CA3222124A1 - Borehole resident electronic device - Google Patents

Abstract

The present invention relates to a borehole resident electronic device for use in a blasting operation, the device comprising a container in which is located one or more electronic components, the container having a wall structure comprising a fibre-reinforced composite thermoset resin layer positioned to shield the one or more electronic components from an explosive shockwave generated during the blasting operation and remote from the device, wherein the fibre is in a form selected from unidirectional fibre, woven fibre, wound fibre, nonwoven fibre, and combinations thereof.

Description

BOREHOLE RESIDENT ELECTRONIC DEVICE
Field of the Invention The present invention relates in general to borehole resident electronic devices used in blasting operations and to a method of reducing or preventing failure of such devices during blasting operations.
Background of the Invention Large scale mining operations form an important part of modern day society.
Often critical to mining operations, be it surface or subsurface, is the use of explosives in blasting operations to expose and gain access to the product being mined.
The use of explosives in mining operations has and will continue to present high-level safety concerns for mine operators.
Modern day mining operations continue to demand an ever-increasing degree of control over and performance from blasting operations.
With factors such as safety. control, efficiency and performance in mind, considerable research has been applied over the years in developing electronic devices to facilitate mining.
Electronic detonation systems for explosives used in blasting operations are now common place. Electronic-based monitors are also commonly used in blasting operations, for example in the form blast movement monitors to track movement in the mining body after being subjected to a blasting operation.
Such electronic devices are typically loaded across multiple boreholes of given blasting operation. For example, electronic explosives initiators and/or electronic blast movement monitor devices may he loaded into multiple boreholes drilled into a blast site for a given blasting operation.
The electronic devices may be operated through wired or wireless means.

- 2 -While such electronic devices offer numerous advantages, they remain to this day prone to failure given the harsh conditions they must endure.
For example, while electronic explosives initiators will ultimately be destroyed in an explosion they initiate, such devices are commonly used to initiate a sequenced series of explosive events in which a blast wave, part of which constitutes a shockwave, propagating from an explosion initiated earlier in the sequence reaches the location of an initiator that has yet to electronically initiate its explosion within the sequence or be electronically signalled to initiate its explosion within another loaded sequence in the area. Electronic blast movement monitors are intended to endure/survive the blasting operations to track movement in the mine site after the blasting operation has been completed.
It is therefore important such electronic devices remain functional upon being subjected to a shockwave generated remote from the device during a blasting operation.
Electronic components of electronic devices are known to be adversely affected upon being subjected to a shockwave generated during the blasting operation. For example, electronic devices exposed to so-called "shock-stop" (i.e., the harsh conditions produced by a shockwave) can undergo partial or total failure. As those skilled in the art will appreciate, any type of malfunction of electronic devices used in association with blasting operations can cause significant economic and/or safety concerns.
Despite attempts to develop such borehole resident electronic devices that are more resistant to failure due to shock-stop effects, it remains a problem in the art to this day.
Accordingly, there remains an opportunity to develop borehole resident electronic devices used in blasting operations that exhibit improved shock-stop resistance relative to the electronic devices currently used in practice.
Summary of the Invention The present invention provides a borehole resident electronic device for use in a blasting operation, the device comprising a container in which is located one or more electronic

- 3 -components, the container having a wall structure comprising a fibre-reinforced composite thermoset resin layer positioned to shield the one or more electronic components from an explosive shockwave generated during the blasting operation and remote from the device, wherein the fibre is in a form selected from unidirectional fibre, woven fibre, wound fibre, nonwoven fibre, and combinations thereof.
The present invention also provides a method of shielding one or more electronic components of a borehole resident electronic device from an explosive shockwave in a blasting operation, the method comprising deploying the device into a borehole of the blasting operation, wherein the device comprises a container in which is located the one or more electronic components, the container having a wall structure comprising a fibre-reinforced composite thermoset resin layer positioned to shield the one or more electronic components from an explosive shockwave generated during the blasting operation and remote from the device, and wherein the fibre is in a form selected from unidirectional fibre, woven fibre, wound fibre, nonwoven fibre, and combinations thereof.
It has now been found borehole resident electronic devices used in blasting operations can exhibit improved shock-stop resistance by locating its shockwave sensitive electronic componentry within a container having a wall structure comprising a fibre-reinforced composite thermoset resin layer positioned such that it shields the electronic componentry from the shockwave. Without wishing to be limited by theory, the container having a wall structure comprising a fibre-reinforced composite thermoset has been found to dissipate the force of the shockwave and also be substantially more resistant to distortion/deformation upon being subjected to an explosive shockwave (relative to conventional containers used in the art).
thereby reducing or preventing damage to the electronic componentry during a blasting operation.
The fibre in the reinforced composite thermoset resin layer is in a form selected from unidirectional fibre, woven fibre, wound fibre, nonwoven fibre, and combinations thereof. The combination of thermoset resin and the fibre form/arrangement has been found to be particularly effective at protecting the integrity of electronic components subjected to an explosive shockwave. The enhanced shielding effect from the explosive shockwave afforded by the thermoset resin layer can advantageously prevent premature failure of the electronic componentry and hence the electronic function of the device itself.

