Alert 21-04 H2S Alarm Activation

WHAT HAPPENED:

While drilling out the casing shoe track of the well, H2S was detected at surface upon bottoms up. The section was previously cemented and the well suspended for 30days (duration of the top- hole batch drilling Campaign). The spacer fluid (spacer chemical mixed fresh water) remaining inside the casing was untreated. H2S detection was activated at the Shale Shakers. The rig sensors and the mudlogging sensors in the shale shaker area detected H2S levels of 57ppm and 43ppm respectively…