The Drilling section is responsible for the majority of Government drilling operations in support of research and applied geological surveys. These include drilling for groundwater, geotechnical and mineral investigation purposes.
Mineral Resources Department has 3 top drive drilling rigs, 2 percussion rigs and 2 diamond drill rigs.
The top drive rigs and percussion rigs are used for borehole drilling and the diamond rigs are used for coring as part of mineral exploration.
Tone Top 300
The Tone Top 300, provided through Japanese AID in 1994, is equipped with rotary mud circulation pump and down the hole hammer drilling equipment. It has a 900 cfm Ingersol compressor. When mud rotary drilling is carried out, the initial roller bit used is 12 ¼". After drilling the regolith (weathered layer) the bit could be changed to 10 ½ ", 9 7/8" and 8 ½" depending on the diameter of the casing to be installed.
Groundwater boreholes are mostly completed with 6" and 8" screens and casings. The 8 ½" roller bit when used in down the hole hammer drilling, is capable of drilling to a depth of 150m.
Tone Top 200
The Tone Top 200 was provided to MRD through Japanese AID,1981 and is equipped with rotary mud drilling and 5 ½" down the hole equipment. This drill rig is also equipped with 500 cfm airmen compressor. Casings of 6" and 8" in diameter have been installed using 12 ¼", 9 5/8" and 7 7/8" roller bits. With down the hole hammer, 5 ½" hammer is initially used and the hole is enlarged by reaming with a larger roller bit.
The GEMCO H22A rig was purchased by MRD and MAFF and is equipped with mud rotary and wire line equipment. Roller bit sizes vary from 7 5/8" to 14". The first bit could be used to drill up to 150m deep. (The 2 old diamond drills use conventional drilling method and are capable of drilling to depths of 300m) The cores can be obtained in two sizes:
NQ producing 47.6mm
BQ producing 36.5mm
This rig is capable of drilling 200m holes using rotary drilling method. A 60m deep borehole can be completed within three days of drilling.
Bourne Drill, was purchased by MRD in 1977 and is percussion drill. This rig is equipped with tools to complete 8" and 6" diameter boreholes. A 30m borehole in hard formations can be drilled in 4 days using this equipment.
Ross Surveyor was provided to MRD though British AID in early 1980’s. It is a hand operated percussion rig capable of drilling sedimentary rocks to depths up to 30m. It is equipped with tools to complete 8" and 6" holes. The average depth drilledper shift is 10-12m. Most of the small islands drilling in Fiji has been carried out using this equipment.