The Background:
Straight hole exploration drilling conventionally uses steel wedges to promote "straight" drilling and minimise deviation. However, as the drilling fraternity and its customers know well, this can be an inexact science. Over a depth of 2 500m, holes can deviate by as much as 100m. Aside from which, wedges can come loose and block the hole, causing costly downtime or - in the worst cases - loss of the hole altogether (which means drilling of a new hole, with all its' associated, negative productivity and cost implications). The Problem:
A customer needed to commence surface exploration hole drilling operations in Ventersdorp lava along a lease boundary line. In view of the drill site location, it was stipulated that a deviation of up to .25° from the collar was permissible (translating into a mere 10m deviation at 2 500m). Even armed with geological survey information provided by the customer, and able to pinpoint the location from which they need core to be extracted, conventional steel wedge technology was unable to economically meet these stringent deviation requirements or guarantee accuracy of core data. The Solution:
The information age has brought with it a host of new tools to make the drilling services task easier and Boart Longyear's Drilling Services Division (CDD) employs them to provide customers with more accurate data more quickly. In this instance, the hole was drilled using Boart Longyear's latest generation BRQ rod string rated to a depth of 3 000m and, to steer the 76mm diameter hole on its course, CDD used a Down-the-Hole 2.3/8" low-torque, high-speed motor and Tensor Measurement-While-Drilling Electronic Survey Equipment. The DTH Motor was used when deviation on the hole exceeded 1 degree. The motor was able to advance at a rate of .5m per hour, with a water flow of 150 litres/min at 4.5mpa. Improved penetration rate and accuracy are two of the key benefits offered by this new technology. Others include: less in-hole torque, less wear and tear on the rods, and - having eliminated steel wedges from the process - greater risk control for both customer and contractor. Caption:
Satisfaction guaranteed: Accurate information was supplied to the customer from the specified location on time and within budget using the latest in-hole technology. Boilerplate:
Boart Longyear Drilling Services Division (CDD) specialises in surface and underground diamond drilling. Operating from bases in Welkom, Fochville
and Orkney, its team of 900 experienced drillers have been providing drilling services equipment and services to the African mining community. BL CDD belongs to the Boart Longyear group and is a key member of its global international Drilling Services Division, which has seamlessly provided drilling services solutions to customers around the world since 1890. BL CDD global drilling crews have drilled millions of metres through every conceivable geological formation on every continent in some of the world’s remotest and inhospitable locations. BL CDD is the worlds’ largest and most successful diamond drilling exploration and drilling services company For further information, please contact: Gordon Hogan
Managing Director
Boart Longyear Drilling Services Division
Fochville
South Africa
Tel: 018 7711000 / 2191
Fax: 018 7712196
Cell: 082 494 4162
Email: Ghogan@cdd.boartlongyear.co.za | 
