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Originally Posted by clive milne
Do you have a reference for this Brad?
Separating CO2 from methane is not a trivial undertaking so I'd be surprised if this is done at the well head.
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No its done from the gas gathering facility not the wellhead. Because the facility is offshore its even less economically appealling to recompress the CO2 and take it off- so they just vent it. It's actually a common practise globally, however, in many western nations they've put a stop to it since people started worrying about carbon. The only reference I have for it is I work with people who have been there. Here's an example from the Netherlands:
http://www.co2-cato.org/cato-2/locat...ection-project
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It has been producing natural gas since 1987 with a relatively high CO2 content. After extracting the natural gas, CO2 is removed from the natural gas.
Until recently the CO2 was vented, but since 2004 it is partly injected into the gas field, at a depth of approximately 4000 m. Up till 2010 approximately 80.000 t CO2 has been re-injected.
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So the field has been producing from 1987 to 2004 and venting at least 13,000t of CO2 per year until they started injecting it (remember they say PARTLY, not mostly, predominantly or some other positive word- so how much is still vented?). As you know hydrocarbon fields produce at higher rates initially and decline naturally over time unles they are facilities constrained so initial CO2 venting may have been much higher.
Another chinese project that vents stripped CO2 to the atmosphere can be found here:
http://www.onepetro.org/mslib/servle...=SPE-138399-PA
By the way, Dong Fang produces 24x10^8 m^3 of methane gas a year from a field that is over 19% CO2. All that CO2 is vented to the atmosphere- they are only just discussing the possibility of using some of it for other industrial processes. That's 5.2 million tons a year from a single project. If it were a country it would be 115th on the list for CO2 production circa 2008.
A 2009 discussion about how carbon capture and storage needs a jump-start in china can be found here:
http://www.nrdc.org/international/ch.../fchinaccs.pdf
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The China Power Investment Corporation has proposed to
build an IGCC facility in Langfang (Beijing area) aiming to capture
8 percent of the CO2 from the syngas produced by two 488 MWe
IGCC units.
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So much for the other 92%. Basically they are saying it will cost them $20 per tonne to sequester and they don't want to pay it and raise the price of energy so they need to find a way to make money off it before they will stop venting it. tick tock.
