Rotary shoes are run on the bottom of the washpipe. They are used to washover a stuck fish and free it, so it can be removed from the well.
Washover or Rotary Shoes dressed with Tungsten are recommended for all types of washover operations. The increased speed of penetration makes these more versatile and economical than a conventional hard metal shoe.
Washover or Rotary shoes are available in a wide range of types and sizes.
There are three basic designs of Rotary shoes: the tooth type, the flat bottom type, and the wavy bottom type. Each type of shoe can be dressed several ways to fit the job. They are constructed of high-grade steel.
When we say “dress a shoe”, we are referring to the type of hard metal (Borium or Tungsten) that is put on the shoe for a cutting surface.
Sometimes a shoe may be run without washpipe if the fish or junk in the well is short enough to not need washpipe, or washing over a packer, etc. Most of the time they are referred to in these cases as a burning shoe or milling shoe. When you are washing over metal, you usually refer to it as burning or milling over it, rather than washing over it.
There is a shoe referred to as a cripple shoe. This is any shoe that is disfigured or modified by choice to help get over a fish. There are so many ideas on how a shoe should be crippled, that I won’t go in to all the ways, but would suggest you look at the different ones in the fishing tool stores you are in. As for the best way to cripple one, I would say, whichever one suits you and the job the best.
Sometimes a shoe has to be built up on the outside to match it better with the hole you are working in. In this case, if it were inside the casing, it would be built up with brass to prevent damaging the casing.
Sometimes there are feelers put in a rotary shoe. These are soft one half-inch pipe welded in the top of the shoe. Sometimes it is three short pieces equally spaced in the shoe. Sometimes it can be one piece all the way across the inside or even two pieces to form a cross inside the shoe, they are to give you an indication when you go over the fish. They will take weight until you apply enough weight to shear them; therefore, you know you are over the fish. I recommend the three short pieces, to keep the amount and size of junk left in the hole to a minimum.
There is a kickpad that can be put in a rotary shoe. It is a pad approximately four inches square placed in the shoe five or six inches from the bottom and is beveled on the leading edge. Be sure it is not thick enough to restrict the I.D. of a shoe where it won’t go over the fish. The kickpad is effective only in an open hole and should not be used inside the casing. When you have drill pipe or drill collars badly wall stuck and the rotary show is binding between the fish and the wall of the hole. A kickpad will cause the shoe to dig away from the pipe so it will only be cutting formation. Most of the time, it will increase the washover rate considerably. The kickpad does not kick the fish out in the hole as it is often explained or misrepresented. If it would do this, the pipe would not be stuck to begin with.
Although you may order a shoe just like the one you have on the job. Don’t take it for granted that the I.D. and O.D. where it is dressed are the same. Check all measurements on every tool before running it in the hole.