diff --git a/ebos/ecloutputblackoilmodule.hh b/ebos/ecloutputblackoilmodule.hh
index 91dcb28ad..331389c03 100644
--- a/ebos/ecloutputblackoilmodule.hh
+++ b/ebos/ecloutputblackoilmodule.hh
@@ -27,6 +27,11 @@
 #ifndef EWOMS_ECL_OUTPUT_BLACK_OIL_MODULE_HH
 #define EWOMS_ECL_OUTPUT_BLACK_OIL_MODULE_HH
 
+#include <array>
+#include <numeric>
+#include <optional>
+#include <stdexcept>
+
 #include <opm/models/blackoil/blackoilproperties.hh>
 
 #include <opm/models/utils/propertysystem.hh>
@@ -65,6 +70,8 @@ struct ForceDisableFluidInPlaceOutput<TypeTag, TTag::EclOutputBlackOil> {
 
 namespace Opm {
 
+
+
 // forward declaration
 template <class TypeTag>
 class EcfvDiscretization;
@@ -114,7 +121,22 @@ class EclOutputBlackOilModule
             GasInPlaceInGasPhase = 6,  //GIPG
             PoreVolume = 7, //PV
         };
-        static const int numFipValues = PoreVolume + 1 ;
+        static const int numFipTypes = PoreVolume + 1 ;
+
+
+        static std::string EclString(int fip_type) {
+            switch(static_cast<FipId>(fip_type)) {
+            case FipDataType::WaterInPlace: return "WIP";
+            case FipDataType::OilInPlace: return "OIP";
+            case FipDataType::GasInPlace: return "GIP";
+            case FipDataType::OilInPlaceInLiquidPhase: return "OIPL";
+            case FipDataType::OilInPlaceInGasPhase: return "OIPG";
+            case FipDataType::GasInPlaceInLiquidPhase: return "GIPL";
+            case FipDataType::GasInPlaceInGasPhase: return "GIPG";
+            case FipDataType::PoreVolume: return "PV";
+            }
+            throw std::logic_error("fip_type:  " + std::to_string(fip_type) + " not recognized");
+        }
     };
     struct WellProdDataType
     {
@@ -181,17 +203,42 @@ class EclOutputBlackOilModule
         static const int numWCNames = 3;
     };
 
+    struct RegionSum {
+        std::size_t ntFip;
+        std::array<ScalarBuffer, FipDataType::numFipTypes> regFipValues;
+        ScalarBuffer regPressurePv;
+        ScalarBuffer regPvHydrocarbon;
+        ScalarBuffer regPressurePvHydrocarbon;
+
+        std::array<Scalar, FipDataType::numFipTypes> fieldFipValues;
+        Scalar fieldPressurePv;
+        Scalar fieldPvHydrocarbon;
+        Scalar fieldPressurePvHydrocarbon;
+    };
+
 public:
     template<class CollectDataToIORankType>
     EclOutputBlackOilModule(const Simulator& simulator, const CollectDataToIORankType& collectToIORank)
         : simulator_(simulator)
     {
-        createLocalFipnum_();
-
-        // Summary output is for all steps
         const Opm::SummaryConfig summaryConfig = simulator_.vanguard().summaryConfig();
+        const auto& fp = simulator_.vanguard().eclState().fieldProps();
+
+        this->regions_["FIPNUM"] = fp.get_int("FIPNUM");
+        for (const auto& region : summaryConfig.fip_regions())
+            this->regions_[region] = fp.get_int(region);
+
+        for (auto& region_pair : this->regions_)
+            createLocalRegion_(region_pair.second);
+
+        this->RPRNodes_  = summaryConfig.keywords("RPR*");
+        this->RPRPNodes_ = summaryConfig.keywords("RPRP*");
+
+        for (int fip_type = 0; fip_type < FipDataType::numFipTypes; fip_type++) {
+            std::string key_pattern = "R" + FipDataType::EclString(fip_type) + "*";
+            this->regionNodes_[fip_type] = summaryConfig.keywords(key_pattern);
+        }
 
-        // Initialize block output
         for (const auto& node: summaryConfig) {
             if (node.category() == SummaryConfigNode::Category::Block) {
                 if (collectToIORank.isCartIdxOnThisRank(node.number() - 1)) {
@@ -244,8 +291,8 @@ public:
         computeFip_ = false;
 
