AU9329598A - Inflatable bore hole plugs and methods of use - Google Patents

Description

S F Ref: 443356

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

I I Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: ASSOCIATED

PROVISIONAL

[31] Application No(s) PP0471 Mintech Pty Ltd 3E, 1-7 Unwins Bridge Road St Peters New South Wales 2044

AUSTRALIA

Geoff Robbins Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Inflatable Bore Hole Plugs and Methods of Use i APPLICATION

DETAILS

[333 Country

AU

[32] Application Date 19 November 1997 The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5815 Inflatable Bore Hole Plugs and Methods of Use Technical Field This invention relates to inflatable bore hole plugs and methods of use of such plugs.

Background Art In the mining industry, bore holes are drilled such that an explosive charge may be placed into the bore hole. This is widely used for ore mining and coal mining.

Often, these bore holes are damp or wet and therefore the cheap and efficient dry ANFO explosive cannot be used and must be substituted by the more expensive heavy ANFO which is also less effective.

Also, the explosion efficiency can be improved if air spaces can be provided above o and/or below the explosive charge. The air space transmits shock.waves to assist in breaking up the ore or coal body during the explosion process.

It is known to provide plugs in the bore hole onto which the explosive can be positioned. By positioning various plugs in various places, the explosive composition can be kept above any water level and air spaces can also be introduced around the explosive charge and between adjacent explosive charges.

A known type of plug is an inflatable bag type arrangement which can be lowered into the bore hole and inflated to plug the bore hole to allow the explosive charge to then be positioned on top of the plug.

Australian patent 579395 discloses a bore hole plug comprising an inflatable bag.

The bag is inflated by generating a gas within the bag and this is achieved by mixing coreagents together to liberate the gas.

A difficulty with this type of bag is that the co-reagents are sealed within the bag and must be kept in an upright position. Therefore, these bags must be handled extremely carefully as excessive vibrations or rough handling may cause the bags to inflate at the wrong time.

A further more severe disadvantage with the above type of bag is that inflation is not always complete. That is, occasionally only partial inflation occurs due to incomplete mixing of the co-reagents or other factors. A partially inflated bag in the bore hole will not support an explosive charge but will instead begin to slide down the bore holes. For this reason, it has been necessary to over compensate in the past by providing excess inflatable bags in the bore hole in case one or more of the bags fail to fully inflate.

An improvement of the above type of bag can be found in Australian patent 595887.

In this arrangement, an inflating medium in the form of co-reagents to be mixed are again placed within the bag. However, in the improvement, a delay mechanism is introduced such that when the co-reagents are mixed, the bag can be lowered into the bore hole to the desired depth before inflation begins to occur due to the delay mechanism.

[N:\LIBxx]00942:S&F A disadvantage of this arrangement and the abovementioned previous arrangement is that the co-reagents are usually housed within metallic canisters or containers. Thus, after the blasting process has been completed, fragments of metal are present in the ore or coal body.

In the coal or mining industry, the metal fragments are particularly troublesome as during the coal or ore screening and cleaning process, the metal fragments can cause shut down of some of the processing machinery.

A further disadvantage with both of the above techniques is that there is very little room or scope for error in positioning the bag. For instance, with the delay mechanism, an operator only has the delaying time to lower the bag into the bore hole and to position it correctly before inflation occurs. Thus, there is no opportunity to reposition any one of the inflatable bags.

Summary of the Invention The present invention has been developed to overcome the above disadvantages by allowing an inflatable bore hole plug to be lowered into a hole and then inflated whenever the operator is ready to do so.

It is therefore an object of the invention to provide an inflatable plug which may overcome the abovementioned disadvantages or provide the public with a useful or commercial choice.

Therefore, in one form, the invention resides in an inflatable bore hole plug comprising an inflatable bag having an inlet, and an optionally flexible, conduit having one end coupled to the inlet in a releasable fashion or in a non-releasable fashion and the other end of the conduit being adapted to be connected to a source of pressurized gas or inflatable substance which can inflate the bag or a pressurized source of a co-reagent which can react with a further co-reagent in the bag to form an inflatable substance which can inflate the bag.

Typically the source of pressurized gas or inflatable substance which can inflate the bag is an aerosol container respectively containing same or pressurized source of a co-reagent is an aerosol container containing same. The aerosol container typically has pressure releasing means. Alternatively, the source of pressurised gas can be a gas cylinder having pressure releasing means. The pressure releasing means is typically a nozzle coupled to an aerosol container via a conduit which incorporates a valve. Typically the nozzle is activated by being depressed by a user. Typically once activated by a user the nozzle continues to discharge the contents of the container even after release by the user, until the contents of the container have been substantially discharged.

