Title: Author: Background: Maximise core recovery: Identify and resolve orientation and data transfer issues at rig:

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1 Title: HOW TO MAXIMISE THE QUALITY AND VALUE OF STRUCTURAL DATA FOR YOUR PROJECT - A PRACTICAL GUIDE TO COMMON PROBLEMS WITH FIELD DATA TRANSFER WHEN ORIENTATING CORE. Author: Gavin McLeod Background: Accurate, auditable and cost effective core orientation (together with borehole logging and surveying) plays a vital role in determining the true structure and viability of any mining or construction geotechnical project. planning, based on quality data provides the best foundation for project profitability. The cost per metre or foot, to drill and extract a core sample from a borehole is significant so it makes basic economic sense to maximise accurate and verifiable structural data from each borehole drilled. If any project is delivering less than 80% of the orientated core runs as high quality and verifiable core orientations, then the core orientation system being used, and/or onsite procedures applied, should be reviewed and re-evaluated. The single greatest issue in attaining and maintaining high quality and consistently verifiable core orientation data does not relate to the type of core orientation tool used, or even the ground conditions being drilled. Transferring and validating the core orientation line from whichever type of core orientation tool is used to the physical core sample at the drill site has been highlighted as the major issue. Unless the Geotechnical Technician or Drill Rig Operator can compare and validate (audit) each specific core orientation reading with the previous core run to immediately identify any issues, it is assumed that the orientation is correct and accurate. Unfortunately this is not always the case and such problems may not be identified until days, weeks or even months later when the core is logged in the core shed and after the drill rig has moved on. Today, because of the variety, innovation and sophistication of core orientation systems available, these problems can be easily addressed and rectified to provide real-time, at rig, verifiable and audit-able core orientation at any borehole angle and any ground type. This paper provides a very brief summary of the accepted types of core orientation methodologies utilised in the mining and geotechnical industries, the specific technical issues each has attempted to address, common problems experienced by each system and practical solutions for such problems. A quick look up chart has been included at the end of this article to allow readers to simply identify the core orientation best suited to their specific situation, and technical and budgetary requirements. As an example, the most common issue affecting all types of core orientation methodology is ground conditions. Ground conditions which have become too soft or broken prevent the orientation tool from either taking a viable face imprint of the bottom of the borehole or retaining or maintaining a viable core sample in the lifter case, inhibiting the effective and reliable transfer of orientation data from the tool to the core sample. To follow is a list of suggestions to improve data collection and transfer in these conditions.. Maximise core recovery: The AMC Minerals COREWELL multifunctional drilling fluid system should be used to encapsulate clay and shale surfaces and produce an intact core sample, improving core recovery by up to 75% and productivity by 65%. 2. Identify and resolve orientation and data transfer issues at rig: A standard procedure should be enacted which requires the Drill Rig Operator to review his

2 operating procedures as well as the orientation tool being used for functionality, then drill at a maximum rate of m (3ft) coring intervals after each failed orientation due to the ground conditions, until the problem can be identified and resolved. 3. Orientation of broken ground with a grouted-stub: If it becomes obvious after approximately three consecutive failed orientations that the ground conditions are not improving, then the bottom 30cm (ft) of the borehole should be grouted to try to bind the ground together and then orientate the grouted-stub. Once the grouted-stub has been re-drilled and at least m (3ft) of natural core past the grout-stub is retrieved, you will have a higher chance of orientating the zone directly below and through the grouted section. As traditional cement grouting can take up to 48 hours for the grout to cure, it would be recommended to use the EZ-GREASE GROUT wireline system to reduce the grouting timeframe down to approximately one or two hours. There are a variety of accepted core orientation methods