- 4 -The present invention also provides a method of performing a blasting operation, the method comprising deploying a borehole resident electronic device into a borehole of the blasting operation, wherein the device comprises a container in which is located one or more electronic components, the container having a wall structure comprising a fibre-reinforced composite thermoset resin layer positioned to shield the one or more electronic components from an explosive shockwave generated during the blasting operation and remote from the device, and wherein the fibre is in a form selected from unidirectional fibre, woven fibre, wound fibre, nonwoven fibre, and combinations thereof.
In one embodiment, one or more voids are located between the fibre-reinforced composite thermoset resin layer and the one or more electronic components.
In a further embodiment, the one or more electronic components are partially or fully embedded within a polymer.
In another embodiment, the borehole resident electronic device is in the form of an explosives initiator.
In a further embodiment, the borehole resident electronic device is in the form of a monitor device.
Examples of monitor devices include those that measure or monitor movement, temperature, pressure, and/or magnetic field.
In another embodiment, the borehole resident electronic device is in the form of a communications device.
Examples of communications devices also include those capable of relaying or transmitting voice, text or data to a remote electronic device.
Additional embodiments and/or aspects of the invention are discussed in more detail below.

- 5 -Brief description of the drawings Embodiments of the invention are herein described with reference to the following non-limiting drawings in which:
Figure 1 illustrates a borehole resident electronic device in the form of a blast movement monitor in accordance with the invention;
Figure 2 illustrates a borehole resident electronic device in the form of an explosives initiator in accordance with the invention;
Figure 3 illustrates the test rig used in Example 2 where (1) represents the booster charge, (2a) and (2b) represent the assembled test samples (with (2a) being comparative and (2b) being of the invention), (3) represents an electronic circuit board, (4) represents an antenna, (5) represents pressure gauges, (6) shows a representative direction of the explosives shockwave derived from booster (1), (7) shows the test rig suspension system, (8) represents water and (9) represents air.
Figure 4 shows damage to the antennas of sample (2a) from Example 2;
Figure 5 illustrates a schematic representation of the deformation of the polycarbonate casing/sleeve of sample 2a showing: (1) the electronic circuit board, (2) the antenna, (3) the original shape of the polycarbonate casing/sleeve, (4) the proposed deformation shape of the polycarbonate casing/sleeve due to dynamic pressure (Force) from the shockwave, (5) the region of major cracking of the polycarbonate casing/sleeve due to deformation, and (6) the impact region on electronic components by the deformed polycarbonate casing/sleeve;
Figure 6 illustrates results from Example 3 of pressure testing a comparative polycarbonate container and a pultruded container of the present invention;
Figure 7 illustrates a schematic of the test set up to measure the internal pressures in a FWC
sleeve exposed to an explosives shockwave, where (1) represents a booster charge, (2a) represents a pressure gauge inside a FWC sleeve (3), (2b) represents a pressure gauge(s) attached externally to the FWC sleeve (3), (4) represents aluminium end caps, (5) represents a

- 6 -pressure gauge wire. (6) represents a suspension system, (7) represents water and (8) represents air.
Detailed description of the invention The present invention relates to borehole resident electronic devices for use in blasting operations.
By being an "electronic device" is meant the device comprises electronic componentry configured to operate one or more features of the device.
By the device being "borehole resident" is meant the device is suitable for and intended to be used in a borehole that has been created as part of a blasting operation. In other words, the electronic device is one that has been manufactured for use in a borehole created as part of a blasting operation. The electronic device therefore has the required characteristics for being resident in a borehole of a given blasting operation.
For avoidance of any doubt, by being "borehole resident" it is not meant the electronic device per se is limited by way of actually residing in a borehole. Rather the electronic device is to be designed and manufactured for and intended to be used in a borehole of a blasting operation.
The borehole resident electronic device may therefore also be described as being an electronic device manufactured for use in a borehole of a blasting operation.
Provided the electronic device can be resident in a borehole and play some role in a blasting operation, there is no particular limitation on the specific form and function of the device.
As the present invention advantageously provides a means for shielding electronic componentry from the detrimental effects of an explosive shockwave generated in a blasting operation, the specific form and function of the electronic device in a blasting operation is not of primary importance.
Examples of suitable borehole resident electronic devices include, but are not limited to, an explosives initiator, a monitor device or communications device.

- 7 -In one embodiment, the borehole resident electronic device is in the form of an explosives initiator.
In another embodiment, the borehole resident electronic device is in the form of a monitor device.
In a further embodiment, the borehole resident electronic device is in the form of a communications device.
Examples of suitable monitor devices include those for measuring blast movement of an ore body, temperature, pressure, magnetic field and combinations thereof. Examples of suitable monitor devices also include those for tracking an ore body through a mining operation.
In one embodiment, the borehole resident electronic device is in the form of a blast movement monitor.
In another embodiment, the borehole resident electronic device is in the form of an ore body tracking monitor.
Examples of suitable communications devices include the aforementioned monitor devices and also devices for transmitting or relaying voice, text or other forms of data.
In the form of an explosives initiator, the borehole resident electronic device will be capable of receiving an electronic signal to initiate detonation of an explosives material that forms part of the device. Such a device will generally comprise relevant electronic componentry together with a primary and possibly also a secondary explosives material. The incoming electronic signal triggers detonation of the primary explosive material that can in turn promote detonation of the secondary explosive material if present. The function of the explosives initiator is to trigger detonation of the primary explosives material, or primary and secondary explosives material, which in turn triggers detonation of a tertiary explosives material that typically resides together with the initiator device within the borehole. The tertiary explosives material is provided in much larger quantities than the initiator-type explosive materials (primary and secondary) and will generally be responsible for the main explosive force output of the blasting

