| Abstract |
Exploitation of geothermal district heating systems, located most often in sensitive, densely populated, urban environments require thorough monitoring of well integrity. The latter is commonly controlled via casing caliper logs and packer leak off tests, provided production equipment, such as submersible pump sets and downhole chemical injection lines, have been previously removed. Tracers, or fresh water, either injected downhole or squeezed from surface, production equipment in hole, may prove a feasible and cheaper alternative in assessing a reliable damage diagnosis. The present paper reviews the figures of merit of candidate tracers, radioactive isotopes (131I, 82Br, 99mTc), chemical (NaI, Li2CO3), fluorescent (Rhodamine WT), fresh water, and field implementation protocols, based on selected Paris Basin case studies. Field achievements led to the selection of combined, short duration, squeeze of Lithium carbonate/fresh water slugs regarded as the most rewarding, routine, and cots effective procedure. |