Runtime-Dependent Variables

Functions containing runtime variables cannot be evaluated before running the simulation. When you define an input variable as a function, and you include Runtime Variables in the function expression, you are turning that input into a runtime-dependent variable. The PetroVR simulation engine defers the evaluation of these functions to the last possible moment, that is, until the time they will be used in the simulation.

(A consequence of this is that runtime variables should only be referred to from PetroVR Plan functions and not from Econ Model Calculations, because the latter are calculated after the simulation has ended and therefore retrieve only the value at the end of the simulation.)

Since not all variables are used with the same frequency during the simulation, the impact of referencing a runtime variable in them varies. Some are generally read and used only once, like a well's Initial Rate or Well Reserves; others are used all the time or over a period, like a facility's capacity.

Well reserves are calculated the day the well is completed; reservoir reserves, on the contrary, are calculated at the beginning of the simulation. This implies that variables used for calculating reservoir-level reserves (like Recovery Factor or Reservoir Area) should not be defined by means of runtime-dependent variables referencing values that will only be known after the simulation starts. The system will issue a warning if any such reservoir reserves definition is found.