Negative Cement LL with DNO

Gomez (2/5-15) – Top hole

What happened:

From among cementers it was decided to disconnect the dust collector before this job. The surge tank was filled up for calibration of load sensor before job, and this led to a plugged up surge tank when cmt job started. The Bi-Vac valve was disabled and the vent valve opened up 100% to unplug surge tank. After plug was removed, the automatic Bi-Vac valve (that regulate the pressure inside surge tank) was not activated. Instead a manual valve was operated by a cement operator for 3,5 hrs to regulate the surge tank pressure. This caused pressure to fluctuate a lot and led to erratic cement supply. A lot of cement was vented out to air & sea since the dust collector was not used. Out of the 3 cementers doing the job: Cementer A was a junior, but had good knowledge to rig, cementer B was a senior, but had not been on this rig in 7 years, cementer C was a senior, but had never been on this rig.

What was planned:

Mix and pump 136 m3 of 1,52 SG Tune Light cmt slurry for 20″ casing

What was learned:

A lot of dust was blown out from the rig to air and sea. Had a very erratic cmt bulk supply. One out of 3 cmt operators was 100% occupied in a ankward working postion operating a manual valve for 3.5 hrs non-stop.

What actions are required:

Never remove dust filter again. Use it as intended.
Use the automatic Bi-vac valve, and turn it back on if it has been by-passed for a short unplugging sequence.
Use the same cementers to follow this rig, running on a schedule.

External Actions

What does ETM mean?

What Was Done

Had to continue job without any changes or stops. We had only cement to do job once, had to wait for days for new cement if job had been aborted.