Frequently Asked Questions About Our Mills
What are the uses for a hurricane mill?
Hurricane mills are recommended when:
- Direct circulating and/or
- Smaller cuttings are desired
Hurricane mills are available in two different types for the following applications:
The primary difference between the two are:
- Cutter placement
- Cutter shape
Hurricane mills designed to drill out cement have chisel shaped carbide inserts, while hurricane mills designed to mill out metal and plugs have dome-shaped carbide inserts.
When would I use the pdc mill?
The pdc mill was specially designed to mill out hard build up on casing such as barium scale that can accumulate on casing and, over time, reduce the well flow.
It is also used to drill out very hard cement.
What is the aardvark used for?
The aardvark mill was originally designed to drill out old Halliburton frac plugs that have a metal retainer ring and there are many of these plugs still in the hole. The metal retainer ring presented a special drilling problem that produced too much outside wear on conventional drill bits. So, the basic design of the chomp was used and modified to drill out the center of the plug first and the outside last thereby reducing wear and stress on the center of the bit.
The aardvark mill can also be used for drilling cemented pipe or casing.
Why would I need a concave mill rather than a convex?
The standard design is convex but concave is available if needed.
Concave design is available for special drilling needs if there is any time the outside needs to be drilled first.
The concave design forces cuttings to the center for recutting into smaller pieces. The concave design will also help the mill to stay centered and mill straighter with less damage to casing.
Your bear claw and chomp mills can be manufactured in either a concave or convex shape. Do your hurricanes also come that way?
Yes, but we do not keep them in stock and are special order only.
Why can’t I drill new formation with your mills?
By definition our products are mills, not drill bits. They can be used for formation, but we do not recommend it. The mills can be used anywhere other drag bits or bladed bits are used for formation drilling but this is not the primary purpose they were designed for.
Will the chomp or hurricane mill drill out stainless steel?
Maybe. Stainless steel is the most difficult of all materials to mill out. The chomp and hurricane are likely to do the job but multiple mills will probably be needed.
What’s the difference between a bear claw or chomp mill and a hurricane?
The hurricane mill is “heavier set”, meaning the carbide inserts are closer together and there is more of them. That fact along with the special spiral design will mill up much smaller cuttings thereby reducing the need for large circulation ports.
In summary, the bear claw and chomp mills will produce large cuttings and the hurricane will produce fine cuttings.
Even though the bear claw and chomp are for reverse circulation, can I run them if I’m direct circulating?
Yes! But you will get larger cuttings than if you were to run a hurricane mill with the smaller ports.
What’s the difference between a bear claw and a chomp?
The long, chisel inserts of the bear claw mill bit were specially designed to give a high ROP when milling out cement but the the hardness of metal will produce too much wear and breakage of the inserts.
The rounded, dome shaped inserts of the chomp mill will produce a slower penetration rate but offer more durability when milling out metals, cast iron, and composite plugs.