using System;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        string data = "2017-02-15T00:00:02+01:00";

        //Regex101: https://regex101.com/r/HL7uMd/1

        string regex = @"(\d+\-\d+\-\d+)\w{1}(\d+\:\d+\:\d+)";

        var matches = Regex.Matches(data, regex, RegexOptions.Multiline);

        foreach(Match item in matches)

        {

            Console.WriteLine("field 1: " + item.Groups[1]);

            Console.WriteLine("field 2: " + item.Groups[2]);

        }

    }

}