CO2 and hydrates 4

[PSP113]

We have multiple wells in a relatively mature oil field. In the last year we set up a pilot project to inject C02 into the formation to get greater oil production. Within the last six months we've seen hydrate formation across the choke spools on our wells. This causes interuption in production and a headache for the operators. Anyone encountered this issue with increased CO2 levels and any thoughts on prevention, fixes?

 

[SJones]

Prevention and fixes can be found in Natural Gas Hydrates: A Guide For Engineers by J J Carroll

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[dcasto]

Are you sure it's water and not solid CO2 else
Get the water out.

HYDRATE FORMATION CURVE TABLE

HYDRATE PRESSURE HYDRATE TEMPERATURE
KG/CM2 C

7.0 -9.3
14.1 1.9
21.1 5.0
28.1 7.5
35.2 9.5
42.2 10.9
49.2 13.0
56.2 13.0
63.3 13.0
70.3 13.0
77.3 13.0
84.4 13.0
91.4 13.0
98.4 13.0
105.5 13.0
112.5 13.1
119.5 13.2
126.6 13.3
133.6 13.4
140.6 13.5
147.6 13.6
154.7 13.7
161.7 13.8
168.7 13.9
175.8 14.0
182.8 14.1
189.8 14.1
196.9 14.2
203.9 14.3
210.9 14.4
218.0 14.5
225.0 14.6
232.0 14.7
239.0 14.7
246.1 14.8
253.1 14.9
260.1 15.0
267.2 15.1
274.2 15.1
281.2 15.2
288.3 15.3
295.3 15.4
302.3 15.5
309.4 15.5
316.4 15.6
323.4 18.5
330.4 18.5
337.5 18.5
344.5 18.5
351.5 18.5

Are you sure it's water and not solid CO2

 

[PSP113]

I'm not sure if it's water or solid CO2. We use a gas lift system in the area, so we thought we weren't properly dehydrating the gas before sending it back to the field, however, our dew points are well within acceptable ranges. If solid CO2 is the issue, how would I address it?

 

[dcasto]

here is a nice explaination.

http://search.msn.com/results.aspx?q=CO2+solid+formation+line&form=QBRE&qs=n

 

[Montemayor]

dcasto:

That's a nice listing of hydrate formation temperatures. Is this for a pure, methane gas or a mixture of typical hydrocarbon natural gases? Is the listed pressure gauge or absolute?

Is this data empirical or theoretical? Are there any references?

Thanks.

 

[dcasto]

it's from WinSim, I entered pure CO2. I checked some numbers with HYDOFF, Dr Dendy Sloan's program you can download from CSM (great school eh?)

WinSim uses these references on their hydrate prediction models:

References for Hydrate Formation

1. Holder, G., "Multiphase Equilibria in methane-ethane-propane-water hydrate forming systems", Ph. D. thesis, U. of Michigan (1976).

2. Robinson, D.B., Ng, H.-J. and Chen, C.-J., "The Measurement and Prediction of the Formation and Inhibition of Hydrates in Hydrocarbon Systems" Paper Presented at 66th Annual GPA Convention, Denver, March, 1987.

3. Ng, H.-J., Chen, C.-J. and Robinson, D.B., "The Influence of High Concentrations of Methanol on Hydrate Formation and the Distribution of Glycol in Liquid-Liquid Mixtures" Gas Processors Association Research Report RR-106, April, 1987, 17 p.