         // Fluid in place
-        for (int i = 0; i<FipDataType::numFipValues; i++) {
-            if (!substep || summaryConfig.require3DField(fipEnumToString_(i))) {
+        for (int i = 0; i<FipDataType::numFipTypes; i++) {
+            if (!substep || summaryConfig.require3DField(FipDataType::EclString(i))) {
                 if (rstKeywords["FIP"] > 0) {
                     rstKeywords["FIP"] = 0;
                     outputFipRestart_ = true;
@@ -256,7 +303,7 @@ public:
             else
                 fip_[i].clear();
         }
-        if (!substep || summaryConfig.hasKeyword("FPR") || summaryConfig.hasKeyword("FPRP") || summaryConfig.hasKeyword("RPR")) {
+        if (!substep || summaryConfig.hasKeyword("FPR") || summaryConfig.hasKeyword("FPRP") || !this->RPRNodes_.empty()) {
             fip_[FipDataType::PoreVolume].resize(bufferSize, 0.0);
             hydrocarbonPoreVolume_.resize(bufferSize, 0.0);
             pressureTimesPoreVolume_.resize(bufferSize, 0.0);
@@ -1025,9 +1072,9 @@ public:
 
 
         // Fluid in place
-        for (int i = 0; i<FipDataType::numFipValues; i++) {
+        for (int i = 0; i<FipDataType::numFipTypes; i++) {
             if (outputFipRestart_ && fip_[i].size() > 0) {
-                sol.insert(fipEnumToString_(i),
+                sol.insert(FipDataType::EclString(i),
                            Opm::UnitSystem::measure::volume,
                            fip_[i],
                            Opm::data::TargetType::SUMMARY);
@@ -1044,106 +1091,204 @@ public:
         }
     }
 
