Drilling the hole is the expensive thing about geothermal power. The heat itself is free, and it’s sitting under pretty much every state in the country. What costs serious money is punching a cased steel well thousands of feet into rock that grinds up drill bits and cooks electronics, and that’s a big reason your power still comes from gas plants instead of hot rock. So when a geothermal company starts posting drilling numbers that look like a Permian shale operation, it gets my attention.<\/p>\n
Mazama Energy, a Texas company drilling on the flank of Newberry Volcano about 25 miles south of Bend, Oregon, said in its September 1 announcement<\/a> that its second well on the mountain, named Athena, reached 10,350 feet in 15 drilling days. The company’s first well needed five times as many drilling days to reach that same depth, roughly a year earlier. Mazama frames it as an 80% reduction, which is the same math stated more politely.<\/p>\n We covered that first Newberry well<\/a> back in July, when Mazama connected two bores through rock at 629 degrees Fahrenheit and claimed the hottest engineered geothermal system ever built. Athena’s the follow-up, and its job is speed: proving the company can reach that kind of heat fast enough for the economics to work.<\/p>\n So what’s a drilling day, and why count only those? A drilling day is a day the bit’s actually making hole, as opposed to days spent running casing, cementing, or fixing whatever broke overnight. It’s how drillers measure themselves, and it means the 15-day figure isn’t calendar time from start to finish. Mazama hasn’t published the date drilling started or the day Athena hit 10,350 feet, and it hasn’t named the rig or the drilling contractor either. I’d have liked those anchors, but company drilling releases rarely include them.<\/p>\n Mostly, the bit stayed in the hole. Mazama reports that one drill bit cut 3,578 feet of rock in a single run and only came out because the well design called for steel casing to be set at that depth. The bit was still cutting when the crew pulled it.<\/p>\n If you haven’t spent time around rigs, here’s why that number matters. Bits wear out, especially in hard volcanic rock, and swapping one means pulling the entire string of drill pipe out of the hole and running it all back in. On a 10,000-foot well, that round trip can eat the better part of a day, every single time. And that’s before the bit even touches new rock. A bit that survives 3,578 feet without a trip is saving you whole days of rig time.<\/p>\n The speed while cutting was up there too. The company says the bit hit instantaneous rates above 350 feet per hour and held above 130 feet per hour across long stretches of the volcano’s rock. At 350 feet an hour, the bit’s dropping about the height of a 30-story building every hour. Mazama also reports zero failures of its downhole motors or directional drilling systems, the steering tools whose electronics are usually the first thing this kind of heat kills. Pat Brand, the director of the Athena project and Mazama’s drilling specialist, said “the performance we are already seeing gives us confidence.”<\/p>\n They’re company-reported numbers, so keep that in mind.<\/p>\n Athena isn’t done. The plan runs to roughly 15,500 feet, about a mile past where the well sits now, into rock Mazama expects to exceed 750 degrees Fahrenheit (around 400 Celsius). The first well bottomed out at 629 degrees, already a record for an engineered geothermal system, so the target’s more than 120 degrees hotter than the hottest hole anyone’s built.<\/p>\n Why bother? Because water gets strange up there. Push water past roughly 700 degrees under enough pressure and it stops behaving like liquid or steam and turns supercritical, a dense state that hauls far more energy per pound up to the surface. In its September 17 funding announcement<\/a>, Mazama put a number on it: a well at 750 degrees can deliver up to 10 times the power of a conventional geothermal well running at 390 degrees. By the company’s math, that lets a project drill 80% fewer wells and use 75% less water than conventional geothermal. Vinod Khosla, whose fund has backed Mazama from early on, boiled the pitch down to “ten times the heat from a fifth of the wells and a fraction of the water.”<\/p>\nSo what actually got faster?<\/h2>\n
Why keep drilling toward 750 degrees?<\/h2>\n