The chemical history of $^{14}{\rm C}$ in deep oilfields

TL;DR

This study investigates the natural processes affecting 14C levels in deep oilfields, revealing methods to significantly reduce 14C contamination for low-background experiments.

Contribution

It provides new insights into the chemical history of 14C in oilfields and demonstrates how to achieve four orders of magnitude reduction in 14C contamination.

Findings

14C purity can be improved by four orders of magnitude.

Low chemical affinity of methane reduces 14C incorporation.

Migration of natural gas decreases 14C levels in mature oilfields.

Abstract

14C is an overwhelming background in low-background underground experiments, to the point where the observation of the all-important (pp) neutrinos from the Sun can not be observed in carbon-containing experiments. This paper shows that 14C purity can be improved by four orders of magnitude by a careful selection of the gas field. Two large reduction factors are at work: the low chemical affinity of methane to single carbon, and the migration of natural gas away from nitrogen-bearing kerogen during as the oilfield matures.