Numa, a designer and manufacturer of down-hole hammers and bits, has released a Vortex Backhead design meant to improve both drilling performance and hammer and bit life. It is designed for Numa’s 12-inch hammer line when drilling conditions require a significant amount of water injection.
The Numa Vortex Backhead prevents a drop-off of drilling performance by ejecting water out the top of the backhead before it can go through internal hammer components, Numa said in a press release. The design allows drillers to gain the benefits of water injection without the wear and loss of hammer performance. Company engineers have accomplished this by creating a spinning process (vortex) in the backhead that leverages the density difference between water and air, Numa said. Fluids entering the top end of the hammer are spun, pushing heavy material (water) to the outside to be ejected out the top of the backhead. Lighter material (air) stays to the inside and travels down the feed tube to power the hammer and clean the bottom of the hole. Two jets, or chokes, found at the top of the backhead control the amount of water ejected. A standard hammer is supplied with 1/8-, 3/16-, and 1/4-inch jets that can be changed to control water injection according to drilling preference and conditions.
Benefits of using the system while injecting significant amounts of water include: improved drilling performance through higher-impact energy and limited wet-bottom conditions; reduced wear from a reduction in non-productive exhaust flow up the outside of hammer and bit; and increased hammer and bit life due to the removal of solid particulate from components passing through.