Unravelling the Processes of the H2S Generation in the North-western Pyrenees (France)

Exact origin of the H2S-rich deep Lacq reservoir remains unclear. In-situ gas analyses coupled to multiple sulfur isotopes analyses in the north-western part of the Pyrenees, lead to better constrain H2S sources and its formation timing. In addition to thermicity studies theses technique confirm that this gas is generated by the Thermochemical Sulfate Reduction (TSR). However, this work show that the H2S has been not generated in-situ in the deep Lacq reservoir, but in the “Chaînons Béarnais” which reached higher temperatures. This multi-methods study leads to trace and understand the H2S behavior from its initial formation to its trapping.