Typically the co-reagent is a solvent (such as water) and the further co-reagent is a solid mixture of an acid and a bicarbonate (such as citric acid (or other similar acid) and sodium bicarbonate (or other similar bicarbonate)).

In another form, the invention resides in an inflatable bore hole plug comprising an inflatable bag having a first inlet and a second inlet, an optionally flexible, first conduit having one end fixed to the first inlet optionally in a non-releasable fashion and the other end [N:\LIBXX100942:S&F adapted to be connected to a pressurized source of a first co-reagent which can react with a second co-reagent to form an inflatable substance which can inflate the bag, an optionally flexible, second conduit having one end fixed to the second inlet optionally in a nonreleasable fashion and the other end adapted to be connected to a pressurized source of the second co-reagent which can react with the first co-reagent to form an inflatable substance which can inflate the bag.

Typically the pressurized sources of the first co-reagent and the second co-reagent are aerosol containers respectively containing same. The aerosol container typically has pressure releasing means. The pressure releasing means is typically a nozzle coupled to an aerosol container via a conduit which incorporates a valve. Typically the nozzle is activated by being depressed by a user. Typically onceac-tivated by-a-user the nozzle continues to discharge the contents of the container even after release by the user, until the contents of the container have been substantially discharged.

Typically the first co-reagent is an acid citric acid, tartaric acid, acetic acid, etc) in a solvent (such as water) and the second co-reagent is a bicarbonate (such as sodium bicarbonate, potassium bicarbonate, etc.) in a solvent (such as water).

It can be seen that in these simple arrangements, an uninflated bag can be lowered into a bore hole typically by the flexible conduit and when the bag has been lowered to the desired position, it can be inflated in the case of when a gas is the inflating substance by a source of pressured gas to inflate the bag). Optionally the inlet and/or the flexible conduit(s) incorporates a one-way valve to prevent the gas or inflatable substance in the inflatable bag from going back up the conduit(s).

In another form of this invention there is provided an inflatable borehole plug comprising a first co-reagent and at least one further co-reagent wherein an inflating substance is generated on reaction of said first co-reagent with said further co-reagent, said first co-reagent and said further co-reagent being contained in a manner such that said first co-reagent does not inadvertently react with said further co-reagent but said first co-reagent and said further co-reagent are capable of being reacted together to form the inflating substance when required, a substantially inflating substance-tight outer container adapted to retain the co-reagents and being dimensioned for dropping or lowering down a borehole, said first and said further co-reagent being contained within said outer container during said reaction, means to enable said reaction to be started when required and to control the rate at which said inflating substance is generated within said outer container to provide sufficient time to permit the plug to be positioned in a borehole at a required location within the borehole, said means being operatively associated with said outer container so as to allow for operation of the means before the inflatable borehole plug is positioned in the borehole.

The means to enable said reaction to be started when required may comprise a conduit coupled to a pressurised container (such as an aerosol can) having pressure releasing means said container including one of said co-reagents said container being coupled to one end of [N:\LlBxxIOO942:S&F the conduit, the other end of the conduit being coupled to the inflatable borehole plug, the conduit and pressurised container being external to the outer container.

The inflating substance may selected from a gas and a foam.

The co-reagents can comprise any of many substances known to react together to form gases such as carbon dioxide, nitrogen, oxygen, H 2 S0 2 S0 3

NH

3 oxides of nitrogen, hydrocarbon gases, halocarbon gases and any other gas. Preferably an inert gas such as carbon dioxide or nitrogen is formed. The term "hydrocarbons" includes methane, ethane, acetylene, 1 ,3-butadiene, 1-butene, 2-butene, butane, propane and other like gases. Carbon dioxide and nitrogen are particularly preferred gases. Generally, the first co-reagent will be a liquid and the second co-reagent or reagents will be solid. Examples of the many suitable S° systems include those for generation of carbon dioxide such as an acid as the first co-reagent and a carbonate or bicarbonate in the form of powder or tablets, for example, as the further co-reagent or water as the first co-reagent and a solid carbonate or bicarbonate together with a solid acid as the further co-reagents. Suitable solid acids include, for example, citric acid and tartaric acid. Suitable nitrogen generating systems include those based on nitrosamines such as dinitrosopentamethylenetetramine. Suitable oxygen generating systems include those based on peroxides and superoxides. The acid is preferably contained in a polyethylene container or sachet(s). Alternatively the first co-reagent and/or the further co-reagent can be contained in spray packs which upon activation release the first co-reagent and/or the further co-reagent at a predetermined rate(s).

