Time Series

Time Series provides a powerful new way for you to look at your planned and current facilities across time, giving you the ability to define and run simulations running out over several days, months or years all from a single case. Use it to look at how well your process facilities can handle changing feeds as wells and reservoirs decline. Use it to look at how fixed bed refinery reaction systems decline in activity over time and much more.

A Time Series is a set of successive steady state simulations over time, running between start and end dates that you define. You define what parameters change over time, nominate the variables you want to study and set up cumulative calculations. Then run the study and use the reporting tools to investigate results.

Defining Changes

We use the idea of Scenarios to help you group changes together, where each scenario affects one or more specification variables through one or more states. If nothing changes then each time step will solve to the same results as the previous and often will not need to solve at all! Typical specifications are:

  • Feed stream conditions, properties and compositions sourced from information such as reservoir decline curves or refinery crude schedules
  • Unit operating conditions
  • Whether a unit is active or not

You build up the sets of specifications using three methods:

  • Get Petro_SIM to record data changes you make to a case, automatically determining the variables involved. (This is often the easiest way to get started)
  • Add variables to a scenario using the variable navigator directly from the scenario
  • Send variables to a scenario as you would to tools like spreadsheets or the databook

States are the values that each specification takes when that state is active:

  • You can manually activate any state
  • You can mark a state as becoming active on a given date (you can also set up interpolations between dates)
  • You can make a state become active based on the logic rule you supply, such as activate the second compressor when the well discharge pressure drops below a threshold

You can combine Scenarios with other tools such as detailed event specifications, workflows and scripts to build up very complex simulations that respond to changes.

Looking at Results

A typical time series simulation will run over your time range and then leave the case at the final steady state pertaining at the simulation end date. You then use trend tools to look at how things change over time and use the Timeline view to give you a high-level glance. Where you want more detail you can export results from each time step to Petro-SIM-generated workbooks in Microsoft Excel and/or to individual cases in the Petro-SIM database.


Typical Timeline view

Handling cumulative variables

You can accumulate any extensive variable in your case and use these accumulated variables to help drive cost and NPV calculations. Examples are building up total production mass, volume or molar flow over the life of your simulation or building total charge rate to Hydrocracker reactors to help drive deactivation studies.