flow assurance

[EngAbdelkader]

Hi every one, I was looking for any advice that could help me sorting out a solution for a practical problem that we have in the field.
The main issue is that we have 3 lines coming from different wells (oil) that are connected in a gathering line (trunk line)which constitute a bottleneck, to the oil plant, we are facing these years an increase in the gas handled within the pipeline that increase the pressure in the lines and so the production of the wells is reduced (back pressure)the solution that our office (engineering) found was to double the lines (line looping) the pressure would be lower (back pressure) and so we could recover the production and face any increase of gas volume due to the evolution of the field (gas breakthrough)

But I was wondering if there wasn't another solution, actually I was thinking of an equalizer-like solution, to release the pressure in the 3 lines that have in fact different pressure, could we connect the 3 pipelines one to the other (cross connection) to equalize the pressure first that should release the pressure downstream (bottle-neck)

any advice about this latter solution?
thanks in advance!

 

[BigInch]

Its possible equalizing could help, but without knowing each well's oil and gas flowrates, distances, elevations and pipe diameters, I can't say for sure, if it would help or how much it would help. It might also tend to equalize flows from the wells, something you might not want to do. It could also be very sensitive to a change in any gas to oil ratios of any one well.

On the other hand, looping is a safer long term solution and will help as long as its done right and the pipe area is not increased too much. You probably don't want to reduce gas velocity so low that oil slugging starts, or so you enter some other undesireable flow regime.



"If everything seems under control, you're just not moving fast enough."
- Mario Andretti- When asked about transient hydraulics

http://virtualpipeline.spaces.msn.com

 

[EngAbdelkader]

thanks BigInch for your reply actually the 3 lines I spoke about above are already coming from clusters so the well issue shouldn't be a problem as in each line a set of well is already producing through, for us the main issue is that the gas oil ratio of some wells starts increasing and we are reaching the limitations in the lines, for other lines it's more a water issue (reality is more difficult than simulation!) so in the 3 lines we have back pressure due to gas volume from one side and water cut from the other side this oblige us to close the wells that are on their limits in term of well head pressure versus flow line pressure, that's why I had the idea to equalize the pressure between the 3 lines a kind of release for the flow.

the looping in my idea should be done from the gathering point where the 3 lines join and downstream this point (for 500 m for example) do release also the bottle neck.

if I can summarise my view, the solution could be as fellow:
- first run 2 cross pipes connecting the 3 lines as an equalizer (the connection should be done on the upper part of the pipelines obviously)
- second to avoid the bottle-neck in the gathering point, loop the trunk line for 500 meters (let's say) this should release also the bottle-neck effect (debottle-necking)

I hope you can give me your point of view about this solution

thanks in advance!
kader

 

[EngAbdelkader]

here bellow a small draft about the problem I am facing to clarify the issue!
thanks and sorry for disturbing you guys!

 

[BigInch]

Its still not apparent how equalizing might help. Do you have specific a problem you are trying to solve, such as, very little flow from one cluster, too much gas in one line and not enough in the other two? Are all lines the same diameter now? How will the elevation profiles affect flow? Only a very detailed analysis will show any possible benefit, and the benefit may be short lived, depending on how long the flowing gas, oil and water ratios can be maintained the same.

The safer bet is looping a few, all, or a portion of one or all of the lines.


"If everything seems under control, you're just not moving fast enough."
- Mario Andretti- When asked about transient hydraulics

http://virtualpipeline.spaces.msn.com

 

[EngAbdelkader]

well the low flow condition is mainly caused by the increase of the gas volume in the lines (mainly because the GOR is getting higher) this causes an increase of the pressure in the lines that acts as back pressure so the flow line starts to have higher pressure or near the well head pressure!
all the lines have the same diameter, but as the volume ratios of the 3 phases are evolving I can't say that they will be allways the same; the next days we'll run a test (injection of drag reducer) to see if the production will change or not.
anyway I see that as you are more experienced than me, your choice is more on the line looping, so thanks for the advice and for your help!
Thank you (muchas gracias as spanish say isn't it)

 

[BigInch]

I always try the simpler solution path first. The reason I favor individual looping is that the primary thing to worry about here is what flow regime you will be having in the future. Gas/oil/water flow can get complicated and slugging makes things very difficult to control and handle and is a common result of larger effective diameters, so trying to control 3 clusters to avoid slugging is much more complicated than controlling each cluster.

"If everything seems under control, you're just not moving fast enough."
- Mario Andretti- When asked about transient hydraulics

http://virtualpipeline.spaces.msn.com

 

[dcasto]

the only way an equalizer would work would be if it was between the boxes marked cluster A to C. or at least close to those points.

 

[EngAbdelkader]

Thanks dcastro for the advice! anyway the bosses chose to implemente the line looping solution

 

[BigInch]

Well done.

If you were plowing a field, which would you rather use? Two strong oxen or 1024 chickens?" - Seymour Cray (1925-1996), father of supercomputing
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http://virtualpipeline.spaces.live.com/