New drill hammer withstands heat of geothermal drilling

Sandia National Laboratories, in collaboration with Atlas Copco, have designed a drilling tool that can withstand the heat of geothermal drilling.

The downhole hammer attaches to the end of a column of drill pipe, and drills through rock with a rapid hammering action akin to a jackhammer.

Although downhole hammers are not new, the older design, which relies heavily on lubricants, plastic and, rubber O-rings, cannot withstand hotter temperatures of geothermal drilling.

The project was funded by the US Department of Energy (DOE) Geothermal Technologies Office.

Mechanical engineer and Sandia’s principal investigator on the project Jiann Su, said “Part of what the DOE’s Geothermal Program is looking to do is help lower the cost of getting geothermal energy out to customers,” in a report by Science News.

“Some of reducing the cost is lowering exploration and development costs, and that’s one of the areas we’re helping to tackle.”

The Geothermal Energy Association’s 2016 annual production report said the United States contained approximately 2.7 gigawatts of net geothermal capacity at the end of last year, with the country developing 1.25 gigawatts of geothermal power.

Su went on to say the hammer can increase drilling rates to between five and 10 times that of conventional drilling operations, and could help them reach their geothermal energy goals.

One of the major parts of the project was developing the lubricious coatings which minimise friction between parts, as the hammer, like a car engine’s piston, has internal moving components that need lubrication.

The three-year project also led to the development of a high-pressure testing facility to test the hammers in real world operating conditions. The high operating temperature (HOT) test facility, a three-sided open concrete structure, has a 6m drill rig, a process gas heater, and a heating chamber that can reach temperatures up to 300°C.

Researchers can also simulate deep underground conditions and the high temperatures affecting the hammer can drill into a range of different rocks such as granite, often found in geothermal-rich areas.

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