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Drilling


drilling for oil

MDM Energy, Inc. contracts with a specialized "drilling company"; to perform the actual drilling. The well is drilled using a bit connected to the surface with drill pipe. As the drilling rig turns the pipe, the rotation of the bit, combined with the weight the pipe, crushes the rock at the drilling face. Drilling "mud" pumped down the pipe and out the bit flushes the rock debris out of the well. After a section of the well is drilled, steel casing is placed in the hole to prevent its collapse. Cement is then pumped into the space between the outside of the casing and the formation. Once it is set, this cement prevents the flow of fluid from the formation and holds the casing in place.

After the cement sets, the drilling company may extend the well by drilling out the bottom of the casing with a smaller bit.

This cycle - drilling a section and placing casing - is repeated many times. The diameter of the drill bit may progress from 36 in. down through progressively smaller diameters: 30, 24, 18 3/8, 12 1/4, to 6 inch or smaller. Each section of well varies in length from several hundred feet to in excess of 10,000 ft, and may take anywhere from a few hours to weeks to complete.

Little information is gleaned during the drilling process. Some data can be derived from measuring the energy required to drill each foot of the well, or by monitoring rock debris or drilling mud pumped from the well. Comprehensive information about the formation is obtained only by lowering electronic instruments into the well.