improve initialization msw new wells

opm/simulators/wells/BlackoilWellModel_impl.hpp

@@ -297,17 +297,6 @@ namespace Opm {
             well->closeCompletions(wellTestState());
         }
 
-        // calculate the well potentials
-        try {
-            updateWellPotentials(reportStepIdx,
-                                 /*onlyAfterEvent*/true,
-                                 ebosSimulator_.vanguard().summaryConfig(),
-                                 local_deferredLogger);
-        } catch ( std::runtime_error& e ) {
-            const std::string msg = "A zero well potential is returned for output purposes. ";
-            local_deferredLogger.warning("WELL_POTENTIAL_CALCULATION_FAILED", msg);
-        }
-
         if (alternative_well_rate_init_) {
             // Update the well rates of well_state_, if only single-phase rates, to
             // have proper multi-phase rates proportional to rates at bhp zero.
@@ -320,6 +309,17 @@ namespace Opm {
             }
         }
 
+        // calculate the well potentials
+        try {
+            updateWellPotentials(reportStepIdx,
+                                 /*onlyAfterEvent*/true,
+                                 ebosSimulator_.vanguard().summaryConfig(),
+                                 local_deferredLogger);
+        } catch ( std::runtime_error& e ) {
+            const std::string msg = "A zero well potential is returned for output purposes. ";
+            local_deferredLogger.warning("WELL_POTENTIAL_CALCULATION_FAILED", msg);
+        }
+
         //update guide rates
         const auto& comm = ebosSimulator_.vanguard().grid().comm();
         const auto& summaryState = ebosSimulator_.vanguard().summaryState();

opm/simulators/wells/MultisegmentWell_impl.hpp

@@ -422,9 +422,15 @@ namespace Opm
 
         // initialized the well rates with the potentials i.e. the well rates based on bhp
         const int np = this->number_of_phases_;
-        const double sign = well_copy.well_ecl_.isInjector() ? 1.0 : -1.0;
+        bool trivial = true;
         for (int phase = 0; phase < np; ++phase){
-            ws.surface_rates[phase] = sign * ws.well_potentials[phase];
+            trivial = trivial && (ws.well_potentials[phase] == 0.0) ;
+        }
+        if (!trivial) {
+            const double sign = well_copy.well_ecl_.isInjector() ? 1.0 : -1.0;
+            for (int phase = 0; phase < np; ++phase) {
+                ws.surface_rates[phase] = sign * ws.well_potentials[phase];
+            }
         }
         well_copy.scaleSegmentRatesWithWellRates(well_state_copy);
 

opm/simulators/wells/WellInterface_impl.hpp

@@ -1013,14 +1013,19 @@ namespace Opm
                 }
             }
         }
-        if (nonzero_rate_index == -1) {
-            // No nonzero rates.
-            return;
-        }
 
         // Calculate the rates that follow from the current primary variables.
         std::vector<double> well_q_s = computeCurrentWellRates(ebosSimulator, deferred_logger);
 
+        if (nonzero_rate_index == -1) {
+            // No nonzero rates.
+            // Use the computed rate directly
+            for (int p = 0; p < this->number_of_phases_; ++p) {
+               ws.surface_rates[p] = well_q_s[this->flowPhaseToEbosCompIdx(p)];
+            }
+            return;
+        }
+
         // Set the currently-zero phase flows to be nonzero in proportion to well_q_s.
         const double initial_nonzero_rate = ws.surface_rates[nonzero_rate_index];
         const int comp_idx_nz = this->flowPhaseToEbosCompIdx(nonzero_rate_index);