Why Produce Thru the Annulus?

[akoester]

Facilities engineer here, hoping some production engineers could lend their experience. My company currently produces our onshore horizontal wet gas/condensate wells through tubing from day 1. We've been asked to evaluate a change to producing from the annular side of the B section of the wellhead. My gut reaction is (1) sand erosion + no well control if the B section valves cut out NO THANK YOU and (2) what does this even buy you from a production standpoint?

I've done an extensive literature search on OnePetro and Knovel - it seems that this is standard operating procedure for the Gulf of Mexico. How is sand erosion mitigated? A review of SPE papers suggests that high gas rate + condensate wells are the most prone to sand erosion. Is anyone doing this onshore?

There are lots of papers on the different methods to calculate erosional vel, but I have failed to find a reference that demonstrates the consequences in situ. Also no references on additonal mitigations that need to be put in place to do this safely.

Any guidane or additional ref docs would be greatly appreciated.

 

[zdas04]

There are something like 300,000 onshore gas wells that either always or often flow gas up the tubing/casing annulus. Reasons for doing it:
[ul]
[li]Pumping liquids up the tubing and flowing gas up the annulus[/li]
[li]Reduce velocity in the flow stream to reduce solids movement[/li]
[li]Minimize total fluid friction to lower flowing bottom hole pressure[/li]
[/ul]

Be careful of the papers you find on errosional velocity. They are all talking about continuous phase liquid. There is not a velocity below about 0.6 Mach that a predominately gas stream creates significant erosion. It can be hard to dig that fact out of some of the One-Petro articles.

David Simpson, PE
MuleShoe Engineering

Law is the common force organized to act as an obstacle of injustice Frédéric Bastiat

 

[akoester]

Thanks for advising, David.