Running the Norne case with Flow

Simulator log output

The Flow simulator produces several logs:

  • Terminal output
  • The PRT file
  • The DBG file
Terminal output

The most important messages are written to the terminal. This includes warning and error messages, timesteps and timestep summaries. Warnings are printed in blue, errors in red, and numerical problems (typically leading to timestep chopping) in pink.

By default, the terminal is limited to displaying a certain number of messages of the same type (note, warning, problem, error etc.), so after displaying a large number of warnings for example it will cease reporting them. Similarly, it will stop repeating similar messages (technical detail: messages with the same “tag”) after 10 such messages have been displayed. For example, you can see that after report step 4, Flow prints the message: “Warning: Message limit reached for message tag: Unhandled output keyword”.

Other than the time steps, the most interesting messages printed to the terminal are the well-control messages printed when wells are switched from one control setting to another due to breaking one or more constraints, and numerical problems encountered. If Flow fails to solve the current timestep for any reason it will retry with a smaller step size. That will be reported like this:

Problem: Solver convergence failure - Iteration limit reached
Timestep chopped to 3.630000 days
The PRT log (NORNE_ATW2013.PRT)

The PRT log file contains a lot more than is printed to the terminal.

First, there are no message limits, so warnings that are eventually silenced in the terminal output, will remains as warnings here.

Second, the log is a bit more verbose. Initially, an overview of all command-line options used is printed. Also, fluid-in-place reports are printed for all fluid-in-place region after every time-step.

The DBG log (NORNE_ATW2013.DBG)

The main difference between this and the PRT log is that this will contain absolutely all messages, including debug messages. In particular, the residuals are printed after every iteration, making it possible to follow the Newton-like nonlinear iteration process. This makes it useful to developers, less so for regular users. If you have a problem however, this log can be valuable in diagnosing your issue.

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