This is one of marginal oil fields, where gas utilization still has to come.
Due to high GOR (near 400 Sm3/m3 of oil), there are huge pressure losses in multiphase line to Central Facility.
In order to reduce the backpressures at wells, the idea is to install separator at the field, that will operate at higher pressure - say 20barg. As the solution gas is mainly methan (more than 85%), the separation will be quite efective (almost 90% of associated gas will be liberated that is flared).
I do not intend to install any pumps at the liquid outlet (containing oil S.G. 0.85 and W.C. 40%, still 10% disolved gas), as there will be enough pressure in system to overcome pressure losses in multiphase line to Central facility.
Liquid rate is 16,000 barrels.
Does anyone see any problem witn non installation of pumps and driving force of gas in separator.

Only safety and environmental issues - you shouldn't have to flare the gas in these days of greenhouse gas concerns and skyrocketing energy prices. If you lose the level in the separator, the old situation is back, so not a concern except for capacity reduction, as long as the pipeline design pressure isn't changed. If you lose pressure in the separator you would feed your flare with oil and gas, which will overwhelm it, and will have to shut down as soon as possible. This is something that requires closer study.
These are my 2 cents, there is probably more to it than I can think of right now.

Dear Kyan,

1. You have mentioned that due to high GOR, huge pressure losses occur in multiphase line. I do not think it is correct. May be you would like to say that high pressure loss due to two phase flow in the line.

2. You have not mentioned the diameter and length of pipeline from well to processing facility without which any calculation is not possible.

3. With 16000 Bbls a day and GOR of 300 sm3/m3 of oil, you'll be handling a gas of around 1 Million sm3/day. It is a huge quantity of energy to be flared under the present energy scenario.

4. you should think of laying another pipeline from field to processing facility for gas transportation and think of utilizing the gas as early as possible.

Kyan,

If you need a pumping device to move a fluid between two points should be a function of the differential pressure between the points and the pressure losses along the way.
But I think this is fundamental and not related to any specific application or flow or size.
Right?


Regards

Kyan,
What is your location? In many of the developed parts of the world, the practice you describe would not be permitted. Best would be to have a separate gas pipeline to consumers. If that were not practical, there are other options, albeit expensive ones, including gas reinjection, conversion to ammonia and/or liquid hydrocarbons, or electricity production.