+    int regionMax(const std::vector<int>& region) {
+        const auto max_value = region.empty() ? 0 : *std::max_element(region.begin(), region.end());
+        return this->simulator_.gridView().comm().max(max_value);
+    }
+
+
+    RegionSum makeRegionSum(const std::vector<int>& region, bool is_fipnum) {
+        RegionSum rsum;
+        rsum.ntFip = this->regionMax(region);
+
+        // sum values over each region
+        rsum.regPressurePv = this->regionSum(this->pressureTimesPoreVolume_, region, rsum.ntFip);
+        rsum.regPvHydrocarbon = this->regionSum(this->hydrocarbonPoreVolume_, region, rsum.ntFip);
+        rsum.regPressurePvHydrocarbon = this->regionSum(pressureTimesHydrocarbonVolume_, region, rsum.ntFip);
+        for (int fip_type = 0; fip_type < FipDataType::numFipTypes; fip_type++)
+            rsum.regFipValues[fip_type] = this->regionSum(this->fip_[fip_type], region, rsum.ntFip);
+
+
+
+        // sum all region values to compute the field total
+        rsum.fieldPressurePv = sum(rsum.regPressurePv);
+        rsum.fieldPvHydrocarbon = sum(rsum.regPvHydrocarbon);
+        rsum.fieldPressurePvHydrocarbon = sum(rsum.regPressurePvHydrocarbon);
+        for (int fip_type = 0; fip_type < FipDataType::numFipTypes; fip_type++) {
+            const auto& regionFip = rsum.regFipValues[fip_type];
+            rsum.fieldFipValues[fip_type] = sum(regionFip);
+        }
+
+        if (is_fipnum) {
+            // The first time the outputFipLog function is run we store the inplace values in
+            // the initialInplace_ member. This has at least two problems:
+            //
+            //   o We really want the *initial* value - now we get the value after
+            //     the first timestep.
+            //
+            //   o For restarted runs this is obviously wrong.
+            //
+            // Finally it is of course not desirable to mutate state in an output
+            // routine.
+            if (!this->regionInitialInplace_) {
+                this->regionInitialInplace_.emplace();
+                for (int fip_type = 0; fip_type < FipDataType::numFipTypes; fip_type++)
+                    this->regionInitialInplace_.value()[fip_type] = rsum.regFipValues[fip_type];
+            }
+
+            if (!this->fieldInitialInplace_)
+                this->fieldInitialInplace_ = rsum.fieldFipValues;
+        }
+        return rsum;
+    }
+
+
+    std::unordered_map<std::string, RegionSum> accumulateRegionSums() {
+        std::unordered_map<std::string, RegionSum> rsum_map;
+        const Opm::SummaryConfig summaryConfig = simulator_.vanguard().summaryConfig();
+
+        rsum_map.emplace("FIPNUM", makeRegionSum(this->regions_.at("FIPNUM"), true));
+        for (const auto& fip_region : summaryConfig.fip_regions()) {
+            if (fip_region == "FIPNUM")
+                continue;
+
+            const auto& region = this->regions_.at(fip_region);
+            rsum_map.emplace(fip_region, makeRegionSum(region, false));
+        }
+        return rsum_map;
+    }
+
+    Scalar sum(const ScalarBuffer& v) {
+        return std::accumulate(v.begin(), v.end(), Scalar{0});
+    }
+
+    void updateSummaryRegionValues(const std::unordered_map<std::string, RegionSum>& rsum_map,
+                                   std::map<std::string, double>& miscSummaryData,
+                                   std::map<std::string, std::vector<double>>& regionData) const {
+
+        const Opm::SummaryConfig summaryConfig = simulator_.vanguard().summaryConfig();
+
+        // The field summary vectors should only use the FIPNUM based region sum.
+        {
+            const auto& rsum = rsum_map.at("FIPNUM");
+            for (int fip_type = 0; fip_type < FipDataType::numFipTypes; fip_type++) {
+                std::string key = "F" + FipDataType::EclString(fip_type);
+                if (summaryConfig.hasKeyword(key))
+                    miscSummaryData[key] = rsum.fieldFipValues[fip_type];
+            }
+            if (summaryConfig.hasKeyword("FOE") && this->fieldInitialInplace_)
+                miscSummaryData["FOE"] = rsum.fieldFipValues[FipDataType::OilInPlace]
+                    / this->fieldInitialInplace_.value()[FipDataType::OilInPlace];
+
+            if (summaryConfig.hasKeyword("FPR"))
+                miscSummaryData["FPR"] = pressureAverage_(rsum.fieldPressurePvHydrocarbon,
+                                                          rsum.fieldPvHydrocarbon,
+                                                          rsum.fieldPressurePv,
+                                                          rsum.fieldFipValues[FipDataType::PoreVolume],
+                                                          true);
+
+            if (summaryConfig.hasKeyword("FPRP"))
+                miscSummaryData["FPRP"] = pressureAverage_(rsum.fieldPressurePvHydrocarbon,
+                                                           rsum.fieldPvHydrocarbon,
