About RoundOne

RoundOne Drilling Solutions specialises mainly in Borehole Drilling in Cape Town Western Cape, Environmental Drilling country wide in South Africa, Geotechnical Drilling country wide in South Africa, Piling and Sampling also country wide in South Africa.

These are some of the drilling methods that we use:

Rotary Mud Drilling

Rotary Mud Drilling (RMD) is the most commonly used method of Borehole drilling. In direct RMD water or water with additives/mud is pumped down a drill pipe out through ports or jets in the drill bit. The fluid then flows up the space between the hole and drill pipe, known as the annular space. The fluid carries the drill cuttings in suspension to the surface of the borehole. At the surface the fluid is channeled into settling pits or tanks where most of the cuttings settle out. Clean drill fluid is then picked up from the opposite end of the settling area. The drilling fluid is then re-circulated down the hole, the process is repeated until the drilling is complete.

Advantages of Rotary Mud Drilling

  • It is the least expensive drilling method
  • Fastest drilling method through soft formations e.g. sand, clay layers and soft rock
  • The hydrostatic pressure of the drilling fluid will keep a otherwise collapsing soft formation open

Disadvantages of Rotary Mud Drilling

  • Not recommended for soil or site investigation drilling due to cross over of soil samples
  • Cannot penetrate hard rock formations

Air Percussion Drilling

This method is similar to direct Mud Rotary Drilling except that compressed air is used to transport the cuttings to the surface. Using compressed air, a percussion hammer attached to the drill string pulverises the rock or material below and then blows it back up the annular space of the borehole to the surface.

Advantages of Air Percussion Drilling

  • Fastest penetrating method through hard rock
  • Immediate visible indication of water with the opportunity to determine quantity and quality of water encountered
  • Excellent method for sampling of hard rock for site investigation methods

Disadvantages of Air Percussion Drilling

  • High cost of sufficient capacity compressors
  • High cost of diesel consumption
  • High cost of percussion equipment and drill bit wear
  • Difficult method for loose overburden formations, due to high up-hole velocities

Odex Drilling / Simultaneous Casing Drilling

A special hammer drill bit is designed to be used inside and at the bottom of steel casing so that the drill bit has a eccentric reamer below the steel casing. With this method the hammer pulverises the material below the casing and then blows it back through the casing to the top of the borehole. As the hammer drives through the material, it also reacts against interior shoulder bevelled inside the steel casing, which pulls the casing down the borehole as the hammer drill is advanced. This method is well suited for drilling through difficult formations such as rock fill and back fill, it can also be used for mini piling.

Advantages of Odex Drilling / Simultaneous Casing Drilling

  • This method can be used in otherwise difficult situations such as drilling through back fill and boulders.
  • Steel casing is simultaneously placed down the borehole as the drill bit advances thus saving time and holding back collapsing formation

Disadvantages of Odex Drilling / Simultaneous Casing Drilling

  • Specialised method that requires experienced drill rig operators
  • Time consuming method
  • High cost of steel
  • High cost of sufficient capacity compressors
  • High cost of diesel consumption

Hollow Stem Auger Drilling

A method often used for site investigation, environmental and geotechnical drilling and sampling. The hole is advanced by turning sections of flighted auger casing into the subsurface formations. Rotating of the auger flights carries the soil to the surface where samples can be easily taken. For accurate location of samples the auger pilot bit can be removed and split spoon sampling can be performed through the inside of the augers at any depth required. The use of hollow stem augers is most effective when used in stable soil conditions which are generally free from building rubble, cobbles and boulders.

Advantages of Hollow Stem Auger Drilling

  • With this method the hole is drilled and simultaneously cased
  • Hole can be advanced without the introduction of drill fluids

Disadvantages of Hollow Stem Auger Drilling

  • Method is generally only used up to nine meters
  • Hollow stem augers cannot drill through hard rock or boulders