Buying the right drill bits: from tricones to fixed tooth, getting the right bit for the job matters

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If you’re a tricone drill bit user, you probably know a little bit about the history and development of tricones as well as the strengths and weaknesses of various types of drilling and drill bits. This articl

e aims to combine that knowledge for a pragmatic assessment of what bits you should use and what methods might be best for various kinds of projects. We’ll be skipping over truly large scale operations as those have so many possible variables that offering generalized advice is rarely possible. Do you need tricones of fixed tooth bits? Is a rotary drill with tricones called for, or can a direct push or cable-tool drill enough for your needs? Hopefully you’ll soon know the answer to those questions.

Inexpensive drilling for small scale wells or making the most of inexpensive labour

The price of labour may seem far removed from tricones and drilling rigs, but it’s a crucial factor to consider. Slower methods of drilling, notably cable-tool drilling, are far less expensive than rotary drilling options, but also far slower. In North America the wages for skilled drill hands tend to be fairly high, making a slow drilling method impractical regardless of how cheap it is, driving companies to use rotary drills and tricones. However, in developing economies with depressed wages the rotary drills and tricones become large expenses and cable-tool drilling becomes practical once again. It may take longer than using tricones, but overall project costs can be significantly lower. Small scale wells (a couple hundred meters or less) can also be tackled through use of cable-tool drilling as opposed to rotary drilling with tricones. The labour costs may be higher but the comparatively small scale means you’ll still come out ahead compared to buying expensive drilling rigs and tricones.

Drilling in soft or medium rock formations: tricones get their time to shine

For soft or medium rock formations tricones are ideal. The scope of the project will most likely justify any costs associated with rotary drilling. Sealed bearing tricones are usually the best bet as they will last much longer and require fewer halts in the drilling process. Tricones for soft formations generally have the largest teeth, with shorter and more blunted teeth used for medium formations. Tungsten Carbide Inserts (or TCI tricones) provide greater strength and superior heat absorption, again increasing the effectiveness of the tricones. In addition to all that, TCI inserts for the buttons allow for higher drilling speeds, resulting in faster projects and lower costs.

Hard formations: TCI tricones highly recommended

Hard rock formations including shale, granite, and limestone can pose a significant level of difficulty for any project. The extra strength and other beneficial properties of TCI highlighted above really come to shine here. Sealed bearing tricones are recommended as well simply to reduce the amount of delays. Drilling in hard rock is always much slower going, so any advantage you can gain is often well worth the reduced labour costs when averaged out. Expect to use tricones with less protruding and smaller teeth. Additionally support vehicles will likely be needed for compressed air and the drilling mud that will be piped down to the tricones. This is a complicated process and should not be undertaken lightly.

The most important advice of all: consult a professional if you’re not sure!

Reading about tricones is no substitute for hands on experience. All of the advice above is strictly guidelines designed to give you a broad overview of factors to consider when planning a project. Tricones are amazing inventions, but they don’t work magic on their own. If you find yourself out of your depth, don’t hesitate to bring in professional assistance before you put those tricones underground.

 

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