Dehydration of carbon dioxide for oil field injection
Dehydration of carbon dioxide for oil field injection
(OP)
Hi All!
We have a gas with the next approximate mole composition:
CO2 90.0%
C1 9.0%
CN 0.9%
H2S 0.1%
Pressure 80 Kg/cm2g
Temperature at gas pipeline inlet 50 ºC.
It is desired to inject this gas in an oilfield. Do you have any idea if a moisture content of 9 lb/MMscfm is convenient for this service?
I don't have any reference value for corrosion rate at this conditions or if corrosion is an important issue with that moisture content.
I assume a condition of supercritical fluid a P, T and I observe that condensation of CO2 is produced in the first 100 m of pipeline.
Other data:
Pipeline lenght 1000 m
Thanks in adevance for your help
jeap
We have a gas with the next approximate mole composition:
CO2 90.0%
C1 9.0%
CN 0.9%
H2S 0.1%
Pressure 80 Kg/cm2g
Temperature at gas pipeline inlet 50 ºC.
It is desired to inject this gas in an oilfield. Do you have any idea if a moisture content of 9 lb/MMscfm is convenient for this service?
I don't have any reference value for corrosion rate at this conditions or if corrosion is an important issue with that moisture content.
I assume a condition of supercritical fluid a P, T and I observe that condensation of CO2 is produced in the first 100 m of pipeline.
Other data:
Pipeline lenght 1000 m
Thanks in adevance for your help
jeap





RE: Dehydration of carbon dioxide for oil field injection
If the pipe does cool off to the point where 8 lbm/MMSCF is above 100% RH then you'll get condensation and standing water. Now you have to guess (and it is a guess) whether the water will absorb the CO2 and become acidic or basic, the activation energy for carbonate or carbonic acid is almost identical. If you can convince yourself it will form carbonate and be basic then you have no worries. If you form the acid then the pipe will disolve before your eyes.
If they were my dice I wouldn't risk it. There are some spoolable composites coming onto the market that can handle this pressure and are chemically inert. I'd look at that if your flow rate is low enough to fit into a 4-inch pipe.
David Simpson, PE
MuleShoe Engineering
www.muleshoe-eng.com
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
The harder I work, the luckier I seem
RE: Dehydration of carbon dioxide for oil field injection
Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdo/
RE: Dehydration of carbon dioxide for oil field injection
Well, I forget to give flowrate and pipeline size, because I was worried about the corrosion issue but here go complemental data:
Flowrate 600M Sm3/d and pipeline size 4" (as you figured out).
In fact after running some simulations in Hysys, I've found that condensation of CO2 and water is possible between tue first 100 m of pipeline because soil temperature at winter conditions drops to 5ºC. I considered a buried depth of 1m.
Since I assumed that no salts were present in the water.I am not sure that pH could be high enough to prevent carbonic acid formation. Both, water and gas, come from primary separation and for environmental regulations it was forbidden to release it longer so operator is in a big hurry!
By rewiewing the articles from SJones, some worries desapeared; manly those concerning to moisture concentration. Simulations showed that is possible to reach that low water content mantaining 25º at compressor suction and in some cases recirculating up to 10% of flow at summer conditions. This is a four stages compressor (2,5 to 80 Kg/cm2). From my point of view it was no necessary to use a TEG unit for dehydrating the mixture but take in to consideration a change of material before entering the third stage of the compressor where condestate is possible
However, pipeline corrosion could be possible under my considerations. Do you have any comment?
Thank you again!
RE: Dehydration of carbon dioxide for oil field injection
I'd use spoolable composite pipe for the line and forget about the corrosion risks. The two high pressure spoolable composites that I've used with succes are FuturePipe (formerly Hydril, http:
David Simpson, PE
MuleShoe Engineering
www.muleshoe-eng.com
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
The harder I work, the luckier I seem
RE: Dehydration of carbon dioxide for oil field injection
Saying all that, the added security of 304SS vs CS on 1000 meters of line is worth the extra cost.
RE: Dehydration of carbon dioxide for oil field injection
Thinking ahead, some other lines could be changed in material, vg. drains and vents...I'm checking conditions.
Well, I really, really thank you all for help and in the future I'll let you know the results...
jeap
RE: Dehydration of carbon dioxide for oil field injection
David
RE: Dehydration of carbon dioxide for oil field injection
RE: Dehydration of carbon dioxide for oil field injection
Are you using a TEG unit in order to dehydrate the gas mixture?
If so, where is it located: interstage or after compression?
Have you observed/meassured corrosion in the compressor interestages?
Considering CO2 a supercritical fluid at P y T after compression I 'assume' that remaining water is to be 'dissolved' in the bulk before entering the wellhead, thus free water should not be present.
On the other hand, models as those explained in GPSA are not in good agreement each other as you can see when compare the figures for CO2, even in the same databook. More...calculations of final moisture using Peng-Robinsong package in hysys differs in great manner from those obtained using sour Peng-Robinson...
I know this is very difficult to estimate, but actually TEG is not to be installed at the beginning of the operation. However, some routine wall thickness meassurements are to be done as well as installation of corrosion coupons to monitoring corrosion rates.