Merge pull request #906 from totto82/livegas

Complete undersaturated PVTG tables by extrapolating from existing data

opm/core/props/pvt/PvtLiveGas.cpp

@@ -11,6 +11,7 @@
 //===========================================================================
 /*
   Copyright 2010 SINTEF ICT, Applied Mathematics.
+  Copyright 2015 IRIS AS
 
   This file is part of the Open Porous Media project (OPM).
 
@@ -92,6 +93,51 @@ namespace Opm
                     undersat_gas_tables_[pvtTableIdx][i][1][j] = 1.0 / undersat_gas_tables_[pvtTableIdx][i][1][j];
                 }
             }
+
+             // Complete undersaturated tables by extrapolating from existing data
+            int iNext = -1;
+            for (int i = 0; i < sz; ++i) {
+                // Skip records already containing undersaturated data
+                if (undersat_gas_tables_[pvtTableIdx][i][0].size() > 1) {
+                    continue;
+                }
+                // Look ahead for next record containing undersaturated data
+                if (iNext < i) {
+                    iNext = i+1;
+                    while (iNext < sz && undersat_gas_tables_[pvtTableIdx][iNext][0].size() < 2) {
+                        ++iNext;
+                    }
+                    if (iNext == sz) {
+                        OPM_THROW(std::runtime_error,"Unable to complete undersaturated table.");
+                    }
+                }
+                // Undersaturated data is added to the current record in the same way as for liveoil.
+                // It is unclear whether this expantion maintains the compressibility and viscosibility,
+                // but it seems like it reproduces eclipse results for spe3.
+                typedef std::vector<std::vector<std::vector<double> > >::size_type sz_t;
+                auto& from_table = undersat_gas_tables_[pvtTableIdx][iNext];
+                auto& to_table = undersat_gas_tables_[pvtTableIdx][i];
+                enum {RV = 0, BG = 1, MUG = 2, BGMUG = 3};
+
+                for (sz_t j = 1; j < from_table[0].size(); ++j) {
+                    double diffSolubility = from_table[RV][j] - from_table[RV][j-1];
+                    double solubility = to_table[RV].back() + diffSolubility;
+                    to_table[RV].push_back(solubility);
+                    double compr = (1.0/from_table[BG][j] - 1.0/from_table[BG][j-1])
+                        / (0.5*(1.0/from_table[BG][j] + 1.0/from_table[BG][j-1]));
+                    double B_var = (1.0/to_table[BG].back()) * (1.0+0.5*compr) / (1.0-0.5*compr);
+                    to_table[BG].push_back(1.0/B_var);
+                    double visc = (from_table[MUG][j] - from_table[MUG][j-1])
+                        / (0.5*(from_table[MUG][j] + from_table[MUG][j-1]));
+                    double mu_var = (to_table[MUG].back()) * (1.0+0.5*visc) / (1.0-0.5*visc);
+                    to_table[MUG].push_back(mu_var);
+
+                    // A try to expolate the 1/BMu with the expolated mu and B
+                    double inverseBMu = 1.0 / (B_var*mu_var);
+                    to_table[BGMUG].push_back(inverseBMu);
+                }
+            }
+
         }
     }