Slim Borehole Scanner (SBS) An Update The Slim Borehole Scanner is a camera inserted into small diameter boreholes in order to assess the immediate roof conditions in underground mining operations. This technology is currently being utilised by Moultrie underground geologists in a number of underground coal operations in New South Wales. We see a huge potential for this technology to be incorporated into safe mining practices as a complementary device to direct measurement methods and as a step forward on optical viewing tools currently available to the mining industry.

An Overview An advanced tool for assessing roof conditions Complements existing measurement methods Images can be assessed by more than just the operator Can be utilised reactively or proactively Objective data collection and analysis Repeatable data collection and analysis Auditable data collection and analysis The Slim Borehole Scanner is a useful tool for enhancing the capability of underground mine operators to assess roof conditions and is a significant advancement on existing assessment methods (e.g. borescope). It is intrinsically safe and delivers high colour photographs of the immediate roof, rib and floor of underground excavations (e.g. tunnels and mine roadways). Data attained through the use of the borescanner is used complementary to existing measurement methods which are commonplace throughout all modern mine operations (e.g. tell-tales and gel-extensometers). The images obtained are accessible to any number of personnel allowing for information sharing. This data is available for geotechnical engineers to assess the type and the level of roof support to be installed for a safe and productive work environment. The tool can be deployed in a reactive role (i.e. in response to deteriorating or poor roof conditions) or in a more proactive sense (i.e. for audit purposes or obtaining a roof profile for support installation or secondary extraction hazard plans).

Current Industry Standard While borescope data is invaluable it relies on the experience and technical ability of the operator. Borescope surveys cannot be peer reviewed, validated or audited without completing a subsequent survey Current photographic or video format tools are not intrinsically safe The borescope is currently utilised at a number of underground mine sites in Australia. This is viewed by a single person who makes notes, and then interprets what he has seen. The borescope interpretation is reliant on the experience of the operator. At sites where a borescope and a borescan have been undertaken on the same borehole on the same day, the difference in results has been obvious.

Slim Borehole Scanner The Slim Borehole Scanner consists of two components: Camera unit Battery and memory module The Slim Borehole Scanner is a compact unit measuring 1.2m long which is separated into two sections for ease of transport, the front camera section and the rear battery/memory module.

Slim Borehole Scanner Borescans are undertaken by a geologist using: Slim Borehole Scanner (SBS) consisting of a camera with a battery/memory module Carbon fibre push-rods Draw wire encoder iROC Personal Digital Assistant (PDA) The equipment that makes up the kit that a geologist employs to scan a borehole consists of: The camera with its battery/memory module Carbon fibre rods used to insert the camera into the borehole A draw wire encoder that measures the distance and initiates the pulse to the camera A personal digital assistant (PDA) used to check the scan underground

Slim Borehole Scanner Portable and lightweight equipment with international IS certification 3600 photographic scan of small diameter (32-48mm) borehole wall Lithology, fractures and bedding planes are easily identified within the immediate roof in underground coal mines Data is stored digitally for later analysis Colour scans with accurate depth recordings and fracture widths The Slim Borehole Scanner is portable and lightweight and has been certified as intrinsically safe, i.e. safe to be used in a potentially explosive atmosphere in a coal mine. A 3600 scan is obtained of the borehole wall in order to identify lithology, fractures and bedding planes in the immediate roof in underground coal mines. This data is stored digitally in the memory module and is downloaded later for analysis. Accurate depth measurements and fracture widths can be measured.

Certification Intrinsic safety certification: IECEx Certificate of Conformity for Explosive Atmospheres (Slim Borehole Scanner) - Issued by Dekra, Germany. Australian/New Zealand Certification for Explosion – Protected Electrical Equipment (iROC PDA) - Issued by TestSafe Australia One of the biggest advantages of the Slim Borehole Scanner is that it is intrinsically safe. The camera has gained international intrinsically safe certification whilst the accompanying PDA unit has been certified as intrinsically safe by the Australian/New Zealand Certification Scheme. Future plans are for Simtars testing so the tool can be employed in Queensland mines.

Applications Coal Industry - New drift development - Install face & relief roads - Intersection and gate road monitoring Hard rock Industry - Immediate roof strata Civil Engineering Industry - Tunnelling - Road cuttings Although at this stage the Slim Borehole Scanner has only been applied to the NSW underground coal mining operations in Australia there is no reason why this technology cannot be applied elsewhere. Borescans have been undertaken recently in order to understand roof prevailing conditions in longwall installation roads as well as for monitoring roof conditions in gate road intersections. Planned borescans on a regular basis can build a database of deteriorating conditions in a roadway. This data can be used as evidence during investigations into an incident. We see scope for continued development into metalliferous mines as well as in civil engineering projects where tunnel roofs or road cuttings can be inspected using the Slim Borehole Scanner.

Operation of the Slim Borehole Scanner Prestart inspections undertaken on the surface Designated borehole is inspected underground Equipment is set up and prepared for scan Slim Borehole Scanner is run up the borehole Equipment is packed up and moved to the next borehole Data is downloaded on the surface Data is processed and delivered to client Inspections on the tool are done on the surface before being used. Site inspections by the electrical department are completed if required before heading underground. Once underground at the designated area, the borehole integrity and surrounding roof is inspected in order to assess any potential risks to the equipment. The equipment is set up and the scan is undertaken by the geologist. The time taken for setup, scanning and completing a 10m borehole is normally around 50 minutes. This process is repeated until all the required boreholes have been scanned. Back in the office, the data is downloaded from the memory module and processed by the geologist. The final product is delivered to the client who can then make informed decisions.

