Rough breakdown of helium-3 use over the past five years. The largest use, by far, is for neutron detectors for security screening by the departments of Homeland Security, Defense and Energy.
A crucial shortage in the world’s supply of helium-3 could alter the use of an important tool for the oil and gas industry.
And that’s just one problem. The rare helium isotope also is used in applications ranging from cryogenic studies to lung imaging in medicine.
Far and away the largest consumer of helium-3 in the United States recently has been the Department of Homeland Security, which uses it in radiation sensors. Think of trying to stop someone who’s smuggling a small amount of plutonium for a nuclear weapon.
“Crisis really is the best word for this situation,” said AAPG member Bo Sears, vice president of Inter-American Corp. in Dallas, one of the industry’s small number of helium explorers.
For oil and gas companies, helium-3 is an essential component in neutron logging tools used worldwide.
“Helium-3 is used in neutron detectors for neutron porosity tools, which are one of the key instruments used to locate hydrocarbons, estimate petroleum reserves and make production decisions,” said Brad Roscoe, scientific advise and nuclear program manager at Schlumberger-Doll Research in Cambridge, Mass.
“The neutron device is particularly used to establish the rock and fluid parameters which help determine these properties,” he added.
Downhole neutron tools measure the amount of hydrogen in rock pores as an indication of porosity.
“Since the neutron porosity measurement is a key measurement,” Roscoe said, “it is run in almost every oil and gas well in the world.”
A Costly Shortage
How bad is the shortage?
The U.S. Department of Energy reportedly has less than a one-year supply. Russia, another helium-3 seller, has essentially stopped exporting it.
While natural gas recently sold for under $4 per thousand cubic feet at the wellhead, and the U.S. Bureau of Land Management raised helium gas prices to $75 per thousand cubic feet, helium-3 now typically sells for at least $500 per liter.
“Two years ago it was $85 a liter. Government agencies didn’t know the U.S. was running out of helium-3 until 2008,” Sears said.
At least one reported helium-3 purchase was for more than $2,000 per liter.
When the severity of the shortage became apparent earlier this year, alarms went off throughout the scientific community, especially among those researchers who had no substitute for helium-3.
The same concern has spread to companies that need helium-3 for commercial applications.
Supplies of the common form of helium found on Earth, helium-4, also are shrinking. That’s an ironic reality, since helium itself is the second most common element in the solar system.
Helium-3 also is fairly abundant, scattered among the planets, in the soil of the Moon, in the Earth’s mantle. But even though it’s present in the Earth, it is increasingly scarce on the Earth.
Inter-American explores for natural gas that contains a significant amount of recoverable helium, Sears said. He acknowledged that helium exploration is a tiny part of the overall industry.
“We’re a traditional oil and gas company but we’ve begun focusing on helium exploration. In our case it makes more sense to go after the high helium-4 reserves,” he noted.
Even when helium is found with natural gas, the percentage content is usually small.
“Economic helium is anywhere from 0.3 percent up to the highest we’ve seen, which was 9 percent. That was in the Four Corners area and that supply was exhausted in the 1960s,” Sears said.
“Ideally,” he added, “we’d want a helium composition of at least 1 percent.”
A Critical Need
Project areas for Inter-American include New Mexico, Utah, Colorado and Kansas. Most helium-rich gas in the United States is found in the mid-continent and southwestern states.
Target helium-rich fields indicate an abundance of uranium and/or thorium in basement rock, since their radioactive decay produces helium, and the presence of heavy, deep-seated faulting.
The very small amount of helium-3 found with helium-4 can be separated out – at considerable cost and in limited quantity.
“It’s in the parts per million. On average in natural gas deposits it’s 0.2 parts per million of the helium-4 content,” Sears said.
Because of the relative abundance of primordial helium-3 in the mantle, geochemists use the helium-3/helium-4 ratio as a tracer to identify the presence of a mantle component in petroleum systems, he noted.
Sears said Inter-American uses the helium-3 ratio to help define helium-4 potential. Analysis of some gas has found an anomalously high ratio, especially in New Mexico.
Helium-3 extraction plants could be built near helium-rich gas fields, but the estimated cost is in the tens of millions of dollars per plant.
Yet the helium scarcity is so critical that all options are on the table.
“At this point in the helium-3 crisis, every little bit helps,” Sears said. “My concern is that the oil and gas industry will be squeezed out entirely. It could have a horrible effect on the industry, because all neutron tools use helium-3.”
Thanks in part to nuclear disarmament, the United States once had a substantial supply of helium-3. Tritium (hydrogen-3) used in nuclear weapons was recovered as the warheads were dismantled. Tritium produces helium-3 as it decays.
A declining amount of recovered tritium and a surge in demand in the years following the 9/11 attacks caused the stockpile to dwindle.
Because the half-life of tritium is over 12 years, Sears said “even if dedicated tritium production began today, which is cost prohibitive, it would be years before you get any meaningful amount of helium-3.”
A Crucial Asset
The usefulness of helium-3 in well logging tools lies partly in its high absorption cross section, which gives it high neutron detection capability.
“In well logging two measurements traditionally have been used to estimate the porosity of sedimentary formations – one based on gamma rays scattering and the other on neutron scattering,” said Darwin Ellis, author of the classic text “Well Logging for Earth Scientists.”
Ellis described the use of the logging tools:
“The gamma ray scattering device measures the bulk density of the rock formation from which the porosity (volume fraction of fluid-filled formation) is estimated, usually assuming that the fluid in the porous volume is water or brine with a density close to 1.0 g/cc.
“If the porous volume is saturated with gas or hydrocarbon with a density much less than 1.0 g/cc, the effect on the density is to reduce its value and the consequent interpretation is to over-estimate the porosity of the formation.
“The neutron scattering device exploits the large influence the presence of hydrogen has on the slowing-down of neutrons, so its response is dominated by the hydrogen content, not the density, of the formation which, in clean, shale-free formations, is associated with the pore fluid.
“These devices are calibrated to give an accurate estimate of the formation porosity when the suturing fluid is water. If the formation contains light hydrocarbon or gas, the hydrogen density is less than that of a water-saturated formation and the consequent estimate of porosity from the device will be less than the actual porosity.
“When the measurements from these two devices are displayed together on a log they are transformed so that the porosity estimates overlap when the formation porosity is water-filled – the two traces lie on top of one another.
“If the pore fluid is replaced by a lower density hydrocarbon or gas, the density estimate of porosity will increase and the neutron porosity estimate will decrease – yielding a graphical signature on the log of a possibly very large separation that even a novice interpreter can recognize as a gas zone.”
Roscoe said helium-3 also allows the industry to create logging tools that are “small and robust” and capable of withstanding difficult and even tortuous downhole conditions.
“Currently, there are no alternatives for our industry that meet all of our requirements,” Roscoe noted.
“These requirements include very small size, very high detection efficiency, high count-rate capability, good gamma-ray discrimination, ability to work at high temperatures – normally 175 C and up to 260 C – and ability to withstand a high shock and vibration environment,” he said.
Industry response to the helium-3 shortage includes an attempt to recycle the gas and ongoing research into possible substitutions.
“The industry is trying to develop alternative technologies to helium-3 for our environment. Until that is in place, the industry is trying to reduce the amount of gas it uses, re-use neutron detectors where possible, and recycle gas from old detectors,” Roscoe said.
If the industry can’t get adequate helium-3 supplies or develop workable alternatives, serious challenges could develop, Roscoe noted.
“This would result in a shortage of information to the oil companies on how to best manage and complete their reservoirs,” he said, “which could have large financial implications and affect the ultimate producible reserves.”