and systems available on the market today, each with its own benefits and limitations. All accepted forms of in-hole core orientation can be divided into five categories as follows:, MANUAL NON AUDIT-ABLE: These core orientation systems have been in use in one form or another for more than 70 years. They either take an impression of or physically mark the bottom of the borehole while the core sample, yet to be drilled, is still part of the parent rock. As manually operated systems they cannot be run in conjunction or parallel with any other part of the drilling process. Productive drilling time, as a consequence, is significantly reduced, making these systems among the most expensive systems to operate. Examples of these types of core orientation systems are the Spear or Pin Impression core orientation systems. 2, MANUAL SEMI AUDIT-ABLE: These core orientation systems were first introduced in the 970 s and take an impression of the bottom of the borehole with a piece of modelling clay while the core sample, yet to be drilled, is still part of the parent rock. As manually operated systems they cannot be run in conjunction to or parallel with any other part of the drilling process. As a consequence, productive drilling time is significantly reduced and overall drilling costs increased. However, a major benefit of this system is that the physical impression taken of the bottom of the borehole can be removed from the tool and placed in the core tray as a semi audit-able record of each core orientation. This is limited to being semi audit-able because it records the core face prior to drilling but the quality and accuracy of the physical orientation is reliant on the accurate observation and data transfer of Drill Rig Operator. An example of this type of core orientation system is the Clay Impression core orientation system. Some of the operational and technical issues as well as suggested solutions for both these types of core orientation systems are as follows: Wear on the outside diameter of the Spear orientation tool - caused by running up and down within the drill string or a bend in the tool, effectively changes the gravitational centre of the tool. Solution: Replace immediately with a new tool. Impact Errors Potential orientation errors of up to 80 degrees can be caused when impacting the bottom of the borehole with the Spear type at a speed any greater than dead slow, resulting in bounce on impact, giving multiple readings, or a large impact smear or chip on the core stub. Solution: Ensure that the Drill Rig Operator carefully and clearly marks the wire-line cable with paint or coloured electrical tape at the open rod, just prior to retrieving the full inner core tube from the borehole. This will act as a depth indicator for the Drill Rig Operator who must reduce the wire-line decent speed to dead slow as the mark appears at the top of the drill mast and before the spear tool impacts with the bottom of the borehole.

3 Inaccurate orientation data transfer - With the Spear type of core orientation system, interpretation by the Drill Rig Operator of the centre, or in the case of steep angled core break, the origin of the orientation mark created by the Orientation Spear that is then transferred to the outer diameter of the core sample, can vary significantly from the original mark and can introduce a potential error of up to plus or minus 20. Solution: It is advisable to provide the Drill Rig Operator with a simple core-marking jig that fits neatly over the diameter of the core sample being drilled, minimising the potential 20 interpretive and compounding error. No verification of gravitational orientation - With the mechanical Pin or Clay Impression core orientation systems, there is no way of confirming or verifying that the orientation line drawn by the drill rig operator on the core sample is the actual gravitational orientation position recorded by the tool. Solution: Either place an independent Geological Field Technician on the drill rig to take control of the actual orientation data transfer process, or require the Drill Rig Operator to take a digital photograph of the Pin Impression Tool aligned to the core sample on each core run as a visual record of the data transfer. 