+                                                           rsum.fieldPressurePv,
+                                                           rsum.fieldFipValues[FipDataType::PoreVolume],
+                                                           false);
+
+        }
+
+        // The region summary vectors should loop through the FIPxxx regions to
+        // support the RPR__xxx summary keywords.
+        {
+            for (int fip_type = 0; fip_type < FipDataType::numFipTypes; fip_type++) {
+                for (const auto& node : this->regionNodes_[fip_type]) {
+                    const auto& rsum = rsum_map.at(node.fip_region());
+                    regionData[node.keyword()] = rsum.regFipValues[fip_type];
+                }
+            }
+
+            // The exact same quantity is calculated for RPR and RPRP - is that correct?
+            for (const auto& node : this->RPRNodes_) {
+                const auto& rsum = rsum_map.at(node.fip_region());
+                regionData[node.keyword()] = pressureAverage_(rsum.regPressurePvHydrocarbon,
+                                                              rsum.regPvHydrocarbon,
+                                                              rsum.regPressurePv,
+                                                              rsum.regFipValues[FipDataType::PoreVolume],
+                                                              true);
+            }
+
+            for (const auto& node : this->RPRPNodes_) {
+                const auto& rsum = rsum_map.at(node.fip_region());
+                regionData[node.keyword()] = pressureAverage_(rsum.regPressurePvHydrocarbon,
+                                                              rsum.regPvHydrocarbon,
+                                                              rsum.regPressurePv,
+                                                              rsum.regFipValues[FipDataType::PoreVolume],
+                                                              false);
+            }
+        }
+    }
+
+
+    void outputFipLogImpl(const RegionSum& rsum) const {
+
+
+        {
+            Scalar fieldHydroCarbonPoreVolumeAveragedPressure = pressureAverage_(rsum.fieldPressurePvHydrocarbon,
+                                                                                 rsum.fieldPvHydrocarbon,
+                                                                                 rsum.fieldPressurePv,
+                                                                                 rsum.fieldFipValues[FipDataType::PoreVolume],
+                                                                                 true);
+            std::array<Scalar, FipDataType::numFipTypes> initial_values = *this->fieldInitialInplace_;
+            std::array<Scalar, FipDataType::numFipTypes> current_values = rsum.fieldFipValues;
+            fipUnitConvert_(initial_values);
+            fipUnitConvert_(current_values);
+
+            pressureUnitConvert_(fieldHydroCarbonPoreVolumeAveragedPressure);
+            outputRegionFluidInPlace_(initial_values,
+                                      current_values,
+                                      fieldHydroCarbonPoreVolumeAveragedPressure);
+        }
+
+        for (size_t reg = 0; reg < rsum.ntFip; ++reg) {
+            std::array<Scalar, FipDataType::numFipTypes> initial_values;
+            std::array<Scalar, FipDataType::numFipTypes> current_values;
+
+            for (std::size_t fip_type = 0; fip_type < FipDataType::numFipTypes; fip_type++) {
+                initial_values[fip_type] = this->regionInitialInplace_.value()[fip_type][reg];
+                current_values[fip_type] = rsum.regFipValues[fip_type][reg];
+            }
+            fipUnitConvert_(initial_values);
+            fipUnitConvert_(current_values);
+
+            Scalar regHydroCarbonPoreVolumeAveragedPressure
+                = pressureAverage_(rsum.regPressurePvHydrocarbon[reg],
+                                   rsum.regPvHydrocarbon[reg],
+                                   rsum.regPressurePv[reg],
+                                   rsum.regFipValues[FipDataType::PoreVolume][reg],
+                                   true);
+            pressureUnitConvert_(regHydroCarbonPoreVolumeAveragedPressure);
+            outputRegionFluidInPlace_(initial_values, current_values, regHydroCarbonPoreVolumeAveragedPressure, reg + 1);
+        }
+    }
+
+
+
+
     // write Fluid In Place to output log
     void outputFipLog(std::map<std::string, double>& miscSummaryData,  std::map<std::string, std::vector<double>>& regionData, const bool substep)
     {
-        const auto& comm = simulator_.gridView().comm();
-        auto maxElement = std::max_element(fipnum_.begin(), fipnum_.end());
-        size_t ntFip = 0;
-        if ( maxElement != fipnum_.end() ) {
-            ntFip = *maxElement;
-        }
-        ntFip = comm.max(ntFip);
+        auto rsum_map = this->accumulateRegionSums();
+        if (!isIORank_())
+            return;
 
