes shown below, to allow for bit wear.
• the PVA liner 16 may not be in the form of a separate inner sleeve 16 as in the illustrated embodiment.
• the liner 16 could be formed integral to the porous sleeve 2, as a layer on the inside or outside of the sleeve 12 which blocks the pores in the porous hessian material.
• the liner helps to prevent the grout powder, typically Portland cement, from leaking through the pores of the porous sleeve 12.
• the liner 16 could be dispensed with altogether if a degree of leakage of the dry grout material during transport and storage can be tolerated.
• the grout material may be selected to be of a particle size that cannot easily escape through the pores of the porous sleeve 12 in its dry form.
• the method preferably comprises filling an elongate sleeve 12 of porous material, adapted to be received in a drill hole, with a volume of dry grout material 14 in particulate form to form a grout plug 10 as described above.
• One or more of the grout plugs 10 are then provided to a mine site ready for use in the event that a drill hole needs to be blocked.
• Rigidity is provided by using a hessian or jute skin, and leakage of a small amount of grout through this skin during handling is inconsequential in comparison to the advantage gained through maintaining simplicity of use and low cost.
• each grout plug 10 is immersed in water for a prescribed time until the water mixes with the grout material 14 to form a slurry. Soaking the grout plug 10 until the cessation of production of bubbles, generally around 2 - 3 minutes, dissolves the PVA liner 16 and automatically wets the grout to a WC ratio of 0.35, which develops a strong, low shrink grout. This avoids the requirement for mixing.
• PVA is commonly used in the concreting industry and has a documented effect of increasing the strength and decreasing the porosity of the cured product. However for the purpose of this application, the diluted PVA content of the water in which the grout plugs soaks is unlikely to provide any advantage. More importantly it will not be detrimental to the integrity of the cured grout.
• One or more wetted grout plugs 10 is then inserted in the drill hole 20 and each grout plug is tamped into the drill hole so that some of the grout material extrudes or squeezes out through the weave of the porous hessian sleeve 12, as shown in Figures 6 and 7. Tamping is typically done using a rigid plastic tube 24, and is similar to the process used for tamping explosives into a drill hole.
• Tamping it into the drill hole 20 avoids the requirement for pumping, and the time to set up and strip down a grout pump.
• the grout quality does not suffer, and in fact the self wetting aspect of the grout plug removes the human error involved in achieving a certain WC ratio.
• the grout material is then allowed to cure so that the one or more of the grout plugs block the drill hole.
• up to five of the 600mm grout plugs 10 may be tamped into the collar of the drill hole 22 to form a 3m plug.
• the method of the invention further comprises the step of maintaining a moist environment in the drill hole during curing by employing a water-absorbent material to make the porous sleeve 12.
• the porous sleeve 12 assists with curing the grout by wicking moisture to the grout.
• the method may include the further step of providing a liner 16 of water-soluble material as noted above.
• the drill hole 20 is effectively sealed off with a 3m grout plug, being five such sausages tamped into place one behind the other, for the purpose of preventing rifling. Mines would be free to use more or less sausages as the circumstances dictate.
• Curing time is achieved with an initial set at 24 hours, early strength at 7 days and full strength at 28 days. A 7 day cure is sufficient to prevent rifling, although earlier set times may be achieved by using alternate cements.
• the hessian or jute sleeve 12 is economical, environmentally sustainable, and allows some storage of moisture and the wicking of moisture to the grout material 14 to assist with curing the grout.
• the curing of grout is essentially the same as curing concrete. It is assisted by continued hydration, resulting in a stronger end result than if it cures in a dry environment.
• the grout plugs 10 are intended to block exploration drill holes to prevent rifling or venting from blasts at any location along the hole if that hole is intersected at a later date.
• the grout plugs 10 are designed to quickly, efficiently and economically make a mine drill hole safe for these circumstances.
• the grout plugs 10 according to the first embodiment are not intended to completely seal off the hole 20 from the flow of groundwater or gases but may in some instances be able to do this.
• a second embodiment of a clay plug 40 of the invention as illustrated in Figure 8 resembles the first embodiment in many ways and will not be described in detail.
• the clay plug 40 comprises an elongate sleeve 42 of porous material containing a volume of clay material 44 which in this instance is bentonite clay (although other clays may also be suitable).
• the clay plug 40 further includes a liner 46 of water-soluble material, and a substantially solid central core 48 running substantially the length of the plug.
• the central core 48 is preferably of low permeability and typically made from a substance such as wood, metal, steel or cured grout.
• the central core 48 forms a substrate against which the clay material may cure or seal. This will prevent the clay material from remaining dry at the core of the plug, and will provide surface pressure for the sealing property of the clay.
• the clay plug 40 has particular application for sealing water flow from a drill hole.
• the advantage of using bentonite clay as the "grouting" material in this embodiment is that bentonite clay slowly expands and seals when in contact with water.
• the bentonite 44 needs to be in a relatively thin annulus (as can be seen in Figure 8), for example about 10mm to 15mm thickness. Therefore to seal a bore hole of 48 to 96mm diameter a low permeability core needs to be included inside the plug.
• a 74mm plug if the bentonite is 10mm thick inside, the central core needs to be 54mm (74mm less two "thicknesses" of 10mm each for the bentonite).
• bentonite The problem with the bentonite is it will seal itself from the water, remaining dry if it is thicker than about 15mm. In this instance it will not provide sealing pressure against the hole because the dry bentonite inside does not expand, and in fact it will compress eliminating the sealing pressure from the wet bentonite in contact with the hole.
• a still further aspect of the invention relates to a plug system for plugging a drill hole, such as in a mine.
• the plug system (not shown in the drawings) comprises a combination of one or more grout plugs 10 with one or more clay plugs 40.
• the system has application for sealing water flow from a drill hole.
• a clay plug 40 with bentonite is firstly placed in a drill hole followed by one or more grout plugs 10 behind the clay plug. The grout plug(s) then cure behind the bentonite plug forming a secure seal.
• VCR Vertical Crater Treatment
• a supply of the grout plugs can easily be kept in storage at the mine site ready for use when required for blocking a drill hole.
• the hessian or jute sleeve is environmentally sustainable and its porosity assists with retaining and wicking moisture during curing.
• the plug assists in sealing off drill holes to prevent water flow.
• porous sleeve may be made from any suitable material. Therefore, it will be appreciated that the scope of the invention is not limited to the specific embodiments described.

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• 2011
  • 2011-09-15 US US13/821,408 patent/US20130175034A1/en not_active Abandoned
  • 2011-09-15 AP AP2013006797A patent/AP3306A/xx active
  • 2011-09-15 WO PCT/AU2011/001188 patent/WO2012034181A1/en active Application Filing
  • 2011-09-15 AU AU2011301781A patent/AU2011301781B2/en not_active Ceased
  • 2011-09-15 EP EP11824360.9A patent/EP2616634A1/en not_active Withdrawn
  • 2011-09-15 PE PE2013000372A patent/PE20131356A1/es not_active Application Discontinuation
  • 2011-09-15 CA CA2809690A patent/CA2809690A1/en not_active Abandoned
  • 2011-09-15 EA EA201390376A patent/EA201390376A1/ru unknown
  • 2011-09-15 CN CN2011800550237A patent/CN103221631A/zh active Pending
  • 2011-09-15 MX MX2013003020A patent/MX2013003020A/es not_active Application Discontinuation
  • 2011-09-15 BR BR112013005961A patent/BR112013005961A2/pt not_active IP Right Cessation
• 2013
  • 2013-03-06 CL CL2013000635A patent/CL2013000635A1/es unknown

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