How to convert excel to datatable

private void copy_excel(string FullPath)
        {

            //Excel command
            string cmdText = "SELECT [COL1], [COL2], [COL3]" +
               " FROM [TABNAME$]";

            //Excel connection string
            string excelConnString = "provider=microsoft.jet.oledb.4.0;" +
                " Data Source=C:\temp\20151207.XLS ;Extended Properties=" +
                "\"Excel 8.0;IMEX=1;TypeGuessRows=0;ImportMixedTypes=Text\"";

            //Oracle Connection
            string oraConnString = Properties.Settings.Default.oraConn;
            OracleConnection oraConn = new OracleConnection(oraConnString);
            
            //OleDb Command using cmdText and Connection to read Excel
            OleDbConnection oleDbConn = new OleDbConnection(excelConnString);
            OleDbCommand oleDbCmd = new OleDbCommand(cmdText, oleDbConn);

            try
            {
                //open excel
                oleDbConn.Open();
                OleDbDataReader dr = oleDbCmd.ExecuteReader();
                DataTable dt = new DataTable();

                dt.Load(dr); //Load the excel we want to write to Oracle
                dr.Close();

                //Oracle Connection

                //instanciate cmd
                OracleCommand oraCmd = new OracleCommand();

                //Delete cmd
                oraCmd.CommandText = "DELETE FROM raw_data.excel_import";
                oraCmd.CommandType = CommandType.Text;
                oraCmd.Connection = oraConn;
                
	//Execute delete
                oraConn.Open();
                oraCmd.ExecuteNonQuery();      

                //BulkCopy data into Oracle
                using (OracleBulkCopy bulkCopy = new OracleBulkCopy(oraConn))
                {
                    bulkCopy.DestinationTableName = "raw_data.excel_import";
                    bulkCopy.WriteToServer(dt);
                }
            }
            catch (Exception ex)
            {
                //Write output file of failure
                string[] errOut = { "Error durring import of file " + FullPath, "Exception occured in " + ex.Source, "Exception: " + ex.Message };
                System.IO.File.WriteAllLines(FullPath.Replace(".xls", "Error.txt"), errOut);
            }
            finally
            {
                if (oraConn.State == ConnectionState.Open)
                {
                    oraConn.Close();
                }
                if (oleDbConn.State == ConnectionState.Open)
                {
                    oleDbConn.Close(); //Close excel connection
                }
                oraConn.Dispose();
                oleDbCmd.Dispose();
                oleDbConn.Dispose();        
            }
        }