BHP behaviour

[Petroleo]

Hello all,

I think when liquid rate increases, BHP should increase as well. The opposite behaviour could be seen when GOR or gas Lift increases, or when water cut decreases, isn't it?. But I am simulating several 12000-15000 ft depth wells, 30API and I am getting lower BHPs at higher liquid rates (1M-10MBOD)at constant water cut,GOR (up to 500) and gas lift (up to 2 MMSCFD). Then, at higher GOR and Gas lift I can see the expected behavior, could you think in a reson for that?

Regards

 

[zdas04]

What program are you running? The system that includes the reservoir, transition from the reservoir to the wellbore, the wellbore tubulars, and any artificial lift is pretty complex. Different programs deal properly with different parts of the system and do a "once over lightly" on the rest.

The condition that you describe for the flowing well is not necessarily wrong. While higher flow rates will give you higher friction drop up the tubing (assuming GLR doesn't change), it might also flatten the pressure traverse across the near wellbore and lower the flowing bottom-hole pressure. My point is that the system is just too complex to reliably take one piece of the system as varying and assume everything else is constant.

David

 

[Petroleo]

Thanks zdas04, I am using Pipesim because I got some previous results with Prosper and BHP decrease appeared as well. I am just generating BHP behaviour at several conditions in order to evaluate future changes in fluid properties on the system. I agree it is a complex system but these results were not what I expected.

Regards

 

[cesarcf1977]

Hi, Petroleo.

I'm not sure to understand your's system description.

If your reservoir conditions keep the same (same deliveravility or IP) and your artificial lift system is able to handle the increase in production up to surface(with an increse in lift gas or a frequency increase in your pump, for instance), the BHP should decrease as your liquid rate increases, as you need to create more drawdown (Res. Pressure minus BHP) to extraxt more fluid from the reservoir...

If you increaee your gas lift rate (or your GOR) up to certain limit, your fluid column up to surface will be less dense and the "weight" of fluid over the bottom of the hole will be lower, getting a lower BHP, a larger drawdown and a higher fluid rate...

Please, if you're not happy with this answer, give us more details about your exact system's original configuration and the changes you apply.

Regards.

 

[Petroleo]

Thanks cesarcf1977 for your comment, I completely agree with you, but if you fix the THP, GOR, Gas Lift and water cut, and increase the flow, I think BHP has to increase as well. I have notice that at low GOR (up to 500) and low gas lift (up to 1 MMSCFD) BHP decreases when production is increased. I think it could be due to fluid column became heavier because gas in solution increases? there is not enough gas to have free gas which is the one that makes the column ligther.

Regards