diff --git a/ApplicationCode/FileInterface/RifCaseRealizationParametersReader.cpp b/ApplicationCode/FileInterface/RifCaseRealizationParametersReader.cpp
index 97f3cd69b0..aba4c2f37d 100644
--- a/ApplicationCode/FileInterface/RifCaseRealizationParametersReader.cpp
+++ b/ApplicationCode/FileInterface/RifCaseRealizationParametersReader.cpp
@@ -32,27 +32,88 @@
 /// Constants
 //--------------------------------------------------------------------------------------------------
 #define PARAMETERS_FILE_NAME    "parameters.txt"
-
+#define RUNSPEC_FILE_NAME       "runspecification.xml"
 
 //--------------------------------------------------------------------------------------------------
 /// 
 //--------------------------------------------------------------------------------------------------
-RifCaseRealizationParametersReader::RifCaseRealizationParametersReader(const QString& fileName)
+RifCaseRealizationReader::RifCaseRealizationReader(const QString& fileName)
 {
     m_parameters = std::shared_ptr<RigCaseRealizationParameters>(new RigCaseRealizationParameters());
     m_fileName = fileName;
     m_file = nullptr;
-    m_textStream = nullptr;
 }
 
 //--------------------------------------------------------------------------------------------------
 /// 
 //--------------------------------------------------------------------------------------------------
-RifCaseRealizationParametersReader::RifCaseRealizationParametersReader()
+RifCaseRealizationReader::~RifCaseRealizationReader()
+{
+    closeFile();
+}
+
+//--------------------------------------------------------------------------------------------------
+/// 
+//--------------------------------------------------------------------------------------------------
+const std::shared_ptr<RigCaseRealizationParameters> RifCaseRealizationReader::parameters() const
+{
+    return m_parameters;
+}
+
+//--------------------------------------------------------------------------------------------------
+/// 
+//--------------------------------------------------------------------------------------------------
+std::shared_ptr<RifCaseRealizationReader> RifCaseRealizationReader::createReaderFromFileName(const QString& fileName)
+{
+    std::shared_ptr<RifCaseRealizationReader> reader;
+
+    if (fileName.endsWith(PARAMETERS_FILE_NAME))
+    {
+        reader.reset(new RifCaseRealizationParametersReader(fileName));
+    }
+    else if (fileName.endsWith(RUNSPEC_FILE_NAME))
+    {
+        reader.reset(new RifCaseRealizationRunspecificationReader(fileName));
+    }
+    return reader;
+}
+
+//--------------------------------------------------------------------------------------------------
+/// 
+//--------------------------------------------------------------------------------------------------
+QFile* RifCaseRealizationReader::openFile()
+{
+    if (!m_file)
+    {
+        m_file = new QFile(m_fileName);
+        if (!m_file->open(QIODevice::ReadOnly | QIODevice::Text))
+        {
+            closeFile();
+            throw FileParseException(QString("Failed to open %1").arg(m_fileName));
+        }
+    }
+    return m_file;
+}
+
+//--------------------------------------------------------------------------------------------------
+/// 
+//--------------------------------------------------------------------------------------------------
+void RifCaseRealizationReader::closeFile()
+{
+    if (m_file)
+    {
+        m_file->close();
+        delete m_file;
+        m_file = nullptr;
+    }
+}
+
+//--------------------------------------------------------------------------------------------------
+/// 
+//--------------------------------------------------------------------------------------------------
+RifCaseRealizationParametersReader::RifCaseRealizationParametersReader(const QString& fileName) :
+    RifCaseRealizationReader(fileName)
 {
-    m_parameters = std::shared_ptr<RigCaseRealizationParameters>(new RigCaseRealizationParameters());
-    m_fileName = "";
-    m_file = nullptr;
     m_textStream = nullptr;
 }
 
@@ -65,15 +126,6 @@ RifCaseRealizationParametersReader::~RifCaseRealizationParametersReader()
     {
         delete m_textStream;
     }
-    closeFile();
-}
-
-//--------------------------------------------------------------------------------------------------
-/// 
-//--------------------------------------------------------------------------------------------------
-void RifCaseRealizationParametersReader::setFileName(const QString& fileName)
-{
-    m_fileName = fileName;
 }
 
 //--------------------------------------------------------------------------------------------------
@@ -137,9 +189,9 @@ void RifCaseRealizationParametersReader::parse()
 //--------------------------------------------------------------------------------------------------
 QTextStream* RifCaseRealizationParametersReader::openDataStream()
 {
-    openFile();
+    auto file = openFile();
 
