co2, page-3

Bit technical for a friday nite, but here's defining 'Manageable' since its the buzz word of the day.

1) The drilling fluid/mud that's circulated downhole & returning to surface after drilling a high CO2 pocket usually comes back contaminated. In short, the mud density & couple of other mud properties will change. This usually is the job of a 'Mud Doctor' & his assistants to monitor the Mud Weight (in, out), viscosity, Strength etc etc.

2) The operator should have requested their mudlogging contractor to install CO2, H2S detectors.

In Indonesia, Malaysia & 'Nam u get high CO2 & H2S pockets, so the proper sensor can alert rig personnel while drilling thro' a anomalous pocket.

3) Wireline logs: If the operator requested an MDT tool to be run, then a 'insitu' fluid sample should have been captured & analysed for a quick compositional breakdown (CO2 in % or ppm, C1, C2 etc) & insitu reservoir pressure.

3) The WL logs should have easily highlighted the average porosity of sand in the 38 metre interval that was perforated. eg: 10% porosity etc. Gamma Ray picks up the 'sand' frm the shale, so is a no brainer.

4) If all of the above appears to b 'manageable' then the JV opts to do flowtest.

5) Finally, the sample from the DST confirms HC's, saltwater or Inerts, in this case a high CO2 proportion.

6) High CO2 is a nasty & is known to affect 'cables' on WL logging tools. So WL contractors inspect their cables routinely to avoid a dodgy cable.

Hope that gives a glimpse of what goes on to keep things Manageable. There could be other factors, but those are the ones u come across commonly.