- 8 -operation.
Primary, secondary and tertiary explosive materials are well known to those skilled in the art.
Examples of the primary explosives include, but are not limited to, lead azide, mercury fulminate, lead styphnate and diazodinitrophenol.
Examples of the secondary explosives include, but are not limited to, pentaerythritol tetranitrate (PETN) and 2, 4, 6-trinotrotoluene (TNT).
Examples of the tertiary explosives include, but are not limited to, ammonium nitrate ¨based systems such as ammonium nitrate/fuel oil (ANFO) and ammonium nitrate emulsions.
Explosive material associated with a borehole resident electronic device in the form of an initiator will typically be located within a separate container that is connected to and in communication with the one or more electronic components being shielded by the fibre-reinforced composite thermoset resin layer in accordance with the invention.
Although not necessarily a requirement, primary or primary and secondary explosives associated with the initiator may also be located in the same container with the one or more electronic components being shielded by the fibre reinforced composite thermoset resin layer in accordance with the invention.
In the form of a monitor or communications device, the borehole resident electronic device will be capable of monitoring a particular parameter and/or receiving and/or sending data including communications data. The device will comprise appropriate electronic components to undertake those tasks.
Irrespective of its practical function, the device in accordance with the invention comprises a container in which is located one or more electronic components. Those one or more electronic components facilitate one or more functions of the device. The specific nature of and function of the one or more electronic components are not particularly relevant in the context of the present application in the sense they can represent any type of electronic component that facilitates a desired function of the device. Rather, an important feature of the one or more

- 9 -electronic components located in the container in the context of the present invention is that they are of a type that can be adversely affected upon being exposed to an explosive shockwave and consequently warrant shielding from that shockwave. Most if not all electronic components used in such borehole resident electronic devices can be adversely affected upon being exposed to an explosive shockwave, prompting the need for the present invention.
The container used in accordance with the present invention is advantageously resistant to distortion/deformation upon being subjected to an explosive shockwave.
Accordingly, in addition to dissipating force of the explosive shockwave on the one or more electronic components located therein, the container itself exhibits improved resistance to undergoing distortion/deformation upon being exposed to the explosives shockwave and thereby further protects the integrity of the one or more electronic components contained therein.
Those skilled in the art will be able to select and configure suitable electronic components for use in a given electronic device as applied in the present invention.
Examples of common electronic components that would be expected to be located within the container in the present invention include, but are not limited to, resistors, capacitors, microprocessors, antennas, batteries, inductors, sensors such as pressure sensors, temperature sensors, magnetic field sensors and accelerometers, circuit boards and connectors.
Blasting operations contemplated herein are intended to embrace those well-known in the art, including surface (open cut) and subsurface (underground) blasting operations.
There is no particular limitation on the shape or size of the container used in the present invention. The shape and size of the container will usually be dictated by the nature of electronic components required by the device.
For example, the container may have a circular or rectangular cross-sectional shape. The container may be spherical or elongated.
To function as a container, it will generally be spherical or have an elongated dimension so as to provide depth within the container to locate the one or more electronic components.

- 10 -In one embodiment, the container has a tubular shape with a circular or rectangular cross-section.
In another embodiment, the container is spherical.
Where the container has an elongated dimension, for example in the form of a tubular shape, the longest dimension or length of the container can, for example, range from about 50 rum to about 500 mm. The width of such a container can, for example, range from about 10 mm to about 100 mm.
Where the container has a spherical shape, it may have, for example, a diameter ranging from about 50 mm to about 500 mm.
The container may form all or only part of the electronic device. For example, the container housing the one or more electronic components may form only part of the electronic device with other features of the device (e.g. non-electronic components) being associated with the container but not located therein.
The device may contain one or more electronic components located outside the container.
However, in that case such electronic components will typically be of a type that are not adversely affected by an explosive shockwave.
In one embodiment, all electronic components of the device having potential to be adversely affected by an explosive shockvvave are located in the container.
The container used in accordance with the invention has a wall structure comprising a fibre-reinforced composite thermoset resin layer. By being a container it will of course have a wall structure that defines the container body. For example, the container may be defined by a tubular or spherical wall structure and thereby have a tubular or spherical shape, respectively.
The container is a "container" in the sense it has located within its confines the one or more electronic components. In that context, the "container" need not necessarily have a shape and configuration suitable for holding or retaining a liquid within it. For example, as discussed herein a container in accordance with the invention may be in the form of a tube open at both ends that functions as a sheath, sleeve or casing within which the one or more electronic

- 11 -components are contained.
The container can be pre-formed prior to the one or more electronic components being located therein. In that case the container will generally be provided with at least one opening through which the one or more electronic components may be passed so as to be housed within the container. For example, as in a container having a tubular wall structure open at one end, or perhaps a container having a spherical wall structure having one opening therein. The container may also have two openings, for example, located at opposite ends of the container in the form of a tube. In that case, the container may be described as being an open-ended tube. In use and after the electronic components have been located therein, the container will typically have all such openings sealed.
Alternatively, the container may be formed or created around the one or more electronic components. In that case, it will be appreciated the so formed container may be described as not having any openings per se through which the one or more electronic components are passed so as to become housed therein. In such an embodiment, the one or more electronic components may be first located in a sub container around which of the container in accordance with the present invention is formed. Such an embodiment advantageously does away with the need to seal an opening through which the one or more electronic components are passed so as to become located within the container. That in turn can further increase the structural integrity of the container and eliminate the chance of defects in sealing the container.
In one embodiment, the one or more electronic components are located in a sub container and the container having the fibre reinforced composite thermosetting resin layer is formed around the sub container. In a further embodiment, the step of forming the container having the fibre reinforced composite thermosetting resin layer around the sub container fully encapsulates the sub container.
In another embodiment, the container has a tubular wall structure open at one or both ends. In that case, upon the one or more electronic components being located within the container through an opening, one or both of the open ends may be sealed, for example with sealing caps.
An open end of the container may be sealed with the same or different material from which the container itself is made. Where some part of the container is sealed with a material different from which the container itself is made, that different material may be of a type that can also