The means to enable said reaction to be started when required may comprise a pressurised container which is capable of holding and discharging when required one of the co-reagents, one of the co-reagents in a solvent or a solvent for the co-reagents.

The means to enable said reaction to be started when required may comprise a pressurised container which is capable of holding and discharging a solvent for the coreagents.

To increase delay of discharge from the container one can reduce valve orifice diameter (orifice in aerosol can actuator/nozzle). Alternatively use propellant with lower vapour pressure to reduce ejection rate of liquid or dip tube diameter can be decreased. If want to increase ejection rate increase one or more of the latter.

Typically the pressurised container is charged to a pressure in the range of from about kPa to about 500 kPa. The pressurised container may be a canister constructed of a material selected from the group consisting of metal, glass, and a plastic. The outer container, as well as being dimensioned for dropping or lowering into a borehole should be gas-tight.

Preferred outer containers are multi-layer plastics bags, for example, polyethylene/nylonpolyethylene multi-layer bags which have suitable strength and low gas permeability. It is preferred that the bags be able to withstand 20 to 25 psi internal pressure and to maintain that pressure for up to four weeks. Low gas permeability can also be achieved by the use of a polyester inner layer or metalised plastic film.

[N:\LIBxx]00942:S&F The inflating substance may be a foam and the co-reagents comprise the components necessary to form an inflating foam of one or more of polystyrene, chlorinated or unchlorinated polyethylene, copolymers of vinylidine fluoride and hexafluoropropylene, polyamides, polytetrafluoroethylene, styrene-acrylonitrite copolymers, polyvinylchloride, polyisocyanurates, polyphenols, epoxy resins, silicone resins, cellulose acetate, cellular rubber, latex foam rubber, urea-formaldehyde resins, polyimides and polyolefins.

The inflating substance may be a foam and the co-reagents comprise an isocyanate and a polyol.

The inflating substance may be a foam and the co-reagents comprise two parts by weight of polymeric methylene di-isocyanate and one part by weight of polyetherol.

The inflatable container comprises at least a gas-tight inner container and a gas-tight outer container. The inflatable container may be a bag comprising multiple layers of plastic.

The plastic is selected from the group consisting of rubber or other elastomerics, nylon/surlyn coextrusions, polyethylene, polypropylene and polyethylene/nylon/polyethylene coextrusions.

In another form the invention provides a combination comprising the inflatable borehole plug of the invention and a substantially non-elastic outer support for said inflatable container. The outer support may be constructed of a material selected from the group consisting of woven polyethylene and woven polypropylene. The outer support may comprises a hole through which the conduit passes.

The plug may further comprise an elongate stiffening member, wherein the axis of said stiffening member is generally aligned with the vertical axis of the inflatable borehole plug and wherein the upper end of the stiffening member is adapted to releasably engage the end of a pole. The lower end of said pole is dimensioned to receive the upper end of the stiffening member and retain it by means of a friction fit.

The plug may further comprise an elongate sleeve having an open upper end and a sealed lower end, wherein the axis of elongation of said elongate sleeve is generally aligned with the vertical axis of the inflatable borehole plug assembly, and wherein said sleeve is dimensioned to receive an end portion of a pole inserted into said open upper end.

The outer container may be enclosed in a further container. The further container is of the same construction as the outer container and large enough to allow full expansion of the outer container.

In another form of the invention there is provided a method of placing a borehole plug in a borehole comprising the steps of taking a borehole plug of the invention, mixing the coreagents so production of the inflating substance commences, lowering the plug down the borehole to the required position, allowing expansion of the inflating substance to continue to form a deck firmly in place against the borehole wall.

[N:\LIBxx]00942:S&F The method may further include lowering an explosive charge down the borehole and placing it on the deck.

A method of locating an inflatable borehole plug according to the invention in a borehole, comprising the steps of placing the inflatable borehole plug into the borehole at a desired depth in the borehole, operating said pressure releasing means of said pressurised container, wherein the quantity of the gas/inflating substance is such as to inflate the inflatable container to form a borehole plug or the quantities of co-reagent and further co-reagent are such as to inflate the o o inflatable container to form a borehole plug.

The method can include lowering the inflatable borehole plug into the borehole prior to operating said pressure releasing means.

One distinct advantage over the earlier proposals is that the operator is not subject to any deadline or time limit in which to have the bag positioned correctly in the bore hole as he can inflate the bag at any suitable time. Furthermore, there is little risk of underinflating the bag as the operator now has control over the inflation sequence.