3 - NON-, AUTOMATIC SEMI AUDIT-ABLE: These core orientation systems first became commercially viable in the early 990s. They do not take an impression of, or physically mark, the bottom of the borehole prior to the coring process but rather orientate the inner core tube either electronically or mechanically at the end of each core run and prior to the core breaking process. The gravitational orientation data is transferred from the inner core barrel to the physical core sample retained in the Inner Core Tube Lifter Case at the surface by the Drill Crew. These systems are fully automated as they are operated in conjunction or parallel with another part of the drilling process (e.g. wire-line retrieval of the inner core tube). As a result, they do not interfere with productive drilling time and represented a quantum leap in drilling efficiency and quality data collection when they were introduced. These systems are also currently semi audit-able as they provide an either electronic or mechanic quality grading of each gravitational orientation. They cannot, however, provide a direct contact record with the core sample while it is still part of the parent rock. The most recent innovation of this type of core orientation system was the introduction of the ACT III system. This system was the first digital core orientation system released in 2004.The most recent mechanical system, the EZ-ORI, was commercially released in 20. Some of the operational technical issues as well as suggested solutions for these types of core orientation systems are as follows: Latent Rotational Torque (LRT) - This can be an issue for non-contact orientation systems if not managed with good drilling practice. LRT is caused by a Drill Rig Operator not drilling out the stretch with subsequent compressive load on a drill string at the end of each core run causing a core orientation reading of up to 720 out in extreme situations. This problem becomes worse with depth. Solution: Ensuring the Drill Rig Operator maintains normal drill rotation and Water Pump Flow Rates for at least 30 seconds and up to 45 seconds without any drill feed, at the end of each core run (depending on the borehole depth). This simple practice will not only significantly reduce or potentially eliminate the LRT affect on each core orientation, but it also has the added advantage of providing the Drill Rig Operator with up to an additional 00mm (4 inches) of core each core run. 4, AUTOMATIC AUDIT-ABLE: These unique types of core orientation system first became commercially available in 200 with the release of the EZ- MARK core orientation system for angled boreholes. More recently, in 200, the commercial release of the VERTI-ORI combined core orientation and borehole survey system for all attitude boreholes including true vertical. Both systems take a physical impression of the bottom of the borehole while the core sample, yet to be drilled, is still part of the parent

4 rock. However, unlike their predecessors, these systems are either partially or fully automated as they are operated in conjunction or parallel with another part of the drilling process (e.g. wire-line retrieval of the inner core tube or the borehole survey etc.). As a result they do not interfere with productive drilling time, saving costs. The combination of these systems with an audit-able record retained in the core tray such as the patented, and the cross referencing of multiple gravity or magnetic orientation readings, allows grading of the quality of each orientation, making these systems the first truly audit-able and verifiable core orientation systems available. Some of the operational technical issues as well as suggested solutions for these types of core orientation systems are as follows: Failed orientations - If the EZ-MARK tool is functioning correctly but is providing consistently failed orientations. The failure observed being that the three ceramic balls are being scattered and the pins on the do not appear to be compressed and/or the profile does not match the core sample. It is highly likely that the inner core tube, containing the loaded EZ-MARK tool has been dropped or allowed, by the Drill Crew, to free fall into the Standing Water Table within the drill string. Solution: Ensure the Drill Crew either always uses a standard Dry-Release Tool on the drill rig Wire-Line Overshot, or ensure the Drill Crew are filling the open drill string with water until it overflows from the open drill string prior to inserting the fresh inner core tube with the loaded EZ-MARK tool. Allowing the Inner Core Tube to free-fall within the drill string, even a short distance will not damage the EZ- MARK tool but may cause the tool to prematurely fire rendering the orientation recorded useless. Flat core breaks - It difficult to align the pins of the with a flat face at the core break to determine actual orientation. Solution: The is supplied with a RED China Graph pencil built into the pin face of the block. The red dot created on the face of the core sample at the point of orientation when the EZ-MARK or VERTI-ORI tool is impressed onto the bottom of the borehole, can be used as a starting point for core alignment with the. A further