- 12 -shield the electronic components from the explosive shockwave. For example, that different material may be a different polymer or a metal.
Suitable metals might include, but are not limited to, aluminium, copper, brass, bronze, steel and stainless steel.
It should be acknowledged certain metals can exhibit properties suitable to effectively shield electronic components from an explosive shockwave.
However, while making the container as described herein entirely from such metals may prove effective at shielding the electronic components from an explosive shockwave, those skilled in the art will appreciate such metal containers can block the transmission of electromagnetic waves, thereby limiting communication for wireless transmitting or receiving systems In the context of explosives initiators, metal-based containers can also present safety concerns in that they will give rise to dangerous high-energy shrapnel. Certain metals can also react with reagents commonly used in explosives operations, for example tertiary explosive such as ammonium nitrate, to form highly sensitised and hazardous explosive products.
In addition, such metal-based containers are highly thermally conductive and prone to transferring heat from the surrounding borehole environment (e.g. from a high-temperature mine site or heated tertiary explosive in which the electronic device is deployed) to the electronic components contained therein and adversely affect their performance.
Manufacturing such containers entirely from metal therefore has numerous shortcomings.
The containers used in accordance with the present invention not only exhibit advantageous properties derived from using polymer in their construction (e.g. having high transparency to electromagnetic waves, relatively low thermal conductivity and good chemical resistance), but the specific form of fibre-reinforced composite thermoset resin used imparts shockwave resistance properties more closely aligned with that of metal containers. The containers used in accordance with the present invention therefore can advantageously derive shock stop resistance properties approaching or exceeding metals but without many of the shortcomings of using metals.

- 13 -Having said that, as previously mentioned the containers used in accordance with the invention may nevertheless comprise at least some metal components, for example metal and caps, provided the function of the electronic components is not adversely affected.
In one embodiment, the container has a tubular wall structure sealed at one end and open at the other end. In that case, after the one or more electronic components are located within the container, the open end of the tubular wall structure may be sealed. It may be sealed with the same or different material from which the container is made.
Where the container has a tubular wall structure open at both ends of the tube, the container may simply be used in that form as an outer sheath. That outer sheath may be placed over and thereby contain a second or sub-container in which is located the one or more electronic components. In such an embodiment the container used in accordance with the invention has an open-ended tubular wall structure that functions as a sheath or sleeve and contains therein a second container in which the one or more electronic components are located.
In other words, the container defined in accordance with the invention may itself have located therein a second container (sub-container) within which is located the one or more electronic components.
The one or more electronic components may therefore be located within a sub-container that itself is located within the container having a wall structure comprising a fibre-reinforced composite thermoset resin layer. Similarly, the container having a wall structure comprising a fibre-reinforced composite thermoset resin layer may itself he located in a super-container or have an overlaying material (e.g. polymer coating or layer) applied thereto.
To assist with describing of the form of the borehole resident electronic device according to the present invention, reference is made to Figure 1. In that case, the electronic device is represented in the form of a blast movement monitor or tracker (10). The blast movement monitor or tracker (10) comprises a container (20) in which is to be located the relevant one or more electronic components (30). The container (20) has a tubular wall structure sealed at one end (20a) and open at the other end (20b). The tubular wall structure of the container (20) comprises a fibre-reinforced composite thermoset resin layer in which the fibre is in the form of unidirectional fibre (not shown). Sub-container (40) is inserted into the open end (20b). Sub-container (40) also has a tubular wall structure that is open at least at one end (40a). The one

- 14 -or more electronic components (30) are inserted into the open end (40a). By sliding parts in the direction (60), the one or more electronic components (30) is located in sub-container (40), which in turn is located in the container (20). Container (20) thereby has the one or more electronic components (30) located therein. The open ends (20b) and (40a) are then sealed with cap (50) to afford a borehole resident electronic device in accordance with the invention. The fibre-reinforced composite thermoset resin layer of the container (20) functions to shield the electronic components (30) contained therein from an explosive shockwave generated remote from the device.
To assist with describing the form of the borehole resident electronic device according to the present invention, reference is made to Figure 2. In that case, the electronic device is represented in the form of explosive initiators (10). The explosive initiators (10) comprise a container (20) in which is located relevant one or more electronic components (not shown).
The container (20) has a tubular wall structure with one sealed end (20a) and one open end (20b) (shown on only one initiator for clarity). The tubular wall structure of the container (20) comprises a fibre-reinforced composite thermoset resin layer in which the fibre is in the form of wound fibre (not shown). The container (20) is placed over and thereby contains the electronic components of the explosive initiator. The container (20) may be described as functioning as a sheath or sleeve that fits over the electronic components. The explosive initiators (10) include a component (30) that contains primary and secondary explosives material and which is joined to the container (20) at its opened end (20b). The fibre-reinforced composite thermoset resin layer of the container (20) functions to shield the electronic components contained therein from an explosive shockwave generated remote from the device.
By the wall structure comprising a "fibre-reinforced composite thermoset resin layer" is meant the wall has a fibre-reinforced composite thermoset resin composition that defines a layer within its structure. That layer may define the entire thickness of the wall structure or part thereof. Generally, the fibre-reinforced composite thermoset resin layer will have a thickness ranging from about 1 mm to about 10 mm, for example from about 4mm to about 8 mm.
The wall structure of the container may contain one or more layers other than the fibre-reinforced composite thermoset resin layer. For example, the wall structure may comprise a thermoplastic polymer layer such that it is positioned in between the fibre-reinforced composite thermoset resin layer and the one or more electronic components.
Alternatively, the wall

