an object reference is required for the non-static field method or property 'page.request'

I am at the initial stage of learning ASP.NET Webforms as a beginner and I am working with this block of code where I need to invoke Request.QueryString from a static method. But I am not being able to do that and instead it throws a compilation error

This is my block of code

[System.Web.Services.WebMethod]
    public static string GetProductImgList(string ProductCode)
    {
        try
        {
            string ProductId = Request.QueryString["ID"].ToString(); //error
            string BatchId = Request.QueryString["Batch"].ToString();//error
            string UserId = Request.QueryString["UID"].ToString();//error

            dalOnlineShop objdalOnlineShop = new dalOnlineShop();
            DataTable dt = objdalOnlineShop.GetProductAllImgs(ProductCode);
            string ImgNames = "";
            for (int i = 0; i < dt.Rows.Count; i++)
            {
                if (dt.Rows.Count == i + 1)
                {
                    ImgNames += dt.Rows[i]["SmallImgPath"].ToString() + ",";
                    ImgNames += dt.Rows[i]["ImgPath"].ToString();
                }
                else
                {
                    ImgNames += dt.Rows[i]["SmallImgPath"].ToString() + ",";
                    ImgNames += dt.Rows[i]["ImgPath"].ToString() + ",";
                }
            }
            return ImgNames;
        }
        catch (Exception ex) { }
        return "";
    }