Perforation inspection of CBM well in Canada

This video is from a coal bed methane well in Canada. The well is flowing water and gas and the video is from the sideview camera and shows the perforations in vivid detail along with gas and water production.

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• Perforation
• inspection
• of
• CBM
• well
• in
• Canada
• with
• sideview
• camera

[jlwhittaker]

I've looked at probably 500 video surveys with perforations and have nearly always seen a crown around the perf on the inside of the casing unless the zone underwent a frac with proppant pumped into the perfs, or a scraper run to smooth off the perfs,

[bs0d]

This is a good camera job video. It appears to me as though a couple of the perforations are plugged off, perhaps due to cement evasion?

[jlwhittaker]

Thanks for your comment. I don't know what is in the blocked off perforations. It's possible its cement or also could be some fines from the coal that has bridged off in the perforation. Did you also notice that some perforations are producing gas and water while others are actually taking in water and gas? Very interesting.

[bs0d]

That is interesting. If those perforations are associated with a different formation of lower pressure, that maybe the cause. Perhaps as a temporary 'thief' zone until the reservior pressures are lowered. Also, if some cement or coal fines are an issue, it might be worth dumping some acid over the perfs in an attempt to clean that up.

[jlwhittaker]

It would be powerful to run a video survey both both before and after an acid treatment on something like this. That's usually the hard part though. If the acid treatment does the job, few go back to take a look and see what changed downhole.

[hopeurforfreedom]

@jlwhittaker We did a number of tests with casing at the surface. We placed casing inside a 55 gal drum, filled the casing with cement and perforated. We work with perforating at an angle to increase the number of bedding planes in contact with a perforation. We get a smooth perforation on the inside, without a crown or burrs of any type. Could it be that our perforations are at a given angle and not 90 degrees as in a typical perf job that gives us the smooth inner wall?

[hopeurforfreedom]

Those perforations look a little strange to me. Normally, the inside of the casing has no burrs from perforating, it tends to be smooth. This almost looks like the outside of perforated tubing to me.

[bs0d]

I believe you are correct in that- because usually you can tell if it worked or not based on the increase in production!

[Cr3ater]

Wow, you can see the salt water flowing out of the perforated holes in bore