Reactive Turbodrilling

a method of drilling large-diameter vertical boreholes by means of reactive turbodrills. Reactive turbodrilling is used to sink the upper intervals of petroleum, gas, water-lowering, engineering, and ventilating boreholes and to construct production and air shafts in coal, oil, and other mineral deposits. It is also used for hydraulic structures, such as piers, docks, shore reinforcements, and railroad and highway bridge abutments.

In reactive turbodrilling the diameter of the drill bit is considerably smaller than the diameter of the hole that is made. This is possible because of the structural design of the drills, in which bottom-hole motors, such as turbodrills, are installed with displacement relative to the axis of rotation of the drilling column. The bottom-hole unit may have two or more turbodrills, depending on the drilling diameter. The shafts of the turbodrills and the roller bits attached to them are driven by the action of the flow of working fluid; interaction with the rock produces reactive forces that turn the drill and drill column in a direction opposite to the rotation of the bits.

In the USSR, vertical boreholes are sunk by means of reactive turbodrills with diameters of 760, 920, 1,020, 1,260, 1,560, 1,730, 2,080, and 2,600–2,860 mm. These turbodrills make it possible to drill a borehole in one operation and without subsequent reaming. Reactive turbodrills were proposed in the 1950’s by the Soviet scientists R. A. loannesian, G. I. Bulakh, and M. T. Gusman.