enhancement for core sample to alignment in such situations is to incorporate the use of ORI-PUTTY to provide a FULL-FACE imprint of the bottom of the borehole prior to drilling. Magnetically influenced data - Magnetic ground conditions or metallic structures within the ground formation near the borehole are interfering with the data accuracy produced by the VERTI-ORI when used in conjunction with the EZ-TRAC magnetic borehole survey tool. Solution: Convert from using the EZ-TRAC, which is a magnetic based borehole survey tool to the EZ-GYRO, which is a robust gyroscopic and non-magnetic based north seeking borehole survey tool. 5 - COMBINED /NON-, AUTOMATIC FULLY AUDIT-ABLE: If the number of viable orientations generated by the core orientation system being employed falls below 80%, or if a drilling contractor wishes to increase productivity by up to 25% by drilling 6- metre (20ft) core runs instead of the traditional 3-metre (0ft) core runs. Then the best way to ensure the integrity of core orientation per core run and maximise data collection intervals, is to operate a Contact based EZ-MARK kit in conjunction with a Non-contact based ACT III kit or a EZ-ORI kit. This unique combination is known as the COMBO KIT. The combination of these two independent core orientation systems more than doubles the number of independent and verifiable core orientation readings per core run, and has the added advantage of providing a level of audit-ability and accuracy verification not previously possible with any other core orientation system. This is achieved by using each system to independently cross check and

5 verify the other within each core run as well as with the previous and next core run. This provides REAL-TIME on-site and at rig audit-ability. This core orientation method takes both an impression of the bottom of the borehole prior to the coring process commencing and combines and compares this with the orientation of the inner core barrel taken at the end of the same core run. The combination of two independent core orientation systems in the same core run not only significantly increases the number of actual orientations per core run, but it also adds a level of audit-ability not previously possible. When evaluating each core orientation method it is important to consider the cost of lost time, accuracy and reliability together with the unit cost to determine the true cost of using the system. Core Orientation Method Comparison Quick Lookup Table: *Please note: The table below is based on orientating core every core run, as per manufacturers recommended operating procedures, in good ground conditions, to a maximum borehole depth of,200 meters (3,937Fft), at a borehole dip angle range of between -60 to -90 below horizontal and at an average coring penetration rate of 2.5cm (5 inches) per minute. ORIENTATION TYPE Maximum Independant Orientations per Core Run SPEAR MARK PIN IMPRESION CLAY IMPRESSION EZ-MARK ECONO NON- ACT III NON- EZ-ORI EZ-MARK NON- COMBO-KIT to 6 ACCURACY 0 to 40 0 to 20 0 to 30 to 5 to 5 to 5 to 5 to 5 RELIABITY Orientated Core Runs DEPENDING ON GROUND CONDITION 30% to 70% 70% to 90% to High to High to High Excellent 85% to 00% AUDIT- ABILITY QA/QC Capable NONE NONE MEDIUM VERY MEDIUM TO VERY METHOD, MODE APPLICATION DIGITAL COMBINED DIGITAL CORING PRODUCTIVITY 54% 27% 54% 27% 54% 27% 2 EVERY SECOND CORE RUN 2% 5% 4% 5% 4% 4% 9% 5% OPERATIONAL MAGNETIC (40 range) -35 TO -75 BELOW HORIZONTAL (30 range) -40 TO -70 BELOW HORIZONTAL (30 range) -40 TO -70 BELOW HORIZONTAL (70 range) (70 range) (70 range) (70 range) (70 range) COST BENEFIT MEDIUM TO AUDITABLE ORIENTATION DATA EVERY SECOND CORE RUN 6 METER (20FT) DOUBLE ORIENTATED CORE RUNS CAN INCREASE PRODUCTIVITY UP TO 25% DIGITAL ALL

6 EZ-TRAC VERTI-ORI EZ-GYRO VERTI-ORI to 5 to 5 VERY VERY MAGNETIC GYROSCOPIC TRUE NORTH 52% 24% 9% 68% 3 20% (80 range) +90 to -90 Vertical ED BY MAGNETISM (00 range) +40 to to -90 Non- ± 40 TO DATA QUAILTY CAN REDUCE DRILLED HOLE REQUIREMENT UP TO 67% TO DATA QUAILTY CAN REDUCE DRILLED HOLE REQUIREMENT UP TO 67% Conclusion: While there are a range of core orientation systems available, these are of no consequence if the basic issues inhibiting the accurate transfer of field data generated by these orientation systems to the physical core sample when orientating core are not addressed. The more checks and balances put in place to ensure the accuracy and validity of this data transfer at the drill rig in a simple and effective manner, the higher the audit-ability of the system. This has a direct and positive impact on the geologists who then have higher confidence in their decisions, based on this data that ultimately translates to project viability and profitability.