Saturation Functions: Add Public Query for Phase Saturations

Simplifies retrieving the phase saturation values in the context of
computing phase fluxes at cell interfaces.

ThirdParty/custom-opm-flowdiag-app/opm-flowdiagnostics-applications/opm/utility/ECLSaturationFunc.cpp

@@ -2578,3 +2578,31 @@ getSatFuncCurve(const std::vector<RawCurve>& func,
 {
     return this->pImpl_->getSatFuncCurve(func, activeCell, scaling);
 }
+
+// =====================================================================
+
+std::vector<double>
+Opm::phaseSaturation(const ECLGraph&       G,
+                     const ECLRestartData& rstrt,
+                     const ECLPhaseIndex   phase)
+{
+    switch (phase) {
+    case ECLPhaseIndex::Aqua:
+        return water_saturation(G, rstrt);
+
+    case ECLPhaseIndex::Liquid: {
+        const auto sg = gas_saturation(G, rstrt);
+        const auto sw = water_saturation(G, rstrt);
+
+        return oil_saturation(sg, sw, G, rstrt);
+    }
+
+    case ECLPhaseIndex::Vapour:
+        return gas_saturation(G, rstrt);
+    }
+
+    throw std::invalid_argument {
+        "Unsupported Phase Index " +
+        std::to_string(static_cast<std::size_t>(phase))
+    };
+}

ThirdParty/custom-opm-flowdiag-app/opm-flowdiagnostics-applications/opm/utility/ECLSaturationFunc.hpp

@@ -41,6 +41,34 @@ namespace Opm {
     class ECLRestartData;
     class ECLInitFileData;
 
+    /// Extract phase saturation of single phase for all active cells in all
+    /// grids.
+    ///
+    /// Handles the case of oil saturation being explicitly stored in a
+    /// result set or implicitly defined from the gas and/or water
+    /// saturations.
+    ///
+    /// \param[in] G Connected topology of current model's active cells.
+    ///    Needed to linearise phase saturations (e.g., SOIL) that are
+    ///    distributed on local grids to all of the model's active cells
+    ///    (\code member function G.rawLinearisedCellData() \endcode).
+    ///
+    /// \param[in] rstrt ECLIPSE restart vectors.  Result set view
+    ///    assumed to be positioned at a particular report step of
+    ///    interest.
+    ///
+    /// \param[in] phase Phase for which to extract the phase saturation
+    ///    values.
+    ///
+    /// \return Phase saturation values of active phase \p phase for all
+    ///    active cells in model \p G.  Empty if phase \p phase is not
+    ///    actually active in the current result set or if the saturation
+    ///    values are not stored on the current report/restart step.
+    std::vector<double>
+    phaseSaturation(const ECLGraph&       G,
+                    const ECLRestartData& rstrt,
+                    const ECLPhaseIndex   phase);
+
     /// Gateway to engine for computing relative permeability values based
     /// on tabulated saturation functions in ECL output.
     class ECLSaturationFunc