Foro Energy, Inc. is working with the U.S. Department of Energy’s ARPA-E and the Colorado School of Mines plus the Big Oil leader Chevron that has geothermal activities underway, and investors ConocoPhillips and General Electric to develop a unique capability and hardware system to transmit high power lasers over long distances via fiber optic cables to the bottom of well bores.
Geothermal drilling is a major change from drilling through the soft sedimentary rock seen in oil and natural gas production. Sedimentary rock is compressed muds, sands and skeletons that while hard are soft compared to the granites, basalts and other very hard rocks seen where high temperature thermal locations are located.
This may be what hard rock geothermal is waiting for because so far hard rock formations are too costly to drill with mechanical drilling bits alone.
Foro Energy’s laser power is integrated with a mechanical drilling bit to enable rapid and sustained penetration of hard rock formations. The laser energy that is directed at the rock basically heats softens cracks and loosens the rock, allowing the mechanical bit to more easily remove it. ARPA-E says in its web page about the effort that Foro Energy’s laser-assisted drill bits have the potential to be up to 10 times more economical than conventional hard-rock drilling technologies, making them an effective way to access the U.S. energy resources currently locked under hard rock formations.
An intense laser beam heats hard rock surfaces so fast that thermal shock fractures the upper few millimeters, leaving a shattered layer that a mechanical drill can sweep away quickly with little accumulating wear.
The differences are dramatic. The change in drilling rate is 2 to 4 times faster. The weight applied to the bit is less than 1000 pounds and the bit needs less than 300 ft-lbs of torque to turn.
Just add to the cheer and motivate, using a Foro Energy drill system would negate the need for explosives and harsh chemicals. One should expect much more straight bores cutting back on completion problems and costs as well as cut long-term maintenance expenses.
On the other hand the technology is not a sure thing. For a high power laser to be effective the light path from the end of the cable delivering the energy to the rock would need to be essentially free from artifacts, water or other bits that would intercept the energy being delivered.
Then there is the matter of down in the hole conditions. Pressures and temperatures can be very high making for tough conditions. The oil business has decades of experience working in soft rock and still is developing better technologies.
An ability to drill thousands of bore holes at low cost into the hard igneous rocks where the heat is would make a dramatic change in the calculations for producing heat energy.
So far Foro Energy has overcame the Stimulated Brillouin Scattering, a “physics effect” that chokes off the transmission of high power laser photons in a fiber optic cable by reflecting the energy backwards to catastrophically destroy both the fiber optic cable and laser source. In short, photons and acoustic phonons interact in a vicious cycle that gets exponentially worse with increasing power and distance.
Foro claims now that their solution has a capability to transmit high power lasers in fiber optic cables over long distances. Should that be the case directional drilling and drilling to great depths may well be possible.
Perhaps the most interesting thing aside from delivering high power laser energy at a distance is a device called an optical slip ring. A slip ring allows a spool of cable to unwind while the energy is passing through. Foro is claiming the loss is less than 3%.
Down hole laser for rock drilling is in its infancy. There is a lot of brainpower across the partners leading one to suspect that the technology has some power in its legs. Just how the various challenges are getting met is likely quite proprietary, but there is no doubt the team knows what the problems are and has ideas on how to resolve them or find opportunities in them.
It’s a step, now testing in the field at working conditions, but rich with potential and opportunity. Once its gets working and can show its potential, geothermal will get a new lease on the future.
That’s not all – the technology would also apply to the oil, natural gas, mining industries and tunnel construction.