Application of 3-D seismics to mine planning at Vaal Reefs gold mine, number 10 shaft, Republic of South Africa

Abstract

During 1994, a 3-D seismic reflection survey was undertaken at Vaal Reefs No. 10 shaft with the objective of mapping the detailed structure of the Ventersdorp contact reef gold orebody. This would provide vital input into future mine planning and development. The survey benefitted from 10 years of 2-D seismic experience and one previous 3-D mine survey, conducted in the Witwatersrand Basin. The seismic survey at No. 10 shaft accurately and spectacularly delineated the 3-D structure of the Ventersdorp contact reef at depths ranging from 1000 to 3500 m, imaging faults with throws in the 20- to 1200-m range. The resultant structure plans were satisfactorily validated by subsequent surface drilling and underground mapping mining operations during the period 1994 to 1996. These plans have been merged with drillhole, underground, and sampling data into an integrated mine modeling, gold reserve estimation, and mine scheduling package. The geology department now manages the planning function at No. 10 shaft, and 3-D seismics has played a significant role in placing this important responsibility firmly within the geologists’ domain. Building on the success of the No. 10 shaft survey, two other 3-D seismic surveys were concluded over mines during 1996 and 1997.

Seismic methods in mineral exploration and mine planning: A general overview of past and present case histories and a look into the future

“…Reflection seismic methods were implemented in the 1980s, rejuvenating exploration activities and contributing to the discovery of the South Deep orebody (Haslett, 1994) and new resources in the Bothaville Gap Tucker et al, 1994). The adaptation of reflection seismic technology to the hard-rock environment over the last quarter century has been described by several authors, e.g., Campbell and Peace (1984), Durrheim (1986), Pretorius et al (1989), Campbell (1990), Campbell and Crotty (1990), ), Campbell (1994), De Wet and Hall (1994, Pretorius et al (1994), Weder (1994), Pretorius and Trewick (1997), Gibson et al (2000), Stuart et al (2000), Pretorius et al (2000), and Gillot et al (2005). A comprehensive review of the use of reflection seismology to map the Witwatersrand Basin is provided by Pretorius et al (2003).…”

“…Between 1996-2002 supported a large number of 2D and 3D seismic surveys for the purpose of deep exploration (<1500 m) in Canada. Adopting an approach of cost-benefit evaluation of 3D seismic used in hydrocarbon exploration, Pretorius et al (1997) conducted the first successful application of 3D seismic for mine planning and development. The first successful 3D seismic delineation of a blind massive sulfide deposit was reported from the western part of the Bathurst mining camp, in the Halfmile Lake area, Canada, at a depth of about 1.2 km (Matthews, 2002;Bellefleur et al, 2004b;Malehmir and Bellefleur, 2009).…”

3D seismic survey at the Millennium uranium deposit, Saskatchewan, Canada: Mapping depth to basement and imaging post-Athabasca structure near the orebody

“…However, for accurate delineation of structure, it is necessary to acquire 3D reflection seismic data. This is exemplified by the importance assigned to 3D surveys in South Africa, in conjunction with mine development where the sinking of the mine shafts are associated with large costs (e.g., Pretorius et al, 2000;Stuart et al, 2000). High-quality 3D seismic data allow major faults to be avoided and help to locate the shafts so that competent rock units are entered at optimum locations.…”

What can seismic in hard rocks do for you?

“…Subsequently, 3D seismic survey for Ni-Cu exploration was conducted in the Sudbury basin in 1995 (Milkereit et al, 2000) and Pretorius et al (1997) who conducted the first successful application of 3D seismic for mine planning and development.…”