-        // sum values over each region
-        ScalarBuffer regionFipValues[FipDataType::numFipValues];
-        for (int i = 0; i < FipDataType::numFipValues; i++) {
-            regionFipValues[i] = computeFipForRegions_(fip_[i], fipnum_, ntFip);
-            if (isIORank_() && origRegionValues_[i].empty())
-                origRegionValues_[i] = regionFipValues[i];
-        }
-
-        // sum all region values to compute the field total
-        std::vector<int> fieldNum(ntFip, 1);
-        ScalarBuffer fieldFipValues(FipDataType::numFipValues, 0.0);
-        bool comunicateSum = false; // the regionValues are already summed over all ranks.
-        for (int i = 0; i<FipDataType::numFipValues; i++) {
-            const ScalarBuffer& tmp = computeFipForRegions_(regionFipValues[i], fieldNum, 1, comunicateSum);
-            fieldFipValues[i] = tmp[0];
-        }
-
-        // compute the hydrocarbon averaged pressure over the regions.
-        ScalarBuffer regPressurePv = computeFipForRegions_(pressureTimesPoreVolume_, fipnum_, ntFip);
-        ScalarBuffer regPvHydrocarbon = computeFipForRegions_(hydrocarbonPoreVolume_, fipnum_, ntFip);
-        ScalarBuffer regPressurePvHydrocarbon = computeFipForRegions_(pressureTimesHydrocarbonVolume_, fipnum_, ntFip);
-
-        ScalarBuffer fieldPressurePv = computeFipForRegions_(regPressurePv, fieldNum, 1, comunicateSum);
-        ScalarBuffer fieldPvHydrocarbon = computeFipForRegions_(regPvHydrocarbon, fieldNum, 1, comunicateSum);
-        ScalarBuffer fieldPressurePvHydrocarbon = computeFipForRegions_(regPressurePvHydrocarbon, fieldNum, 1, comunicateSum);
-
-        // output on io rank
-        // the original Fip values are stored on the first step
-        // TODO: Store initial Fip in the init file and restore them
-        // and use them here.
-        const Opm::SummaryConfig summaryConfig = simulator_.vanguard().summaryConfig();
-        if (isIORank_()) {
-            // Field summary output
-            for (int i = 0; i<FipDataType::numFipValues; i++) {
-                std::string key = "F" + fipEnumToString_(i);
-                if (summaryConfig.hasKeyword(key))
-                    miscSummaryData[key] = fieldFipValues[i];
-            }
-            if (summaryConfig.hasKeyword("FOE") && !origTotalValues_.empty())
-                miscSummaryData["FOE"] = fieldFipValues[FipDataType::OilInPlace] / origTotalValues_[FipDataType::OilInPlace];
-
-            if (summaryConfig.hasKeyword("FPR"))
-                miscSummaryData["FPR"] = pressureAverage_(fieldPressurePvHydrocarbon[0], fieldPvHydrocarbon[0], fieldPressurePv[0], fieldFipValues[FipDataType::PoreVolume], true);
-
-            if (summaryConfig.hasKeyword("FPRP"))
-                miscSummaryData["FPRP"] = pressureAverage_(fieldPressurePvHydrocarbon[0], fieldPvHydrocarbon[0], fieldPressurePv[0], fieldFipValues[FipDataType::PoreVolume], false);
-
-            // Region summary output
-            for (int i = 0; i<FipDataType::numFipValues; i++) {
-                std::string key = "R" + fipEnumToString_(i);
-                if (summaryConfig.hasKeyword(key))
-                    regionData[key] = regionFipValues[i];
-            }
-            if (summaryConfig.hasKeyword("RPR"))
-                regionData["RPR"] = pressureAverage_(regPressurePvHydrocarbon, regPvHydrocarbon, regPressurePv, regionFipValues[FipDataType::PoreVolume], true);
-
-            if (summaryConfig.hasKeyword("RPRP"))
-                regionData["RPRP"] = pressureAverage_(regPressurePvHydrocarbon, regPvHydrocarbon, regPressurePv, regionFipValues[FipDataType::PoreVolume], false);
-
-            // Output to log
-            if (!substep) {
-
-                fipUnitConvert_(fieldFipValues);
-                if (origTotalValues_.empty())
-                    origTotalValues_ = fieldFipValues;
-
-                Scalar fieldHydroCarbonPoreVolumeAveragedPressure = pressureAverage_(fieldPressurePvHydrocarbon[0], fieldPvHydrocarbon[0], fieldPressurePv[0], fieldFipValues[FipDataType::PoreVolume], true);
-                pressureUnitConvert_(fieldHydroCarbonPoreVolumeAveragedPressure);
-                outputRegionFluidInPlace_(origTotalValues_, fieldFipValues, fieldHydroCarbonPoreVolumeAveragedPressure, 0);
-                for (size_t reg = 0; reg < ntFip; ++reg) {
-                    ScalarBuffer tmpO(FipDataType::numFipValues, 0.0);
-                    for (int i = 0; i<FipDataType::numFipValues; i++) {
-                        tmpO[i] = origRegionValues_[i][reg];
-                    }
-                    fipUnitConvert_(tmpO);
-                    ScalarBuffer tmp(FipDataType::numFipValues, 0.0);
-                    for (int i = 0; i<FipDataType::numFipValues; i++) {
-                        tmp[i] = regionFipValues[i][reg];
-                    }
-                    fipUnitConvert_(tmp);
-                    Scalar regHydroCarbonPoreVolumeAveragedPressure = pressureAverage_(regPressurePvHydrocarbon[reg], regPvHydrocarbon[reg], regPressurePv[reg], regionFipValues[FipDataType::PoreVolume][reg], true);
-                    pressureUnitConvert_(regHydroCarbonPoreVolumeAveragedPressure);
-                    outputRegionFluidInPlace_(tmpO, tmp, regHydroCarbonPoreVolumeAveragedPressure, reg + 1);
-                }
-            }
-        }
+        updateSummaryRegionValues(rsum_map,
+                                  miscSummaryData,
+                                  regionData);
 
