Despite being the second most common element in the universe, helium is relatively scarce on earth. When helium is present at the earth's surface, unconfined, it immediately begins rising until it escapes the planet. Consequently, we must look for where it might be 'trapped' before it can escape, not dissimilar to what we routinely look for in the oil and gas industry.
Helium is typically produced as a minor constituent of natural gas, with the bulk of present-day production from North America and the Middle East. It coexists with natural gas due to the same migration and trapping processes that create "gas" accumulations in the subsurface. Helium is commonly sourced from the decay of certain minerals and elements (principally uranium and thorium) found in igneous intrusions and/or ancient basement but also in areas of relatively concentrated (pre-)historic meteoric bombardment. Helium is so buoyant and has such a small atomic radius that the only sedimentary cap-rocks capable of trapping helium are halite and anhydrite. The seismic project management team at RPS are experts in locating and modelling these rocks. Some more kerogenic shales can sometimes also serve as a less effective, perhaps shorter term, barrier
In natural gas reservoirs, helium concentrations above 0.3% are considered economically viable. However, gas reservoirs with over 10% helium concentration do exist. Extracting helium, in addition to natural gas, can become an important revenue source for resource companies, especially as demand increases and supply shrinks. Helium prices are at almost record highs and are only likely to increase. This can make relatively low concentrations of helium almost, if not more, valuable than the natural gas revenue, depending on proximity to market and power requirements.