black-oil: fix some stupid errors with vaporized oil

obviously if the switching variable is interpreted as x_g^O, the gas
phase is present, because in this case it is the only phase. Also,
when the oil phase appears, the gas saturation is 1-Sw, not 1. (the
last issue only happened in the vaporized case because the switch
variable would never get the meaning of "oil component's mole fraction
in the gas phase".)

applications/ebos/eclequilinitializer.hh

@@ -116,6 +116,9 @@ public:
         for (int elemIdx = 0; elemIdx < numElems; ++elemIdx) {
             auto &fluidState = initialFluidStates_[elemIdx];
 
+            // get the PVT region index of the current element
+            int regionIdx = simulator_.problem().pvtRegionIndex(elemIdx);
+
             // set the phase saturations
             for (int phaseIdx = 0; phaseIdx < numPhases; ++phaseIdx) {
                 Scalar S = opmBlackoilState.saturation()[elemIdx*numPhases + phaseIdx];
@@ -138,6 +141,7 @@ public:
             Scalar po = opmBlackoilState.pressure()[elemIdx];
             for (int phaseIdx = 0; phaseIdx < numPhases; ++phaseIdx)
                 fluidState.setPressure(phaseIdx, po + (pC[phaseIdx] - pC[oilPhaseIdx]));
+            Scalar pg = fluidState.pressure(gasPhaseIdx);
 
             // reset the phase compositions
             for (int phaseIdx = 0; phaseIdx < numPhases; ++phaseIdx)
@@ -158,6 +162,10 @@ public:
                 // mass fraction to mole fraction
                 Scalar xoG = XoG*MO / (MG*(1 - XoG) + XoG*MO);
 
+                Scalar xoGMax = FluidSystem::saturatedOilGasMoleFraction(T, pg, regionIdx);
+                if (fluidState.saturation(gasPhaseIdx) > 0.0 || xoG > xoGMax)
+                    xoG = xoGMax;
+
                 fluidState.setMoleFraction(oilPhaseIdx, oilCompIdx, 1 - xoG);
                 fluidState.setMoleFraction(oilPhaseIdx, gasCompIdx, xoG);
             }
@@ -171,6 +179,10 @@ public:
                 // mass fraction to mole fraction
                 Scalar xgO = XgO*MG / (MO*(1 - XgO) + XgO*MG);
 
+                Scalar xgOMax = FluidSystem::saturatedGasOilMoleFraction(T, pg, regionIdx);
+                if (fluidState.saturation(oilPhaseIdx) > 0.0 || xgO > xgOMax)
+                    xgO = xgOMax;
+
                 fluidState.setMoleFraction(gasPhaseIdx, oilCompIdx, xgO);
                 fluidState.setMoleFraction(gasPhaseIdx, gasCompIdx, 1 - xgO);
             }

applications/ebos/eclproblem.hh

@@ -567,6 +567,12 @@ public:
      */
     template <class Context>
     int pvtRegionIndex(const Context &context, int spaceIdx, int timeIdx) const
+    { return pvtRegionIndex(context.globalSpaceIndex(spaceIdx, timeIdx)); }
+
+    /*!
+     * \brief Returns the index the relevant PVT region given a cell index
+     */
+    int pvtRegionIndex(int elemIdx) const
     {
         Opm::DeckConstPtr deck = this->simulator().gridManager().deck();
 
@@ -575,10 +581,7 @@ public:
 
         const auto& gridManager = this->simulator().gridManager();
 
-        // this is quite specific to the ECFV discretization. But so is everything in an
+        int cartesianDofIdx = gridManager.cartesianCellId(elemIdx);
-        // ECL deck, i.e., we don't need to care here...
-        int compressedDofIdx = context.globalSpaceIndex(spaceIdx, timeIdx);
-        int cartesianDofIdx = gridManager.cartesianCellId(compressedDofIdx);
 
         return deck->getKeyword("PVTNUM")->getIntData()[cartesianDofIdx] - 1;
     }