III.2.1. General

HTO or 1H3HO is a commonly used radiotracer in many industrial applications, particularly in interwell communication studies (water flooding) during enhanced oil recovery operations in oilfields and various investigations in geothermal fields. Tritium is a radioactive isotope of hydrogen, which decays by emission of very low energy beta particles (Emax = 18.6 keV) and has a half-life of 12.3 y). As tritium emits a very low energy beta particle, it cannot be measured on-site or on-line. The samples are required to be taken to the laboratory for measurement by liquid scintillation counter. A liquid scintillator is added to the sample vial, which acts as a detector for beta particles. When beta particles interact with the scintillator, it emits scintillation photons, which are, in turn, detected by two PMTs placed around the sample vial. The unit of tritium commonly used in hydrology is the tritium unit. One tritium unit represents the ratio of tritium in common hydrogen atoms as: 1 tritium unit = 10-18 [3H]/[1H].

The unit of tritium measurement commonly used in industrial applications, including the oil industry, is becquerel per kilogram (Bq/kg) or becquerel per litre (Bq/L). One becquerel is equal to one disintegration per second. One tritium unit is equal to 0.11919 Bq/L.