Only compute well potential if needed

A boolen user parameter is added to controll the computation of well
potential.

This is a temporary fix to assure that no extra computation time is used
on well potential calculation if it is not needed. The long term fix
will require a more thorough revising of the well group implementation.

opm/autodiff/BlackoilModelBase_impl.hpp

@@ -1703,6 +1703,8 @@ namespace detail {
                           const std::vector<ADB>& b_perfcells,
                           WellState& well_state)
     {
+        //only compute well potentials if they are needed
+        if (param_.compute_well_potentials_) {
             const int nw = wells().number_of_wells;
             const int np = wells().number_of_phases;
             const Opm::PhaseUsage pu = fluid_.phaseUsage();
@@ -1790,6 +1792,7 @@ namespace detail {
                 cq += superset(well_potentials[phase].value(), Span(nperf, np, phase), nperf*np);
             }
             well_state.wellPotentials().assign(cq.data(), cq.data() + nperf*np);
+        }
 
     }
 

opm/autodiff/BlackoilModelParameters.cpp

@@ -48,6 +48,7 @@ namespace Opm
         tolerance_wells_ = param.getDefault("tolerance_wells", tolerance_wells_ );
         solve_welleq_initially_ = param.getDefault("solve_welleq_initially",solve_welleq_initially_);
         update_equations_scaling_ = param.getDefault("update_equations_scaling", update_equations_scaling_);
+        compute_well_potentials_ = param.getDefault("compute_well_potentials", compute_well_potentials_);
     }
 
 
@@ -65,6 +66,7 @@ namespace Opm
         tolerance_wells_ = 1.0e-3;
         solve_welleq_initially_ = true;
         update_equations_scaling_ = false;
+        compute_well_potentials_ = false;
     }
 
 

opm/autodiff/BlackoilModelParameters.hpp

@@ -49,6 +49,10 @@ namespace Opm
         /// Update scaling factors for mass balance equations
         bool update_equations_scaling_;
 
+        /// Compute well potentials, needed to calculate default guide rates for group
+        /// controlled wells
+        bool compute_well_potentials_;
+
         /// Construct from user parameters or defaults.
         explicit BlackoilModelParameters( const parameter::ParameterGroup& param );
 

opm/autodiff/SimulatorBase_impl.hpp

@@ -222,12 +222,13 @@ namespace Opm
             // Increment timer, remember well state.
             ++timer;
             prev_well_state = well_state;
-            // Compute Well potentials (only used to determine default guide rates for group controlled wells)
-            // TODO: add some logic to avoid unnecessary calulations of well potentials.
+            // Compute Well potentials if they are needed
+            // Only used to determine default guide rates for group controlled wells
+            if ( param_.getDefault("compute_well_potentials", false ) ) {
                 asImpl().computeWellPotentials(wells, state, well_state, well_potentials);
-
             }
 
+        }
         // Write final simulation state.
         output_writer_.writeTimeStep( timer, state, prev_well_state );