- 15 -structure may comprise a thermoplastic polymer layer such as that of the fibre-reinforced composite thermoset resin layer is positioned in between the thermoplastic polymer layer and the one or more electronic components. The wall structure might also comprise a thermoset resin layer absent reinforcement fibre in substitution for the aforementioned thermoplastic polymer layer.
There is no particular limitation on the type of thermoset resin that may be used in forming the layer.
In one embodiment, the thermoset resin is selected from epoxy, melamine formaldehyde, polyester, urea formaldehyde, vinyl ester, phenolic, cyanate esters, polyimide, maleimide resins, and combinations thereof.
The thermoset resin forms part of a fibre-reinforced composite. In other words, the thermoset resin provides for a polymer matrix throughout which the fibre is located and gives rise to the reinforced composite material.
Provided the fibre can present in the composite in a form required in accordance with the present invention (discussed below) there is no particular limitation on the material from which it is made. For example, the fibre may comprise ceramic, metal, metal oxide, metal carbide, glass, polymer or carbon material.
If the fibre to be used in the composite is a polymer fibre, to form a true composite that polymer will of course be of a different composition to the thermoset polymer matrix throughout which it is located.
In one embodiment, the fibre is glass fibre.
Fibre used in accordance with the invention will generally have a circular cross-section with a diameter ranging from about 0.5 pm to about 40 pm, or about 0.5 !MI_ to about 30 p.m, or about 0.8 pm to about 25 i.tm.
The wall structure of the container will define a perimeter and the fibre-reinforced composite thermoset resin layer will generally be present along the entire perimeter.
For example, where

- 16 -the wall structure is tubular having a circular cross-section, the fibre-reinforced composite thermoset resin layer will generally be present around the entire circumference of that circular cross-section.
An important feature of the present invention is that the fibre-reinforced composite thermoset resin layer is positioned as part of the container to shield the one or more electronic components from an explosive shockwave generated during the blasting operation and remote from the device. By the resin layer being "positioned to shield" the one or more electronic components from the explosive shockwave is meant the resin layer will be located in between the one or more electronic components and the general direction of an incoming explosive shockwave. In that way, the resin layer serves to protect the one or more electronic components from the explosive shockwave.
It will be appreciated the device may itself be an explosives initiator that generates its own explosive shockwave and the device will consequently be destroyed in the process. The relevant explosive shockwave in accordance with the invention will therefore be one generated remote from the device itself.
For example, the electronic device in accordance with the present invention may represent one of many explosives initiators used in a blasting operation that provides for a sequenced explosives event whereby individual or groups of individual explosives initiators are shielded from an explosive shockwave generated remote by other explosives initiators that form part of the sequenced explosives event.
Alternatively, an electronic device in accordance with the present invention may be in a form, for example a monitoring or communications device, that is not intended to be destroyed during the blasting operation. In that case, it remains equally important the electronic device be protected from the adverse effects of the explosive shockwave generated in the blasting operation.
The fibre-reinforced composite thermoset resin layer has been found to improve the shock stop resistance of the borehole resident electronic devices by shielding its electronic components from the explosive shockwave. Depending upon the configuration of the container comprising the resin layer, the degree of shielding of the electronic components may vary. Generally, the

- 17 -fibre-reinforced composite thermoset resin layer shields at least 50%, 60%, 70%, 80%, 90%, or 95% of the surface area defined by the one or more electronic components from the explosive shockwave originating remote from the device.
An important feature of the fibre-reinforced composite thermoset resin layer in shielding the one or more electronic components from the explosive shockwave is that the fibre embedded in the resin layer is in a form selected from unidirectional fibre, woven fibre, wound fibre, nonwoven fibre, and combinations thereof.
Without wishing to be limited by theory, it is believed the particular form of fibre used as part of the fibre-reinforced composite thermoset resin layer imparts to the device an excellent ability to shield the one or more electronic components located in the container from high pressures imparted by the explosive shockwave. The fibre reinforced composite resin layer also imparts excellent structural integrity thereby presenting increased deformation/distortion resistance to the container. Those combined properties have been found to protect and prevent failure of the device.
In one embodiment, the fibre-reinforced composite thermoset resin layer shields the one or more electronic components from an explosive shockwave that exerts on the device a pressure ranging from greater than about 200 bar, or greater than about 300 bar, or greater than about 400 bar, or greater than about 500 bar, or greater than about 600 bar, or greater than about 700 bar, or greater than about 800 bar, or greater than about 900 bar, or greater than about 1000 bar, or greater than about 1100 bar.
In another embodiment, the fibre-reinforced composite thermoset resin layer shields the one or more electronic components from an explosive shockwave that exerts on the device a pressure ranging from about 200 to about 1100 bar, or about 300 bar to about 1100 bar, or about 400 bar to about 1100 bar, or about 500 bar to about 1000 bar, or about 600 bar to about 1000 bar, or about 700 bar to about 1000 bar, or about 800 bar to about 1000 bar, or about 900 bar to about 1000 bar.
Containers suitable for use in accordance with the invention (i.e. those having a wall structure comprising a fibre-reinforced composite thermoset resin layer in which the fibre is in a form selected from unidirectional fibre, woven fibre, wound fibre, nonwoven fibre, and combinations

- 18 -thereof) can be prepared using techniques well-known to those skilled in the art.
In one embodiment, the fibre used is the form selected from unidirectional fibre or wound fibre.
For example, fibre-reinforced composite thermoset resin layers having unidirectional fibre may be manufactured using a technique known as pultrusion.
Fibre-reinforced composite thermoset resin layers having a woven or nonwoven fibre may be manufactured using so called prepregs.
In one embodiment, the fibre used is wound fibre.
Fibre-reinforced composite thermoset resin layers having wound fibre may be manufactured using rotating mandrels around which the fibre (also referred to as a roving or filament) is laid down. The fibres can be laid down on the rotating mandrel in a desired pattern or angle to the rotational axis. Generally, the fibres will be laid down on the rotating mandrel at an angle ranging from about 20 to about 90 to the rotational axis.
In one embodiment, the wall structure is elongated and comprises a wound fibre-reinforced composite thermoset resin layer in which the wound fibre has an angle ranging from about 20' to about 90 or about 30 to about 90 , or about 40 to about 90 , or about 50 to about 90 , or about 60 to about 90 , or about 70 to about 90 , or about 80 to about 90 , or about 90 , relative to the axis of elongation.
It is common for wound fibre reinforced composites to include wound fibre having a combination of different fibre angles, relative to the access of elongation.
Containers having a wall structure comprising a wound fibre-reinforced composite thermoset resin layer have been found to exhibit superior ability to shield the one or more electronic components located in the container from high pressures imparted by the explosive shockwave.
The containers will be manufactured having a suitable size and shape to accommodate the one or more electronic components to be located therein. The containers may also be designed so as to be coupled to other components that form part of the electronic device.