-    m_textStream = new QTextStream(m_file);
+    m_textStream = new QTextStream(file);
     return m_textStream;
 }
 
@@ -159,15 +211,81 @@ void RifCaseRealizationParametersReader::closeDataStream()
 //--------------------------------------------------------------------------------------------------
 /// 
 //--------------------------------------------------------------------------------------------------
-void RifCaseRealizationParametersReader::openFile()
+RifCaseRealizationRunspecificationReader::RifCaseRealizationRunspecificationReader(const QString& fileName) :
+    RifCaseRealizationReader(fileName)
 {
-    if (!m_file)
+    m_xmlStream = nullptr;
+}
+
+//--------------------------------------------------------------------------------------------------
+/// 
+//--------------------------------------------------------------------------------------------------
+RifCaseRealizationRunspecificationReader::~RifCaseRealizationRunspecificationReader()
+{
+    if (m_xmlStream)
     {
-        m_file = new QFile(m_fileName);
-        if (!m_file->open(QIODevice::ReadOnly | QIODevice::Text))
+        delete m_xmlStream;
+    }
+}
+
+//--------------------------------------------------------------------------------------------------
+/// 
+//--------------------------------------------------------------------------------------------------
+void RifCaseRealizationRunspecificationReader::parse()
+{
+    auto xml = openDataStream();
+    QString paramName;
+
+    while (!xml->atEnd())
+    {
+        xml->readNext();
+
+        if (xml->isStartElement())
         {
-            closeFile();
-            throw FileParseException(QString("Failed to open %1").arg(m_fileName));
+            if (xml->name() == "modifier")
+            {
+                paramName = "";
+            }
+
+            if (xml->name() == "id")
+            {
+                paramName = xml->readElementText();
+            }
+
+            if(xml->name() == "value")
+            {
+                QString paramStrValue = xml->readElementText();
+
+                if (paramName.isEmpty()) continue;
+
+                if (RiaStdStringTools::startsWithAlphabetic(paramStrValue.toStdString()))
+                {
+                    m_parameters->addParameter(paramName, paramStrValue);
+                }
+                else
+                {
+                    if (!RiaStdStringTools::isNumber(paramStrValue.toStdString(), QLocale::c().decimalPoint().toAscii()))
+                    {
+                        throw FileParseException(QString("RifEnsembleParametersReader: Invalid number format in line %1").arg(xml->lineNumber()));
+                    }
+
+                    bool parseOk = true;
+                    double value = QLocale::c().toDouble(paramStrValue, &parseOk);
+                    if (!parseOk)
+                    {
+                        throw FileParseException(QString("RifEnsembleParametersReader: Invalid number format in line %1").arg(xml->lineNumber()));
+                    }
+
+                    m_parameters->addParameter(paramName, value);
+                }
+            }
+        }
+        else if (xml->isEndElement())
+        {
+            if (xml->name() == "modifier")
+            {
+                paramName = "";
+            }
         }
     }
 }
@@ -175,22 +293,25 @@ void RifCaseRealizationParametersReader::openFile()
 //--------------------------------------------------------------------------------------------------
 /// 
 //--------------------------------------------------------------------------------------------------
-void RifCaseRealizationParametersReader::closeFile()
+QXmlStreamReader * RifCaseRealizationRunspecificationReader::openDataStream()
 {
-    if (m_file)
-    {
-        m_file->close();
-        delete m_file;
-        m_file = nullptr;
-    }
+    auto file = openFile();
+
+    m_xmlStream = new QXmlStreamReader(file);
+    return m_xmlStream;
 }
 
 //--------------------------------------------------------------------------------------------------
 /// 
 //--------------------------------------------------------------------------------------------------
-const std::shared_ptr<RigCaseRealizationParameters> RifCaseRealizationParametersReader::parameters() const
+void RifCaseRealizationRunspecificationReader::closeDataStream()
 {
-    return m_parameters;
+    if (m_xmlStream)
+    {
+        delete m_xmlStream;
+        m_xmlStream = nullptr;
+    }
+    closeFile();
 }
 
