Spike in production when switching to a bhp mode
ahmadreza shojaee
Dear all,
I am currently running a compositional simulation involving several cycles of hydrogen injection, shut-in, and production. The injection and production rates are set to be equal, with a bottomhole pressure (BHP) constraint applied during the production phase.
I’ve observed that when the well switches to BHP control mode, there is a spike in the production rate. Is this behavior normal?
Any insights would be greatly appreciated.
Kind regards,
Ahmad
Olav Møyner
Sent: Tuesday, May 13, 2025 15:15
To: MRST-users: The Matlab Reservoir Simulation Toolbox User Group <sinte...@googlegroups.com>
Subject: [MRST Users] Spike in production when switching to a bhp mode
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ahmadreza shojaee
Thank you for your reply.
If the pressure difference between the producing cell and the BHP is large enough to allow a higher production rate, why does the well switch to BHP mode? I reviewed the data and noticed that the well produces more gas for two time steps after the switch, and then the rate drops below the previously constant value.
Is there a way to set a production rate limit or a rest period for wells operating under BHP control? If so, could you please advise how this can be implemented?
Kind regards,
Ahmad
ELYES AHMED
Dear Ahmad,
To set limits on well controls in MRST, you can use the 'lims' parameter in the addWell function. For example:
W = addWell([], G, rock, well_cells, 'val', rate_value, 'type', 'rate', 'lims', 20*barsa);
This will be interpreted as a lower bound on the computed BHP when the well is rate-controlled and is an injector (W.sign>0) . The 'lims' option can also be used to set upper bound when W is a producer.
You can do the same for setting a maximum OR minumum rate when the well is BHP-controlled.
To set a rest period, you can deactivate the well by setting W.status = false for the desired time steps in the schedule.control structure.
Let me know if you need further clarification.
Best regards,
Elyes Ahmed
SINTEF Digital
ahmadreza shojaee
Dear Elyes,
Thank you very much for your detailed response and guidance.
I’m currently using the following line to set a BHP limit for my well after defining it:
W.lims.bhp = 150 * barsa;
The challenge I’m facing is that we don’t know in advance when the pressure will fall below this limit and cause a switch from rate to BHP control. Similarly, for setting a rest period using W.status = false, it seems that we’d also need to know the switch time ahead of time, which is not always possible.
Additionally, I’m still a bit concerned about the well's behavior after switching to BHP control. As mentioned in my initial email, I observed that the well actually produces more fluid for two time steps right after the switch, which seems counterintuitive. I would have expected a lower production rate after switching to BHP, since the rate condition previously caused the pressure to drop below the 150 barsa limit.
Any insight you might have on this behavior would be greatly appreciated.
Kind regards,
Ahmad
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