diff --git a/opm/core/simulator/BlackoilState.cpp b/opm/core/simulator/BlackoilState.cpp
index 1dd0c1edc..b210af6e5 100644
--- a/opm/core/simulator/BlackoilState.cpp
+++ b/opm/core/simulator/BlackoilState.cpp
@@ -4,11 +4,16 @@
 using namespace Opm;
 
 void
-BlackoilState::init(int number_of_cells, int number_of_phases, int num_phases) {
-    SimulatorState::init(number_of_cells, number_of_phases, num_phases);
-   gor_.resize(number_of_cells, 0.) ;
-   rv_.resize(number_of_cells,0.);
+BlackoilState::init(int number_of_cells, int number_of_phases, int num_phases)
+{
+   SimulatorState::init(number_of_cells, number_of_phases, num_phases);
+
+   // register cell data in base class
+   gorId_ = SimulatorState::registerCellData( "GASOILRATIO", 1 );
+   rvId_  = SimulatorState::registerCellData( "RV", 1 );
+
    // surfvol_ intentionally empty, left to initBlackoilSurfvol
+   surfaceVolId_ = SimulatorState::registerCellData( "SURFACEVOL", 0 );
 }
 
 void
diff --git a/opm/core/simulator/BlackoilState.hpp b/opm/core/simulator/BlackoilState.hpp
index ea9c968a4..c5c6bdab6 100644
--- a/opm/core/simulator/BlackoilState.hpp
+++ b/opm/core/simulator/BlackoilState.hpp
@@ -32,8 +32,10 @@ namespace Opm
     class BlackoilState : public SimulatorState
     {
     public:
+        using SimulatorState :: cellData ;
+
         virtual void init(const UnstructuredGrid& grid, int num_phases);
-        
+
         virtual void init(int number_of_cells, int number_of_faces, int num_phases);
 
         /// Set the first saturation to either its min or max value in
@@ -47,18 +49,22 @@ namespace Opm
         virtual bool equals(const SimulatorState& other,
                             double epsilon = 1e-8) const;
 
-        std::vector<double>& surfacevol  () { return surfvol_; }
-        std::vector<double>& gasoilratio () { return gor_   ; }
-        std::vector<double>& rv () {return rv_ ; }
+        std::vector<double>& surfacevol  () { return cellData()[ surfaceVolId_ ]; }
+        std::vector<double>& gasoilratio () { return cellData()[ gorId_ ] ; }
+        std::vector<double>& rv () {return cellData()[ rvId_ ] ; }
 
-        const std::vector<double>& surfacevol  () const { return surfvol_; }
-        const std::vector<double>& gasoilratio () const { return gor_   ; }
-        const std::vector<double>& rv () const {return rv_ ; }
+        const std::vector<double>& surfacevol  () const { return cellData()[ surfaceVolId_ ]; }
+        const std::vector<double>& gasoilratio () const { return cellData()[ gorId_ ] ; }
+        const std::vector<double>& rv () const { return cellData()[ rvId_ ] ; }
 
     private:
-        std::vector<double> surfvol_; // no entries = no cells * no phases
-        std::vector<double> gor_   ;  // no entries = no cells
-        std::vector<double> rv_ ;     // no entries = no cells
+        int gorId_ ;   // no entries = no cells (gas oil ratio id)
+        int rvId_ ;    // no entries = no cells ( rv id )
+        int surfaceVolId_ ; // no entries = no cells * no phases (surfaceVol id )
+
+        //std::vector<double> surfvol_; // no entries = no cells * no phases
+        //std::vector<double> gor_   ;  // no entries = no cells
+        //std::vector<double> rv_ ;     // no entries = no cells
     };
 } // namespace Opm