Drilling Techniques Sample Clauses

Drilling Techniques. To provide consistency of measurements, and to ensure that the coring equipment is functioning as efficiently as possible, the following general drilling techniques shall be adopted as standard practice: i) Taping of Borehole depth relative to temporary marker using an accurate metric tape after each core run. The level of the temporary marker shall be measured daily to ensure the depth measurements are referenced to a working level. ii) Measurement and calculation of Borehole depth relative to temporary marker after each core run summing the total length of core barrel and drill rods. iii) No drill run shall exceed 1.5m in length. If core recovery in any one run is less than 80%, the length of the subsequent run shall not exceed 0.5m. iv) Ensure drill position is maintained such that the drill rods remain central within the Borehole. v) Restriction of the flush medium flow rate to the minimum required for the maintenance of reasonable progress. vi) Immediate removal of non-retractable core barrels on change of materials from hard to soft and replacement with retractable core barrel (vice-versa for soft to hard). vii) In water flush holes when a retractable core barrel is in use, completing the final 50mm of each run without water. viii) Smooth removal of drill rods and core barrel from the Borehole. ix) Hosing out of core barrel and sediment catcher after each core run. Check the core barrel length is equal to the empty standard length to ensure the barrel is fully cleared prior to taking another core length. x) Advance casing by a rotary action without surging. xi) Avoid advancing casing beyond the depth penetrated by the core barrel. xii) Ensuring that all equipment and components are maintained in a good, clean, lubricated condition and otherwise maintained in accordance with manufacturer's instructions. For relevant core barrels this should include the replacement of the extrusion piston using a loading device and carrying out of frequent checks on the ball valves and extrusion tests to check for leakage past the piston. Retractable core barrels should be checked to ensure free movement of the retractable shoe against the tensioning spring.