Suitably, the inflatable bag is formed from a flexible but tough material. Such material may be a plastic or plastic multi-layered bag and such bags are know. The suitable bag may be a polyethylene/nylon polyethylene multi-layered bag.

These bags can be typically inflated to about 16-36 psi more typically 20-26 psi, which will inflate the bag sufficiently to grip the sides of the bore hole and to provide a stable and firm platform on which the explosive charge can be placed.

Another advantage of the present invention is that the bag in practice does not need to be of a clear or transparent material and therefore a greater selection of bag materials can be used. In the previous arrangements, the bag must be clear so that the operator can see the coreagent canisters to allow them to be mixed prior to lowering the bag into the bore hole. In this known arrangement, the selection of bag materials is severely limited to those which are substantially clear.

The flexible conduit can be of any suitable type and typically comprises a plastic or rubber hose. It is important that the hose is rigidly fixed to the bag inlet and that it cannot be separated from the bag during normal use.

This is because the flexibility of the bag and the way it is positioned in the bore hole often results in the inlet of the bag not being positioned in an upper portion. Thus, if the hose is one that can be detachably removed from the bag, there is very often risk of a slow leak developing. This in turn will slowly deflate the bag and cause it to fail or slide down the bore hole especially when an explosive charge is placed thereon.

[N:\LlBxxIOO942:S&F The other end of the flexible conduit is preferably attached to a container/canister containing pressurized gas. Such a canister can be in the form of a known type of aerosol can which can dispense a pressurized gas such as a hydrocarbon. However, typically the nozzle of such a can, once depressed by a user, stays depressed even after release by the user whereby the contents of the can are substantially discharged. The rate of discharge can be controlled in part by the pressure in the can (the lower the pressure in the can the slower the discharge from the can typically the can is pressurised slightly greater than atmospheric to provide a slow discharge), the diameter of the nozzle and the diameter of the conduit connecting the nozzle with the internal contnets of the can.

It is preferred that the hose is also attached to the can in a non-removable fashion such that the entire assembly can be bought and used as a kit.

It is found that an 11" diameter bore hole typically requires about 100 g of hydrocarbon in an aerosol can to inflate the inflatable bag.

In use, a deflated bag (typically loosely tied, folded or wrapped into a plug form) is lowered into the hole by a flexible conduit/hose. The hose may have markings on it to show how far the bag passes into the hole. When the desired position is reached, the aerosol can/cannister can be activated which will pass pressurized gas/inflating substance/co-reagent through the hose and into the bag to inflate the bag. The bag will then be inflated to the pressure dictated by the can and it can be seen that in a further variation, the pressure can be varied by increasing the pressure in the can (or the amount of inflating substance in the can or the amount of first co-reagent and second co-reagent). Thus, by being able to regulate the pressure within the bag, there is very little or no likelihood of the bag being improperly inflated. Furthermore, heavier than normal explosive charges may be safely positioned on the bag with the knowledge that the bag will not fail.

The bag can be made of stronger and cheaper material as there is no requirement for the bag to be optically clear as the bag does not contain any inflating canisters and the like.

Furthermore, the bag would have a particular advantage in the coal industry where metal fragments should not be present in the coal body.

Brief Description of the Drawings Figure 1 is a schematic illustration of an inflatable borehole plug assembly according to a first embodiment of this invention.

Figure 2 is a schematic illustration of an inflatable borehole plug assembly according to a second embodiment of this invention.

Figure 3 is a schematic illustration of an inflatable borehole plug assembly according to the invention located in a borehole.

[N:\LlBxx]00942:S&F Figures 4A-4H are a schematic illustration of one method of making an inflatable borehole plug of the invention and also illustrate the method of locating it according to the invention.

Detailed Description of the Preferred embodiment Referring to the accompanying drawings, Figure 1 is a schematic illustration of an inflatable borehole plug according to a first embodiment of this invention. The borehole plug 1 includes an inflatable bag 2 having an inlet 3 with a conduit 4 having one end connected to the inlet 3 and the other end connected to a pressurised container or vessel 5. In a preferred form the conduit 4 is a flexible plastic hose which forms a non-releasable, pressure tight fit with both the inlet 4 and the pressurised container 5. In the form illustrated in Figure 1, the pressurised container 5 takes the form of an aerosol container which contains a pressurised gas or inflatable substance 6 which can inflate the bag 2. The pressurised container 5 has a valve means 7 which can be activated to release the pressure in the container 5 and allow discharge of the gas or inflatable substance 6 in the container 5 into the bag 2 via the conduit 4. In one preferred embodiment the inlet 3 incorporates a one way valve to prevent the gas or inflatable substance 6 from passing out of the inlet 3 once it has entered the bag 2.

