Pump Selection for Production Separator Liquid transfer

[Khansahib]

I have been asked to look for a suitable pump that can pump liquid from two phase separator to another platform. The production separator will be operating at 40 PSIG whereas the pump discharge reuirement is 140 psig. The amount of liquid is around 30,000 blpd (oil+water). Neither electricity nor high pressure gas/air is available on the platform however, on recommendations either can be provided. There a lift gas line passing close by which is operating at 300 psig, it can be tapped for provision of gas to run pump otherwise electric cable (2.5 km) is to be laid down from another platform. To my mind a reciprocating pump can be best suited as the liquid will be a mixture of oil and water, the viscosity and sp. gravity will keep on changing minute by minute. However, I am also thinking a vertical pump due to space constraints on the platform. I have reservation on opting the gas option to run the pumps because of gland leakage and disposing it. Your valuable suggestion and recommendations shall be appreciated.

 

[micalbrch]

140 pisg isn't much for a positive displacement pump but you will need either electricity of a diesel engine for it. Anything else isn't impossible but hard to find.

Just to enlighten me: What unit is blpd? How much is that in GPM or m³/h?

 

[zdas04]

It is 875 gpm.

Anytime you're pumping a gas-oil mixture (especially with a plunger pump, but a centrifugal to a lesser extent) the shear forces tend to emulsify the mixture and make it really hard to separate. If you can avoid big shearing forces you'll be better off.

I would get the 300 psig gas and use a blowcase. The key to moving this kind of volume with a blowcase is the size of the vent back to the primary separator. I can get 10,000 bbl/day with a 2-inch vent, but for three times that I'd use a 4-inch vent with a ball valve and a bi-directional pneumatic actuator. I'd also use an actuated ball valve for the blowcase dump and for the power gas. This thing would require some pretty special design, but it absolutely could do the job (and it has a very small footprint, and it doesn't care what fluid it is moving, and very little of the power gas goes with the liquid).

If you don't like blocases, then I'd run the electric power and use a progressing cavity pump for the transfer. They turn pretty slowly and have about the lowest shear force of any pump (they were developed originally to move fluids that were modified by shear within a peanut butter plant). This kind of pump could be mounted vertically with the bottom end extending through the deck and don't take much room.

David Simpson, PE
MuleShoe Engineering

http://www.muleshoe-eng.com

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