Energies Media
The oldest drilling technique is percussion or cable drilling. This slow, limited depth method, which is seldom used, involves crushing rock by raising and dropping a heavy chisel bit and stem on the end of a cable. At intervals, the bit is removed and the cuttings are suspended in water and removed by flushing or pumping to the surface. As the hole deepens, it is lined with steel casing to prevent cave-in and protect against contamination of groundwater. Considerable work is required to drill even a shallow well, and upon striking oil or gas, there is no way to control the immediate flow of product to the surface.