+        if (!substep)
+            outputFipLogImpl(rsum_map.at("FIPNUM"));
     }
 
+
     // write production report to output
     void outputProdLog(size_t reportStepNum, const bool substep, bool forceDisableProdOutput)
     {
@@ -1772,14 +1917,8 @@ private:
 
     }
 
-    void createLocalFipnum_()
+    void createLocalRegion_(std::vector<int>& region)
     {
-        const auto& gridView = simulator_.vanguard().gridView();
-        if (simulator_.vanguard().eclState().fieldProps().has_int("FIPNUM"))
-            fipnum_ = simulator_.vanguard().eclState().fieldProps().get_int("FIPNUM");
-        else
-            fipnum_.resize(gridView.size(/*codim=*/0), 1);
-
         ElementContext elemCtx(simulator_);
         ElementIterator elemIt = simulator_.gridView().template begin</*codim=*/0>();
         const ElementIterator& elemEndIt = simulator_.gridView().template end</*codim=*/0>();
@@ -1787,19 +1926,19 @@ private:
         for (; elemIt != elemEndIt; ++elemIt, ++elemIdx) {
             const Element& elem = *elemIt;
             if (elem.partitionType() != Dune::InteriorEntity)
-                fipnum_[elemIdx] = 0;
+                region[elemIdx] = 0;
         }
     }
 
     // Sum Fip values over regions.
-    ScalarBuffer computeFipForRegions_(const ScalarBuffer& fip, std::vector<int>& regionId, size_t maxNumberOfRegions, bool commSum = true)
+    ScalarBuffer regionSum(const ScalarBuffer& property, const std::vector<int>& regionId, size_t maxNumberOfRegions) const
     {
         ScalarBuffer totals(maxNumberOfRegions, 0.0);
 
-        if (fip.empty())
+        if (property.empty())
             return totals;
 
-        assert(regionId.size() == fip.size());
+        assert(regionId.size() == property.size());
         for (size_t j = 0; j < regionId.size(); ++j) {
             const int regionIdx = regionId[j] - 1;
             // the cell is not attributed to any region. ignore it!
@@ -1807,18 +1946,17 @@ private:
                 continue;
 
             assert(regionIdx < static_cast<int>(maxNumberOfRegions));
-            totals[regionIdx] += fip[j];
-        }
-        if (commSum) {
-            const auto& comm = simulator_.gridView().comm();
-            for (size_t i = 0; i < maxNumberOfRegions; ++i)
-                totals[i] = comm.sum(totals[i]);
+            totals[regionIdx] += property[j];
         }
 
+        const auto& comm = simulator_.gridView().comm();
+        for (size_t i = 0; i < maxNumberOfRegions; ++i)
+            totals[i] = comm.sum(totals[i]);
+
         return totals;
     }
 
-    ScalarBuffer pressureAverage_(const ScalarBuffer& pressurePvHydrocarbon, const ScalarBuffer& pvHydrocarbon, const ScalarBuffer& pressurePv, const ScalarBuffer& pv, bool hydrocarbon)
+    ScalarBuffer pressureAverage_(const ScalarBuffer& pressurePvHydrocarbon, const ScalarBuffer& pvHydrocarbon, const ScalarBuffer& pressurePv, const ScalarBuffer& pv, bool hydrocarbon) const
     {
         size_t size = pressurePvHydrocarbon.size();
         assert(pvHydrocarbon.size() == size);
@@ -1832,7 +1970,7 @@ private:
         return fraction;
     }
 