- 19 -Such other components will typically not have a requirement to be shielded from the explosive shockwave.
The one or more electronic components may be located within the container such that one or more voids are positioned between the fibre-reinforced composite thermoset resin layer and the one or more electronic components. In that context, reference to one or more "voids" is intended to mean a solid or liquid free space that may be in vacuum or comprise or a gas, for example, air, nitrogen, or argon. By positioning one or more voids in between the electronic components and the thermoset resin layer of the container it is believed the shock-stop resistance afforded by the container can be enhanced. In particular, it is believed the presence of such a void reduces propagation of any shockwave passing through the resin layer and impacting the electronic components.
In one embodiment, one or more voids are positioned between the fibre-reinforced composite thermoset resin layer and the one or more electronic components.
In one embodiment, the one or more voids are filled with a gas.
In a further embodiment, the one or more voids are under vacuum.
In some embodiments, it may also be desirable for the one or more electronic components to he coated with or embedded fully or partially in polymer. For example, the one or more electronic components located in the container may be so-called "potted".
Examples of polymers that may coat or embed the one or more electronic components include polydimethylsiloxane, polyurethane, epoxy resin and melamine resin.
In one embodiment, the one or more electronic components are partially or fully coated by or embedded within polymer.
In some embodiments, the one or more electronic components are not partially or fully coated by or embedded within polymer.
Where present, the one or more voids may define a distance between the wall structure of the

- 20 -container and the one or more electronic components of at least 0.1 mm.
Generally, the one or more voids, when present, will define a distance between the wall structure of the container and the one or more electronic components of about 0.1 mm to about 10 mm.
The borehole resident electronic devices in accordance with the invention may be wired or wireless devices. Where the devices are wireless they will of course comprise electronic components that enable the device to wirelessly communicate with a second remote electronic device. To facilitate such wireless communication the container may comprise an aerial or antenna connected to the one or more electronic components.
The containers used in accordance with the invention can advantageously be readily fitted with conventional aerials/antennas.
In one embodiment, the wall structure comprises an aerial or antenna that is in communication with the one or more electronic components.
In a similar vein, the containers used in accordance with the invention may comprise electrically-conductive wires that can be used to heat the containcr and assist with regulating the temperature of the one or more electronic components contained therein.
That heating effect can be powered by a battery contained in the electronic device and find application in environments where the borehole temperature in which the device is deployed is sufficiently low to interfere with the function of the electronic components.
In a further embodiment, the wall structure comprises electrically conducting wire.
In another embodiment, the electrically conducting wire is connected to a power source and promotes heating of the container.
The electrically conducting wire may be metallic or polymeric.
The present invention also provides a method of shielding one or more electronic components of a borehole resident electronic device from an explosive shockvvave in a blasting operation.
The method comprising deploying the device into a borehole of the blasting operation.

- 21 -By "shielding" the one or more electronic components is meant at least protecting them from the adverse effects of an explosive shockwave. As described herein, the container in which the one or more electronic components are located functions to provide that protection. However, the container may also serve to protect or shield the one or more electronic components from other potentially adverse factors such as the harsh environmental conditions often presented in borehole of a blasting operation. Such harsh environmental conditions in include temperature extremes and exposure to petroleum products such as diesel and oil, corrosive, acidic, and basic conditions.
Shielding the one or more electronic components as described in herein can advantageously reduce or prevent premature failure of the one or more electronic components.
By "premature"
failure is intended mean failure of the device absent using a container of the type in accordance with the invention. In particular, the type of electronic devices relevant to the present invention are intended to perform a particular task or function. Absent the container used in accordance with the present invention that task or function may not occur due to one or more electronic components in the device failing as a result of being exposed to an explosive shockwave.
Having failed upon exposure to an explosive shockwave, those one or more electronic components will be considered to have undergone premature failure (i.e., they have not been able to function as intended). The method in accordance with the present invention can reduce or prevent the occurrence of such premature failure through use of the borehole resident electronic device as described herein.
Those skilled in the art will be familiar with the process of drilling boreholes as part of a blasting operation and the deployment therein of products to effect the blasting operation or facilitate it in some way. Such products include the borehole resident electronic devices described herein, which may be used in combination with tertiary explosive in a case where the electronic device is an explosives initiator.
Producing the boreholes and deployment of such borehole resident electronic devices can advantageously be performed in accordance with the invention using techniques well known to those skilled in the art.
The present invention also provides a method of performing a blasting operation, the method comprising deploying a borehole resident electronic device into a borehole of the blasting