Optimal conditions 32 mm borehole diameter is preferred (operating range 32 – 48mm) Holes drilled at 90o to the roof or rib or with limited deviation Use of spade drill bit is preferred to ensure a smooth side wall Borehole flushed thoroughly to remove drill fines and mud Scan should be completed within 24 hrs of drilling where swelling units (e.g. claystones) are present to reduce the likelihood of hole closure Indicative lithology section for the area available to allow for adjustment of camera settings Trial and error and experience has shown that the best result is obtained when the optimal conditions are met.

Slim Borehole Scanner Complements data attained from tell-tales, GEL extensometers and sonic extensometers Borescans are used in the development of a Coal Mine Roof Rating (CMRR) Identification of zones of weakness within the roof Data is an aid in the planning of roof support levels Permanent and transparent record of overlying strata Data obtained from a borescan can be, and has been, used for a variety of applications: To verify information obtained from static roof monitoring equipment such as tell tales. The exact location of the roof movement can be confirmed using the borescan. Data collected can be used to calculate the Coal Mine Roof Rating (CMRR) as an added tool in deciding on the nature of roof support to be installed. Zones of weakness (fractures or bedding planes) can be identified (reactively) in the roof and additional roof support can be installed to counter these zones. When used proactively, the data is used to plan roof support as well as to monitor the behavior of the strata immediately above the road by regularly scanning the same boreholes in an area and building up a database of strata behavior.

Sandstone Siltstone Coal Conglomerate Borescan data obtained at various sites.

Rifling Defects Broken Zones Defects and broken zones found in overlying strata, as well as the rifling effect obtained from using wing drill bits for drilling the boreholes.

Slim Borehole Scanner Data collected is compared to logs obtained from surface boreholes Objective means of detecting changes in fracture partings over time Lithological identification of roof material Permanent and transparent record of overlying strata Borescan data can be compared to logs obtained from surface boreholes. The borescan is a cheap method of filling in the gaps between surface boreholes when irregular or problematic lithology is encountered and this data is a permanent and transparent record of the overlying strata.

Slim Borehole Scanner Borescans are used to fill in the gaps between surface borehole logs and can easily identify zones of change within the roof. Data collected from the roof of underground roadways can be used to identify the immediate lithology. Scans to date have been up to 10m into the roof which has given the geologists and geotechnical engineers a good picture of the overlying strata. Weak strata, fractures and bedding planes can be classified as units and roof support is designed accordingly. When repeating scans in the same area at a later stage, any changes in the roof can be identified and remedied. The scans obtained allow for the correct identification of zones of weakness (e.g. fracturing and bedding planes) in the immediate roof strata. The high quality scan produced allows for the correct identification of lithological roof units and enables geotechnical staff to compile a database of roof conditions encountered along headings, gateroads, install faces and the like.

Slim Borehole Scanner Use of images for forensic analysis of roof failures can improve future roadway design Permanent digital record is obtained Data interpretation allows subjectivity Roof failures usually lead to an investigation in an attempt to find out what went wrong and how it can be avoided in the future. The Slim Borehole Scanner is a tool that can be used to investigate the roof and the data collected can be used visually in a report.

Slim Borehole Scanner In the example, a roof fall has taken place. A massive sandstone overlying the coal seam has traditionally meant a strong roof. A mudstone lens has weakened this roof leading to a fall. The Slim Borehole Scanner can be deployed to ascertain the extent of the weaker mudstone in order to install adequate roof support in the weakened zone.

Slim Borehole Scanner Reporting The borescan is interpreted by a geologist for lithology and structure (bedding planes, joints, faults, fractures and broken zones) producing a final report using WellCAD software.

Slim Borehole Scanner Reporting SBS image can be enhanced (e.g. brightness, contrast, colour saturation etc.) for lithology and defect identification An inverse image can be included to add detail to coal sections of the hole Image adjustments, i.e. playing with light, are used to enhance detail.

Advantages Supplies a digital image of the borehole wall in the immediate roof Objective information for a quantitative analysis of roof behaviour An objective and permanent digital record Allows advance notice of potential roof problems A reduced risk of unexpected roof failure To date the borescanner has returned excellent images on holes up to a diameter of 48mm. Dissipation of light has proven to lessen the picture quality at borehole diameters greater than 55mm. Best results have been achieved at 32mm diameter with the level of detail being impressive. Bedding planes, fractures, delamination, rubble zones, clast size and lithological units can be easily identified and picked to millimeter accuracy with depth in the borehole (height above the road way) being accurately recorded through the use of a wire line encoder.

Borescope/Slim Borehole Scanner Comparison Black/grey image visible Visible to operator only Operator interpretation only Interpretation underground Unit thickness estimated Apertures estimated Standardised report 3600 colour photograph Permanent record Auditable record Transparent record Repeatable record Interpretation in office Image can be enhanced Unit thickness measured (WellCAD) Apertures measured (WellCAD) Easy to customise report

Conclusion Thanks to Moultrie Geology Lithoview Aaron Jones I would like to thank Moultrie Geology and Lithoview for giving me this opportunity to present the Slim Borehole Scanner to you today. I would also like to thank Aaron Jones of Moultrie Geology for his valued input and assistance in preparing this for you today. The Slim Borehole Scanner is relatively easy to use and can be operated by one person. The tool is intrinsically safe and should be considered by geotechnical engineers as an added tool in their arsenal when assessing roof control issues.