Figure 2 is a schematic illustration of an inflatable borehole plug according to a second embodiment of this invention. In this embodiment, the inflatable bag 2 is depicted in an uninflated form and includes two inlets 3a and 3b, both inlets 3a and 3b being com ected via respective conduits 4a and 4b to pressurised containers or vessels 5a and 5b respectively containing a first co- reagent 8a and a second co-reagent 8b. In one preferred embodiment, the bag 2 is formed from one or more layers of plastic such as polyethylene. polypropylene and polyethylene/nylon/polyethylene coextrusion. The pressurised containers 5a and 5b have respective valve means 7a and 7b which can be activated to allow discharge of the coreagents 8a and 8b into the bag 2 via the conduits 4 and inlets 3a and 3b. When both coreagents 8a and 8b flow into the bag 2 via inlets 3a and 3b, they mix and react to form an inflatable substance which inflates the bag 2. In a preferred form of this embodiment, the first co-reagent 8a is an acid in a solvent, and the second co-reagent is a bicarbonate in a solvent.

Figure 3 is a schematic illustration of an inflatable borehole plug assembly according to the invention located in a borehole. The borehole 9 is drilled in the ground to be blasted by an explosive charge. An inflatable bore hole plug of the invention is then inserted into the borehole 9 to the desired level. When the desired level is reached, the valve means 7 on the pressurised container 5 is activated and the pressurised gas or inflatable substance 6 discharges from the container 5, flows down the conduit 4 and into the bag 2 via the inlet 3.

The bag 2 is then inflated to its full capacity until it it is firmly lodged against the walls of the borehole 9. It is thus firmly positioned at the required location. The explosive can then be placed on the plug. In the form illustrated in Figure 3, the bag 2 is in a semi inflated state.

[N:\LBxx]00942:S&F Figures 4A-4F illustrate one method of preparing an inflatable bore plug assembly of the invention. Referring to Figure 4A, a plastic tubing of the lay flat form is taken, having dimensions suitable for a typical borehole of 2 70-311mm. Each of the open ends of the plastic tubing is heat welded to form a flat bag 2 being fully closed at all ends as shown in Figure 4B. An inlet 3 is formed, and in the form illustrated in Figure 4C, the inlet is a plastic nipple formed with spigot means. This inlet 3 is then heat welded into one surface of the bag 2 (see Figure 4D). A pressurised container 5, which in the form illustrated in Figure 4E is an aerosol can with spigot, is then attached to one end of a conduit 4 via the spigot arrangement.

The conduit 4 which in the form illustrated in Figure 4F is a flexible plastic hose, is connected at its other end to the inlet 3. The connections of the conduit 4 to both the inlet 3 and pressurised container 5 are pressure tight and in one preferred embodiment, nonreleasable. The inflatable bore plug of the invention can then be lowered in an uninflated form into a borehole to be blasted with explosive. When the plug is correctly positioned in teh borehole as represented in Figure 4G, it can then be inflated from the surface by activation of the pressurised container to release its pressurised contents as shown in Figure 4H.

By use of the form of the invention illustrated in the Figures, borehole plugs can be positioned at any desired location in a borehole which provides for much greater flexibility and efficiency in blasting.

Example Sodium bicarbonate (solid powder) citric acid (solid powder) are located inside an uninflated borehole plug (60 gms of citric acid to 80 gins of sodium bicarbonate) (other alternatives could be used e.g. potassium bicarbonate and tartaric acid etc.). These have the advantage of not being hazardous products. The bag is lowered down a borehole to the required depteh by means of a conduit coupled at one end to the bag and at the other end to the aerosol can. The can is then activated by a user a water is ejected from the can into the plug via the conduit.. Rate of CO 2 production in plug is dependent on dissolution of the solid alkali and acid in H 2 0. One can control rate of CO 2 production by controlling rate at which water is delivered to components (sodium bicarbonate and citric acid). The volume of should be sufficient so that at least one of the phases is completely soluble citric).

This reaction gets cold. The greater the amount of water the greater it acts as a heat source.

Slaked slime may be used as a heat source. One can compensate for the cool reaction by adding more citric acid, for example. Alternatively, one can use an exothermic substance that doesn't react with either acid or base ingredient. This could be important in colder climates.