- 22 -operation, wherein the device comprises a container in which is located one or more electronic components, the container having a wall structure comprising a fibre-reinforced composite thermoset resin layer positioned to shield the one or more electronic components from an explosive shockwave generated during the blasting operation and remote from the device, and wherein the fibre is in a form selected from unidirectional fibre, woven fibre, wound fibre, nonwoven fibre, and combinations thereof.
The present invention further provides use of a borehole resident electronic device in a blasting operation, the device comprising a container in which is located one or more electronic components, the container having a wall structure comprising a fibre-reinforced composite thermoset resin layer positioned to shield the one or more electronic components from an explosive shockwave generated during the blasting operation and remote from the device, wherein the fibre is in a form selected from unidirectional fibre, woven fibre, wound fibre, nonwoven fibre, and combinations thereof.
The present invention also provides use of a borehole resident electronic device located in borehole of a blasting operation, the device comprising a container in which is located one or more electronic components, the container having a wall structure comprising a fibre-reinforced composite thermoset resin layer positioned to shield the one or more electronic components from an explosive shockwave generated during the blasting operation and remote from the device, wherein the fibre is in a form selected from unidirectional fibre, woven fibre, wound fibre, nonwoven fibre, and combinations thereof.
The present invention will hereinafter be described with reference to the following non-limiting examples.
EXAMPLES
Example 1 To determine the ability of different configurations to survive damage a trial was carried out using an impact tester where a 10Kg weight was dropped from a height of lm onto a polycarbonate (comparative), pultruded and fibre wound composite (FWC) sample container (made using epoxy resin and glass fibre), all having a wall thickness of -3mm.
The

- 23 -polycarbonate sample underwent significant deformation, in some instances cracking of the part and a large impression from the impact head of the machine was left in the sample. The pultruded sample showed cracking along the length of the tube where the glass fibre had delaminated. Only the FWC sample showed negligible damage from the test with some minor delamination at the impact point and no loss of integrity of the sample.
Example 2 To compare the performance between polycarbonate (comparative) and FWC
protective sleeves (where the fibres are wound around the radial direction of a central core at different angles) an assembly similar to the structure shown in Figure 1 was tested with the sleeve (40) being either made from polycarbonate (comparative) or FWC (of the invention).
The test rig used is described with reference to Figure 3. A 150-gram charge identified as a booster (1), pressure gauges (5), the assembled test samples (2a and 2b) (comprising electronic circuit board (3) and antenna (4)) were suspended by wooden rod (7), all spaced at known distances. The test assembly was lowered into water (8) below an air interface (9). The electronic board (3) and antenna (4) were orientated so they faced toward the shockwave generated from the detonation of the booster (1).
Sample 2a represents a comparative polycarbonate sleeve system and sample 2b represents a FWC sleeve system of the invention, apart from those differences in the sleeves, the test samples were the same. The samples were sealed so that the internal atmosphere was air (9) to prevent ingress of water (8) which may adversely affect the electronics.
Pressure gauges (5) were placed throughout the test rig to obtain a pressure profile with distance and when compared to a calibration chart the actual pressures on the test samples (2a and 2b) could he calculated. The test samples (2a and 2h) were placed equidistance on either side of the charge (booster) (1) to experience the same pressure profile and allow direct comparison. The location of the pressure gauges (5) throughout the experiment is arbitrary (other than known distance from the donor charge) and did not affect the result. In Figure 3 the pressure gauges (5) are shown on one side of the test set up only, but any number could have been placed on either side.

- 24 -In Figure 3 the shockwave force (6) is represented for clarity only as going in one direction toward sample 2a. It will be appreciated the shockwave from (1) will actually radiate out in all directions out from the donor charge (1). Both test samples 2a and 2b received the same shockwave force.
The tests were completed a number of times.
On completion of the test, some of the comparative 2a samples exhibited clear damage to larger components such as antennas and batteries (see Figure 4). Damage to the antennas, which included complete fracture, tended to be located at the extreme edges of the electronic components located closest to the wall of the inner casing. After being subjected to the explosives shockwave the electronic circuit board of comparative 2a also failed to function.
Test samples 2b using the FWC in accordance with the invention did not exhibit any damage after being subjected to the explosives shockwave and remained fully functional as per their intended design.
The electronic componentry of samples 2a and 2b were also contained (in addition to the polycarbonate sleeve and FWC sleeve) within an inner polycarbonate casing, not shown in Figure 1. For test sample 2a, which used the comparative polycarbonate sleeve, damage was also observed to its inner polycarbonate casing. That damage consisted of longitudinal cracks along the length of the casing at 900 to the direction of the generated force (6) as well as several other large cracks randomly around the comparative sample. It is believed such longitudinal cracks are associated with a point of flexure of the inner and outer polycarbonate casings/sleeves. As the casings/sleeves of the comparative test sample is compressed down by the shockwave it is also forced outwards at 90 to the point shockwave impact (see Error!
Reference source not found. 5). That extension exceeds the mechanical properties of the polycarbonate casing/sleeve causing it to fail in the form of crack stress relief. Figure 5 illustrates a schematic representation of the deformation of the polycarbonate casing/sleeve of sample 2a showing: (1) the electronic circuit board, (2) the antenna, (3) the original shape of the polycarbonate casing/sleeve, (4) the proposed deformation shape of the polycarbonate casing/sleeve due to dynamic pressure from shockwave, (5) the region of major cracking of the polycarbonate casing/sleeve due to deformation, and (6) the impact region on antenna by the deformed polycarbonate casing.

