A chemical pod labeled as Baker Petrolite SX-2185 (H2S Scavenger) containing Tolcide PS75 - concentrated biocide was filled into the platform storage tank for H2S Scavenger.
The unintended mixing of the two chemicals caused an exothermal reaction with increased temperature in the tank and vaporization of fluids through and out of the tank vent line, below the open deck of the module.
The release of vapor caused a fishy smell alike the one recognized as specific for H2S Scavenger, still much more intense and wide spread.