-    Scalar pressureAverage_(const Scalar& pressurePvHydrocarbon, const Scalar& pvHydrocarbon, const Scalar& pressurePv, const Scalar& pv, bool hydrocarbon)
+    Scalar pressureAverage_(const Scalar& pressurePvHydrocarbon, const Scalar& pvHydrocarbon, const Scalar& pressurePv, const Scalar& pv, bool hydrocarbon) const
     {
         if (pvHydrocarbon > 1e-10 && hydrocarbon)
             return pressurePvHydrocarbon / pvHydrocarbon;
@@ -1840,7 +1978,7 @@ private:
         return pressurePv / pv;
     }
 
-    void fipUnitConvert_(ScalarBuffer& fip)
+    void fipUnitConvert_(std::array<Scalar, FipDataType::numFipTypes>& fip) const
     {
         const Opm::UnitSystem& units = simulator_.vanguard().eclState().getUnits();
         if (units.getType() == Opm::UnitSystem::UnitType::UNIT_TYPE_FIELD) {
@@ -1872,7 +2010,7 @@ private:
         }
     }
 
-    void pressureUnitConvert_(Scalar& pav)
+    void pressureUnitConvert_(Scalar& pav) const
     {
         const Opm::UnitSystem& units = simulator_.vanguard().eclState().getUnits();
         if (units.getType() == Opm::UnitSystem::UnitType::UNIT_TYPE_FIELD) {
@@ -1890,7 +2028,9 @@ private:
         }
     }
 
-    void outputRegionFluidInPlace_(const ScalarBuffer& oip, const ScalarBuffer& cip, const Scalar& pav, const int reg)
+    void outputRegionFluidInPlace_(const std::array<Scalar, FipDataType::numFipTypes>& oip,
+                                   const std::array<Scalar, FipDataType::numFipTypes>& cip,
+                                   const Scalar& pav, const int reg = 0) const
     {
         if (forceDisableFipOutput_)
             return;
@@ -1901,7 +2041,7 @@ private:
 
         const Opm::UnitSystem& units = simulator_.vanguard().eclState().getUnits();
         std::ostringstream ss;
-        if (!reg) {
+        if (reg == 0) {
             ss << "                                                  ===================================================\n"
                << "                                                  :                   Field Totals                  :\n";
         }
@@ -2043,22 +2183,6 @@ private:
         Opm::OpmLog::note(ss.str());
     }
 
-    std::string fipEnumToString_(int i)
-    {
-        typedef typename FipDataType::FipId FipId;
-        switch(static_cast<FipId>(i))
-        {
-        case FipDataType::WaterInPlace: return "WIP";
-        case FipDataType::OilInPlace: return "OIP";
-        case FipDataType::GasInPlace: return "GIP";
-        case FipDataType::OilInPlaceInLiquidPhase: return "OIPL";
-        case FipDataType::OilInPlaceInGasPhase: return "OIPG";
-        case FipDataType::GasInPlaceInLiquidPhase: return "GIPL";
-        case FipDataType::GasInPlaceInGasPhase: return "GIPG";
-        case FipDataType::PoreVolume: return "PV";
-        }
-        return "ERROR";
-    }
     std::string WPEnumToString_(int i)
     {
         typedef typename WellProdDataType::WPId WPId;
@@ -2171,10 +2295,17 @@ private:
 
     std::vector<int> failedCellsPb_;
     std::vector<int> failedCellsPd_;
-    std::vector<int> fipnum_;
-    ScalarBuffer fip_[FipDataType::numFipValues];
-    ScalarBuffer origTotalValues_;
-    ScalarBuffer origRegionValues_[FipDataType::numFipValues];
+    std::unordered_map<std::string, std::vector<int>> regions_;
+    std::array<ScalarBuffer, FipDataType::numFipTypes> fip_;
+    std::optional<std::array<ScalarBuffer, FipDataType::numFipTypes>> regionInitialInplace_;
+    std::optional<std::array<Scalar, FipDataType::numFipTypes>> fieldInitialInplace_;
+
+    std::vector<Opm::SummaryConfigNode> RPRNodes_;
+    std::vector<Opm::SummaryConfigNode> RPRPNodes_;
+    std::array<std::vector<Opm::SummaryConfigNode>, FipDataType::numFipTypes> regionNodes_;
+
+
+
     ScalarBuffer hydrocarbonPoreVolume_;
     ScalarBuffer pressureTimesPoreVolume_;
     ScalarBuffer pressureTimesHydrocarbonVolume_;