For example: Vinegar sodium bicarbonate antifreeze could have water antifreeze in aerosol can excess hydrocarbon is usually used in aerosol can in colder climates [N:\LIBxx]00942:S&F One could use an additional barrier around the acid and/or alkali to increase delay further: vinyl acetate cardboard pouch non woven fabric etc dissolve one of ingredients in solvent in can One needs sufficient propellant to expel liquid against pressure in bag (liquid comes out in about 20 seconds) start siphoning and maintain siphoning of liquid.

for lower pressures the can may be declared as a non-pressure vessel (1 psi than atmosphere say 16 psi) the gas in the can expelling the liquid may be compressed air, CO 2 any gas that does not dissolve in liquid.

e.g. if use citric dissolved in water could simply add carbonate prior to sealing can with valve to provide the pressure inside of CO 2 sufficient to start and maintain siphoning of liquid from can (pressure equivalent to soft drink (carbonated)). No longer an aerosol.

One way valve on can gives control of evolution of liquid which in turn gives control of evolution of reactant gas.

Advantages non hazardous (manufacture, transport storage and use aerosols are normally class 2 i.e. contains flammable liquids and gases).

because can is no longer a pressure vessel, the product (can) can be left in the open without fear of explosion. Doesn't have to be stored in flammable store. Don't have to worry about them getting too hot.

Could use plastic container like soft drink bottles. Use compatible valve. Particularly useful when don't want to contaminant ore body e.g. coal, gold etc. with metal from can.

Gives control via amount of water and rate at which it is ejected.

External rubber band around outer container can control rate of expansion of borehole plug.

straight aerosol very difficult to use as a submersible as it is half expanded before it can be put into water.

Additional control on expansion of bag may be included: preferable for bag to expand uniformly cylindrically for ease of placement in borehole.

seal and fold inner bag. Place folded bag in outer bag which is in turn folded and sealed. On activation of the aerosol the inner bag is controlled in expansion by the restriction of the outer bag since the inner bag has to unfold against outer bag.

Preferably use aluminium can or plastic bag or rust inhibitor [N:\LIBxx]00942:S&F 2 plastic bags within a woven polypropylene bag.

disadvantage of pure aerosol is the bigger the bag more propellant is required. If use more chemical it is cheaper than popellant.

roll bag to keep solid and aerosol on one side of bag. Rolling bag is a way of not using reactor bag.

3" to 16" diameter borehole 75mm diameter to 400mm borehole.

2 7 0 311mm 6" quarry market 9" small mines preferred 10 12 1/4" most mines, open cut (270mm) (311 mm) only some mines (38 1mm) old technique.

7m strings can be attached to external bag (stick with string wound around it) dropped to bottom of hole to seal off 2-3m water.

half way or 5-7 or half way 5-7 meters premeasured string submersible attachment an optional elastic attachment allows bag to be lowered on shock tube (as compared to lowering via a conduit in this way the conduit used may be kept relatively short 1 cm for example) reason is to make bag more use/operator friendly.

inner bag slightly larger than outer bag. Sealed edge is supported by outer bag.

Welds are not on top or bottom they are down the sides to they are supported by borehole wall.

300 500 ml water for 270/311 mm hole 100Og citric 140g bicarb.

It should be appreciated that various other changes and modifications may be made to the embodiment described without departing from the sprit and scope of the invention.

[N:\LBxx]00942:S&F

Claims (48)

1. An inflatable bore hole plug including an inflatable bag having an inlet, and a conduit having one end coupled to the inlet in a releasable fashion or in a non-releasable fashion and the other end of the conduit being adapted to be connected to a source of pressurized gas or inflatable substance which can inflate the bag, or a pressurized source of a co-reagent which can react with a further co-reagent in the bag to form an inflatable substance which can inflate the bag.

2. An inflatable bore hole plug according to claim 1 wherein said conduit is flexible.

3. An inflatable bore hole plug according to claim 1 or claim 2 wherein the source of pressurized gas or inflatable substance which can inflate the bag is an aerosol container containing said pressurized gas or inflatable substance.

4. An inflatable bore hole plug according to claim 1 or claim 2 wherein the pressurized source of a co-reagent is an aerosol container containing said co-reagent.

An inflatable bore hole plug according to claim 3 or claim 4 wherein the aerosol container has pressure releasing means.

6. An inflatable bore hole plug according to claim 1 or claim 2 wherein the source of pressurised gas is a gas cylinder having pressure releasing means.

7. An inflatable bore hole plug according to claim 5 or claim 6 wherein the pressure releasing means is a nozzle coupled to said aerosol container or gas cylinder via a conduit which incorporates a valve.

8. An inflatable bore hole plug according to claim 7 wherein once the nozzle is activated by a user, the contents of the container or cylinder are continued to be discharged by the nozzle even after cessation of the activation by the user, until the contents have been substantially discharged.

