Development of a novel percussion mechanism for downhole hammer drilling

◼ Downhole hammer drilling increases the performance in hard rock formations by generating a percussive force on the formation, similar to a jackhammer ◼ Cost-efficient drilling for deep geothermal wells demands extended service life while enabling additives in the fluid (drill mud) to stabilize the drilling process ◼ Fraunhofer IEG develops a novel hammer run by a static valve that features - less relative movement between parts - fewer parts than in current hammers - no dynamic sealings or tight tolerances ➢ The goal: Optimizing the drilling performance to make percussive drilling more affordable for geothermal drilling Approach ◼ State-of-the-art hammers use a mechanical valve to actuate the weight - Friction and erosion on surfaces wear the parts down and demand frequent maintenance - Sealings and tight tolerances make the use of drill mud nearly impossible ◼ This valve is substituted by a fluid-driven oscillator, also called a fluidic switch - The fluid itself performs the oscillation, which makes the part less vulnerable to friction and erosion from relative movement (Figure 1 left):