Thanks Ptolemic. Makes sense about the methane flare. I still...

Thanks Ptolemic. Makes sense about the methane flare. I still expect high ethane content in there and probably ~1% propane though.

It wouldn't surprise me if the whole thing is pretty complicated, e.g. coal is not a very strong rock it is possible at this depth and stresses that as you reduce the pressure the any fractures and other permeability starts to close pretty quickly so your drawdown goes up in the area around the well the pressure becomes very low and you start desorbing gas, but it is hard to get a big flow rate because the permeability has dropped and therefore the area that is being influenced has also dropped. It may work with highly deviated/horizontal wells but unless they have massively choked back the wells they are testing it is hard to see how a vertical well can be economic.

Yes this is something I have mentioned several times going back months. Permeability technically shouldn't exist at this depth so it's impossible to really know how the reservoir will behave under drawdown. That's why ultimately the proof is in the flow rates. At 90% saturation though, it opens a host of new possibilities in terms of horizontal drilling and fraccing.

What is encouraging though is that there has been no real decline in water rates in either well since the frac flowback stopped. If the situation you describe was happening (reaching desorption pressure in a small area, producing a small gas flow, because of only localised permeability and no chance of sustained high flow rates) I would expect the water flow rates to be dropping like a rock. They don't seem to be. That water must be coming from somewhere and the only options are from the coals or from a sandstone they've fracced into.

rexsh,

I don't think separators "need" any minimum amount of gas to work. They are just gravity-based tanks where the water drops out and is collected from the bottom of the tank. If gas flows in, it's collected from the top of the tank.

mir911,

Well I have the Davenport Well Completion Report sitting in front of me now and it certainly doesn't show any strong gas signature over the Toolachee coals. There is some gas over the Epsilon coals though. Davenport is in a slightly different location from Klebb and Chiffre so it may be different there.

The Davenport WCR is very interesting but probably too technical for most people here. I have some misgivings over some of the analysis work done by contractors but there is enough there to get a general idea.

It reports about 30% CO2 in the well and some ethane, 5-10% as I expected. The CO2 was interesting as I don't recall BPT or STX mentioning this before.