9. An inflatable bore hole plug according to any one of claims 1 to 7 wherein the co- reagent is a solvent and the further co-reagent is a solid mixture of an acid and a bicarbonate.

An inflatable bore hole plug according to claim 9 wherein the co-reagent is water and the further co-reagent is a solid mixture of an acid selected from the group consisting of tartaric acid, citric acid, or other similar acid and sodium bicarbonate or other similar bicarbonate including potasssium bicarbonate.

11. An inflatable bore hole plug including an inflatable bag having a first inlet and a second inlet, a first conduit having one end fixed to the first inlet and the other end adapted to be connected to a pressurized source of a first co-reagent which can react with a second co- reagent to form an inflatable substance which can inflate the bag, a second conduit having one end fixed to the second inlet and the other end adapted to be connected to a pressurized source of the second co-reagent which can react with the first co-reagent to form an inflatable substance which can inflate the bag.

12. An inflatable bore hole plug according to claim 11 wherein said first and/or second conduit is flexible. [N:\LIBxx]00942:S&F

13. An inflatable bore hole plug according to claim 11 or claim 12 wherein said first conduit has one end fixed to the first inlet in a non-releasable fashion.

14. An inflatable bore hole plug according to any one of claims 11 13 wherein said second conduit has one end fixed to the second inlet in a non-releasable fashion.

An inflatable bore hole plug according to claim 14 wherein the pressurized source of the first co-reagent is an aerosol container containing said first co-reagent.

16. An inflatable bore hole plug according to any one of claims 11 15 wherein the pressurized source of the second co-reagent is an aerosol container containing said second co- reagent.

17. An inflatable bore hole plug according to claim 15 or claim 16 wherein said aerosol container typically has pressure releasing means.

18. An inflatable bore hole plug according to claim 17 wherein the pressure releasing means is typically a nozzle coupled to said aerosol container via a conduit which incorporates a valve.

19. An inflatable bore hole plug according to claim 18 wherein once the nozzle is activated by a user, the contents of the container are continued to be discharged by the nozzle even after cessation of the activation by the user, until the contents have been substantially discharged.

An inflatable bore hole plug according to any one of claims 11 19 wherein the first co-reagent is an acid in a solvent and the second co-reagent is a bicarbonate in a solvent.

21. An inflatable bore hole plug according to claim 20 wherein the first co-reagent is an acid selected from the group consisting of citric acid, tartaric acid and acetic acid, wherein the second co-reagent is a bicarbonate selected from the group consisting of sodium bicarbonate and potassium bicarbonate, and wherein said solvents are water.

22. An inflatable bore hole plug according to any one of claims 1 21 wherein the inlet(s) and/or the conduit(s) coupled or fixed to said inlet(s) incorporate(s) a one-way valve to prevent the gas or inflatable substance in the inflatable bag from going back up the conduit(s).

23. An inflatable borehole plug including a first co-reagent and at least one further co- reagent wherein an inflating substance is generated on reaction of said first co-reagent with said further co-reagent, said first co-reagent and said further co-reagent being contained in a manner such that said first co-reagent does not inadvertently react with said further co- reagent but said first co-reagent and said further co-reagent are capable of being reacted together to form the inflating substance when required, a substantially inflating substance- tight outer container adapted to retain the co-reagents and being dimensioned for dropping or lowering down a borehole, said first co-reagent and said further co-reagent being contained within said outer container during said reaction, means to enable said reaction to be started when required and to control the rate at which said inflating substance is generated within said outer container to provide sufficient time to permit the plug to be positioned in a [N:\LIBxx]00942:S&F borehole at a required location within the borehole, said means being operatively associated with said outer container so as to allow for operation of the means before the inflatable borehole plug is positioned in the borehole.

24. An inflatable bore hole plug according to claim 23 wherein the inflating substance may selected from a gas and a foam.

An inflatable bore hole plug according to claim 24 wherein the co-reagents are selected from any substances known to react together to form a gas selected from the group including carbon dioxide, nitrogen, oxygen, H 2 S02, S0 3 NH 3 oxides of nitrogen, hydrocarbon gases and halocarbon gases.

26. An inflatable bore hole plug according to claim 24 or 25 wherein said gas is an inert gas including carbon dioxide or nitrogen.

27. An inflatable bore hole plug according to claim 23 wherein the first co-reagent is a liquid and the second co-reagent or reagents is/are solid.