- 25 -No damage to the inner polycarbonate casing or electronic componentry was observed for sample 2a that was shielded/protected from the shockwave buy the FWC sleeve.
Example 3 In a series of trials for the development of the products shown in Figure 2, a system comprising of an outer polycarbonate casing, either a polycarbonate (comparative) or a pultruded inner sleeve, and an inner polycarbonate casing, in which was housed the electronics for the control system, was tested at pressures between 200 and 1200 bar (without the explosive booster labelled (30) in Figure 2). Following exposure to the explosives shockwave, the samples were examined for integrity of the casings/sleeves and damage to the electronics board and components. A sample was considered to pass if the total system appeared undamaged. The sample with the pultruded sleeve passed the test at pressures nearly double than could be sustained by the comparative system using the polycarbonate sleeve (see Figure 6).
Example 4 To determine the effect of a FWC sleeve (of the invention) to reduce the incident pressure experienced by the electronics contained therein a test using the set up shown in Figure 7 was performed. A pressure gauge (2a) was placed centrally inside the FWC sleeve (3). To prevent water ingress during the experiment the FWC sleeve (3) was sealed using aluminium end caps (4) which were glued onto the ends of the FWC sleeve (3). The top end cap (4) had a hole drilled through it to allow the pressure gauge wire (5) to pass through and this hole was sealed with epoxy resin to prevent water ingress during the experiment. The internal environment within the sleeve during the test was air (8). A second pressure gauge (2b) was attached to the outside wall of the FWC sleeve (3) to measure the incident pressure delivered by the charge booster (1). The booster (1) and FWC sleeve (3) assembly were suspended from wooden rods (6) and suspended in water (7) beneath an air interface (8). Suspension in water ensured direct coupling of the shockwave and the sample. By measuring the distance between the charge booster (1) and the pressure sensor (2b) attached to the outside wall of the FWC sleeve (3) and the use of calibration curves the incident pressure can be calculated. Based on the measured signal from the pressure gauge (2a) inside the FWC sleeve assembly (3 and 4) and use of the

- 26 -calibration curve the pressure exerted on the internal sensor (2(a)) can be calculated. The expected pressure that the internal sensor (2a) should experience based on its distance from the donor charge (1) if the protective FWC sleeve (3) had not been in place can also be calculated using the known distance and calibration curve.
Six samples were tested in the Figure 7 set up. Based on previous calibration curves the expected pressures and the measured pressures without and with the FWC sleeve in place could be determined. As shown Table 1 there is a significant drop in measured pressure for all 6 samples compared to the calculated expected pressure if the FWC sleeve had not been present.
Table 1: Pressure data Thctanc¨\\1 \\I
.\\\\ --\\\bir1.\\\ \\\\
gica(Jtdoke.
gi 150 6.07M 608 N/A
Free Field) ..t.RG gauge N/A
(Free. Field) MF'Ci D R X C. 1 108 19 861 *iii#GP R X miiii6$

. =
RiD:RXC 4 113 24 819 1066 FGD:RXC 6 130 34 : 711 892 That data demonstrates the effectiveness of the fibre-reinforced composite thermoset resin layer used in accordance with the invention to shield/protect electronic components from an explosive shockwave.
The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

- 27 -Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as ''comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Claims (15)

Claims:

1. A borehole resident electronic device for use in a blasting operation, the device comprising a container in which is located one or more electronic components, the container having a wall structure comprising a fibre-reinforced composite thermoset resin layer positioned to shield the one or more electronic components from an explosive shockwave generated during the blasting operation and remote from the device, wherein the fibre is in a form selected from unidirectional fibre, woven fibre, wound fibre, nonwoven fibre and combinations thereof.

2. The borehole resident electronic device according to claim 1, wherein one or more voids are located between thc fibre-reinforced composite thermoset resin layer and the one or more electronic components.

3. The borehole resident electronic device according to claim 1, wherein the one or more electronic components are coated with or embedded in a polymer.

4. The borehole resident electronic device according to any one of claims 1 to 3 in the form of an explosives initiator.

5. The borehole resident electronic device according to any one of claims 1 to 3 in the form of a monitor or communications device.

6. The borehole resident electronic device according to any one of claims 1 to 5, wherein the one or more electronic components are configured to communicate wirelessly to a second electronic device remote from the borehole resident electronic device.

7. The borehole resident electronic device according to any one of claims 1 to 6, wherein the fibre-reinforced composite thermoset resin layer is a fibre wound composite thermoset resin layer.

8. The borehole resident electronic device according to any one of claims 1 to 7, wherein the thermoset resin is selected from epoxy, melamine formaldehyde, polyester, urea formaldehyde, vinyl ester, phenolic, cyanate esters, polyimide, maleimide resins and combinations thereof.

9. The borehole resident electronic device according to any one of claims 1 to 8, wherein the fibre is glass fibre.

10. The borehole resident electronic device according to any one of claims 1 to 9, wherein thermoset resin layer has a thickness ranging from about 1 mm to about 10 mm.

11. The borehole resident electronic device according to any one of claims 1 to 10, wherein the container includes an antenna or aerial that facilities transmission of an electromagnetic signal to or from the one or more electronic components.

12. The borehole resident electronic device according to any one of claims 1 to 10, wherein fibre-reinforced composite thermoset resin layer shields at least 80%
of surface area defined by the one or more electronic components from the explosive shockwave originating remote from the device.

13. A method of shielding one or more electronic components of a borehole resident electronic device from an explosive shockwave in a blasting operation, the method comprising deploying the device into a borehole of the blasting operation, wherein the device comprises a container in which is located the one or more electronic components, the container having a wall structure comprising a fibre-reinforced composite thermoset resin layer positioned to shield the one or more electronic components from an explosive shockwave generated during the blasting operation and remote from the device, and wherein the fibre is in a form selected from unidirectional fibre, woven fibre, wound fibre, nonwoven fibre, and combinations thereof.

14. The method according to claim 13, wherein the borehole resident electronic device is in the form of an explosives initiator and it is deployed in the borehole with a tertiary explo sive.

15. Use of a borehole resident electronic device in a blasting operation, the device comprising a container in which is located one or more electronic components, the container having a wall structure comprising a fibre-reinforced composite thermoset resin layer positioned to shield the one or more electronic components from an explosive shockwave generated during the blasting operation and remote from the device, wherein the fibre is in a form selected from unidirectional fibre, woven fibre, wound fibre, nonwoven fibre, and combinations thereof.