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Drilling a well involves using equipment to push through, and often remove, the layers of earth to get to the substance that is wanted, such as natural gas, oil or water. The general process of drilling has not changed much over the years; however, the equipment used to drill and the advances in technology have progressed greatly from the wooden structures initially used. A kelly driver is a piece of equipment shaped like a pipe that is used in modern drilling. It is the hexagonal piece of steel pipe located at the top of the drill string between the swivel and the drill pipe. The drill string is a hollow piece of pipe that sends drilling fluid to and from the drill bit.
In order to understand how a kelly driver is used in well drilling, it is essential to have an understanding of how the process of drilling works. Drilling a well requires a drill rig, which is a large piece of motorized equipment that is placed over the spot where the drilling will occur. A derrick is attached to the rig to allow the pipes to be raised in and out of the well. The crown is a cluster of large pulleys and cables that are mounted to the top of the derrick to raise and lower the blocks that will hold the drill pipe. The rotary table at the base of the rig allows the drill pipe to turn so holes can be drilled.
The kelly driver rotates the steel piece that hangs down from the swivel in the rotary table, which is connected to the top joint of the drill pipe. The swivel is the piece that is used to support the drill pipe. It allows the drill itself to remain stationary as the rotary table revolves around it. The kelly driver is attached to a piece of drill pipe and as the driver is turned, the drill pipe enters the ground until reaching the desired depth.
A kelly driver can be either four- or six-sided and fits into the slot where the rotary table turns. It is the most heavily weighed-down part of the drill string. The weight of the kelly driver is due to the fact that it is manufactured from pieces of high grade heat-treated chrome and steel to create the strength to be able to drill into the earth.