Generally speaking, the drilling equipment is able to adjust to an inclination in the order of three to five degrees in each sequential step. "Both the technology itself and the incremental steps in which drilling takes place, are governed by the technical and design capability of the down-hole motors used," Bevelander points out. The next section of drilling is then carried out in the same way. A section of drilling is done, the equipment is removed from the hole, and a down-hole survey is carried out to confirm that drilling is progressing in the correct direction. Once the deflection is completed, the directional drilling equipment is removed from the hole and classical core cutting technology is used to traverse the lithology," he says.Ĭontinual further directional drilling is done in increments, taking the hole in the preferred direction. "The objective is, in a pre-planned way, to aim the deflection in three dimensions out of the mother hole towards the geographic point that one needs to intersect. Once the hole is of the correct dimension, a down-hole motor with an appropriate diamond cutting head is lowered down the mother hole and can begin to start drilling a hole which deflects out of it. If the geology is problematic, the lithology must be traversed in a planned and engineered fashion. He explains that the first step is to drill a mother hole from the surface down. The planning of the points of intersection with the ore body is based on the structural geology and geostatistics of the ore body. "Variability of ore bodies in terms of their geological geometry and structure has led to the need to be able to target, in three dimensions, the intersection of an ore body or reservoir from the surface at a reasonably accurate position," Bevelander notes. Various players in the industry began to look at the possibility of employing directional drilling technology to achieve multiple intersections on an ore body through a single mother hole. The time taken to drill many holes from the surface down to an ore body in the traditional way also frequently has an effect on the advancement of projects along their timelines. The production of oil through this single hole is greatly increased.Ĭosts of drilling in the mineral resources industry have escalated significantly over time. This results in the intersection of the oil-bearing reservoir at multiple points from the single 'mother’ hole. In these scenarios a single 'mother’ hole is drilled, and from this multiple deflections are made in preferred predetermined directions. The need to achieve multiple intersections of oil-bearing reservoirs through a single 'parent’ drill hole gave birth to the idea of direct drilling. "Oil reservoirs were often located in positions that were not accessible by ordinary surface drilling, due to surface infrastructure limitations and/or geological constraints," he points out. Martin Bevelander, surface drilling manager at Murray & Roberts Cementation, explains that the directional drilling technology had its birth in the oil industry some 25 years ago. Murray & Roberts Cementation is at the forefront of developing directional drilling technology at depth and in a hard rock environment. It also has the potential to enhance exploration efficiency and production greatly. While technology still needs to advance if its application is to be successfully integrated into the hard rock environment, it has significant implications for cost and time saving in exploration. Directional drilling is a relatively new aspect of exploration technology in the mineral resources industry.
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