Spring support is suitable for flowline on wellhead?

[Redpipe]

Hi gents,

I work in oil and gas exploration and production company. We have many wellhead platforms for production. Normally when we operater wellhead, X'mas tree will have some vertical growth depend on pressure and temperature (maximum 100 mm.). Some wellhead, I design pipe support of flowline without spring support. Some wellhead, I design to have spring support as per result of CAESAR II.

Now I feel spring supports are not necessary for flowline. I think we can allow flowline float from support without any effect.

What do you think about requirement of spring support for the flowline?

 

[KernOily]

There are several ways around this problem. Why are you using a spring support? Most of the time you only use a spring if you are trying to control secondary stress-induced (thermal) reaction loads on a flange, or if you are trying to control the growth to some degree. At the wellhead you don't need to do this because API wellheads are hell for stout - they are not like a steam turbine flange. Do not use spring supports for this - you need to design a way around them - too much maintenance hassle for this application.

Most folks around here in thermal EOR use some type of swivel joint for this application, e.g. swivel joints made by Barco. The steam injector casings around here grow vertically about 2 ft (300 mm) when the injector goes into service. You can anchor the pipe near the wellhead and then put in three Barco joints about 3' (600 mm) apart to make a two-bar linkage. Works perfectly. Use your CII software to work it out. There is a tutorial in the CII manual on modeling a swivel joint - just follow that.

Or use a Z-bend or expansion loop in the pipe at the wellhead.

If your growth is only 100 mm then you could also anchor the pipe some distance off the wellhead and then take advantage of the natural flexibility in the pipe. This only works for small pipe sizes like 2" and 3" (50 mm or 75 mm) because the pipe gets too stiff for sizes larger than that, for reasonable lengths of pipe. Pete

Thanks!
Pete

 

[11echo]

I work in the Calif. oil fields. The oil companies here use the basic design 74Elsinore was talking about (loops or "Z" bends) but they don't go to the expense of specialized joints. They use either a union or a threaded coupling ...this is on 2" flowlines. Seems to work fine on all the wells out here. Good Luck! ...Mark

 

[KernOily]

Hmmmm... You can use unions or couplings in this application but I would caution you to remember that (1) this is not what they are designed for (2) they WILL leak. Period. If you have a large number of cycles then I would definitely go with the engineered solution (swivel joint - Barco or Chik-San).

If the degree of rotation is small then you could probably use a hammer union with pretty good success but realize that it will leak at some point in the future. I would be sure to do my homework first and I would weigh their use accounting for the experience level and technical sophistication of your operation especially if you have a thermal operation (steam drive or cyclic steam). The Barco joints are just not that much money for the degree of minimization of risk that you get by their use.

If I was in your shoes I would run my CII model and try a z-bend or expansion loop first at the wellhead. If you only have 100mm of growth then I am fairly sure either of those will work perfectly. Pete

Thanks!
Pete

 

[11echo]

Pete ...You know up until recently they were using S.S. hose ...although rated for the pressure, they were finding these were failing. At some wells they are getting up to 7" of vert. movement. I have seen the Barco joints over on the coast, but to date haven't made to much of a dent here. The engineers are aware of them, but seem to lean toward the unions and couplings, I'm guessing availability and cost are the leading factors. I'm afraid I'm directed by the adage "you can lead a horse to water, but you can make him drink"! ...Mark

 

[KernOily]

Well like so many other things in the oil patch, the use of a particular technique is not necessarily technology-driven, but it's done that way due to sacred tradition or 'whatever the foreman wants' or 'whatever we did last time'. And that's not a bad thing either as long as it works, it's safe, and it doesn't bear repeated failures. Our wellhead growths around here (Midway-Sunset) are anywhere from 7" to 2'. We also have some union-couplng arrangements but most of ours are Barco swivels or hard-pipe with z-bends. Pete

Thanks!
Pete