28. An inflatable bore hole plug according to any one of claims 23 27 wherein the first co-reagent and/or the further co-reagent can be contained in spray packs which upon activation release the first co-reagent and/or the further co-reagent at a predetermined rate(s).

29. An inflatable bore hole plug according to claim 23 wherein the means to enable said reaction to be started when required comprise a conduit coupled to a pressurised container having pressure releasing means, said container including one of said co-reagents, said container being coupled to one end of the conduit with the other end of the conduit being coupled to the inflatable borehole plug, the conduit and pressurised container being external to the outer container.

An inflatable bore hole plug according to claim 23 wherein the means to enable said reaction to be started when required comprise a pressurised container which is capable of holding and discharging when required one of the co-reagents, one of the co-reagents in a solvent or a solvent for the co-reagents.

31. An inflatable bore hole plug according to claim 29 or claim 30 wherein the pressurised container is an aerosol can.

32. An inflatable bore hole plug according to claim 31 wherein the pressurised container is pressurised container is charged to a pressure in the range of from about 10 kPa to about 500 kPa.

.33. An inflatable bore hole plug according to claim 32 wherein the pressurised container is constructed of a material selected from the group consisting of metal, glass, and a plastic which have suitable strength and low gas permeability.

34. An inflatable bore hole plug according to claim 24 wherein the co-reagents are selected from any substances known to react together to form an inflating foam selected from the group including polystyrene, chlorinated or unchlorinated polyethylene, copolymers of vinylidine fluoride and hexafluoropropylene, polyamides, polytetrafluoroethylene, styrene- [N:\LIBxx]OO942:S&F acrylonitrite copolymers, polyvinylchloride, polyisocyanurates, polyphenols, epoxy resins, silicone resins, cellulose acetate, cellular rubber, latex foam rubber, urea-formaldehyde resins, polyimides and polyolefins.

An inflatable bore hole plug according to claim 34 wherein the co-reagents comprise an isocyanate and a polyol.

36. An inflatable bore hole plug according to claim 34 wherein the co-reagents comprise two parts by weight of polymeric methylene di-isocyanate and one part by weight of polyetherol.

37. An inflatable bore hole plug according to any one of claims 23 36 wherein the outer S container is gas tight and includes at least a gas-tight inner container.

38. An inflatable bore hole plug according to claim 37 wherein the outer container is a bag comprising multiple layers of plastic.

39. An inflatable bore hole plug according to claim 38 wherein the plastic is selected from the group consisting of rubber or other elastomerics, nylon/surlyn coextrusions, polyethylene, polypropylene and polyethylene/nylon/polyethylene coextrusions.

An inflatable borehole plug according to any one of claims 23 39 further including a substantially non-elastic outer support for said outer container.

41. An inflatable borehole plug according to any one of claims 1 40 further including an elongate stiffening member, wherein the axis of said stiffening member is generally aligned with the vertical axis of the inflatable borehole plug and wherein the upper end of the stiffening member is adapted to releasably engage an end of a pole.

42. An inflatable borehole plug according to claim 41 wherein the lower end of said pole is dimensioned to receive the upper end of the stiffening member and retain it by means of a friction fit.

43. An inflatable borehole plug according to any one of claims 1 40 wherein the plug may further comprise an elongate sleeve having an open upper end and a sealed lower end, wherein the axis of elongation of said elongate sleeve is generally aligned with the vertical axis of the inflatable borehole plug assembly, and wherein said sleeve is dimensioned to receive an end portion of a pole inserted into said open upper end.

44. A method of placing a borehole plug in a borehole including the steps of taking a borehole plug according to any one of claims 1 43, mixing the co-reagents so production of the inflating substance commences, lowering the plug down the borehole to the required position, allowing expansion of the inflating substance to continue to form a deck firmly in place against the borehole wall.

A method according to claim 44 further including the step of lowering an explosive charge down the borehole and placing it on the deck. [N:\LBxx]00942:S&F C 16

46. A method of locating an inflatable borehole plug according to any one of claims 1 43 in a borehole, comprising the steps of: placing the inflatable borehole plug into the borehole at a desired depth in the borehole, and operating said pressure releasing means of said pressurised container, wherein the quantity of the gas/inflating substance is such as to inflate the inflatable container to form a borehole plug or the quantities of co-reagent and further co-reagent are such as to inflate the inflatable container to form a borehole plug.

47. An inflatable borehole plug according to the invention substantially as hereinbefore described with reference to the Example.

48. An inflatable borehole plug according to the invention substantially as hereinbefore described with reference to any one of the drawings. Dated 19 November, 1998 Mintech Pty Ltd Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON [N:\LBxx]00942:S&F