Choice the valid radius of curvature for drilling small diameter channels by the Perfodrill technical system

This article describes the experience of using a part of the bottom of the layout of the drill string perfodrill of small screw motor section and flexible interbody and between the rotor joints that reduce the radius of curvature to a value of5.3 m, and possibly less, as evidenced by bench tests.Moreover, the analytical studies suggest that the use of flexible compounds in the bottom of the layout of the drill string perfodrill provides trajectories of perforations with a minimum radius of curvature similar to the arc of a circle which is inscribed the Perfodrill BHA.
Materials and methods
1. Determination of the smallest radius of perforation channel curvature drilled by a technical system «Perfodrill». 2. Research of the perforation channel trajectory in applying the «Perfodrill» technology. 3. The stand experiments of the drillingchannels in concrete block by the new technology with flexible connections.
Results
The article describes the smallest radius of perforation channel curvature drilled by the«Perfodrill» technical system. Analytically and experimentally established that the use in the BHA of Perfodrill special flexible connection allows to drill a channels with a radius of curvature from 3.5 to 12 meters. Modernized Perfodrill BHA can drilling perforations channel with small radius of curvature from 3.5 to 12 meters, controlling their length and trajectory up to 14 meters (on the first stage of the project).
Сonclusions
1. Analytically proved that using flexible connections in the composition perfodrill BHA allows to obtain perforation path with minimum curvature radius similar to a circular arc which fits into the layout. 2. The analytic dependence between geometric parameters of compact layout of the technical system «Perfodrill» and path curvature channel is obtained. 3. Possibility to drilling perforations with the smallest curvature radius depending on the diameter of the bit and the linear dimensions of spindle section that is 2.6 m at 200 mm long spindle was estimated and proved by calculation and graphical methods. 4. Analytical comparative profiles of perforations with various curvature radius: 3.5 m, 5.5 m, 7.7 m, 12 m were constructed for functional-designed layouts with centering elements placed in the field of structural technical system «Perfodrill».