We qualify sonic rig drilling as more of a rotary vibratory drill. These equipments can carry out high drilling speeds and are capable of completing tasks like continuous coring which other equipment will have much difficulty or would have trouble carrying out.
At first glance, it will give you the impression that it is resembling a conventional mud or air rotary drill rig. If there should be any difference between the two of them, it should be in the drill head. The drill head is much bigger when compared to the standard rotary head.The head is crucially important in such a way that it holds the mechanism needed to facilitate rotary motion. The same is true with the oscillator, it is responsible for creating a high frequency force .
As for the drill bit, aside from being rotated and pushed down, it will also vibrate up and down . All the three forces working together will make drilling process possible. It will proceed in a very seamless fashion through various kinds of geological formations, and this includes even the different types of rock.
The hydraulic motor drives the oscillator and uses the out of balance weights to produce high sinusoidal forces. They are eventually relayed to the drill bit. The alternating forces can be confined to the drill string by incorporating air spring.
As for the frequency, this can be varied in order to make way for suitable operation conditions. Generally this would come between 50 to 160 hertz or cycles per second. For the sake of comparison, household current conditions in other countries are alternating at 60 hertz.
The said frequency range is within the range of vibration of sounds which the human ear can sense and hear. This is the reason why the term “sonic drill” found its way to this type of rotary-vibratory machine for drilling jobs.
Sonic Rig Drilling Advantages and Disadvantages
Borehole advancement in sonic drilling is tantamount to rotary. This strategy seems to be working oaky and is effective even in what can be described as difficult drilling conditions such as boulders, gravel and landfill or fill. Also with softer formations such as weathered basalt or sandstone limestone.
Compared to rotary drilling, sonic drilling is known to produce only about 10% less volume of drilling waste. Vibrations that come hand in hand with sonic drilling will relieve removal of casing for grouting tasks. Air can be taken advantage to reduce wall smearing in borehole for environment and geotechnical downhole testing and sampling.
Vibratory motions due to drilling activities can bring about disturbance to the surrounding rock formations. It is also likely that it will engender new fractures to form in hard bedrock. If things like this come to transpire, it will likely have an adverse impact to the aquifer or to structural testing.
Sonic drilling method is not supposed to be the method of choice if the project you have involve shallow borings. The same is true for for drilling into hard bedbrock or in some other easier drilling conditions.
The drilling heat brought about by sonic rig drilling may alter texture, contaminant conditions or influence moisture levels. It is a relief to know though that you can put some level of control on this side effect by virtue of drilling fluid.
Finally, when sonic vibrations are generated, this mean to say that you will need to give your sense of hearing some good level of protection. Otherwise, you will run the risk of exposing them to damage, which of course is not worth taking.
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