 //--------------------------------------------------------------------------------------------------
@@ -212,7 +333,8 @@ QString RifCaseRealizationParametersFileLocator::locate(const QString& modelPath
         QStringList files = qdir.entryList(QDir::Files | QDir::NoDotAndDotDot);
         for (const QString& file : files)
         {
-            if (QString::compare(file, PARAMETERS_FILE_NAME, Qt::CaseInsensitive) == 0)
+            if (QString::compare(file, PARAMETERS_FILE_NAME, Qt::CaseInsensitive) == 0 ||
+                QString::compare(file, RUNSPEC_FILE_NAME, Qt::CaseInsensitive) == 0)
             {
                 return qdir.absoluteFilePath(file);
             }
diff --git a/ApplicationCode/FileInterface/RifCaseRealizationParametersReader.h b/ApplicationCode/FileInterface/RifCaseRealizationParametersReader.h
index 549a0d9943..23080e8739 100644
--- a/ApplicationCode/FileInterface/RifCaseRealizationParametersReader.h
+++ b/ApplicationCode/FileInterface/RifCaseRealizationParametersReader.h
@@ -34,38 +34,76 @@
 
 class QStringList;
 class QTextStream;
+class QXmlStreamReader;
 class QFile;
 
 //==================================================================================================
 //
 //
 //==================================================================================================
-class RifCaseRealizationParametersReader
+class RifCaseRealizationReader
 {
 public:
-    RifCaseRealizationParametersReader();
-    RifCaseRealizationParametersReader(const QString& fileName);
-    ~RifCaseRealizationParametersReader();
+    RifCaseRealizationReader(const QString& fileName);
+    virtual ~RifCaseRealizationReader();
 
-    void                                                setFileName(const QString& fileName);
-    void                                                parse();
+    virtual void                                        parse() = 0;
     const std::shared_ptr<RigCaseRealizationParameters> parameters() const;
 
+    static std::shared_ptr<RifCaseRealizationReader>    createReaderFromFileName(const QString& fileName);
+
+protected:
+    QFile*                          openFile();
+    void                            closeFile();
+
+    std::shared_ptr<RigCaseRealizationParameters>  m_parameters;
+
+private:
+    QString                                 m_fileName;
+    QFile*                                  m_file;
+};
+
+//==================================================================================================
+//
+//
+//==================================================================================================
+class RifCaseRealizationParametersReader : public RifCaseRealizationReader
+{
+public:
+    RifCaseRealizationParametersReader(const QString& fileName);
+    virtual ~RifCaseRealizationParametersReader();
+
+    virtual void                    parse() override;
+
 private:
     QTextStream*                    openDataStream();
     void                            closeDataStream();
-    void                            openFile();
-    void                            closeFile();
 
 private:
-    std::shared_ptr<RigCaseRealizationParameters>  m_parameters;
-
-    QString                                 m_fileName;
-    QFile*                                  m_file;
-    QTextStream*                            m_textStream;
+    QTextStream*                    m_textStream;
 };
 
 
+//==================================================================================================
+//
+//
+//==================================================================================================
+class RifCaseRealizationRunspecificationReader : public RifCaseRealizationReader
+{
+public:
+    RifCaseRealizationRunspecificationReader(const QString& fileName);
+    virtual ~RifCaseRealizationRunspecificationReader();
+
+    virtual void                    parse() override;
+
+private:
+    QXmlStreamReader *              openDataStream();
+    void                            closeDataStream();
+
+private:
+    QXmlStreamReader*               m_xmlStream;
+};
+
 //==================================================================================================
 //
 //
diff --git a/ApplicationCode/ProjectDataModel/Summary/RimSummaryCaseMainCollection.cpp b/ApplicationCode/ProjectDataModel/Summary/RimSummaryCaseMainCollection.cpp
index c23fd8e89c..16fa6d3275 100644
--- a/ApplicationCode/ProjectDataModel/Summary/RimSummaryCaseMainCollection.cpp
+++ b/ApplicationCode/ProjectDataModel/Summary/RimSummaryCaseMainCollection.cpp
@@ -44,15 +44,17 @@ void addCaseRealizationParametersIfFound(RimSummaryCase& sumCase, const QString
     QString parametersFile = RifCaseRealizationParametersFileLocator::locate(modelFolderOrFile);
     if (!parametersFile.isEmpty())
     {
-        RifCaseRealizationParametersReader reader(parametersFile);
-
-        // Try parse case realization parameters
-        try
+        auto reader = RifCaseRealizationReader::createReaderFromFileName(parametersFile);
+        if (reader)
         {
-            reader.parse();
-            sumCase.setCaseRealizationParameters(reader.parameters());
+            // Try parse case realization parameters
+            try
+            {
+                reader->parse();
+                sumCase.setCaseRealizationParameters(reader->parameters());
+            }
+            catch (...) {}
         }
-        catch (...) {}
     }
 
 }