<Window x:Class="OxyPlotAreaSeriesProbrem.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:OxyPlotAreaSeriesProbrem"
        xmlns:oxy="http://oxyplot.org/wpf"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="450">
    <Grid>
        <oxy:PlotView x:Name="ThisPlot" Background="Transparent">
        </oxy:PlotView>
    </Grid>
</Window>

using OxyPlot.Axes;
using OxyPlot.Series;
using OxyPlot;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace OxyPlotAreaSeriesProbrem
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();

            ThisPlot.Model = new PlotModel();
            ThisPlot.Model.PlotType = PlotType.Cartesian;
            ThisPlot.Model.Axes.Add(new LinearAxis { Position = AxisPosition.Bottom, MajorStep = 500.0, MinorStep = 500.0, MajorGridlineStyle = LineStyle.Solid, MajorGridlineColor = OxyColors.Gray, MajorGridlineThickness = 1 });
            ThisPlot.Model.Axes.Add(new LinearAxis { Position = AxisPosition.Left, MajorStep = 500.0, MinorStep = 500.0, MajorGridlineStyle = LineStyle.Solid, MajorGridlineColor = OxyColors.Gray, MajorGridlineThickness = 1 });
            
            var workOutlineSeries = new AreaSeries()
            {
                StrokeThickness = 4,
                LineStyle = LineStyle.Solid,
                Color = OxyColors.Red,
                Color2 = OxyColors.Transparent,
                Fill = OxyColors.LightPink,
                Selectable = false,
            };
            var sqearOutlineSeries = new AreaSeries()
            {
                StrokeThickness = 2,
                LineStyle = LineStyle.Solid,
                Color = OxyColors.LimeGreen,
                Color2 = OxyColors.Transparent,
                Fill = OxyColors.Transparent,
                Selectable = false,
            };
            DataPoint[] work = new DataPoint[]{
                new DataPoint(2254,2740),
                new DataPoint(5028,2873),
                new DataPoint(5709,986),
                new DataPoint(2751,1477),
                new DataPoint(2254,2740),
            };

            workOutlineSeries.Points.AddRange(work);

            DataPoint[] sqear = new DataPoint[]
            {
                new DataPoint (2254,986),
                new DataPoint (2254,2873),
                new DataPoint (5709,2873),
                new DataPoint (5709,986),
                new DataPoint (2254,986),
            };

            sqearOutlineSeries.Points.AddRange(sqear);

            ThisPlot.Model.Series.Add(workOutlineSeries);
            ThisPlot.Model.Series.Add(sqearOutlineSeries);

            ThisPlot.Model.ResetAllAxes();

            ThisPlot.Model.InvalidatePlot(true);
        }
    }
}