Flowline design for dual string completed wells.

[Oghenereke]

Hello,

This is my first real pipeline design at my place of work (I just left school). I have been asked to do the flowline concept design for two wells. The challenge I have is that both wells are dual string completed. My question is, is it better to construct four flowlines to the processing facility or use a manifold to collect both strings and then use two gathering lines to flow the fluid to the processing facility ( the wells are 1km and 3km from the processing facility)? is there a standard to follow with regards to dual completed wells? Any ideas and pointer as to what to do is really appreciated.

 

[georgeverghese]

The flowstrings are usually manifolded before transported through a single pipeline to the processing facility. For pipelines 1km and 3km, you'd need pigging facilities on the terminal ends for each of the pipeline also.

 

[Oghenereke]

Thanks so much george. That's really helpful.

 

[LittleInch]

As with many things - it depends.

It depends on why this / these wells are being dual strung and whether the reservoir engineers want to keep the fluids separate or not.

Maybe they want to test one formation whilst producing the other - Can't be done if you co-mingle at the well head.
Maybe one needs or uses a different arrival pressure at the CPF - many CPFS have different pressure manifolds - again can't be done if you've co-mingled at the wellhead.

So in short, you need to ask the reservoir guys / process engineers what they want to do with this well. They should have produced a P&ID for you to work off or a design description, not leave it up to you.

There are many different ways of collecting well fluids dependant on process requirements, distance and orientation from the wellhead and how they operate pressure control and design pressure breaks.

Welcome to the world of pipeline design - it's not a simple cookbook approach, but a balancing between competing issues.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Oghenereke]

Thanks littleinch

 

[zdas04]

In addition, in many oil fields, you don't have onsite processing and have to go to a tank battery with well test equipment, for that you need to home run all four strings (usually) to the tank battery so that you can test them. Bottom line is that LittleInch is right and the other post is a bit short sighted, you need to understand why there are four strings and honor that reason. For gas fields, maybe you need a 3-phase separator for one of the strings, two-phase separators for the other three, and gas measurement on each of the four before combining them. Or maybe (like in the San Juan Basin) you can't send gas from the coal seam (high CO2, low chance of hydrocarbon liquids or NGL) to the plant designed for the conventional and tight gas seams (low CO2 and lots of liquids). Understanding why the wellheads are configured as they are is key.

[bold]David Simpson, PE[/bold]
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

 

[Oghenereke]

Thanks so much for the insight David.

The field is actually an oil producing field. And all the separation is to be done at the flow station. As you guys have suggested I will speak to the reservoir guys on the wellheads configuration.